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Home My WebLink About3.1Item 3.1 TOWN OF LOS ALTOS HILLS April 5, 2012 Staff Report to the Planning Commission SUBJECT: INITIAL STUDY AND NEGATIVE DECLARATION FOR THE ARASTRADERO TRAIL IMPROVEMENT PROJECT FROM: Debbie Pedro, Planning Director RECOMMENDATION: That the Planning Commission: 1. Review and forward a recommendation that, based on the Initial Study, the City Council adopt the attached Mitigated Negative Declaration for the Arastradero Trail Improvement Project; and 2. Make a recommendation to the City Council on the design of the retaining wall along Arastradero Road. BACKGROUND The Arastradero Trail Improvement Project includes the restoration of existing pathways, construction of new pathways, and bike lane striping within the project area. The project area begins at the intersection of Arastradero Road and Purissima Road; continue along Arastradero Road under the I-280 freeway to Page Mill Road; continue along Page Mill Road to the intersection of Baleri Ranch Road/Arastradero Road; and ends at the Los Altos Hills Town boundary on Arastradero Road west of Tracy Court. The project site encompasses approximately one lineal mile and all improvements are located within existing Town of Los Altos Hills pedestrian and equestrian path easements and road Right -Of -Way. DISCUSSION At the December 1, 2011 study session, the Planning Commission directed staff to redesign the segment of the trail on Arastradero Road west of Stirrup Way where a 3'-10' retaining wall is proposed. The Commission directed staff to make the retaining wall as small as possible, and to reduce the road to its minimum legal width. The approximately 475 feet long retaining wall along Arastradero Road, originally proposed at 3' to 10' tall now has an average height of approximately 18". This is accomplished by reducing the vehicular travel lanes to a minimum width of 12' and reconfiguring/shifting the travel way to the north. The centerline of the travel way is held at the intersection of Arastradero Road and Stirrup Way due to the existing left turn pocket, but begins tapering to the north as we move west of Stirrup Way. Since the existing left turn pocket limits the ability to shift the vehicular travel way to the north, there is a 35 feet retaining wall section at the corner of Stirrup Way and Planning Commission Arastradero Trail Improvement Project April 5, 2012 Page 2 Arastradero Road with a height of 2.1' to 3.9', the next 120 feet wall section along Arastradero Road drops to a height of 1.2' to 2.4', and the remaining 320 feet section is between 0.5' to 1.2' high. The wall is necessary to retain a cut slope for the installation of the Town's. standard Type 2B path. The grading and retaining wall height is in conformance with the Town's Grading Policy. The retaining wall will be a cast in place concrete wall with the following possible architectural finishes: 1. Soil Nail Shotcrete Wall with Stone Facing; or: 2. Soil Nail Shotcrete Wall with Boulderscape (Faux Rock) Finish Landscape treatment including vines and small shrubs in front of the taller portions of the wall at the intersection of Stirrup Way could also be added to screen the structure because irrigation is available in the area. In addition to the retaining wall redesign, the project has undergone a number of modifications since it was first reviewed by the Commission in March 2011. The following table summarizes the key changes: Original opoProposal Pedestrian and equestrian bridge over Matadero No bridge proposed Creek near Baleri Ranch Road Convert existing off road path along Matadero Creek between Berry Hill Court and Baleri Existing off road path to remain a native path Ranch Road from native to Type IIB path Number of trees to be removed: 13 Number of trees to be removed: 11 New retaining wall along the south side of Arastradero Road, west of Stirrup Way with Retaining wall redesigned with an average heights ranging from 3 to 10 feet to height of approximately 18". accommodate the Type IIB roadside path. Painted crosswalk at Page Mill and Arastradero Painted crosswalk at Page Mill and Arastradero Road with flashing beacons or stop signs Road with in pavement flashing system Public Outreach Since March 2011, the Town has scheduled eight (8) public meetings and workshops to engage the public in the discussions and solicit feedback on the Arastradero Trail Improvement Project. A webpage on the Town's website was created in April 2011 to provide reports and updates on the project. An email list was also created so that in addition to the mailed hearing notices, interested parties can receive email notifications for the project. Planning Commission Arastradero Trail Improvement Project April 5, 2012 Page 3 Environmental Review In conformance with the California Environmental Quality Act (CEQA), an Initial Study/Mitigated Negative Declaration has been prepared for the project. Based on the analysis contained in the study, any potential significant impacts will be reduced to a less than significant level with mitigation. A detailed analysis of the potential impacts and mitigation measures are discussed in the Initial Study. (Attachment 1) As of this date, the Town has received six written comments from the public regarding the project. (Attachment 2) Previous staff reports containing additional background information about the project are included in attachment 3. ATTACHMENTS 1. Initial Study/Negative Declaration 2. Comments from the public received on March 29 and March 30, 2012 3. Planning Commission and City Council staff reports dated March 3, March 17, and December 1, 2011 4. Project plans Attachment 1 NOTICE Town of Los Altos Hills Mitigated Negative Declaration 29 Lead Agency: Town of Los Altos Hills Planning Department 26379 Fremont Road Los Altos Hills, CA 94022 Project Title: Arastradero Trail Improvement Project Location: Arastradero Road and Page Mill Road between Purissima Road and Baleri Ranch Road Project Description: The Arastradero Trail Improvement Project includes restoration of existing pathways, construction of new pathways, and bike lane striping within the project area. A retaining wall with an average height of approximately 1.5' is proposed along Arastradero Road to accommodate a walking path and edge widening for bike lane improvements. The improvements begin at the intersection of Arastradero Road and Purissima Roads; continue along Arastradero Road under the I-280 freeway to Page Mill Road; continue along Page Mill Road to the intersection of Baleri Ranch Road/Arastradero Road; and ends at the Los Altos Hills Town boundary on Arastradero Road west of Tracy Court. The trail alignment is located within existing Town of Los Altos Hills pedestrian and equestrian trail easements and road right-of-way. The project site encompasses approximately one lineal mile, incorporating existing trails and bike lanes where possible. Finding: Although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because the mitigation measures listed below have been added to the project, mitigating potential impacts to a less -than -significant level. An Environmental Impact Report will not be required. Mitigation Measures: 1. Aesthetics: None required. 2. Agriculture Resources: None required. 3. Air Quality: AIR -1 Bay Area Air Quality Management District (BAAQMD) dust control measures will be incorporated into Final Improvements Plans/Grading Plans and will be adhered to during construction for all improvements including the following. a. Water all active construction areas at least twice daily and more often during windy periods. b. Active areas adjacent to residences should be kept damp at all times. c. All trucks to maintain at least two feet of freeboard and all hauling trucks to be covered pursuant to governing agency requirements. Dust -proof chutes shall be used as appropriate to load debris onto trucks during demolition. d. Pave, apply water at least twice daily, or apply (non-toxic) soil stabilizers on all unpaved access roads, parking areas, and staging areas. e. Sweep as necessary (with water sweepers) all paved access roads, parking areas, and staging areas and sweep streets daily (with water sweepers) if visible soil material is deposited onto the adjacent roads. FEBRUARY, 2012 MITIGATED NEGATIVE DECLARATION — ARASTRADERO TRAIL IMPROVEMENT PROJECT f. Hydroseed or apply (non-toxic) soil stabilizers to inactive construction areas (i.e., previously graded areas that are inactive for 10 days or more). g. Enclose, cover, water twice daily, or apply (non-toxic) soil binders to exposed stockpiles. h. Limit traffic speeds on any unpaved roads to 15 mph. i. Replant vegetation in disturbed areas as quickly as possible. j. Suspend construction activities that cause visible dust plumes to extend beyond the construction site. k. The contractor shall install temporary electrical service eat the earliest period of the building phase to avoid the need for independently powered equipment (e.g. compressors). 1. Diesel equipment standing idle for more than five minutes shall be turned off. This would include trucks waiting to deliver or receive soil, aggregate, or other bulk materials. Rotating drum concrete trucks could keep their engines running continuously as long as they were onsite. 4. Biological Resources: BIO -1 All ground disturbance associated with trail building activities on site will be conducted during the dry season (April 15 — October 15). BIO -2 Staging areas and access routes to the work area will be delineated and inspected by the project biologist prior to establishment to avoid unnecessary impacts to California red -legged frogs and their habitat. BIO -3 Exclusion fencing will be erected around portions of the construction site adjacent to Matadero Creek and Deer Creek prior to the onset of project activities. Fencing will be a minimum of 3 feet in height and buried in the soil 4 to 6 inches to inhibit California red -legged frogs from entering the project area. BIO -4 Once the exclusion fence is installed, a pre -construction survey will be conducted to ensure that no California red -legged frogs are present in the project area. BIO -5 If California red -legged frogs are detected on site, the USFWS would be contacted for guidance on moving the animal(s) to a safe location. No CRF would be handled without permission from the USFWS. BIO -6 During project activities, all trash that may attract predators will be properly contained, removed from the work site and disposed of regularly. Following construction, all trash and construction debris will be removed from work areas. BIO -7 All practicable erosion control Best Management Practices (BMPs) will be implemented to minimize the potential of impacts to water quality of Matadero Creek and Deer Creek. BIO -8 No smoking except in vehicles will be permitted within vegetated areas. BIO -9 Trash dumping will be prohibited. BIO -10 Woodrat nests within 100 feet of ground disturbing activities shall be surveyed and monitored to determine if nests are active. FEBRUARY, 2012 2 MITIGATED NEGATIVE DECLARATION — ARASTRADERO TRAIL IMPROVEMENT PROJECT BIO -11 For woodrat nests that can be avoided, orange construction/ protective fencing will be placed between work areas and woodrat nests, and will include a 2 -foot buffer between the protective fencing and the nest. BIO -12 For woodrat nests that cannot be avoided, woodrat nests shall be dismantled by a qualified biologist. Dismantling will be conducted during the time of year that would least impact breeding woodrats (i.e. late fall/ winter: November/December/January). Dismantling will be conducted slowly to avoid impacting neonate woodrats. If woodrat neonates are detected in the nest, dismantling will cease and the nests will be checked every 48 hours to determine if the neonates are still present. Dismantling will continue once it is determined that the neonates are no longer present and have either been weaned from their mothers, or the mothers have moved them from the nest. BIO -13 DFG shall be consulted if any San Francisco dusky -footed woodrats (adults, subadults or neonates) are harmed by project activities. BIO -14 If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for nesting birds including raptors such as white-tailed kite and Cooper's hawk, shall be conducted by a qualified biologist within 300 feet of the construction area, where access is available, within two weeks prior to construction. BIO -15 If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical iso- activity buffer zones are 300 feet for active raptor nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. BIO -16 If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for migratory birds, shall be conducted by a qualified biologist. For migratory raptors including red-tailed hawk, surveys shall be conducted within 300 feet of the project area where access is available. For non -raptor migratory bird species, surveys shall be conducted within 100 feet of the project area, where access is available. Surveys for migratory birds shall be conducted within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. BIO -17 If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical iso- activity buffer zones are 300 feet for active raptor nests, and 100 feet for active migratory bird nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. BIO -18 To avoid impacts to roosting bats within the project area, including pallid bat and western red bat, pre -construction surveys for roosting bats shall be conducted by a qualified bat biologist within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. Any tree removal on site shall be done according to the recommendations of the qualified bat biologist. If active bat maternity roosts are detected (this season is typically between April and August) within tree that will be impacted by the project, the roost would need to be FEBRUARY, 2012 3 MITIGATED NEGATIVE DECLARATION — ARASTRADERO TRAIL IMPROVEMENT PROJECT avoided until all young are volant, and the Department of Fish and Game will be consulted for permission in the use of any bat exclusion devices. BI0-19 To avoid impacts to special status plant species, (San Francisco collinsia and western leatherwood), one or more preconstruction surveys shall be conducted by a qualified biologist prior to any ground disturbance and/or vegetation removal within the project area. The survey (s) should be timed to occur at the most suitable time of year (i.e. bloom period) to detect San Francisco collinsia and western leatherwood. BIO -20 If San Francisco collinsia and/or western leatherwood are identified within the project area, and one or more individual plants could potentially be impacted by project activities, the California Native Plant Society and the Department of Fish and Game will be consulted to develop appropriate mitigation measures. Mitigation measures may include seed/plant material collection, propagation and replanting in an appropriate restoration area(s). BIO -21 Under no circumstances shall spoils, gravel, paving materials or other construction materials or debris be placed, even temporarily, along or below the top of bank of the creek. BIO -22 Best Management Practices (BMPs) to prevent pollutants, construction materials or debris from entering the creek and storm drains shall be installed prior to the initiation of work and properly maintained. For further clarification refer to Hydrology and Water Quality Mitigation Measure HYD -5. BIO -23 The project proponent shall avoid planting ornamental species reported by the California Invasive Plant Council to have the potential to be invasive. Species on this list shall be prohibited from use in landscaping. 6e Cultural Resources: CUL -1 In the event that archaeological traces are encountered, all construction within a 50 -meter radius of the find will be halted, the Planning Director will be notified, and an archaeologist will be retained to examine the find and make appropriate recommendations. CUL - 2If human remains are discovered, the Santa Clara County Coroner will be notified. The Coroner will determine whether or not the remains are Native American. If the Coroner determines that the remains are not subject to his authority, he will notify the Native American Heritage Commission, who shall attempt to identify descendants of the deceased Native Americans. CUL - 3If the Planning Director finds that the archaeological find is not a significant resource, work will resume only after the submittal of a preliminary archaeological report and after provisions for reburial and ongoing monitoring are accepted. Provisions for identifying descendants of a deceased Native American and for reburial will follow the protocol set forth in CEQA Guidelines Section 15064.5(e). If the site is found to be a significant archaeological site, a mitigation program will be prepared and submitted to the Community Development Director for consideration and approval, in conformance with the protocol set forth in Public Resources Code Section 21083.2. CUL 4 A final report shall be prepared when a find is determined to be a significant archaeological site, and/or when Native American remains are found on the site. The final report will include background information on the completed work, a description and list of identified resources, the FEBRUARY, 2012 4 MITIGATED NEGATIVE DECLARATION - ARASTRADERO TRAIL IMPROVEMENT PROJECT disposition and curation of these resources, any testing, other recovered information, and conclusions. 7. Geology and Soils: GEO — 1 The applicant shall incorporate all recommendations listed by Cornerstone Earth Group in Sections 6.0 through 9.0 of the draft Geotechnical Investigation for the project dated December 2, 2011 for; earthwork, retaining walls, and pedestrian pavements. The applicant shall retain the services of Cornerstone Earth Group to review the geotechnical aspects of the project structural, civil, and landscape plans and specifications, allowing sufficient time to provide the design team with any comments prior to issuing the plans for construction. GEO — 2 Cornerstone Earth Group shall be retained by the applicant to conduct geotechnical observation and testing during earthwork and foundation construction stages. GEO -3 Cornerstone Earth Group shall prepare a letter at the end of construction regarding contractor compliance with project plans and specifications, and with the recommendations of the Geotechnical Investigation dated December 2, 2011 and shall submit the letter to the Town Public Works Director. 8. Greenhouse Gases: Refer to Air Quality Mitigation Measure AIR -la. through if 9. Hazards and Hazardous Materials: None required. 10. Hydrology and Water Quality: HYD — 1 Erosion and sedimentation control measures, such as silt fencing and use of straw wattles, shall be implemented during and after construction. HYD — 2 Prepare a Storm Water Pollution Prevention Plan (SWPPP) incorporating the following Best Management Practices (BMPs) into grading and construction plans to prevent inadvertent discharge of materials into Matadero Creek in compliance with the National Pollutant Discharge Elimination System (NPDES) permit. a. The contractor will identify and implement specific procedures for the handling and containment of hazardous materials. This will include establishing dedicated fueling and maintenance areas for construction vehicles and equipment (including small equipment such as chainsaws), which will be located at least 65 feet from any drainage, riparian habitat or water body. Fueling must be performed on level ground. b. The contractor will identify and implement as appropriate specific procedures for handling and containment of hazardous materials. These will include catch basins for refueling and having absorbent pads on hand to respond to accidental spills. c. Absorbent spill clean-up materials and spill kits shall be available in fueling areas and on fueling trucks and shall be disposed of properly after use. d. Drip pans or absorbent pads shall be used during vehicle and equipment fueling, unless the fueling is performed over an impermeable surface in a dedicated fueling area. e. Fuel tanks shall not be "topped -off' f. Vehicles and equipment shall be inspected on each day for evidence of leaks. Leaks shall be repaired immediately or problem vehicles or equipment shall be removed from the project site. g. Absorbent spill clean-up materials shall be available in fueling and maintenance areas and FEBRUARY, 2012 MITIGATED NEGATIVE DECLARATION — ARASTRADERO TRAIL IMPROVEMENT PROJECT used on small spills instead of hosing down or burying techniques. The spent absorbent material shall be removed promptly and disposed of properly. HYD — 3 The construction plans shall clearly identify all proposed fueling, cleaning or maintenance areas in accordance with the following: h. No fueling, cleaning, or maintenance of vehicles or equipment shall take place within the riparian corridor to avoid the release of deleterious substances into surface waters. i. During construction, there will be no use of pesticides for maintenance, or dumping of waste or refuse. j. Equipment cleaning and temporary concrete washout area shall comply with the following: i. Location of temporary concrete washout facilities will be identified at least 24 hours prior to a scheduled pour. ii. Temporary concrete washout facilities, cleaning stations, and staging areas shall be located on level ground at least 200 feet from channel banks. Each facility shall be located away from construction traffic or access areas to prevent disturbance or tracking. iii. Temporary concrete washout. facilities shall be constructed and maintained to sufficiently maintain all liquid and concrete wastes generated by washout operations. iv. Once concrete wastes are washed into the designated area and allowed to harden, the concrete shall be broken up, removed and properly disposed of 11. Land Use and Planning: None required. 12. Mineral Resources: None required. 13. Noise: None required. 14. Population and Housing: None required. 15. Public Services: None required. 16. Recreation: None required. 17. Transportation and Traffic: None required. 18. Utilities and Service Systems: None required. Copies of the Initial Study used to make the above recommendation are on file and available for public inspection during regular business hours at the Town Planning Department, 26379 Fremont Road, Los Altos, California. Date Debbie Pedro, AICP, Planning Director FEBRUARY, 2012 REVISED DRAFT INITIAL STUDY ARASTRADER0 TRAIL IMPROVEMENT PROJECT LOS ALTOS HILLS, CALIFORNIA TRAIL AND BIKE LANE IMPROVEMENTS AT ARASTRADERO AND PAGE MILL ROADS PREPARED FOR TOWN OF LOS ALTOS HILLS PLANNING DEPARTMENT 26379 FREMONT ROAD Los ALTOS HILLS, CA 94022 FEBRUARY 2012 METROPOLITAN PLANNING GROUP, INC. 579 CLYDE AvENuE #340 MOUNTAIN VIEw, CA 94043 (650) 938-1111 FEBRUARY, 2012 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT REVISIONS TO THE DRAFT INITIAL STUDY OF FEBRUARY 17, 2011 This document is an updated version of an Initial Study that was circulated between February 17, 2011 and March 17, 2011 for the Arastradero Trail Improvement project. The project was reviewed by the Planning Commission at a public hearing on March 3, 2011 and by the Town Council at a public hearing on March 17, 2011. The Town received a number of comments from private parties regarding the project. Subsequent to circulation of the Initial Study several traffic analysis were conducted and a geotechnical report was prepared. The project has also been modified to omit a proposed pedestrian bridge across Matadero Creek, omit the pedestrian trail improvements adjacent to Matadero Creek, to remove two additional eucalyptus trees along Arastradero Road, and to reduce the height of a proposed retaining wall along Arastradero Road. This Initial Study revises the original Initial Study to address comments, reflect changes to the proposed project and provide additional information resulting from additional traffic analyses and geotechnical report. These revisions include: • An expanded discussion of Aesthetics Issues. • Inclusion of updated Bay Area Air Quality Management District dust control measures adopted subsequent to circulation of this Initial Study. • An expanded discussion of Geology and Soils Issues. • Addition of three new mitigation measures pertaining to geotechnical conditions for construction of the retaining wall. • Deletion of references to the proposed pedestrian bridge across Matadero Creek and mitigation measures pertaining to the bridge construction. • Modification of references to the proposed retaining wall along Arastradero Road • Modification of references to tree removal • Deletion of a native soil surface trail along Arastradero Road • An expanded discussion of Traffic Issues. FEBRUARY, 2012 2 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT TOWN OF LOS ALTOS HILLS PLANNING DEPARTMENT ENVIRONMENTAL CHECKLIST FORM PROJECT INFORMATION PROJECT TITLE: Arastradero Trail Improvement Project LEAD AGENCY NAME AND ADDRESS: Town of Los Altos Hills Planning Department 26379 Fremont Road Los Altos Hills, CA 94022 PROPERTY OWNER: Various GENERAL PLAN DESIGNATION: Residential and Open Space Conservation Area PROJECT DESCRIPTION PROJECT LOCATION: Arastradero Road and Page Mill Road between Purissima Road and Baleri Ranch Road (Figure 1) CONTACT PERSON AND PHONE NUMBER: Debbie Pedro AICP, LEED AP Planning Director Town of Los Altos Hills (650) 947-2517 PROJECT APPLICANT: Town of Los Altos Hills ZONING: Residential -Agriculture (R -A) The Arastradero Trail Improvement Project includes restoration of existing pathways, construction of new pathways, and bike lane striping within the project area. A retaining wall with an average height of approximately 1.5' is proposed along Arastradero Road to accommodate a walking path and edge widening for bike lane improvements. A free -span pedestrian bridge across Matadero Creek had previously been proposed as part of the trail improvements, but is no longer a part of the proposed project. The improvements begin at the intersection of Arastradero Road and Purissima Roads; continue along Arastradero Road under the I-280 freeway to Page Mill Road; continue along Page Mill Road to the intersection of Baleri Ranch Road/Arastradero Road; and ends at the Los Altos Hills Town boundary on Arastradero Road west of Tracy Court. The trail alignment is located within existing Town of Los Altos Hills pedestrian and equestrian trail easements and road right-of-way. The project site encompasses approximately one lineal mile, incorporating existing trails and bike lanes where possible. The proposed trails will be constructed consistent with the Town's Type 2B Roadside Path requirements, including: • 5 -feet width with 2 -feet wide shoulders where possible Surface: 6 -inches of Stevens Creek Quarry Crusher Fines 2 -inch x 6 -inch wood headers along trail edges where necessary The bike lanes will be striped on existing asphaltic concrete ("AC") paved roadways. In some areas the existing AC surface will require edge widening to accommodate the bike lanes. The bike lanes on FEBRUARY, 2012 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Arastradero from Purissima to Page Mill Road, and on Page Mill to Berry Hill Court will be constructed in a Class II configuration (separate, striped lanes in both directions). On Page Mill between Berry Hill and Baleri Ranch Road, the bike lanes will be Class III (bikes merge with vehicular traffic in both directions). Appropriate striping and signage will be included throughout the Project. The Project includes an approximately 475 -foot -long, concrete retaining wall (varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way) on the south side of Arastradero Road, west of Stirrup Way. The wall is necessary to support cut slopes to allow for pathway installation and edge widening needed to accommodate the new bike lane. The retaining wall is designed as a cast -in-place concrete wall with an architectural finish. There will be a Type 2B roadside path at the base of the wall. Intersection safety improvements and restriping at the Page Mill Road/Baleri Ranch-Arastradero (including in -pavement lighting at the crosswalk), Page Mill Road/Berry Hill Court, and Arastradero Road/Stirrup Way intersections will be completed to accommodate pedestrians. Eleven trees (consisting of six eucalyptus and five Coast live oaks) will require removal to accommodate project construction. They include six Eucalyptus trees on the west side of Arastradero (east of Page Mill Road) to accommodate the eastbound bike lanes; five Coast live oaks less than 12" in trunk diameter, including three along Arastradero Road at Stirrup Way to accommodate the new retaining wall and bike lane. BACKGROUND In February 2006, the Board of Trustees of Leland Stanford Junior University and the County of Santa Clara entered into an Agreement for Trail Easements, Construction, Management and Maintenance and Grant of Trail Easements. This Trail Agreement obligated Stanford to offer to fund improvements to an existing trail within the Town of Los Altos Hills, identified as the C-2 Trail in the Santa Clara Countywide Trails Master Plan. PURPOSE OF THE PROJECT The purpose of the project is to provide a safe and convenient pedestrian/bicycle connection between the residential neighborhoods to the north and south of I-280. The proposed trail connection would improve the network of pedestrian and bike facilities, providing additional opportunities for recreation. The proposed project is consistent with the Town of Los Altos Hills General Plan Pathways Element (2008) and Open Space and Recreation Element (2007). The proposed project will be designed and constructed in compliance with the Town of Los Altos Hills Municipal Code. The project is designed to accommodate non -motorized modes of travel, including biking, horseback riding, jogging, hiking and walking. VEGETATION REMOVAL. The vegetation within the proposed walking path alignment consists primarily of California Annual Grassland, Central Coast Riparian Scrub and suburban forest. The project includes the removal of eleven trees. Minor tree trimming and removal of low-lying vegetation may also be required to accommodate the proposed walking path and bike lanes. As described in the Biological Resources section, potential impacts to regulated waters, special status species and special status communities resulting from project construction activities can be avoided or mitigated to a less than significant level. Santa Clara Valley Water Resources Protection Collaborative Guidelines and Standards for Land Uses Near Streams will be implemented to further minimize impacts to water quality, wildlife, and vegetation. FEBRUARY, 2012 4 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT GRADING AND DRAINAGE Substantial grading will not be required to construct the proposed project. A moderate amount of cut will be required for construction of the retaining wall along Arastradero Road to accommodate a walking path and new bike lane. CONSTRUCTION INFORMATION All construction work and equipment staging would occur within Los Altos Hills, Cal Trans, and Santa Clara County road right-of-way, or Town easements. 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Ids Project area 141 .. - .ice �w..'tfsw +� - -�- �'.�-Y �.V 1 � �• A- C; �'� New path sections , (z, Ora Zi Or lie, �v1 1-11- ro ,/`r,�Jfls H'ttVJ '��5 , .nr ` .}J.'al� ' F•, 1?� -7 - ) '✓ a=1- A • ., �, �, .� ate, �� f• r`� ��+ �, Y� � 1� '��'��z'_' PEDESTRIAN, EQUESTRIAN, AND BICYCLE SAFETY IMPROVEMENTS Repair/restoration of existing pathways Construction of new pathways • Bike lanes striping and road widening REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT SURROUNDING LAND USES AND SETTING The project site is comprised of approximately one linear mile of trail and bicycle path improvements located off Page Mill Road and Arastradero Road near the intersection with the I-280 freeway. The project site is currently developed with asphaltic concrete (AC) road surfaces, existing bike lanes and both improved and unimproved trails along the length of the project site. The site is surrounded by residential development, property owned by Santa Clara Valley Water District north of Baleri Ranch Road, Caltrans right of way and a Park and Ride lot at the intersection of Arastradero and Page Mill Roads (Santa Clara County maintained), and the I-280 freeway. OTHER AGENCIES WHOSE APPROVAL IS REQUIRED (e.g. permits, financing approval, or participation agreement) Removal of trees within the County road right-of-way would be subject to requirements of the Santa Clara County Department of Roads and Airports for tree removal. Construction of the bike lanes would require an encroachment permit from the Santa Clara County Department of Roads and Airports, and Caltrans District 4. USE OF THE INITIAL STUDY This Initial Study will be used to obtain a Mitigated Negative Declaration (MND) for the project, which determines that with the implementation of the mitigation measures identified, that the project would not have a significant effect on the environment. ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED: The environmental factors checked below would be potentially affected by this project, involving at least one impact that is a "Potentially Significant Impact" as indicated by the checklist on the following pages: FEBRUARY, 2012 Aesthetics Agriculture Resources X Air Quality X Biological Resources X Cultural Resources X Geology/Soils X Greenhouse Gases Hazards & Hazardous Materials Hydrology/Water Quality Land Use/Planning Mineral Resources Noise Population/Housing Public Services Recreation Transportation/Traffic Utilities/Service Systems Mandatory Findings of Significance FEBRUARY, 2012 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT DETERMINATION° (TO BE COMPLETED BY THE LEAD AGENCY) On the basis of this initial evaluation: Debbie Pedro AICP, LEED AP, Planning Director, Los Altos Hills Date FEBRUARY, 2012 I fmd that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared. X I find that although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because revisions in the project have been made by or agreed to by the project proponent. A MITIGATED NEGATIVE DECLARATION will be prepared. I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required. I find that the proposed project MAY have a "potentially significant impact" or "potentially significant unless mitigated" impact on the environment, but at least one effect 1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and 2) has been addressed by mitigation measures based on the earlier analysis as described on attached sheets. An ENVIRONMENTAL IMPACT REPORT is required, but it must analyze only the effects that remain to be addressed. I find that although the proposed project could have a significant effect on the environment, because all potentially significant effects (a) have been analyzed adequately in an earlier EIR or NEGATIVE DECLARATION pursuant to applicable standards, and (b) have been avoided or mitigated pursuant to that earlier EIR or NEGATIVE DECLARATION, including revisions or mitigation measures that are imposed upon the proposed project, nothing further is required. Debbie Pedro AICP, LEED AP, Planning Director, Los Altos Hills Date FEBRUARY, 2012 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT EVALUATION OF ENVIRONMENTAL IMPACTS Issues: DISCUSSION: The project entails development of trails and bike lanes with associated site improvements including an approximately 475 foot long retaining wall (varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way) located within existing Town pedestrian and equestrian trail easements. A previously proposed free -span pedestrian bridge across Matadero Creek has been eliminated from the proposed project. Several trees would be removed from the area south of Arastradero Road to accommodate the retaining wall and bike lane improvements. These trees include six Eucalyptus trees, and five Coast live oak trees. None of the trees proposed for removal are considered heritage oak tree as defined by Town Municipal Code regulations. Six large eucalyptus trees that are visible from I-280 would be removed. However these trees are not protected by Town Code regulations and are not visually prominent or distinctive trees. Two of these eucalyptus trees, identified as tree #21 and #22, appear to straddle the Town and County boundary line and may be subject to County tree removal requirements. Three young coast live oak trees, in the vicinity of two of the eucalyptus trees #21 and #22, have recently been planted and appear to have established themselves. Five Coast live oak trees are proposed for removal, including three near the intersection of Stirrup way to accommodate the proposed retaining wall. The project proposes nine new 5 -gallon Coast live oak trees to be planted in the vicinity of Stirrup Way to enhance the area. Over the next several years these oak trees will mature and contribute to the aesthetic quality of this stretch of roadway. The majority of trees in the project site would remain. The proposed project would not have a substantial adverse effect on a scenic vista or scenic resources. While the site is visible from adjacent residences and roadways the project site is not located in a scenic corridor, or part of a broader scenic vista widely visible from a public vantage point. The introduction of project improvements would not be considered a substantial degradation of the visual character of the site. The improvements will be visually consistent with the existing natural and man-made features of the corridor. FEBRUARY, 2012 10 Potentially Significant Impact Unless Less Than Issues (and Supporting Information Sources) Potentially Mitigation Significant No Significant Incorporated Impact Impact Impact 1. Aesthetics - Would the project: a) Have a substantial adverse effect on a scenic vista? X b) Substantially damage scenic resources, including, but not X limited to, trees, rock outcroppings, and historic buildings within a state scenic highway? c) Substantially degrade the existing visual character or X quality of the site and its surroundings? d) Create a new source of substantial light or glare which X would adversely affect day or nighttime views in the area? DISCUSSION: The project entails development of trails and bike lanes with associated site improvements including an approximately 475 foot long retaining wall (varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way) located within existing Town pedestrian and equestrian trail easements. A previously proposed free -span pedestrian bridge across Matadero Creek has been eliminated from the proposed project. Several trees would be removed from the area south of Arastradero Road to accommodate the retaining wall and bike lane improvements. These trees include six Eucalyptus trees, and five Coast live oak trees. None of the trees proposed for removal are considered heritage oak tree as defined by Town Municipal Code regulations. Six large eucalyptus trees that are visible from I-280 would be removed. However these trees are not protected by Town Code regulations and are not visually prominent or distinctive trees. Two of these eucalyptus trees, identified as tree #21 and #22, appear to straddle the Town and County boundary line and may be subject to County tree removal requirements. Three young coast live oak trees, in the vicinity of two of the eucalyptus trees #21 and #22, have recently been planted and appear to have established themselves. Five Coast live oak trees are proposed for removal, including three near the intersection of Stirrup way to accommodate the proposed retaining wall. The project proposes nine new 5 -gallon Coast live oak trees to be planted in the vicinity of Stirrup Way to enhance the area. Over the next several years these oak trees will mature and contribute to the aesthetic quality of this stretch of roadway. The majority of trees in the project site would remain. The proposed project would not have a substantial adverse effect on a scenic vista or scenic resources. While the site is visible from adjacent residences and roadways the project site is not located in a scenic corridor, or part of a broader scenic vista widely visible from a public vantage point. The introduction of project improvements would not be considered a substantial degradation of the visual character of the site. The improvements will be visually consistent with the existing natural and man-made features of the corridor. FEBRUARY, 2012 10 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT The proposed retaining wall will change the existing visual character of the hillside adjacent to Arastradero Road at I-280, however the average height is approximately 1.5 feet therefore the impact is considered less -than -significant. Removal of trees within the project site area will not substantially increase visibility of the adjacent roadways from neighboring residences or other vantage points, nor will it significantly degrade the existing vegetative screening. The vegetation along Matadero Creek will remain largely undisturbed. An additional tree near the stop sign at Baleri Ranch road will be relocated to improve the safety of the intersection, and three Coast Live Oak trees at Stirrup Way will be removed to accommodate the proposed retaining wall. None of the trees are Heritage Oak trees as defined by the Town Municipal Code, or are of a significant size to warrant an environmental impact. The project proponent has proposed planting nine new Coast live oak trees as replacement for several small oak trees that will be removed in the project area, while there is no significant impact associated with the removal of these trees, planting of new oak trees will further reduce the visual impacts of the tree removals over the long term. As proposed the project meets all Town Municipal Code requirements for construction and is in conformance with all General Plan policies. The project would have a less than significant impact and would not substantially degrade the existing visual character of the site or surroundings. MITIGATION: None required. DISCUSSION The project site is within an existing urban area zoned for residential and related uses. The site is not classified a prime farmland, under Williamson Act contract, or designated as forest land. The project site area is not presently utilized for any agricultural purposes. Development of the proposed project would cause no impact to agricultural resources. MITIGATION: None required. FEBRUARY, 2012 11 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 2. Agriculture Resources - Would the project: a) Convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and X Monitoring Program of the California Resources Agency, to non-agricultural use? b) Conflict with existing zoning for agricultural use, or a X Williamson Act contract? c) Involve other changes in the existing environment which, X due to their location or nature, could result in conversion of Farmland, to non-agricultural use? DISCUSSION The project site is within an existing urban area zoned for residential and related uses. The site is not classified a prime farmland, under Williamson Act contract, or designated as forest land. The project site area is not presently utilized for any agricultural purposes. Development of the proposed project would cause no impact to agricultural resources. MITIGATION: None required. FEBRUARY, 2012 11 REVISED INITIAL STUDY —ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The project entails development of trails and bike lanes with associated site improvements including an approximately 475 foot long retaining wall (varying in height from varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way) located within existing Town pedestrian and equestrian trail easements. A previously proposed free -span pedestrian bridge across Matadero Creek had has been removed from the scope of the project. Project construction and grading activities would generate short-term emissions of criteria pollutants, including suspended and inhalable particulate matter (airborne dust) and equipment exhaust emissions and could be considered a potentially significant impact to neighboring residences and construction workers on a temporary and localized basis. Standard dust control measures, as stipulated by the Air Quality Management District (BAAQMD), will be used which will ensure that any air quality impacts remain insignificant. Therefore the impact of grading activities on air quality or sensitive receptors for the proposed improvements would be considered potentially significant impact and the following mitigation measures will be required. MITIGATION: AIR -1 Bay Area Air Quality Management District (BAAQMD) dust control measures will be incorporated into Final Improvements Plans/Grading Plans and will be adhered to during construction for all improvements including the following. a. Water all active construction areas at least twice daily and more often during windy periods. b. Active areas adjacent to residences should be kept damp at all times. c. All trucks to maintain at least two feet of freeboard and all hauling trucks to be covered pursuant to governing agency requirements. Dust -proof chutes shall be used as appropriate to load debris onto trucks during demolition. FEBRUARY, 2012 12 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 3. Air Quality - Would the project: a) Conflict with or obstruct implementation of the applicable X air quality plan? b) Violate any air quality standard or contribute substantially X to an existing or projected air quality violation? c) Result in a cumulatively considerable net increase of any X criteria pollutant for which the project region is non - attainment under an applicable federal or state ambient air quality standard (including releasing emissions, which exceed quantitative thresholds for ozone precursors)? d) Expose sensitive receptors to substantial pollutant X concentrations? e) Create objectionable odors affecting a substantial number X of people? DISCUSSION The project entails development of trails and bike lanes with associated site improvements including an approximately 475 foot long retaining wall (varying in height from varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way) located within existing Town pedestrian and equestrian trail easements. A previously proposed free -span pedestrian bridge across Matadero Creek had has been removed from the scope of the project. Project construction and grading activities would generate short-term emissions of criteria pollutants, including suspended and inhalable particulate matter (airborne dust) and equipment exhaust emissions and could be considered a potentially significant impact to neighboring residences and construction workers on a temporary and localized basis. Standard dust control measures, as stipulated by the Air Quality Management District (BAAQMD), will be used which will ensure that any air quality impacts remain insignificant. Therefore the impact of grading activities on air quality or sensitive receptors for the proposed improvements would be considered potentially significant impact and the following mitigation measures will be required. MITIGATION: AIR -1 Bay Area Air Quality Management District (BAAQMD) dust control measures will be incorporated into Final Improvements Plans/Grading Plans and will be adhered to during construction for all improvements including the following. a. Water all active construction areas at least twice daily and more often during windy periods. b. Active areas adjacent to residences should be kept damp at all times. c. All trucks to maintain at least two feet of freeboard and all hauling trucks to be covered pursuant to governing agency requirements. Dust -proof chutes shall be used as appropriate to load debris onto trucks during demolition. FEBRUARY, 2012 12 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT d. Pave, apply water at least twice daily, or apply (non-toxic) soil stabilizers on all unpaved access roads, parking areas, and staging areas. e. Sweep as necessary (with water sweepers) all paved access roads, parking areas, and staging areas and sweep streets daily (with water sweepers) if visible soil material is deposited onto the adjacent roads. f. Hydroseed or apply (non-toxic) soil stabilizers to inactive construction areas (i.e., previously graded areas that are inactive for 10 days or more). g. Enclose, cover, water twice daily, or apply (non-toxic) soil binders to exposed stockpiles. h. Limit traffic speeds on any unpaved roads to 15 mph. i. Replant vegetation in disturbed areas as quickly as possible. j. Suspend construction activities that cause visible dust plumes to extend beyond the construction site. k. The contractor shall install temporary electrical service eat the earliest period of the building phase to avoid the need for independently powered equipment (e.g. compressors). 1. Diesel equipment standing idle for more than five minutes shall be turned off. This would include trucks waiting to deliver or receive soil, aggregate, or other bulk materials. Rotating drum concrete trucks could keep their engines running continuously as long as they were onsite. FEBRUARY, 2012 13 Potentially Issues (and Supporting Information Sources) SignificantPotentially Impact Unless Less Than Significant Mitigation Significant No Im act Inco orated hn act Impact 4. Biological Resources - Would the project: a) Have a substantial adverse effect, either directly or through X habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? b) Have a substantial adverse effect on any riparian habitat or X other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? c) Have a substantial adverse effect on federally protected X wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? d) Interfere substantially with the movement of any native X resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? FEBRUARY, 2012 13 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Issues (and Supporting Information Sources) Potentially Significant Impact Potentially Significant Impact Unless Mitigation Incorporated Less Than Significant Impact No Impact e) Conflict with any local policies or ordinances protecting X biological resources, such as a tree preservation policy or ordinance? f) Conflict with the provisions of an adopted Habitat X Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan? DISCUSSION The project area is located within the Town of Los Altos Hills and borders Page Mill Road and Arastradero Road. The trail alignment is bordered by existing roadways, open lots, residential properties and Matadero Creek along its western section. The trail alignment parallels Arastradero Road and Highway 280 on the east, and Page Mill Road and Matadero Creek on the west. The Town is located in the foothills on the eastern flank of the Santa Cruz Mountains, and consists of flat to moderately steep topography. Annual rainfall for the Town of Los Altos Hills averages 13.5 inches per year. The most prominent water feature in the vicinity of the project is Matadero Creek. Matadero Creek is a perennial creek that emanates from the foothills to the west and flows through the Town of Los Altos Hills and the City of Palo Alto before entering San Francisco Bay. Other water bodies in the area include Felt Lake which is located approximately 0.9 miles northwest of the trail alignment and Deer Creek, a perennial creek that crosses under the trail alignment on the east side of the I-280 Freeway. There are no other ponds, streams or other wetland habitats located within the project area. A 350 -foot section of the trail follows an existing trail along Matadero. The trail alignment was surveyed for biological resources on November 29 and December 7, 2010 by Coast Ridge Ecology (Attachment 1 Biological Resources Assessment). All plant and animal species encountered on site were documented as well as plant communities and habitat types that could support special status species. PLANT COMMUNITIES AND HABITATS Vegetation Vegetation within the trail alignment project area includes Grassland (California Annual Grassland Series); Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance), and suburban forest that is associated with residential properties that border the trail alignment (Sawyer 2009). The project area also includes several planted roadside trees, most of which will not be impacted by the project. Grassland habitat within the project area is primarily annual grassland. Annual grassland is dominated by nonnative Mediterranean annual grasses and an assemblage of non-native forbs. Scattered oak species are also present. This vegetation type is the most dominant plant community along the trail alignment. Most of the trailside areas have been heavily disturbed as result of past road building, and vegetation consists of nonnative plant species that colonize disturbed habitats. Species observed include annual grasses such as wild oat (Avena barbata), Italian wildrye (Lolium multiorum), and herbaceous weeds such as black FEBRUARY, 2012 14 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT mustard (Brassica nigra), cut -leaf geranium (Geranium dissectum) and bristly ox -tongue (Picris echioides). Central Coast Riparian Scrub consisting of shining willow (Salix lucida ssp. lasiandra), arroyo willow (Salix lasiolepis) and black walnut (Juglans californica var. hindsii) is present within Matadero Creek along the trail alignment. This habitat type is dominated by native tree species and a predominately nonnative shrub understory that includes Himalaya blackberry (Rubus discolor) and poison hemlock (Conium maculatum). Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance) is considered a rare plant community (CDFG 2006). Suburban forest includes ornamental vegetation as well as remnant native trees such as valley oak (Quercus lobata). Roadside trees that will require removal as part of the project include: Six Eucalyptus trees on the west side of Arastradero Road, east of Page Mill Road to accommodate the eastbound bike lanes; five Coast live oak trees to accommodate the new retaining wall. Two of the six eucalyptus trees proposed for removal, identified as tree #21 and #22, appear to straddle the Town and County boundary line and may be subject to County tree removal requirements. There are no wetland habitats within the project alignment. One wetland feature borders the eastern portion of the alignment. This is a narrow drainage swale on the west side of Arastradero Drive. The drainage is approximately 700 feet long and extends along Arastradero Drive between Stirrup Way on the north and Twin Oaks Court on the south. The dominant plant species within the swale is field mustard (Brassica rapa), an upland species. No wetland vegetation was observed within the swale, and approximately 50% of the length of the swale is contained in a concrete v -ditch. To meet the US Army Corps of Engineers (ACOE) definition of wetland, an area must demonstrate three critical characteristics: wetland vegetation, wetland hydrology, and wetland soils (Federal Interagency Committee for Wetland Delineation, 1989). Additionally, to fall under jurisdiction of the ACOE, a wetland must have some evident hydrological connection to other wetlands and/or waters of the United States. The US Fish and Wildlife Service definition of wetland is similar: at least periodically, the land must support predominantly hydrophytes; the substrate must be predominantly undrained hydric soil; or the substrate is non -soil that is saturated with water or covered by shallow water at some time during the growing season of the year (Cowardin, et al., 1979). No hydrophytic vegetation or wetland hydrologic indicators were observed within the project area. Wildlife Habitat The habitat types along the trail alignment provide potential foraging and breeding habitat for a variety of native wildlife species. Bird species that utilize grassland habitat include chestnut -backed chickadee, oak titmouse, Cooper's hawk, sharp -shinned hawk (Accipiter striatus), white-tailed kite (Elanus leucurus) and great blue heron (Ardea herodias), among others. Oak savannah/ grassland provides good foraging habitat and cover for herbivorous mammals such as California meadow vole (Microtus californicus), pocket Botha's pocket gopher, black -tailed hare (Lepus californicus) and black -tailed mule deer (Odocoileus hemionus). Predators that utilize oak savannah/ grassland include gopher snake (Pituophis catenifer), red-tailed hawk (Buteo jamaicensis) and bats such as pallid bat (Antrozous pallidus). FEBRUARY, 2012 15 REVISED INITIAL STUDY—ARASTRADERO TRAIL IMPROVEMENT PROJECT The riparian woodland habitat associated with Matadero Creek provides excellent habitat for passerine birds such as song sparrow (Melospiza melodia), Wilson's warbler (Wilsonia pusilla), spotted towhee (Pipilo maculatus), and bats such as California myotis (Myotis californicus) and Yuma bat (Myotis yumanensis). Stream habitat combined with understory vegetation and woody debris within the riparian forest supports amphibians such as Pacific tree frog (Hyla regilla), California red -legged frog (Rana aurora draytonii) and California newt (Taricha torosa). Predators that likely utilize the riparian habitat include raccoon (Procyon lotor), gray fox (Urocyon cinereoargenteus), red -shouldered hawk (Buteo lineatus), and aquatic garter snakes (Thamnophis sp.), among others. Matadero Creek in the vicinity of the project area supports native and nonnative fishes. Species of native fish expected to be present in the reach of creek near the project site include Sacramento sucker (Catostomus occidentalis) and California roach (Hesperoleucus symmetricus). Non-native fish species within the watershed that may be present in the creek include bluegill (Lepomus macrochirus), green sunfish (Lepomis cyanellus) and goldfish (Carassius auratus), (SCVURPPP 2008). Suburban forest provides habitat for a variety of wildlife, especially birds such as mourning dove (Zenaida macroura), house wren (Troglodytes aedon), and house finch (Carpodacus mexicanus) among others. Remnant native trees, especially larger and older trees, such as large valley oaks (Quercus lobata) and coast live oaks, increase the habitat value of suburban areas through providing food resources for wildlife in the form of acorns and insects, as well as providing important structure for nesting and roosting. Wildlife observed by sight or sign during the site visits included red-tailed hawk (Buten jamaicensis), Cooper's hawk (Accipiter cooperii), hairy woodpecker (Picoides pubescens), Nuttall's woodpecker (Picoides nuttallii), bushtit (Psaltriparus minimus), scrub jay (Aphelocoma californica), Bewick's wren (Thryomanes bewickii), brown creeper (Certhia americana), oak titmouse (Baeolophus inornatus), American kestrel (Falco sparverius), chestnut backed chickadee (Poecile rufescens), golden -crowned sparrow (Zonotrichia atricapilla), Audubon's warbler (Dendroica coronata), black -tailed mule deer, Botha's pocket gopher (Thomomys bottae), San Francisco dusky -footed woodrat (Neotoma fuscipes annectens). Larger carnivore species that may also utilize habitats within the project area on an infrequent basis include bobcat (Felis rufus), coyote (Canis latrans), and on rare occasion Mountain lion (Fells concolor). Owl pellets (possibly from a Great homed owl; Bubo virginianus), were observed beneath trees #21 and #22 along the trail alignment, adjacent to Arastradero Road on November 29, 2010. Both trees are eucalyptus trees and are proposed for removal. Tree #21 has a possible raptor nest located at approximately 70 feet in height. Several San Francisco dusky -footed woodrat nests are located near the trail alignment. All of these nest structures are outside of the project area however one nest is located within a Coast live oak tree located along Arastradero Road near Stirrup Way that is proposed for removal. Wildlife Movement Corridors Habitat loss, fragmentation, and degradation resulting from land use changes or habitat conversion can alter the use and viability of wildlife movement corridors (i.e. linear habitats that naturally connect and provide passage between two or more otherwise disjunct larger habitats or habitat fragments). In general, studies suggest that habitat corridors provide connectivity for, and are used by wildlife and as such, are an important conservation tool. According to Beier and Loe (1992), wildlife habitat corridors fulfill several functions. They maintain connectivity for daily movement, travel, mate -seeking, and migration; plant FEBRUARY, 2012 16 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT propagation; genetic interchange; population movement in response to environmental change or natural disaster; and recolonization of habitats subject to local extirpation. The suitability of a habitat as a wildlife movement corridor is related to, among other factors, the habitat corridor's dimensions (length and width), topography, vegetation, exposure to human influence, and the species in question. Species utilize movement corridors in several ways. "Passage species" are those species that use corridors as thru-ways between outlying habitats. The habitat requirements for passage species are generally less than those for corridor dwellers. Passage species use corridors for brief durations, such as for seasonal migrations or movement within a home range. As such, movement corridors do not necessarily have to meet any of the habitat requirements necessary for a passage species' everyday survival. Large herbivores, such as deer and elk, and medium -to -large carnivores, such as coyotes, bobcats and mountain lions, are typically passage species. "Corridor dwellers" are those species that have limited dispersal capabilities — a category that includes most plants, insects, reptiles, amphibians, small mammals, and birds — and use corridors for a greater length of time. As such, wildlife movement corridors must fulfill key habitat components specific to a species' life history requirements in order for them to survive. In general, however, the suitability and/or utility of the landscape — specifically, of the landscape as corridor habitat — is best evaluated on a species -level. Movement corridors for resident and migratory wildlife are not expected to be disrupted by the proposed trail alignment. The trail will not present any obstacles to existing wildlife movement, and follows an existing footpath along existing roadways for most it's length. REGULATORY CONSIDERATIONS Federal and state -listed species (endangered, threatened, fully -protected) receive various levels of legal protection under the federal and state endangered species acts and the California Fish and Game Code. The federal Migratory Bird Treaty Act of 1918 and Section 3500 of the California Fish and Game Code protect active nests of migratory and other birds, and provide criminal penalties for take of hawks, owls, and take or disturbance of all bird nests or eggs. Potential impacts to other special status or otherwise sensitive species must be disclosed and evaluated pursuant to the California Environmental Quality Act (CEQA). Wetland permitting requirements that may provide additional protections for species and habitats include the California Department of Fish and Game (DFG) 1600 Streambed Alteration Agreement permit process, US Army Corps of Engineers (ACOE) Section 404 permit and the State Regional Water Quality Control Board (RWQCB) 401 Certification permit. Federal and State Endangered Species Acts The United States Endangered Species Act (ESA) is administered by the United States Fish and Wildlife Service (USFWS). The California Endangered Species Act (CESA), the Native Plant Protection Act (LAPPA), and CEQA afford protection to species of concern included on State -maintained lists. The California Department of Fish and Game (CDFG) has statutory responsibility for the protection of State listed species, and is a trustee agency under CEQA. Both the Federal and State endangered species acts provide protection for listed species. In particular, the Federal act prohibits "take". "Take" is defined by the ESA as "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect a federally listed, endangered species of wildlife, or to attempt to FEBRUARY, 2012 17 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT engage in any such conduct." Take not specifically allowed by Federal permit under Section 10(a)(1)(B) of the ESA is subject to enforcement through civil or criminal proceedings under Section 9 of the ESA. While "take" is easily understood in the sense of deliberately capturing or killing individual animals, Federal regulations also define take to include the incidental destruction of animals in the course of an otherwise lawful activity, such as habitat loss due to development. Under those rules the definition of take includes significant habitat modification or degradation that actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding, or shelter (50 CFR Section 17.3). Section 10(a) of the ESA permits the incidental take of an endangered or threatened species. Similarly, Section 2081 of the CDFG Code or use of the CESA allows the Department to enter into management agreements that make lawful activities which may otherwise result in habitat loss or take of individuals of a state listed species. Species of Special Concern The California Department of Fish and Game has designated certain animal species as "Species of Special Concern" due to concerns about declining population levels, limited ranges, and continuing threats that have made these species vulnerable to extinction. The goal of this designation is to bring attention to these species in the hope that their population decline will be halted through mitigation or project redesign to avoid impact. Species of special concern are protected only through environmental review of projects under CEQA. The California Department of Fish and Game is a trustee agency and is solicited for its comments during the CEQA process. Federal species of concern are any species that may become vulnerable to extinction on a National level from declining population trends, limited range, and/or continuing threats'. Nesting Birds Nesting birds, including raptors, are protected by the California Department of Fish and Game Code 3503, which reads, "It is unlawful to take, possess, or needlessly destroy the nest or eggs of any bird, except as otherwise provided by this code or any regulation made pursuant thereto." Passerines and non - passerine landbirds are further protected under the Federal Migratory Bird Treaty Act. As such, the CDFG typically recommends pre -construction surveys for potentially suitable nesting habitat that will be directly (actual removal of trees/vegetation) or indirectly (noise disturbance) impacted by construction - related activities. California Environmental Quality Act Some species that are otherwise not protected by the ESA or CESA and do not have a special CDFG or Fish and Game Code designation (e.g., fully protected) may still, under CEQA, be determined to be significantly impacted by a project. For example, if a project were to destroy or disturb a roosting site for either a bat maternity colony or a wintering monarch butterfly colony it could significantly impact the local and/or regional population of either species. Although loss of an individual bat or monarch butterfly would likely be considered an insignificant impact, loss of a roost site where multiple individuals are ' This is no longer an official U.S. Fish and Wildlife Service category, but is still considered in this document because it contains many species that could become threatened or endangered FEBRUARY, 2012 18 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT present may be considered significant. This is because roost sites may be limited in availability and often have very specific habitat and/or microclimate conditions. When a roost site is lost, individuals may not be able to find an alternate roost in sufficient time for protection from the elements before expiring. However unless a roost site has already been studied and the local population of the subject species is well known, the significance of the loss cannot .be readily evaluated. In order to avoid a potential finding of significant impact to species such as roosting bats or monarchs, all potential habitats should be seasonally avoided or field surveys should be completed to determine presence/absence. California Native Plant Society and CEQA The California Native Plant Society (CNPS) has developed a rating system for the state's rare, threatened and endangered plants. Plants rated by CNPS are subject to protection under CEQA, and may also be protected by state and federal endangered species laws if they are listed by the state or federal government. Regulated Waters Impacts to stream channels (bed and bank) are regulated by the California Department of Fish and Game Code § § 1600 et seq., and may require a DFG Streambed Alteration Agreement. Impacts to wetlands and streams may also fall under the jurisdiction of the Clean Water Act §404 permit process and the Porter - Cologne Water Quality Control Act. The U.S. Army Corp of Engineers (USACE) enforces permit provisions of the Clean Water Act regulating dredge and fill operations. The USACE also exerts jurisdiction over "waters of the U.S." which include territorial seas, tidal waters, and non tidal waters in addition to wetlands and drainages that support wetland vegetation, exhibit ponding or scouring, show obvious signs of channeling, or have discernible banks and high water marks. The State of California Regional Water Quality Control Board (RWQCB) enforces permit provisions of the Porter -Cologne Water Quality Control Act. Projects that may potentially impact wetlands in the state of California require a 401 Certification permit. Each 401 Certification is decided on a case-by-case basis, and is guided by the applicable requirements of the CWA, Porter -Cologne and the regulations. Stormwater Control Requirements In urbanized areas, stormwater runoff is the largest source of pollution to waters in creeks, ponds and lakes. Pollution caused by stormwater runoff can be controlled through obtaining and complying with a municipal stormwater permit from the National Pollutant Discharge Elimination System (NPDES). Controls set forth in the permit offer an opportunity for development and redevelopment projects to reduce impacts to water quality. Town of Los Altos Hills Heritage Tree Designation Title 12, Chapter 2 of The Town of Los Altos Hills Municipal Code (Section 101), defines a Heritage Oak Tree as "any tree of the genus Quercus, including but not limited to Valley Oak (Quercus lobata), California Live Oak (Quercus agrifolia), Black Oak (Quercus kelloggii) and Blue Oak (Quercus douglasii) that has a trunk or multiple trunk thirty-six (36) inches in circumference (approximately twelve (12) inches in diameter) at a point four (4) feet above the root crown". No heritage oak trees are proposed for removal as part of this project. FEBRUARY, 2012 19 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Santa Clara Valley Water District Streamside Standards and Guidelines In their publication User Manual: Guidelines and Standards for Land Use Near Streams, the Santa Clara Valley Water Resources Protection Collaborative (SCVWRPC 2006)2 emphasizes the vital role of riparian vegetation in "maintaining stream stability, providing valuable wildlife habitat, and moderating downstream flooding" , as well as regulating water quality by filtering pollutants from stormwater, such as oil and grease from roadways, fertilizer runoff from lawns, and excess sediments from upstream. Specifically, the stream -side environment supports riparian vegetation and the functions riparian vegetation provides. Riparian vegetation benefits terrestrial species, as well as semi -aquatic amphibians and reptiles and fish. Such habitat functions include: • Sediment stabilization: provided by riparian trees, shrubs, and grasses; • Shading and water temperature moderation: provided by mature riparian shrubs and trees; • Overhanging escape cover: provided by shrubs and grasses near the stream edge; • Coarse particulate organic matter: organic material dropping into the stream in the form of leaves, insects, etc., that provide input for aquatic food webs; • Bird breeding and foraging habitat: provided by mature native riparian species, such as cottonwoods and willows, oaks, other trees, shrubs, forbs, grasses, and the stream banks; • Foraging, refugia, aestivation, and breeding habitat for semi -aquatic amphibian and reptile species: provided by low vegetation, rocks, downed materials, and the stream banks; • Foraging, breeding, hibernacula, and dispersal habitat for mammals: provided by the riparian vegetation and the stream bank substrate. Significance Criteria The significance criteria are based in part on the Environmental Checklist (CEQA Guidelines Appendix G [Title 14 CCR, Section 15000-15387]). These criteria are used to determine the extent to which the proposed project would impact sensitive biological resources. The threshold of significance may vary for each species or habitat, and is determined by the lead agency. Using these guidelines, the Project would result in a significant impact if it would: • Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special -status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service. • Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service. • Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means. • Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites. 2 Chapters 2 and 3 of the Guidelines contain the adopted requirements of the Town of Los Altos Hills for construction near a stream. Chapter 4 contains detailed specifications for use by architects, engineers and other project designers. Chapters 5-11 do not contain adopted requirements; these chapters are provided as reference material and background information for homeowners and developers. FEBRUARY, 2012 20 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance. Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan. SPECIAL STATUS PLANTS, ANIMALS, AND NATURAL COMMUNITIES The California Department of Fish and Game (CDFG) Natural Diversity Data Base (CNDDB) maintains records of reported occurrences of sensitive plant, animal and natural plant communities of concern. CNDDB records provide useful information about what species have been found in a given project area, and what species may be expected in similar habitat types. An area that has not been surveyed or visited may support sensitive species that have not been discovered and reported, and may require site-specific surveys to rule out special status species occurrences. The U. S. Fish and Wildlife Service (USFWS), Sacramento, also maintains lists of listed species and other species of concern that may occur in or be affected by projects in a given USGS topographic quadrangle. CNDDB records for the Palo Alto 7.5 minute topographic quadrangle and eight surrounding quadrangles were reviewed for sensitive element occurrences on the project site (CDFG 2010a). Review of the US Fish and Wildlife Service list of endangered and threatened species for the nine 7.5 minute quadrangles, and the CNPS on-line Inventory of Rare and Endangered Plants (CNPS 2010) was also conducted. Special status species that were identified in the region as having at least some minimal potential for occurrence based on proximity to the site, or similar habitat utilization were included in Appendix B of the Biological Assessment (Attachment 1). Special -status species that have a higher probability for occurrence onsite, based on habitat types and/or recorded observations within 5 miles of the property are discussed in greater detail below. Special status species found exclusively within habitats not present on the property (i.e. sand dune, serpentine grassland, salt marsh, freshwater marsh and/or marine habitats, etc.) were excluded from analysis due to the lack of these habitats on or adjacent to the property. • There is potential for one federally listed species, the California red -legged frog, (Rana aurora draytonii) and one state fully protected species, white-tailed kite (Elanus leucurus) to utilize the project area. • One non -listed special status species was found to occur within the trail alignment, the San Francisco dusky -footed woodrat (Neotoma fuscipes annectens). Four additional non -listed special status wildlife species were identified as having potential for presence within the project area, Cooper's hawk (Accipiter cooperii), loggerhead shrike (Lanius ludovicianus), western red bat (Lasiurus blossevilliz) and pallid bat (Antrozous pallidus),. • Eight species on various watch lists that also have potential for presence within the project area include fringed myotis (Myotis thysanodes), long-legged myotis (Myotis volans), hoary bat (Lasiurus cinereus), Yuma bat (Myotis yumanensis), long-eared bat (Myotis evotis), California thrasher (Toxostoma redivivum), Nuttall's woodpecker (Picoides nuttallii) and oak titmouse (Baeolophus inornatus). • Two special status plant species: western leatherwood (Dirca occidentalis) and San Francisco collinsia (Collinsia multicolor) were identified as having potential to occur within the project area. FEBRUARY, 2012 21 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT • One rare plant community, Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance) was identified within Matadero Creek, adjacent to the trail alignment. Three additional federally and/or state listed species that are a high priority for conservation are included in the following discussion. These are San Francisco garter snake (Thamnophis sirtalis tetrataenia), California tiger salamander (Ambystoma californiense) and steelhead (Oncorhynchus mykiss irideus). Though these species are not expected to occur on site they are federally listed species and have been detected in the region (CDFG 2010a). California Red -legged Frog The California red -legged frog (CRF) is a federally listed Threatened species and a California Species of Special Concern. Red -legged frogs are known to occur in slow -flowing streams, and marshes with heavily vegetated shores for breeding as well as grasslands, riparian woodland, oak woodland and coniferous forests. These frogs stay near the shore hidden in vegetation rather than in open water. Seasonal bodies of water are frequently occupied by red -legged frogs, and in some areas these may be critical for persistence. It is speculated that California red -legged frogs may lie dormant during dry periods of the year or during drought. California red -legged frogs are thought to disperse widely during autumn, winter, and spring rains. Juveniles use the wet periods to expand outward from their pond of origin and adults may move between aquatic areas. Frogs disperse through many types of upland vegetation and use a broader range of habitats outside of breeding season. CRF have been observed to move extensively and travel up to 2 miles or more between breeding ponds without apparent regard to topography, vegetation type, or riparian corridors (Bulger in litt.1998, in USFWS, 2002). The breeding season for CRF generally begins in January and lasts through March. Minimum breeding age appears to be two years in males and three years in females (Jennings and Hayes 1985). Females lay 750-4000 eggs in clusters attached to aquatic vegetation, two to six inches below the water surface. Eggs hatch in two to three weeks. Once hatched, the tadpoles generally take between 11 and 20 weeks to metamorphose, doing so between May and August. Although most tadpoles are expected to transform in the summer, they can also over -winter, so transformation can take from about 4 tol3 months. CRF typically require a permanent water source with a minimum depth of 0.7 meters (2.5 feet) (USFWS 2004). Successful breeding has been observed in sub -optimal habitats with little or no emergent vegetation present (USFWS 2004). In the absence of vegetation CRF will attach their eggs to rocks, wood or other debris. CRF has been extirpated from 70 percent of its former range and now is found primarily in coastal drainages of central California, from Marin County, California, south to northern Baja California, Mexico. Potential threats to the species include elimination or degradation of habitat from land development and land use activities and habitat invasion by non-native aquatic species (USFWS 2002). The project area is outside of CRF Critical Habitat (USFWS 2005). The nearest recorded observation of CRF (Occ. #230 ; 2001) is located at Matadero Creek, approximately 1.0 miles northeast of the project site (CDFG 2010a). Both adults and tadpoles were observed at this site between 1997 and 2001. There are several more observations of CRF that have been recorded within 5 miles of the project area including sightings in Bear Creek and San Francisquito Creek (CDFG 2010a). There are also several additional FEBRUARY, 2012 22 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT creeks and ponds within the Los Altos Hills, Woodside and Portola Valley area that provide potential habitat for CRF. There is potential habitat for CRF to occur within the section of Matadero Creek that is adjacent to the project area. Because CRF can utilize upland habitats and travel up to 2 miles when dispersing from breeding areas, there is potential that CRF to occur within the trail alignment when dispersing in the rainy season. Avoidance and minimization measures should be followed to insure CRF are not impacted by the proposed trail project. California Tiger Salamander California tiger salamander (Ambystoma californiense; hereafter referred to as CTS) is a large, terrestrial salamander with a black body and white to yellow spots and bars (Stebbins 2003). The Central California Distinct Population Segment (DPS) is federally -listed as Threatened (USFWS 2010b) and is designated as a California Species of Special Concern (CDFG 2010b). California tiger salamanders are distributed throughout the Central Valley and Central Coast ranges from Colusa County south to San Luis Obispo and Kern counties from sea level to 1054 meters (3,460 feet) in elevation. Two disjunct populations are located within Sonoma County and Santa Barbara County, which are geographically isolated from the Central Valley population. Critical habitat for the Central California DPS of CTS was designated in 2005 (USFWS 2005) and there are ten critical habitat units within Santa Clara County. The project area does not overlap with any critical habitat unit for CTS. The nearest CNDDB record of CTS (Occ. #63; 2005) is from Lake La Unita, approximately 2.3 miles northeast of the project site (CDFG 2010a). CTS have also been documented using restored ponds on the west side of Junipero Serra Boulevard near Lake Lagunita, approximately 2.1 miles northeast of the project site. CTS have not been detected at Felt Lake (pers. comm. Dr. Alan Launer). No breeding or suitable summer aestivation habitat is present on site or in the immediate project vicinity and CTS is not expected to occur within or adjacent to the project area. San Francisco Garter Snake The San Francisco garter snake (SFGS) is federally and state listed as endangered and is a fully protected species under §5050 of the California Fish and Game Code. A highly aquatic subspecies of the common garter snake endemic to the San Francisco Bay Area, San Francisco garter snakes are distributed along the western San Francisco Peninsula from the southern San Francisco County border south to Waddell Lagoon south of Ano Nuevo and as far west as Crystal Springs Reservoir. It occurs sympatrically with its primary prey species, the California red -legged frog (Rana aurora draytonii); however, it will opportunistically prey on a variety of species including frogs, tadpoles, egg masses, newts, small fish, salamanders, reptiles, small mammals, birds and their eggs and several small invertebrates (Stebbins 2003). The nearest recorded observation of SFGS is located near the Stanford Linear Accelerator, approximately 4.0 miles west of the project area (CNDDB 2010a). The only other occurrence within the region is located approximately 5.1 miles northwest of the project site on a private property on Portola Road. The closest aquatic habitat that could potentially support SFGS within the vicinity of the project area is Matadero Creek. This habitat, though it has been documented to support the California red -legged frog which is an important prey species of the San Francisco garter snake, is unlikely to support San Francisco FEBRUARY, 2012 23 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT garter snakes due to a lack of suitable marsh and/or pond habitat associated with the creek. No other potentially suitable habitat for this species exists within the vicinity. This species is not expected to occur within the project area. Steelhead Steelhead (Oncorhynchus mykiss irideus) within the Central California Coast ESU was federally -listed as threatened on August 18, 1997. The Central California Coast ESU Ecologically Significant Unit (ESU) includes all naturally spawned populations of steelhead (and their progeny) in California streams from the Russian River to Aptos Creek, and the drainages of San Francisco and San Pablo Bays eastward to the Napa River (inclusive), excluding the Sacramento -San Joaquin River Basin (NOAA 2005a). Major river basins containing spawning and rearing habitat for this ESU comprise approximately 6,516 square miles in California. The following counties lie partially or wholly within these basins (or contain migration habitat for the species): Alameda, Contra Costa, Marin, Mendocino, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma. Steelhead are anadromous fish that migrate from the ocean into fresh water streams to spawn (Moyle 2002). Rainbow trout refers to the resident form of the species that inhabits lakes or streams and does not migrate to the ocean. Steelhead build redds (i.e., spawning beds) at the head of riffles where water is well oxygenated and nearby pools with deeper water provide safe refuge for juveniles. Optimal temperatures for growth are 15-18°C. While in freshwater streams, steelhead feed on drifting aquatic organisms, terrestrial insects and bottom dwelling invertebrates (Moyle 2002The Santa Clara Hydrologic Unit includes South Bay creeks from San Francisquito Creek in Palo Alto eastward to Coyote Creek (NOAA 2005b). Matadero Creek occurs within this region, but is excluded from this critical habitat designation for Central California Coast steelhead ESU. Matadero Creek watershed probably supported a small steelhead run in the past and steelhead continue to enter the system from San Francisco Bay, according to local residents (SCBWMI 2001). Channelization, flood control projects, and barriers such as culverts have drastically reduced fish habitat (SCBWMI 2001). Currently this watershed is not expected to support a steelhead population (Leidy, et al, 2005). Deer Creek, a small tributary to Matadero Creek on the east side of the trail alignment, is unlikely to support steelhead currently, or historically, due to the steepness and low flows of this small watershed (Leidy, et al, 2005). San Francisco Dusky -footed Woodrat The San Francisco dusky -footed woodrat is a California species of special concern and is one of eleven recognized subspecies. The San Francisco dusky -footed occurs in the Santa Cruz Mountains and in the East Bay hills. The dusky -footed woodrat is generally a nocturnal mammal that occurs in a variety of brushy and wooded areas. They inhabit oak and riparian woodlands, coastal scrub, and chaparral habitats with a well-developed understory. The woodrat builds stick structures (`houses') for nesting up to 2 meters long and a meter in height that may last for tens of years. These stick houses are constructed on the ground, within shrubs and trees, tree hollows, rock crevices and sometimes in human structures such as wood sheds. The elaborate stick houses help protect the woodrat from seasonal temperature extremes and predators. Woodrats exhibit high site fidelity and are highly arboreal. They are generalist herbivores and live in loosely -cooperative societies. The dusky -footed woodrat eats primarily woody plants, including leaves, flowers, nuts and berries. Coast live oak trees are an important food resource for this species. FEBRUARY, 2012 24 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT Several San Francisco dusky -footed woodrat nests are located near the trail alignment. All of these nest structures are outside of the project area however one nest is located within a Coast live oak tree located along Arastradero Road near Stirrup Way that is proposed for removal. Raptors and Nesting Birds No special status birds were observed on the property, however the property provides potential habitat for several special status birds. Three special status raptors, white tailed kite, Cooper's hawk, and sharp - shinned hawk have potential to utilize the property. White-tailed Kite This species potentially nests within grasslands and oak savannah habitats in the foothills of Woodside and Portola Valley. White-tailed kites forage over grassland and nest in shrubs and trees. The species is a year-round resident of Central and Coastal California. This species was not observed during biological surveys of the property however potential suitable foraging and nesting habitat is present along the trail alignment. Cooper's Hawk This species inhabits dense stands of oak woodlands, riparian deciduous forests, or other forest habitats often near water and suburban areas (Baicich & Harrison 2005). This woodland raptor hunts in broken woodlands, along forest edges and suburban areas for medium-sized birds and mammals. Typical nest site selection is characterized by mature trees with significant canopy cover; although, species will nest in suburban areas in a variety of trees (Curtis et al. 2006). One Cooper's hawk was observed flying near the eastern boundary of the property on November 29, 2010. There is potentially suitable foraging and nesting habitat for this species along the trail alignment. Loggerhead Shrike The loggerhead shrike is designated a California Species of Special Concern by the California Department of Fish and Game (CDFG 2010b). Loggerhead shrikes inhabit a variety of habitats from open grasslands and scrub to woodlands and riparian areas (Yosef 1996, Baicich & Harrison 2005). This species is a year-round resident throughout much of California; however, population declines have been observed in the San Francisco Bay Area in areas where oak savannah habitat has been lost (Shuford and Gardali 2008). Trees, shrubs, and fence posts are important habitat features, which serve as hunting perches and an announcement site for territory pair maintenance (Shuford and Gardali 2008). Breeding begins in February and is double- to triple -brooded (Baicich & Harrison 2005). There is potentially suitable nesting and foraging habitat within the project area. Other Migratory Birds The native plant communities and ornamental vegetation on the property provide potential nesting habitat for a variety of native songbirds, raptors and other species. Species observed that may forage and nest within the project area include red-tailed hawk, American kestrel, oak titmouse, Nuttall's woodpecker, Bewick's wren, bushtit, scrub jay, Oregon junco, chestnut -backed chickadee, Anna's hummingbird, Stellar's jay, scrub jay, and spotted towhee, among others. Bats Potential bat roosting and foraging habitat is located on the property due to the habitats present within the project area and on adjacent properties (annual grassland, riparian, suburban forest). Two special status bat species were determined to have potential to occur within the project area, pallid bat and western red bat. FEBRUARY, 2012 25 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT Pallid Bat The pallid bat is a California Species of Special Concern and a U.S. Forest Service and Bureau of Land Management Sensitive Species, and a High Priority species by the Western Bat Working Group (CDFG 2010b). The pallid bat is found in a variety of habitats including all types of woodland especially oak savanna, grassland, riparian areas and wetlands, orchards, vineyards, and irrigated cropland if appropriate roosting sites are available. A very social bat, the pallid bat occupies a wide variety of habitats throughout California, including grasslands, shrublands, woodlands, and forests. The species is most common in open, dry areas with rocky areas necessary for roosting. Roosts in rock crevices, caves, mine shafts, under bridges, in buildings and tree hollows. It feeds on a variety of insects and arachnids. There is moderate potential for pallid bats to use the property for roosting and foraging. Western Red Bat The western red bat is designated as a California Species of Special Concern by the California Department of Fish and Game and a High Priority species by the Western Bat Working Group (CDFG 2010b). The western red bat is easily distinguished by its distinctive reddish coloration. Roosting typically occurs individually in dense clumps of tree foliage in riparian areas, especially willows, cottonwoods and sycamores, and within orchards and suburban areas in trees and shrubs. Roosts are.often hidden from view and only access from below (Bolster 2005). Red bats are primarily moth specialists, but individuals will forage for a variety of other insects. Individuals have been observed foraging around street lamps and flood lights in suburban areas (Bolster 2005). The western red bat migrates long distances, but has been reported to over -winter in the Bay Area with interspersed winter foraging bouts on warm days (Bolster 2005). The property provides habitat for additional species that are on watch lists including fringed myotis, long legged myotis, long-eared myotis, Yuma myotis and hoary bat. Additional bats within the region may utilize the property such as Mexican free -tailed bat (Tadarida brasiliensis), big brown bat (Eptesicus fuscus) and others. Though these species do not have protected status under ESA or CESA, impacting a roosting bat colony could be considered a significant impact under CEQA, due to the limited amount of suitable roosting habitat and the slow reproductive rate of bats. Monarch Butterfly Monarch butterfly is not a state or federally listed species, however due to its unique life history and habitat requirements it is given special consideration under the California Environmental Quality Act (CEQA) review process. Winter roost sites extend along the western coast from Mendocino in northern California, south to Baja California, Mexico. Roost habitat consists of wind -protected tree groves, typically eucalyptus (Eucalyptus globulus), Monterey pine (Pinus radiata) and Monterey Cypress (Cupressus macrocarpa), with nectar and water sources nearby. Roost sites consist of congregations of several hundred to several thousand adult butterflies. Along the Central California coast, monarch butterflies typically roost between October and February. The closest record of a monarch roost site is located at Ardenwood Farms Regional Preserve in Newark, approximately 13.3 miles northeast of the site (CDFG 2010a). The row of Eucalyptus trees along Arastradero Road provides potential habitat for monarchs, however monarch roost sites typically consist FEBRUARY, 2012 26 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT of groves of trees that are protected from the wind, with nectar and water sources nearby. These habitat components are not present within the project area. No Monarch butterflies were observed during biological surveys in November and December 2010, and trees proposed for removal along the trail alignment are unlikely to support monarch butterflies. Special Status Plants and Rare Plant Communities No special status plant species were observed on the property, however the property was surveyed in the fall, when many plants, especially annuals, are past their bloom stage, and are less visible. Two special status plants were determined to have potential for presence on site based on habitat types. These are western leatherwood (Dirca occidentalis) and San Francisco collinsia (Collinsia multicolor). One rare plant community, Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance), was identified within the project area (Holland 1986; CDFG 2006; CDFG 2007). MITIGATION: California Red -legged Frog Potential impacts to California red -legged frogs can be avoided and/or minimized by implementing minimization and avoidance measures (USFWS 1999b). The following mitigation measures shall be followed: BIO -1 All ground disturbance associated with trail building activities on site will be conducted during the dry season (April 15 — October 15). BIO -2 Staging areas and access routes to the work area will be delineated and inspected by the project biologist prior to establishment to avoid unnecessary impacts to California red -legged frogs and their habitat. BIO -3 Exclusion fencing will be erected around portions of the construction site adjacent to Matadero Creek and Deer Creek prior to the onset of project activities. Fencing will be a minimum of 3 feet in height and buried in the soil 4 to 6 inches to inhibit California red -legged frogs from entering the project area. BIO -4 Once the exclusion fence is installed, a pre -construction survey will be conducted to ensure that no California red -legged frogs are present in the project area. BIO -5 If California red -legged frogs are detected on site, the USFWS would be contacted for guidance on moving the animal(s) to a safe location. No CRF would be handled without permission from the USFWS. BIO -6 During project activities, all trash that may attract predators will be properly contained, removed from the work site and disposed of regularly. Following construction, all trash and construction debris will be removed from work areas. BIO -7 All practicable erosion control Best Management Practices (BMPs) will be implemented to minimize the potential of impacts to water quality of Matadero Creek and Deer Creek. BIO -8 No smoking except in vehicles will be permitted within vegetated areas. FEBRUARY, 2012 27 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT BIO -9 Trash dumping will be prohibited. San Francisco Dusky Footed Woodrat Potential impacts to San Francisco Dusky Footed Woodrat can be avoided and/or minimised by implementing minimization and avoidance measures (USFWS 1999b). The following mitigation measures shall be followed: BIO -10 Woodrat nests within 100 feet of ground disturbing activities shall be surveyed and monitored to determine if nests are active. BIO -11 For woodrat nests that can be avoided, orange construction/ protective fencing will be placed between work areas and woodrat nests, and will include a 2 -foot buffer between the protective fencing and the nest. BIO -12 For woodrat nests that cannot be avoided, woodrat nests shall be dismantled by a qualified biologist. Dismantling will be conducted during the time of year that would least impact breeding woodrats (i.e. late fall/ winter: November/December/January). Dismantling will be conducted slowly to avoid impacting neonate woodrats. If woodrat neonates are detected in the nest, dismantling will cease and the nests will be checked every 48 hours to determine if the neonates are still present. Dismantling will continue once it is determined that the neonates are no longer present and have either been weaned from their mothers, or the mothers have moved them from the nest. BIO -13 DFG shall be consulted if any San Francisco dusky -footed woodrats (adults, subadults or neonates) are harmed by project activities. Special Status Raptors The trees and shrubs on the property provide potential nesting habitat for birds including raptors such as Cooper's hawk and white-tailed kite. Ground disturbance and construction activities on the property could impact nesting birds, including raptors. The following mitigation measures shall be followed: BIO -14 If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for nesting birds including raptors such as white-tailed kite and Cooper's hawk, shall be conducted by a qualified biologist within 300 feet of the construction area, where access is available, within two weeks prior to construction. BIO -15 If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical iso- activity buffer zones are 300 feet for active raptor nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. Nfigratory Birds The native plant communities and ornamental vegetation on the property provide potential nesting habitat for a variety of native songbirds, raptors and other species. The following mitigation measures shall be followed: FEBRUARY, 2012 28 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT BIO -16 If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for migratory birds, shall be conducted by a qualified biologist. For migratory raptors including red-tailed hawk, surveys shall be conducted within 300 feet of the project area where access is available. For non -raptor migratory bird species, surveys shall be conducted within 100 feet of the project area, where access is available. Surveys for migratory birds shall be conducted within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. BIO -17 If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical iso- activity buffer zones are 300 feet for active raptor nests, and 100 feet for active migratory bird nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. Special Status and Non -Special Status Bats The property provides potential habitat for roosting bats. There are several trees on the property that may provide day and/or night roosts for special status and non -special status bat species. The following mitigation measure shall be followed: BIO -18 To avoid impacts to roosting bats within the project area, including pallid bat and western red bat, pre -construction surveys for roosting bats shall be conducted by a qualified bat biologist within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. Any tree removal on site shall be done according to the recommendations of the qualified bat biologist. If active bat maternity roosts are detected (this season is typically between April and August) within tree that will be impacted by the project, the roost would need to be avoided until all young are volant, and the Department of Fish and Game will be consulted for permission in the use of any bat exclusion devices. Special Status Plants and Plant Communities To avoid impacts to special status plants and plant communities, the following mitigation measures shall be followed: BIO -19 To avoid impacts to special status plant species, (San Francisco collinsia and western leatherwood), one or more preconstruction surveys shall be conducted by a qualified biologist prior to any ground disturbance and/or vegetation removal within the project area. The survey (s) should be timed to occur at the most suitable time of year (i.e. bloom period) to detect San Francisco collinsia and western leatherwood. BIO -20 If San Francisco collinsia and/or western leatherwood are identified within the project area, and one or more individual plants could potentially be impacted by project activities, the California Native Plant Society and the Department of Fish and Game will be consulted to develop appropriate mitigation measures. Mitigation measures may include seed/plant material collection, propagation and replanting in an appropriate restoration area(s). Regulated Waters and Wetlands While the proposed project does not include any in -channel work or grade alteration or construction below the top of bank, indirect effects on the aquatic environment of Matadero Creek and Deer Creek FEBRUARY, 2012 29 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT could result from project implementation. In addition, direct and indirect impacts to California red -legged frog habitat within Matadero Creek could be considered significant under CEQA guidelines. Project implementation could affect the regulated waters and wetlands in the following ways: Erosion from the project site during construction could release sediments into the creek channels, adversely affecting the aquatic habitat and indirectly impacting aquatic species. Inadvertent spills of cement, oil and grease, or other contaminants during construction could reach the creek channels, adversely affecting the aquatic habitat and indirectly impacting aquatic species. In order to avoid indirect impacts regulated waters and wetlands, the measures outlined below shall be implemented. With the incorporation of these measures, project implementation would not result in any inadvertent impacts on downstream water quality. BIO -21 Under no circumstances shall spoils, gravel, paving materials or other construction materials or debris be placed, even temporarily, along or below the top of bank of the creek. BIO -22 Best Management Practices (BMPs) to prevent pollutants, construction materials or debris from entering the creek and storm drains shall be installed prior to the initiation of work and properly maintained. For further clarification refer to Hydrology and Water Quality Mitigation Measure HYD -5. Invasive Plant Species The following measure will avoid impacts from introduced invasive plant species. The following mitigation measure shall be followed: BIO -23 The project proponent shall avoid planting ornamental species reported by the California Invasive Plant Council to have the potential to be invasive. Species on this list shall be prohibited from use in landscaping. FEBRUARY, 2012 30 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 5. Cultural Resources - Would the project: a) Cause a substantial adverse change in the significance of a X historical resource as defined in 15064.5? b) Cause a substantial adverse change in the significance of X an archaeological resource pursuant to 15064.5? c) Directly or indirectly destroy a unique paleontological X resource or site or unique geologic feature? FEBRUARY, 2012 30 REVISED INITIAL STUDY—ARASTRADERO TRAIL IMPROVEMENT PROJECT d) Disturb any human remains, including those interred X outside of formal cemeteries? DISCUSSION The project site is located on Arastradero and Page Mill Roads near the intersection of Page Mill Road and the I-280 freeway. Matadero Creek flows through the project site and residential development surrounds the project site. Proposed surface improvements will be located in both disturbed and undisturbed areas. There is typically a higher potential for encountering archaeological resources in areas adjacent to a creek. Although the extent of surface disturbance at the site would be minimal, the potential for such resources cannot be completely eliminated due to the site's proximity to the Matadero Creek corridor. Therefore, the impacts of construction are considered potentially significant and the following mitigation measures will be required: MITIGATION: CUL -11n the event that archaeological traces are encountered, all construction within a 50 -meter radius of the find will be halted, the Planning Director will be notified, and an archaeologist will be retained to examine the find and make appropriate recommendations. CUL - 2If human remains are discovered, the Santa Clara County Coroner will be notified. The Coroner will determine whether or not the remains are Native American. If the Coroner determines that the remains are not subject to his authority, he will notify the Native American Heritage Commission, who shall attempt to identify descendants of the deceased Native Americans. CUL - 3If the Planning Director finds that the archaeological find is not a significant resource, work will resume only after the submittal of a preliminary archaeological report and after provisions for reburial and ongoing monitoring are accepted. Provisions for identifying descendants of a deceased Native American and for reburial will follow the protocol set forth in CEQA Guidelines Section 15064.5(e). If the site is found to be a significant archaeological site, a mitigation program will be prepared and submitted to the Community Development Director for consideration and approval, in conformance with the protocol set forth in Public Resources Code Section 21083.2. CUL 4 A final report shall be prepared when a find is determined to be a significant archaeological site, and/or when Native American remains are found on the site. The final report will include background information on the completed work, a description and list of identified resources, the disposition and curation of these resources, any testing, other recovered information, and conclusions. FEBRUARY, 2012 31 REVISED INITIAL STUDY—ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The project will consist of a new bike path and paved trail alongside Arastradero Road beginning just north of Highway 280 and continuing west to the Santa Clara County line. A portion of the bike path on the south side of Arastradero Road will require a retaining wall with an approximate average height of 1.5 feet to support the path width. Cornerstone Earth Group conducted a geotechnical investigation of the site including the location of the proposed retaining wall and the pedestrian pathway adjacent to Matadero Creek. The site area is underlain Monterey Formation bedrock. Matadero Creek cuts through the Monterey Formation hills flowing through flat alluvial terrace floor nearly 600 feet wide. With thin soil overlaying soft bedrock, liquefaction is not considered a site hazard. The retaining wall site is located .6 miles north of the Monte Vista fault and about 3 miles northeast of the San Andreas Fault. The site is not located within an Alquist Priolo fault zone or Santa Clara County fault hazard zone. Since no known surface expressions of fault traces is thought to cross the site, fault rupture hazard is not a significant geologic hazard at the site. The retaining wall site is not located in a State -designated liquefaction hazard zone FEBRUARY, 2012 32 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 6. Geology and Soils - Would the project expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: a) Rupture of a known earthquake fault, as delineated on the X most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. b) Strong seismic ground shaking? X c) Seismic -related ground failure, including liquefaction? X d) Landslides? X e) Result in substantial soil erosion or the loss of topsoil? X f) Be located on a geologic unit or soil that is unstable, or that X would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? g) Be located on expansive soil, as defined in Table 18-1-B of X the Uniform Building Code (1994), creating substantial risks to life or property? h) Have soils incapable of adequately supporting the use of X septic tanks or alternative wastewater disposal systems where sewers are not available for the disposal of waste water? DISCUSSION The project will consist of a new bike path and paved trail alongside Arastradero Road beginning just north of Highway 280 and continuing west to the Santa Clara County line. A portion of the bike path on the south side of Arastradero Road will require a retaining wall with an approximate average height of 1.5 feet to support the path width. Cornerstone Earth Group conducted a geotechnical investigation of the site including the location of the proposed retaining wall and the pedestrian pathway adjacent to Matadero Creek. The site area is underlain Monterey Formation bedrock. Matadero Creek cuts through the Monterey Formation hills flowing through flat alluvial terrace floor nearly 600 feet wide. With thin soil overlaying soft bedrock, liquefaction is not considered a site hazard. The retaining wall site is located .6 miles north of the Monte Vista fault and about 3 miles northeast of the San Andreas Fault. The site is not located within an Alquist Priolo fault zone or Santa Clara County fault hazard zone. Since no known surface expressions of fault traces is thought to cross the site, fault rupture hazard is not a significant geologic hazard at the site. The retaining wall site is not located in a State -designated liquefaction hazard zone FEBRUARY, 2012 32 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT (CGS, Palo Alto Quadrangle, 2006) or a Santa Clara County liquefaction hazard zone (Santa Clara County, 2003). No serpentine soils exist within the trail alignment or in adjacent areas near the project area. As the site consists of thin soils overlaying soft bedrock, liquefaction is not considered a site hazard for the planned retaining wall. There are no open faces within 200 feet of the retaining wall where lateral spreading could occur and Cornerstone Earth Group has concluded that the potential for lateral spreading to affect the retaining wall is low. The unsaturated soils encountered at the retaining wall location was predominately stiff to very stiff clays or stiff to very stiff silts overlying soft bedrock and Cornerstone Earth Group has concluded that the potential for significant differential seismic settlement affecting the proposed improvements is low. The retaining wall area is located along the south side of Arastradero Road between Stirrup Way on the east and continuing about 500 feet west of Stirrup Way. The existing cut slope on the south side of the road in the area of the proposed retaining wall is inclined at 11/z: l (horizontal:vertical) and appears to be mostly planar and stable, since construction occurred more than 30 years ago. A few small depressions were seen that could mark landslide scarps; however, lobes of accumulated debris were not observed except at the northwestern end of the retaining wall alignment. This landslide is located at one end of the road cut so probably involves soil or deeply weathered Monterey Shale and appears to be less than 5 feet thick. No other signs of slope instability were seen along Arastradero Road; however, desiccation cracks in the clayey soils indicate creep or expansive soils may have to be considered. Grading for proposed retaining wall construction will require a grading permit issued by the Town, the project will be subject to policies and standards for grading and erosion control, such as silt fencing, and reseeding graded areas to minimise the potential for soil erosion on the site. The project will not expose people or structures to seismic ground shaking or failure, and is not located on unstable soils. All engineering aspects of the project will be conditioned by the requirements of the Town Engineering Division. It is anticipated that impacts dues to geology and soils will be considered a less than significant impact with mitigation. MITIGATION: GEO —1 The applicant shall incorporate all recommendations listed by Cornerstone Earth Group in Sections 6.0 through 8.0 of the draft Geotechnical Investigation for the project dated December 2, 2011 for; earthwork, retaining walls, and pedestrian pavements. The applicant shall retain the services of Cornerstone Earth Group to review the geotechnical aspects of the project structural, civil, and landscape plans and specifications, allowing sufficient time to provide the design team with any comments prior to issuing the plans for construction. GEO — 2 Cornerstone Earth Group shall be retained by the applicant to conduct geotechnical observation and testing during earthwork and foundation construction stages. GEO -3 Cornerstone Earth Group shall prepare a letter at the end of construction regarding contractor compliance with project plans and specifications, and with the recommendations of the Geotechnical Investigation dated December 2, 2011 and shall submit the letter to the Town Public Works Director. FEBRUARY, 2012 33 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION In 2006 California passed the California Global Warming Solutions Act (AB 32), which limits statewide greenhouse gas (GHG) to 1990 levels and establishes a goal of achieving these emission reductions by 2020. AB 32 required the California Air Resources Board-(CARB) to adopt a comprehensive blueprint for limiting GHG emissions by the end of 2008 and complete the necessary rulemaking to implement the plan by the end of 201 1.1n addition the adoption of SB 97 in 2007 mandates that the California Office of Planning and Research (OPR) prepare CEQA Guidelines to establish standards for evaluation of GHG emissions including the creation of feasible mitigation measures. The California Resource Agencies adopted amendments to the CEQA Guidelines for GHG emissions that require public agencies in California to evaluate GHG emissions within their CEQA documents using either qualitative or quantitative methods. Although the modified CEQA Guidelines require that CEQA documents evaluate GHG emissions to determine if they will be significant, the CEQA Guidelines do not establish a methodology or quantitative thresholds for making this determination. The Bay Area Air Quality Management District (BAAQMD) has adopted revisions to their CEQA Guidelines for addressing Air Quality impacts. These guidelines include proposed quantitative thresholds for GHG emissions. The proposed project entails construction of new trails, bike lanes and a 475 foot long retaining wall (varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way). The project would not generate new motor vehicle traffic and will generate GHG emissions tp substantially below the BAAQMD thresholds. Temporary construction activities could generate greenhouse gas emissions and is considered a potentially significant impact. Bay Area Air Quality Management District emissions control measures will be adhered to during construction for all improvements and implementation of Air Quality mitigation measures 1 a. through If. will reduce temporary construction impacts to less than significant. NIITIGATION: Refer to Air Quality Mitigation Measure AIR -1 a. through 1 f. FEBRUARY, 2012 34 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 7. Greenhouse Gases - Would the project: a) Generate greenhouse gas emissions, either directly or X indirectly, that may have a significant impact on the environment, based on any applicable threshold of significance? b) Conflict with any applicable plan, policy or regulation of X an agency adopted for the purpose of reducing the emissions of greenhouse gases? DISCUSSION In 2006 California passed the California Global Warming Solutions Act (AB 32), which limits statewide greenhouse gas (GHG) to 1990 levels and establishes a goal of achieving these emission reductions by 2020. AB 32 required the California Air Resources Board-(CARB) to adopt a comprehensive blueprint for limiting GHG emissions by the end of 2008 and complete the necessary rulemaking to implement the plan by the end of 201 1.1n addition the adoption of SB 97 in 2007 mandates that the California Office of Planning and Research (OPR) prepare CEQA Guidelines to establish standards for evaluation of GHG emissions including the creation of feasible mitigation measures. The California Resource Agencies adopted amendments to the CEQA Guidelines for GHG emissions that require public agencies in California to evaluate GHG emissions within their CEQA documents using either qualitative or quantitative methods. Although the modified CEQA Guidelines require that CEQA documents evaluate GHG emissions to determine if they will be significant, the CEQA Guidelines do not establish a methodology or quantitative thresholds for making this determination. The Bay Area Air Quality Management District (BAAQMD) has adopted revisions to their CEQA Guidelines for addressing Air Quality impacts. These guidelines include proposed quantitative thresholds for GHG emissions. The proposed project entails construction of new trails, bike lanes and a 475 foot long retaining wall (varying in average height from 6 inches to 2 feet with a maximum height of 3.9 feet at one location near Stirrup Way). The project would not generate new motor vehicle traffic and will generate GHG emissions tp substantially below the BAAQMD thresholds. Temporary construction activities could generate greenhouse gas emissions and is considered a potentially significant impact. Bay Area Air Quality Management District emissions control measures will be adhered to during construction for all improvements and implementation of Air Quality mitigation measures 1 a. through If. will reduce temporary construction impacts to less than significant. NIITIGATION: Refer to Air Quality Mitigation Measure AIR -1 a. through 1 f. FEBRUARY, 2012 34 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The project site is not located in the vicinity of an air strip and will not include the routine transport or release of hazardous materials, and will not interfere with an adopted emergency response plan. Since the site is mostly undeveloped, the potential for encountering hazardous materials during project construction would be low. Construction of the project will include roadway paving, retaining wall construction, and installation of Stevens Creek Quarry Crusher Fines on trails and may involve the temporary use and transport of potentially hazardous materials. Standard safety conditions and compliance with local and State ordinances concerning the use and transport of toxic substances and use of hazardous materials related to construction of the project will ensure that any potential public health risks would be less than significant. FEBRUARY, 2012 35 Potentially Issues (and Supporting Information Sources) Potentially Significant hnpact Unless Less Than Significant Mitigation Significant No Impact Incorporated Impact hnpact 8. Hazards and Hazardous Materials - Would the project: a) Create a significant hazard to the public or the environment X through the routine transport, use, or disposal of hazardous materials? b) Create a significant hazard to the public or the environment X through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment? c) Emit hazardous emissions or handle hazardous or acutely X hazardous materials, substances, or waste within one- quarter mile of an existing or proposed school? d) Be located on a site which is included on a list of X hazardous materials sites compiled pursuant to Government Code Section 65962.5 and, as a result, would it create a significant hazard to the public or the environment? e) For a project located within an airport land use plan or, X where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a safety hazard for people residing or working in the project area? 0 For a project within the vicinity of a private airstrip, would X the project result in a safety hazard for people residing or working in the project area? g) Impair implementation of or physically interfere with an X adopted emergency response plan or emergency evacuation plan? h) Expose people or structures to a significant risk of loss, X injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands? DISCUSSION The project site is not located in the vicinity of an air strip and will not include the routine transport or release of hazardous materials, and will not interfere with an adopted emergency response plan. Since the site is mostly undeveloped, the potential for encountering hazardous materials during project construction would be low. Construction of the project will include roadway paving, retaining wall construction, and installation of Stevens Creek Quarry Crusher Fines on trails and may involve the temporary use and transport of potentially hazardous materials. Standard safety conditions and compliance with local and State ordinances concerning the use and transport of toxic substances and use of hazardous materials related to construction of the project will ensure that any potential public health risks would be less than significant. FEBRUARY, 2012 35 REVISED INITIAL STUDY —ARASTRADERO TRAIL IMPROVEMENT PROJECT MITIGATION: None required. FEBRUARY, 2012 36 Potentially Significant Potentially Impact Unless Less Than Issues (and Supporting Information Sources) Significant Mitigation Significant No Impact Incorporated Impact Impact 9. Hydrology and Water Quality - Would the project: a) Violate any water quality standards or waste discharge X requirements? b) Substantially deplete groundwater supplies or interfere X substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)? c) Substantially alter the existing drainage pattern of the site X or area, including through the alteration of the course of a stream or river, in a manner which would result in substantial erosion or siltation on- or off-site? d) Substantially alter the existing drainage pattern of the site X or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner, which would result in flooding on- or off-site? e) Create or contribute runoff water which would exceed the X capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff? f) Otherwise substantially degrade water quality? X g) Place housing within a 100 -year flood hazard area as X mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? h) Place within a 100 -year flood hazard area structures, which X would impede or redirect flood flows? i) Expose people or structures to a significant risk of loss, X injury or death involving flooding, including flooding as a result of the failure of a levee or dam? j) Inundation by seiche, tsunami, or mudflow? X FEBRUARY, 2012 36 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION: Construction activities and ground disturbance in proximity to Matadero Creek have the potential to degrade water quality if soil materials exposed during construction, or hazardous materials were accidentally released into the tributary. These impacts are prohibited by Section 9 of the Clean Water Act. Protection measures are considered necessary to prevent excavated soil and construction or hazardous materials from inadvertently entering Matadero Creek during construction. The proposed trails project consists of a five foot wide trail, approximately one linear mile in length, constructed of pervious Stevens Creek Quarry Crusher fines and new bike lanes. It is expected that the project will disturb more than one acre of land and will be subject to the Notice of Intent (NOI) requirements of the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) under the State Nation Pollutant Discharge Elimination System (NPDES). A Storm Water Pollution Prevention Plan will be developed and implemented consistent with mitigation measure HYD -3 through HYD -6 will reduce water quality impacts to a less than significant level. The proposed trail improvements are consistent with the Water Collaborative Guidelines and Standards for Land Uses Near Streams in that disturbed soils are limited to the trail improvements will not require grading or revegetation of any areas adjacent to the creek or creek -bank. Implementation of erosion control measures, post construction re -vegetation measures and measures requiring designation of storage areas for hazardous materials and washing areas for equipment will decrease the potential impacts to hydrology and water quality to less than significant with mitigation. MITIGATION: HYD —1 Erosion and sedimentation control measures, such as silt fencing and use of straw wattles, shall be implemented during and after construction. HYD — 2 Prepare a Storm Water Pollution Prevention Plan (SWPPP) incorporating the following Best Management Practices (BMPs) into grading and construction plans to prevent inadvertent discharge of materials into Matadero Creek in compliance with the National Pollutant Discharge Elimination System (NPDES) permit. a. The contractor will identify and implement specific procedures for the handling and containment of hazardous materials. This will include establishing dedicated fueling and maintenance areas for construction vehicles and equipment (including small equipment such as chainsaws), which will be located at least 65 feet from any drainage, riparian habitat or water body. Fueling must be performed on level ground. b. The contractor will identify and implement as appropriate specific procedures for handling and containment of hazardous materials. These will include catch basins for refueling and having absorbent pads on hand to respond to accidental spills. c. Absorbent spill clean-up materials and spill kits shall be available in fueling areas and on fueling trucks and shall be disposed of properly after use. d. Drip pans or absorbent pads shall be used during vehicle and equipment fueling, unless the fueling is performed over an impermeable surface in a dedicated fueling area. e. Fuel tanks shall not be "topped -off' f. Vehicles and equipment shall be inspected on each day for evidence of leaks. Leaks shall be repaired immediately or problem vehicles or equipment shall be removed from the project site. FEBRUARY, 2012 37 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT g. Absorbent spill clean-up materials shall be available in fueling and maintenance areas and used on small spills instead of hosing down or burying techniques. The spent absorbent material shall be removed promptly and disposed of properly. HYD — 3 The construction plans shall clearly identify all proposed fueling, cleaning or maintenance areas in accordance with the following: h. No fueling, cleaning, or maintenance of vehicles or equipment shall take place within the riparian corridor to avoid the release of deleterious substances into surface waters. i. During construction, there will be no use of pesticides for maintenance, or dumping of waste or refuse. j. Equipment cleaning and temporary concrete washout area shall comply with the following: i. Location of temporary concrete washout facilities will be identified at least 24 hours prior to a scheduled pour. ii. Temporary concrete washout facilities, cleaning stations, and staging areas shall be located on level ground at least 200 feet from channel banks. Each facility shall be located away from construction traffic or access areas to prevent disturbance or tracking. iii. Temporary concrete washout facilities shall be constructed and maintained to sufficiently maintain all liquid and concrete wastes generated by washout operations. iv. Once concrete wastes are washed into the designated area and allowed to harden, the concrete shall be broken up, removed and properly disposed of. DISCUSSION The Los Altos Hills General Plan designates the areas within the project site as "Residential" with an "Open Space Conservation" overlay. Surrounding land uses include residential development, property owned by Santa Clara Valley Water District north of Baleri Ranch Road, Caltrans right of way and a Park and Ride lot at the intersection of Arastradero Road and Page Mill Road, and the I-280 freeway. The Los FEBRUARY, 2012 38 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 10. Land Use and Planning - Would the project: a) Physically divide an established community? X b) Conflict with any applicable land use plan, policy, or X regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? c) Conflict with any applicable habitat conservation plan or X natural community conservation plan? DISCUSSION The Los Altos Hills General Plan designates the areas within the project site as "Residential" with an "Open Space Conservation" overlay. Surrounding land uses include residential development, property owned by Santa Clara Valley Water District north of Baleri Ranch Road, Caltrans right of way and a Park and Ride lot at the intersection of Arastradero Road and Page Mill Road, and the I-280 freeway. The Los FEBRUARY, 2012 38 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Altos Hills General Plan does not identify any habitat conservation plans or natural community conservation plans that apply to the project site. Based on the scope of the proposed project and surrounding uses, the proposed project will not physically divide an established community or conflict with any special policies. Based on the scope of the proposed project, site location and surrounding uses it is anticipated that the project would have no impact on land use or conflict with any specific plan, habitat conservation or natural community conservation plan. MITIGATION: None required. DISCUSSION The Los Altos Hills General Plan does not identify any regionally or locally -important mineral resources on the project site or in its vicinity. The project will not result in significant grading or excavation. There will be little to no disturbance of mineral resources. Therefore the project would have no impact on mineral resources. MITIGATION: None required. FEBRUARY, 2012 39 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated hnpact Impact 11. Mineral Resources - Would the project: a) Result in the loss of availability of a Imown mineral X resource that would be of value to the region and the residents of the state? b) Result in the loss of availability of a locally -important X mineral resource recovery site delineated on a local general plan, specific plan or other land use plan? DISCUSSION The Los Altos Hills General Plan does not identify any regionally or locally -important mineral resources on the project site or in its vicinity. The project will not result in significant grading or excavation. There will be little to no disturbance of mineral resources. Therefore the project would have no impact on mineral resources. MITIGATION: None required. FEBRUARY, 2012 39 REVISED .INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The project will not result in a permanent increase in ambient noise levels, nor expose people to the generation of noise levels in excess of existing conditions, or any noise standards established by the Town of Los Altos. Further, the project will not expose persons to groundborne vibration or groundborne noise levels. The temporary noise created during the grading and construction phases of the project could create a temporary disturbance to neighboring properties. The project will conform to the Town's construction hours (Municipal Code Chapter 6 - Section 5-6.02) regulations and Noise regulations (Municipal Code Chapter 2). Compliance with these regulations will ensure that the neighboring properties are not significantly impacted. With enforcement of time restrictions and noise level standards, contained in the Town Noise regulations, construction noise levels will be made to comply with the Town Noise regulations. Therefore the project will not result in the exposure of persons to noise levels in excess of applicable standards or increase ambient noise levels and impacts from temporary construction noise will be less than significant. MITIGATION: None required. FEBRUARY, 2012 40 Potentially Issues (and Supporting Information Sources) Potentially Significant Impact Unless Less Than Significant Mitigation Significant No Impact Incorporated Impact Impact 12. Noise - Would the project result in: a) Exposure of persons to or generation of noise levels in X excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? b) Exposure of persons to or generation of excessive X groundborne vibration or groundborne noise levels? c) A substantial permanent increase in ambient noise levels in X the project vicinity above levels existing without the project? d) A substantial temporary or periodic increase in ambient X noise levels in the project vicinity above levels existing without the project? e) For a project located within an airport land use plan or, X where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? 0 For a project within the vicinity of a private airstrip, would X the project expose people residing or working in the project area to excessive noise levels? DISCUSSION The project will not result in a permanent increase in ambient noise levels, nor expose people to the generation of noise levels in excess of existing conditions, or any noise standards established by the Town of Los Altos. Further, the project will not expose persons to groundborne vibration or groundborne noise levels. The temporary noise created during the grading and construction phases of the project could create a temporary disturbance to neighboring properties. The project will conform to the Town's construction hours (Municipal Code Chapter 6 - Section 5-6.02) regulations and Noise regulations (Municipal Code Chapter 2). Compliance with these regulations will ensure that the neighboring properties are not significantly impacted. With enforcement of time restrictions and noise level standards, contained in the Town Noise regulations, construction noise levels will be made to comply with the Town Noise regulations. Therefore the project will not result in the exposure of persons to noise levels in excess of applicable standards or increase ambient noise levels and impacts from temporary construction noise will be less than significant. MITIGATION: None required. FEBRUARY, 2012 40 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The proposed project would not result in development for human occupancy and will not increase growth in the area. The proposed project will not displace existing housing, nor cause the construction of replacement housing. The proposed project is consistent with the Los Altos Hills General Plan and zoning designations. Therefore, the project will have no impact on population and housing. MITIGATION: None required. Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 13. Population and Housing - Would the project: a) Induce substantial population growth in an area, either X directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other infrastructure)? b) Displace substantial numbers of existing housing, X necessitating the construction of replacement housing elsewhere? c) Displace substantial numbers of people, necessitating the X construction of replacement housing elsewhere? X DISCUSSION The proposed project would not result in development for human occupancy and will not increase growth in the area. The proposed project will not displace existing housing, nor cause the construction of replacement housing. The proposed project is consistent with the Los Altos Hills General Plan and zoning designations. Therefore, the project will have no impact on population and housing. MITIGATION: None required. FEBRUARY, 2012 41 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 14. Public Services - a) Would the project result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the public services: Fire protection? X Police protection? X Schools? X Parks? X Other public facilities? X FEBRUARY, 2012 41 REVISED INITIAL STUDY — ARASTRADERo TRAIL IMPROVEMENT PROJECT DISCUSSION The proposed project would result in the construction of new and resurfaced trails and separate bike lanes. The project would not require the need for additional school facilities, parks, and fire or police services. Therefore the project would have no impact on public services or facilities. MITIGATION: None required. DISCUSSION The project will not result in a substantial increase of park usage or require new or expanded services. The project will improve the safety of the bike lanes and trails for pedestrian and equestrian users. The project would be consistent with the goals and policies of the Open Space and Conservation Element of the Town's General Plan. Therefore potential impacts will be kept at a less than significant level. MITIGATION: None required. Issues (and Supporting Information Sources) Potentially Significant Impact Potentially Less Than Significant Impact No Impact 16. Transportation/Traffic - Would the project: Significant a) Conflict with an applicable plan, ordinance or policy Potentially Impact Unless Less Than X Issues (and Supporting Information Sources) Significant Mitigation Significant No of the circulation system, taking into account all modes of Impact Incorporated Impact Impact 15. Recreation - a) Would the project increase the use of existing X neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? b) Does the project include recreational facilities or require X the construction or expansion of recreational facilities, which might have an adverse physical effect on the environment? DISCUSSION The project will not result in a substantial increase of park usage or require new or expanded services. The project will improve the safety of the bike lanes and trails for pedestrian and equestrian users. The project would be consistent with the goals and policies of the Open Space and Conservation Element of the Town's General Plan. Therefore potential impacts will be kept at a less than significant level. MITIGATION: None required. Issues (and Supporting Information Sources) Potentially Significant Impact Potentially Significant Impact Unless Mitigation Incorporated Less Than Significant Impact No Impact 16. Transportation/Traffic - Would the project: a) Conflict with an applicable plan, ordinance or policy X establishing measures of effectiveness for the performance of the circulation system, taking into account all modes of transportation including mass transit and non -motorized travel and relevant components of the circulation system, including but not limited to intersections, streets, highways and freeways, pedestrian and bicycle paths, and mass transit? FEBRUARY, 2012 42 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The proposed project includes trail improvements, bike lanes and bicycle and pedestrian safety improvements along Arastradero and Page Mill Roads. The project will encourage greater use of non - motorized travel along this corridor by addressing key safety concerns. The proposed improvements include the following: • Pedestrian crossings at the south and east portions of the intersection of Baleri Ranch and Page Mill Roads. • Restriping of the stop signs and installation of crosswalks at Berry Hill Court and Stirrup Way. • Restriping of the stop sign at Twin Oaks. • Restriping of turn lanes at the intersection of Page Mill and Arastradero Roads. • Restriping of bike lanes along Page Mill Road and the western portion of Arastradero Roads. • Road widening to accommodate new bike lanes along the eastern portion of Arastradero Road The proposed trail improvement project is designed in conformance with applicable pathways and circulation plans of the Town of Los Altos Hills and the County of Santa Clara. The project supports the County's congestion management program through bike lane improvements, and would not result in any increase to traffic levels or safety risks in the project vicinity or to air traffic patterns. The project will result in trail improvements designed to get people out of their cars by providing safe pathways and bike lanes, and therefore are not viewed as new traffic generators. Additionally, no new parking lots or parking spaces are proposed with the project, and new NO PARKING signage has recently been installed to increase safety and limit disturbances to existing residents. The project will have a less than significant increase in hazards due to project design and will not result in an inadequate emergency access. The FEBRUARY, 2012 43 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact b) Conflict with an applicable congestion management X program, including, but not limited to level of service standards and travel demand measures, or other standards established by the county congestion management agency for designated roads or highways? c) Result in a change in air traffic patterns, including either an X increase in traffic levels or a change in location that results in substantial safety risks? d) Substantially increase hazards due to a design feature (e.g., X sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? e) Result in inadequate emergency access? X f) Conflict with adopted policies, plans, or programs X regarding public transit, bicycle, or pedestrian facilities, or otherwise decrease the performance or safety of such facilities? DISCUSSION The proposed project includes trail improvements, bike lanes and bicycle and pedestrian safety improvements along Arastradero and Page Mill Roads. The project will encourage greater use of non - motorized travel along this corridor by addressing key safety concerns. The proposed improvements include the following: • Pedestrian crossings at the south and east portions of the intersection of Baleri Ranch and Page Mill Roads. • Restriping of the stop signs and installation of crosswalks at Berry Hill Court and Stirrup Way. • Restriping of the stop sign at Twin Oaks. • Restriping of turn lanes at the intersection of Page Mill and Arastradero Roads. • Restriping of bike lanes along Page Mill Road and the western portion of Arastradero Roads. • Road widening to accommodate new bike lanes along the eastern portion of Arastradero Road The proposed trail improvement project is designed in conformance with applicable pathways and circulation plans of the Town of Los Altos Hills and the County of Santa Clara. The project supports the County's congestion management program through bike lane improvements, and would not result in any increase to traffic levels or safety risks in the project vicinity or to air traffic patterns. The project will result in trail improvements designed to get people out of their cars by providing safe pathways and bike lanes, and therefore are not viewed as new traffic generators. Additionally, no new parking lots or parking spaces are proposed with the project, and new NO PARKING signage has recently been installed to increase safety and limit disturbances to existing residents. The project will have a less than significant increase in hazards due to project design and will not result in an inadequate emergency access. The FEBRUARY, 2012 43 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT project will increase the safety and performance of bicycle, and pedestrian facilities through trail and bike lane improvements. Providing a trail along Arastradero Road would increase the number of pedestrians in that corridor since pedestrians currently must walk in the street which discourages some potential users. However, it is unlikely that the number of users would increase markedly. Hexagon Transportation Consultants estimated that during the busiest four hour period of Saturday mornings, the number of pedestrians using the new trial could increase from an average of 14 users to an average of 30 users. Hexagon Transportation Consultants conducted counts of potential trail usage in March 2011, June 2011 and again in December 2011 after the opening of the new Stanford trail near Deer Creek. All counts were done on a Saturday between the hours of 10:00 AM and 2:00 PM and the weather conditions were clear and sunny on all days. The counts were taken at: Fremont Road near Town Hall, Arastradero Road at Stirrup Way, and at Page Mill Road near Arastradero Road. At all locations the counts were higher in March, prior to the opening of the Stanford trail near Deer Creek. Hexagon Transportation Consultants concluded that the opening of the Stanford trail near Deer Creek has had no effect on the usage of other nearby roads or trails (Hexagon Transportation Consultants: Pedestrian, Bicycle, and Equestrian Recounts for the Arastradero Road Trail Project, June 17, 2011). Parked cars were counted at the Arastradero Preserve, and nearby streets, and also at the Page Mill Road park-and-ride lot. Of the cars on the streets during all surveys, a maximum of one vehicle was parked on Tracy Court or Liddicoat Drive, and the rest were parked on Arastradero Road. The 46 -space Page Mill Road park-and-ride lot was counted in June and December and was found to be 2/3 full during both counts, while the Arastradero Preserve lot was found to be full or mostly full during all counts. Arastradero Road and Page Mill Road are heavily used by experienced bicyclists. Experienced bicyclists are comfortable on roads without bike lanes and Hexagon Transportation Consultants estimates that by adding bike lane striping to these roads that usage by experienced bicyclists will not change. The benefit of bike lanes is that they allow less -experienced bicyclists to feel comfortable and safe, and they make drivers more aware of bicyclists, which can increase safety. The presence of bike lanes on Arastradero Road and Page Mill Road leading to the Arastradero Preserve will encourage more Los Altos Hills residents to ride bikes to the Preserve. Hexagon Transportation Consultants estimated that if all the Los Altos Hills residents normally visiting the Preserve during the busiest four hour period of a Saturday morning were to ride bicycles that would add about 8% more bicyclists, or about 31 additional bicyclists during the four hour peak period. The Town will work with the contractor to install appropriate signage and striping at the bike lane termination on Page Mill Road at the narrow bridge crossing. This requirement will reduce potential traffic safety hazards to a less -than -significant level. RECON MENDED CONDITION OF PROTECT APPROVAL: The project plans shall incorporate bike lane signage and striping on Page Mill Road to the satisfaction of the Public Works Director. Throughout the course of project review and public hearings Town residents and neighbors of the project have raised several concerns regarding existing traffic and parking conditions in the vicinity of the project area. In response to those concerns the Town made a number of public improvements this past spring which include: • The Town installed bike lane signage at Purissima/Arastradero Roads to direct bike traffic onto an existing off-road trail. FEBRUARY, 2012 44 REVISED INITIAL STUDY—ARASTRADERO TRAIL IMPROVEMENT PROJECT • The Town installed no parking signs on Arastradero Road at Liddicoat near the Arastradero Preserve. • The Town installed barriers/wood blocks along Arastradero Road near the Arastradero Preserve to separate the parking area from the pathway. • The Town hired Hexagon Transportation Consultants to conduct a traffic safety evaluation at Stirrup Way and Arastradero Road. The Town also reported an erosion problem located on Page Mill Road near Berry Hill Court to Caltrans in August 2010. In March of 2011 Caltrans informed the Town that repair work would take 1-2 years, but Caltrans would consider implementing temporary measures to minimize further erosion. Project construction would entail grading of excavated soil for construction of a proposed retaining wall. Export of material off-site could generate several truckloads of off -haul. Truck operations would occur between 8:00 a.m. 5:30 p.m during permitted construction hours. The Town will work with the contractor to devise a traffic control plan to ensure safe and efficient traffic flow under periods when soil is hauled on or off the project site. This would include, but would not be limited to, provisions for the contractor to place construction notification signs noting the dates and time of construction and hauling activities, or providing additional traffic control. All trucks hauling soil, sand, and other loose debris will need to be covered (refer to Air Quality mitigation measure lb.). This requirement will reduce potential traffic safety hazards to a less -than -significant level. NIITIGATION: None required. FEBRUARY, 2012 45 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Inco orated linpact Im act 17. Utilities and Service Systems —Would the project: a) Exceed wastewater treatment requirements of the X applicable Regional Water Quality Control Board? b) Require or result in the construction of new water or X wastewater treatment facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? c) Require or result in the construction of new storm water X drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? d) Have sufficient water supplies available to serve the X project from existing entitlements and resources, or are new or expanded entitlements needed? e) Result in a determination by the wastewater treatment X provider, which serves or may serve the project that it has adequate capacity to serve the projects projected demand in addition to the providers existing commitments? FEBRUARY, 2012 45 REVISED INITIAL STUDY—ARASTRADERO TRAIL IMPROVEMENT PROJECT DISCUSSION The project will not require the construction of new utilities or necessitate new service demands. Therefore the project will have no impact to utilities, sewer and water or storm water treatment systems. MITIGATION: None required. FEBRUARY, 2012 46 Potentially Significant Potentially Impact Unless Less Than Issues (and Supporting Information Sources) Significant Mitigation Significant No Impact Incorporated Impact Impact f) Be served by a landfill with sufficient permitted capacity to X accommodate the projects solid waste disposal needs? g) Comply with federal, state, and local statutes and X regulations related to solid waste? DISCUSSION The project will not require the construction of new utilities or necessitate new service demands. Therefore the project will have no impact to utilities, sewer and water or storm water treatment systems. MITIGATION: None required. FEBRUARY, 2012 46 REVISED INITIAL STUDY — ARASTRADERO TRAIL IMPROVEMENT PROJECT Through review of the proposed project the Town of Los Altos Hills finds that there are no potentially significant impacts with the implementation of mitigation measures as recommended. The mitigation measures provided in this Initial Study demonstrate that the proposed project does not have the potential to substantially degrade the quality of the environment, reduce the habitat or cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce or restrict the number or the range of a rare or endangered plant or animal, or eliminate important examples of the major periods of California history or prehistory. The proposed project includes development of new and resurfaced trails, road widening to accommodate new bike lanes, a 475 foot long retaining wall varying in average height of 1.5 feet, roadway striping to improve bicycle, and pedestrian safety. Surrounding uses include single family residences, Santa Clara Valley Water District land north of Baleri Ranch Road, Caltrans right of way, a Park and Ride lot at the intersection of Arastradero Road and Page Mill Road, and the I-280 freeway. Overall the proposed project would not significantly degrade the quality of the environment, have substantial adverse effects on human beings directly or indirectly, or have any cumulatively considerable impacts. FEBRUARY, 2012 47 Potentially Significant Issues (and Supporting Information Sources) Potentially Significant Impact Unless Mitigation Less Than Significant No Impact Incorporated Impact Impact 18. Mandatory Findings of Significance - a) Does the project have the potential to degrade the quality X of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history orprehistory? b) Does the project have impacts that are individually X limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)? c) Does the project have environmental effects which will X cause substantial adverse effects on human beings, either directly or indirectly? Through review of the proposed project the Town of Los Altos Hills finds that there are no potentially significant impacts with the implementation of mitigation measures as recommended. The mitigation measures provided in this Initial Study demonstrate that the proposed project does not have the potential to substantially degrade the quality of the environment, reduce the habitat or cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce or restrict the number or the range of a rare or endangered plant or animal, or eliminate important examples of the major periods of California history or prehistory. The proposed project includes development of new and resurfaced trails, road widening to accommodate new bike lanes, a 475 foot long retaining wall varying in average height of 1.5 feet, roadway striping to improve bicycle, and pedestrian safety. Surrounding uses include single family residences, Santa Clara Valley Water District land north of Baleri Ranch Road, Caltrans right of way, a Park and Ride lot at the intersection of Arastradero Road and Page Mill Road, and the I-280 freeway. Overall the proposed project would not significantly degrade the quality of the environment, have substantial adverse effects on human beings directly or indirectly, or have any cumulatively considerable impacts. FEBRUARY, 2012 47 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT ATTACHMENT 1 BIOTIC ASSESSMENT OF THE PROPOSED STANFORD TRAILS PROJECT AT ARASTRADERO ROAD AND PAGE MILL ROAD LOS ALTOS HILLS, CALIFORNIA BY COAST RIDGE ECOLOGY FEBRUARY 2012 FEBRUARY, 2012 48 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT ATTACHMENT 2 DRAFT GEOTECHNICAL INVESTIGATION Los ALTOS HILLS C-2 TRAIL ARASTRADERO ROAD Los ALTOS HILLS, CALIFORNIA BY CORNERSTONE EARTH GROUP DECEMBER, 2011 FEBRUARY,2012 49 REVISED INITIAL STUDY - ARASTRADERO TRAIL IMPROVEMENT PROJECT ATTACHMENT 3 PEDESTRIAN, BICYCLE, AND EQUESTRIAN RECOUNTS FOR THE ARASTRADERO ROAD TRAIL PROJECT DECEMBER 19, 2011 4 PEDESTRIAN, BICYCLE, AND EQUESTRIAN RECOUNTS FOR THE ARASTRADERO ROAD TRAIL PROJECT JUNE 179 2011 01 PEDESTRIAN, BICYCLE, AND EQUESTRIAN STUDY FOR THE PROPOSED ARASTRADERO ROAD TRAIL PROJECT APRIL 47 2011 BY HEXAGON TRANSPORTATION CONSULTANTS, INC. FEBRUARY, 2012 50 BIOLOGICAL RESOURCES ASSESSMENT FOR TOWNT OF LOS ALTOS HILLS ARASTRADERO TRAIL IMPROVEMENT PROJECT LOS ALTOS HILLS, CALIFORNIA PREPARED FOR: Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, CA 94022 _PREPARED BY: Coast Ridge Ecology 1072 Geneva Avenue San Francisco, CA 94112 Phone: 415-404-6757 — Fax: 415-404-6097 Email: Crecology@gmail.com February 2012 BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 -- Page i TABLE OF CONTENTS I. SUMMARY..........................................................................................................................1 H. PROPERTY LOCATION.................................................................................................. 3 III. PROJECT DESCRIPTION.............................................................................................. 3 IV. METHODS......................................................................................................................... 3 V. EXISTING SETTING....................................................................................................... 4 A. SOILS................................................................................................................................. 4 B. HYDROLOGY AND WATER RESOURCES.............................................................................. 4 VI. PLANT COMMUNITIES AND HABITAT TYPES ...................................................... 5 A. VEGETATION..................................................................................................................... 5 B. WILDLIFE HABITAT........................................................................................................... 9 C. WILDLIFE MOVEMENT CORRIDORS................................................................................. 10 VH. REGULATORY CONSIDERATIONS........................................................................11 A. FEDERAL AND STATE ENDANGERED SPECIES ACTS ......................................................... 11 B. SPECIES OF SPECIAL CONCERN........................................................................................ 12 C. NESTING BIRDS................................................................................................................ 12 D. CALIFORNIA ENVIRONMENTAL QUALITY ACT................................................................. 12 E. CALIFORNIA NATIVE PLANT SOCIETY AND CEQA.......................................................... 13 F. REGULATED WATERS....................................................................................................... 13 G. STORMWATER CONTROL REQUIREMENTS....................................................................... 13 H. TOWN OF LOS ALTOS HILLS HERITAGE TREE DESIGNATION ........................................... 14 I. SANTA CLARA VALLEY WATER DISTRICT STREAMSIDE STANDARDS AND GUIDELINES... 14 J. SIGNIFICANCE CRITERIA................................................................................................... 15 VIH. SPECIAL STATUS PLANTS, ANIMALS, AND NATURAL COMMUNITIES ..16 A. CALIFORNIA RED -LEGGED FROG..................................................................................... 17 B. CALIFORNIA TIGER SALAMANDER.................................................................................... 18 C. SAN FRANCISCO GARTER SNAKE..................................................................................... 19 D. STEELHEAD..................................................................................................................... 20 E. SAN FRANCISCO DUSKY -FOOTED WOODRAT................................................................... 21 F. RAPTORS AND NESTING BIRDS......................................................................................... 22 G. BATS................................................................................................................................23 H. MONARCH BUTTERFLY.................................................................................................... 24 I. SPECIAL STATUS PLANTS AND RARE PLANT COMMUNITIES ............................................. 24 IX. RECOMMENDED AVOIDANCE AND MINIMIZATION MEASURES ................ 26 A. CALIFORNIA RED -LEGGED FROG..................................................................................... 26 B. SAN FRANCISCO DUSKY -FOOTED WOODRAT................................................................... 27 C. PROTECTION OF SPECIAL STATUS RAPTORS..................................................................... 27 D. PROTECTION OF MIGRATORY BIRDS................................................................................. 27 E. PROTECTION OF SPECIAL STATUS AND NON -SPECIAL STATUS BATS ............................... 28 F. PROTECTION OF SPECIAL STATUS PLANTS AND PLANT COMMUNITIES ............................. 28 G. PROTECTION OF REGULATED WATERS AND WETLANDS ................................................... 29 H. EXCLUSION OF INVASIVE SPECIES.................................................................................... 29 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 -- Page ii I. WILDLIFE CORRIDORS....................................................................................................... 30 XI. REFERENCES................................................................................................................ 31 LIST OF FIGURES Figure1. Project Location..................................................................................8 Figure 2. Aerial Image of Project Area..................................................................9 APPENDICES Appendix A. Representative Photos of the Site.....................................................A-1 Appendix B. Special Status Plant and Animal Species Evaluated for the Project Site ......... B-1 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 F -mail• rRcnnlnnvrlmmnil rnm . ennnni rRnrnlnni �nm BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page I I. SUMMARY A biological assessment was conducted for the Arastradero Trail Improvement Project located in the Town of Los Altos Hills, California (Figure 1). The trail starts at the intersection of Arastradero and Purissima Roads, follows Arastradero Road under I-280 westerly to Page Mill Road, then south along Page Mill Road to the intersection with Baleri Ranch Road/Arastradero Road (Fiug re 2). The Trail Project includes a walking path and separate bike lanes. The trail covers approximately one lineal mile and incorporates existing paths where possible. Intersection improvements at Page Mill Road/ Baleri Ranch-Arastradero will be completed to accommodate pedestrians. The Town of Los Altos Hills is located in the foothills on the eastern flank of the Santa Cruz Mountains, and consists of flat to moderately steep topography. Annual rainfall for the Town of Los Altos Hills averages 13.5 inches per year. Land uses within and surrounding the project area include roadways, residential areas, and a carpool parking area at the intersection of Page Mill Road and Arastradero Road. Trees that will require removal include 6 Eucalyptus (Eucalyptus globulus) trees and 5 Coast live oak (Quercus agrifolia) trees. None of the trees proposed for removal are considered heritage oak tree as defined by the Town Municipal Code regulations. The trail alignment was surveyed for biological resources on November 29 and December 7, 2010 by wildlife biologist Patrick Kobernus. All plant and animal species encountered on site were documented as well as plant communities and habitat types that could support special status species. The California Department of Fish and Game (CDFG) Natural Diversity Database (CNDDB), US Fish and Wildlife Service List of Endangered and Threatened Species, the California Museum of Vertebrate Zoology and the California Native Plant on-line Inventory of Rare and Endangered Plants were consulted for known occurrences of sensitive plant, animal and native plant communities of concern in the region. The CNDDB query and the US Fish and Wildlife Service search included the Palo Alto 7.5' USGS topographic quadrangle, and eight surrounding quadrangles (CDFG 2010a). Vegetation within the trail alignment project area includes Grassland (California Annual Grassland Series); Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance), and suburban forest that is associated with residential properties that border the trail alignment (Sawyer 2009; Holland 1986). The project area also includes several planted roadside trees, most of which will not be impacted by the project. The most prominent water feature in the vicinity of the project area is Matadero Creek. A 350 -foot section of the trail follows an existing trail along Matadero Creek (Appendix A, Photo A-1). Matadero Creek is a perennial creek that emanates from the foothills to the west and flows through the Town of Los Altos Hills and the City of Palo Alto before entering San 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 2 Francisco Bay. Other water bodies in the area include Felt Lake which is located approximately 0.9 miles northwest of the trail alignment and Deer Creek, a perennial creek that crosses under the trail alignment on the east side of the I-280 Freeway. There are no other ponds, streams or other wetland habitats located within the project area. Three soil map units were identified within the project area. These soil units are derived from weathered sandstone or calcareous shale. Along most areas of the trail alignment these soils have been highly disturbed from road -building and grading activities (MRCS 2010). No serpentine soils exist within the trail alignment or in adjacent areas near the project area. Based on the field assessment and review of database and literature sources such as the California Natural Diversity Database (CNDDB), the following special status species were identified as having potential for occurrence within the project area. Additional special status species within the region that were ruled out from potential occurrence or are not expected based on habitat requirements and/or other factors are included in Appendix B. • There is potential for one federally listed species, the California red -legged frog, (Rana aurora draytonii) and one state fully protected species, white-tailed kite (Elanus leucurus) to utilize the project area. One non -listed special status species was found to occur within the trail alignment, the San Francisco dusky -footed woodrat (Neotoma fuscipes annectens). Four additional non -listed special status wildlife species were identified as having potential for presence within the project area, Cooper's hawk (Accipiter cooperii), loggerhead shrike (Lanius ludovicianus), western red bat (Lasiurus blossevillii) and pallid bat (Antrozous pallidus),. Eight species on various watch lists that also have potential for presence within the project area include fringed myotis (Myotis thysanodes), long-legged myotis (Myotis volans), hoary bat (Lasiurus cinereus), Yuma bat (Myotis yumanensis), long-eared bat (Myotis evotis), California thrasher (Toxostoma redivivum), Nuttall's woodpecker (Picoides nuttallii) and oak titmouse (Baeolophus inornatus). • Two special status plant species: western leatherwood (Dirca occidentalis) and San Francisco collinsia (Collinsia multicolor) were identified as having potential to occur within the project area. • One rare plant community, Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance) was identified within Matadero Creek, adjacent to the trail alignment. Three additional federally and/or state listed species that are a high priority for conservation are included in the following discussion. These are San Francisco garter snake (Thamnophis sirtalis tetrataenia), California tiger salamander (Ambystoma californiense) and steelhead (Oncorhynchus mykiss irideus). Though these species are not expected to occur on site, a discussion of each is provided because they are federally listed species and have been detected in the region (CDFG 2010a). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 F_maii- rPorninnvnmmnii rnm . WIMA, rParninnv rnm BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 3 No impacts are anticipated to special status species or rare plant communities as a result of the proposed project. Potential impacts and recommended measures to mitigate impacts to regulated waters, special status species and special status communities are provided in Section IX. II. PROPERTY LOCATION The Arastradero Trail Improvement project is located in the Town of Los Altos Hills, California (Figure 1). The C-2 trail starts at the intersection of Arastradero and Purissima Roads, follows Arastradero Road under I-280 westerly to Page Mill Road, then south along Page Mill Road to the intersection with Baleri Ranch Road/Arastradero Road i e 2). III. PROJECT DESCRIPTION The Trail Project includes a walking path and separate bike lanes. The trail covers approximately one lineal mile and incorporates existing paths where possible. The path portion will be constructed consistent with the Town's Type 2B Roadside Path requirements, including: 5 -feet width with 2 -feet wide shoulders where possible Surface, 6 -inches of Stevens Creek Quarry Crusher Fines 2 -inch x 6 -inch wood headers The bike lanes will be striped on existing asphaltic concrete ("AC") paved roadways. In some areas the existing AC surface will require edge widening to accommodate the bike lanes. The bike lanes on Arastradero from Purissima to Page Mill Road, and on Page Mill to Berry Hill Court will be constructed in a Class II configuration (separate, striped lanes in both directions). On Page Mill between Berry Hill and Baleri Ranch Road, the bike lanes will be Class III (bikes merge with vehicular traffic in both directions). Appropriate striping and signage will be included throughout the Project. Trees that will require removal include 6 Eucalyptus (Eucalyptus globulus) trees on the west side of Arastradero east of Page Mill Road and 5 Coast live oak (Quercus agrifolia) trees less than 12" in trunk diameter including three along Arastradero Road at Stirrup Way to accommodate the new retaining wall and bike lane. IV. METHODS The trail alignment was surveyed for biological resources on November 29 and December 7, 2010 by wildlife biologist Patrick Kobemus. Weather was overcast and calm with air temperatures in the 60's (F) on both visits. All plant and animal species encountered on site were documented as well as plant communities and habitat types that could support special status species. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894. Fax: 415-404-6097 E-mail: CRecoloavoamail.com • www.CRecoloov.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 4 The California Department of Fish and Game (CDFG) Natural Diversity Database (CNDDB), US Fish and Wildlife Service List of Endangered and Threatened Species, the California Museum of Vertebrate Zoology and the California Native Plant on-line Inventory of Rare and Endangered Plants were consulted for known occurrences of sensitive plant, animal and native plant communities of concern in the region. The CNDDB query and the US Fish and Wildlife Service search included the Palo Alto 7.5' USGS topographic quadrangle, and eight surrounding quadrangles (CDFG 2010a). V. EXISTING SETTING The project area is located within the Town of Los Altos Hills and borders Page Mill Road and Arastradero Road. The trail alignment is bordered by existing roadways, open lots, residential properties and Matadero Creek along its western section. The trail alignment parallels Arastradero Road and Highway 280 on the east, and Page Mill Road and Matadero Creek on the west. The surrounding land -uses are primarily roadways, residential areas, and also include a carpool parking area at the intersection of Page Mill Road and Arastradero Road. The Town is located in the foothills on the eastern flank of the Santa Cruz Mountains, and consists of flat to moderately steep topography. Annual rainfall for the Town of Los Altos Hills averages 13.5 inches per year. A. Soils Three soil map units were identified within the project area, Diablo-Urbanland complex, 9 to 15 percent slopes, Cropley clay, 2 to 9 percent slopes, and Zeppelin-Mccoy complex, 15 to 30 percent slopes. These soil units are derived from weathered sandstone or calcareous shale. Along most areas of the trail alignment these soils have been highly disturbed from road - building and grading activities (NRCS 2010). No serpentine soils exist within the trail alignment or in adjacent areas near the proj ect area. B. Hydrology and Water Resources The project site is a linear trail that borders existing roadways (Arastradero Road and Page Mill Road). A 350 -foot section of the trail follows an existing trail along Matadero Creek (Appendix A, Photo A-1). Matadero Creek is a perennial creek that emanates from the foothills to the west and flows through the Town of Los Altos Hills and the City of Palo Alto before entering San Francisco Bay. The section of the creek that borders the trail alignment is natural and has mature riparian forest along its banks. Other water bodies in the area include Felt Lake which is located approximately 0.9 miles northwest of the trail alignment and Deer Creek, a perennial creek that crosses under the trail alignment on the east side of the I-280 Freeway. There are no other ponds, streams or other wetland habitats located within the project area. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 5 Matadero Creek consists of approximately eight miles of channel and enters the San Francisco Estuary via the Palo Alto flood basin. Its drainage area is approximately 14 square miles. Matadero Creek is similar to many tributary streams to San Francisco Bay, in that upper portions of the creek provide good habitat for native fish and other aquatic species, while the lower portions of the Creek that flow through urban areas have been highly impacted by channelization, pollution and invasive species. Deer Creek is a tributary to Purissima Creek, which in turn is tributary to Matadero Creek. Deer Creek drains an area of 1.6 square miles and comprises approximately 2.5 miles of channel. The San Francisco Bay Regional Water Quality Control Board has established in its Basin Plan (RWQCB 1995), several beneficial uses for Matadero Creek, including Wildlife Habitat, Warm and Cold Freshwater Habitat, Fish Spawning, Fish Migration and Contact (RECl) and Non -contact water recreation. VI. PLANT COMMUNITIES AND HABITAT TYPES A. Vegetation Vegetation within the trail alignment project area includes Grassland (California Annual Grassland Series); Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance), and suburban forest that is associated with residential properties that border the trail alignment (Sawyer 2009). The project area also includes several planted roadside trees, most of which will not be impacted by the project. Grassland habitat within the project area is primarily annual grassland. Annual grassland is dominated by nonnative Mediterranean annual grasses and an assemblage of non-native forbs. Scattered oak species are also present. This vegetation type is the most dominant plant community along the trail alignment. Most of the trailside areas have been heavily disturbed as result of past road building, and vegetation consists of nonnative plant species that colonize .disturbed habitats. Species observed include annual grasses such as wild oat (Avena barbata), Italian wildrye (Lolium multiflorum), and herbaceous weeds such as black mustard (Brassica nigra), cut -leaf geranium (Geranium dissectum) and bristly ox -tongue (Picris echioides). Central Coast Riparian Scrub consisting of shining willow (Salix lucida ssp. lasiandra), arroyo willow (Salix lasiolepis), red willow (Salix laevigata) and black walnut (Juglans californica var. hindsii) is present within Matadero Creek along the trail alignment. This habitat type is dominated by native tree species and a predominately nonnative shrub understory that includes Himalaya blackberry (Rubus discolor) and poison hemlock (Conium maculatum). Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance) is considered a rare plant community (CDFG 2006). Suburban forest includes ornamental vegetation as well as remnant native trees such as valley oak (Quercus lobata). 1072 Geneva Avenue, San Francisco CA 94112 . Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 F -mail• CRornlnnvnnmail rnm . www C'Rarnlnnv rnm BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 6 Eleven trees (consisting of six eucalyptus and five Coast live oaks) will require removal to accommodate project construction. They include six Eucalyptus trees on the west side of Arastradero (east of Page Mill Road) to accommodate the eastbound bike lanes; five Coast live oaks less than 12" in trunk diameter, including three along Arastradero Road at Stirrup Way to accommodate the new retaining wall and bike lane. There are no wetland habitats within the project alignment. One other wetland feature borders the eastern portion of the alignment. This is a narrow drainage swale on the west side of Arastradero Drive. The drainage is approximately 700 feet long and extends along Arastradero Drive between Stirrup Way on the north and Twin Oaks Court on the south. The dominant plant species within the swale is field mustard (Brassica rapa), an upland species. No wetland vegetation was observed within the swale, and approximately 50% of the length of the swale is contained in a concrete v -ditch (Appendix A: Photo A-2). To meet the US Army Corps of Engineers (ALOE) definition of wetland, an area must demonstrate three, critical characteristics: wetland vegetation, wetland hydrology, and wetland soils (Federal Interagency Committee for Wetland Delineation, 1989). Additionally, to fall under jurisdiction of the ACOE, a wetland must have some evident hydrological connection to other wetlands and/or waters of the United States. The US Fish and Wildlife Service definition of wetland is similar: at least periodically, the land must support predominantly hydrophytes; the substrate must be predominantly undrained hydric soil; or the substrate is non -soil that is saturated with water or covered by shallow water at some time during the growing season of the year (Cowardin, et al., 1979). No hydrophytic vegetation or wetland hydrologic indicators were observed within the project area. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 7 Figure 1. Los Altos Hills., Trail (U) Project Location, Los Altos: Hills, Califomia. base Map: TopowExplorler. M-4 by Coast Ridge Ecology, Ddcamber 2010. 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Wildlife Habitat The habitat types along the trail alignment provide potential foraging and breeding habitat for a variety of native wildlife species. Bird species that utilize grassland habitat include chestnut -backed chickadee, oak titmouse, Cooper's hawk, sharp -shinned hawk (Accipiter striatus), white-tailed kite (Elanus leucurus) and great blue heron (Ardea herodias), among others. Oak savannah/ grassland provides good foraging habitat and cover for herbivorous mammals such as California meadow vole (Microtus californicus), pocket Botha's pocket gopher, black -tailed hare (Lepus californicus) and black -tailed mule deer (Odocoileus hemionus). Predators that utilize oak savannah/ grassland include gopher snake (Pituophis catenifer), red-tailed hawk (Buteo jamaicensis) and bats such as pallid bat (Antrozous pallidus). The riparian woodland habitat associated with Matadero Creek provides excellent habitat for passerine birds such as song sparrow (Melospiza melodia), Wilson's warbler (Wilsonia pusilla), spotted towhee (Pipilo maculatus), and bats such as California myotis (Myotis californicus) and Yuma bat (Myotis yumanensis). Stream habitat combined with understory vegetation and woody debris within the riparian forest supports amphibians such as Pacific tree frog (Hyla regilla), California red -legged frog (Rana aurora draytonii) and California newt (Taricha torosa). Predators that likely utilize the riparian habitat include raccoon (Procyon lotor), gray fox (Urocyon cinereoargenteus), red -shouldered hawk (Buteo lineatus), and aquatic garter snakes (Thamnophis sp.), among others. Matadero Creek in the vicinity of the project area supports native and nonnative fishes. Species of native fish expected to be present in the reach of creek near the project site include Sacramento sucker (Catostomus occidentalis) and California roach (Hesperoleucus symmetricus). Non-native fish species within the watershed that may be present in the creek include bluegill (Lepomus macrochirus), green sunfish (Lepomis cyanellus) and goldfish (Carassius auratus), (SCVURPPP 2008). Suburban forest provides habitat for a variety of wildlife, especially birds such as mourning dove (Zenaida macroura), house wren (Troglodytes aedon), and house finch (Carpodacus mexicanus), among others. Remnant native trees, especially larger and older trees, such as large valley oaks (Quercus lobata) and coast live oaks, increase the habitat value of suburban areas through providing food resources for wildlife in the form of acorns and insects, as well as providing important structure for nesting and roosting. Wildlife observed by sight or sign during the site visits included red-tailed hawk (Buten jamaicensis), Cooper's hawk (Accipiter cooperii), hairy woodpecker (Picoides pubescens), Nuttall's woodpecker (Picoides nuttallii), bushtit (Psaltriparus minimus), scrub jay (Aphelocoma californica), Bewick's wren (Thryomanes bewickii), brown creeper (Certhia americana), oak titmouse (Baeolophus inornatus), American kestrel (Falco sparverius), chestnut backed chickadee (Poecile rufescens), golden -crowned sparrow (Zonotrichia atricapilla), Audubon's warbler (Dendroica coronata), black -tailed mule deer, Botha's pocket gopher (Thomomys bottae), and San Francisco dusky -footed woodrat (Neotoma 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 . Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 10 fuscipes annectens). Larger carnivore species that may also utilize habitats within the project area on an infrequent basis include bobcat (Fells rufus), coyote (Canis latrans), and on rare occasion Mountain lion (Felis concolor). Owl pellets (possibly from a Great homed owl; Bubo virginianus), were observed beneath trees #21 and #22 along the trail alignment, adjacent to Arastradero Road on November 29, 2010. Both trees are eucalyptus trees and are proposed for removal. Tree #21 has a possible raptor nest located at approximately 70 feet in height. Several San Francisco dusky -footed woodrat nests are located near the trail alignment. All of these nest structures are outside of the project area however -one nest is located within a Coast -live oak tree located along Arastradero Road near Stirrup Way that is proposed for removal. Many of the wildlife species observed will also utilize ornamental vegetation, roadside trees, and suburban yards that are adjacent to the grassland and riparian habitat along the trail alignment. C. Wildlife Movement Corridors Habitat loss, fragmentation, and degradation resulting from land use changes or habitat conversion can alter the use and viability of wildlife movement corridors (i.e. linear habitats that naturally connect and provide passage between two or more otherwise disjunct larger habitats or habitat fragments). In general, studies suggest that habitat corridors provide connectivity for, and are used by wildlife and as such, are an important conservation tool. According to Beier and Loe (1992), wildlife habitat corridors fulfill several functions. They maintain connectivity for daily movement, travel, mate -seeking, and migration; plant propagation; genetic interchange; population movement in response to environmental change or natural disaster; and recolonization of habitats subject to local extirpation. The suitability of a habitat as a wildlife movement corridor is related to, among other factors, the habitat corridor's dimensions (length and width), topography, vegetation, exposure to human influence, and the species in question. Species utilize movement corridors in several ways. "Passage species" are those species that use corridors as thru-ways between outlying habitats. The habitat requirements for passage species are generally less than those for corridor dwellers. Passage species use corridors for brief durations, such as for seasonal migrations or movement within a home range. As such, movement corridors do not necessarily have to meet any of the habitat requirements necessary for a passage species' everyday survival. Large herbivores, such as deer and elk, and medium -to -large carnivores, such as coyotes, bobcats and mountain lions, are typically passage species. "Corridor dwellers" are those species that have limited dispersal capabilities — a category that includes most plants, insects, reptiles, amphibians, small mammals, and birds — and use corridors for a greater length of time. As such, wildlife movement corridors must fulfill key habitat components specific to a species' life history requirements in order for them to survive. In general, however, the suitability and/or utility of the landscape — specifically, of the landscape as corridor habitat — is best evaluated on a species -level. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 11 Movement corridors for resident and migratory wildlife are not expected to be disrupted by the proposed trail alignment. The trail will not present any obstacles to existing wildlife movement, and follows an existing footpath along existing roadways for most it's length. VII. REGULATORY CONSIDERATIONS Federal and state -listed species (endangered, threatened, fully -protected) receive various levels of legal protection under the federal and state endangered species acts and the California Fish and Game Code. The federal Migratory Bird Treaty Act of .1918 and Section 3500 of the California Fish and Game Code protect active nests of migratory and other birds, and provide criminal penalties for take of hawks, owls, and take or disturbance of all bird nests or eggs. Potential impacts to other special status or otherwise sensitive species must be disclosed and evaluated pursuant to the California Environmental Quality Act (CEQA). Wetland permitting requirements that may provide additional protections for species and habitats include the California Department of Fish and Game (DFG) 1600 Streambed Alteration Agreement permit process, US Army Corps of Engineers (ACOE) Section 404 permit and the State Regional Water Quality Control Board (RWQCB) 401 Certification permit. A. Federal and State Endangered Species Acts The United States Endangered Species Act (ESA) is administered by the United States Fish and Wildlife Service (USFWS). The California Endangered Species Act (CESA), the Native Plant Protection Act (LAPPA), and CEQA afford protection to species of concern included on State -maintained lists. The California Department of Fish and Game (CDFG) has statutory responsibility for the protection of State listed species, and is a trustee agency under CEQA. Both the Federal and State endangered species acts provide protection for listed species. In particular, the Federal act prohibits "take". "Take" is defined by the ESA as "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect a federally listed, endangered species of wildlife, or to attempt to engage in any such conduct." Take not specifically allowed by Federal permit under Section I0(a)(1)(B) of the ESA is subject to enforcement through civil or criminal proceedings under Section 9 of the ESA. While "take" is easily understood in the sense of deliberately capturing or killing individual animals, Federal regulations also define take to include the incidental destruction of animals in the course of an otherwise lawful activity, such as habitat loss due to development. Under those rules the definition of take includes significant habitat modification or degradation that actually kills or injures wildlife by significantly impairing essential behavioral patterns, including breeding, feeding, or shelter (50 CFR Section 17.3). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 12 Section 10(a) of the ESA permits the incidental take of an endangered or threatened species. Similarly, Section 2081 of the CDFG Code or use of the CESA allows the Department to enter into management agreements that make lawful activities which may otherwise result in habitat loss or take of individuals of a state listed species. B. Species of Special Concern The California Department of Fish and Game has designated certain animal species as "Species of Special Concern" due to concerns about declining population revels, limited ranges, and continuing threats that have made these species vulnerable to extinction. The goal of this designation is to bring attention to these species in the hope that their population decline will be halted through mitigation or project redesign to avoid impact. Species of special concern are protected only through environmental review of projects under CEQA. The California Department of Fish and Game is a trustee agency and is solicited for its comments during the CEQA process. Federal species of concern are any species that may become vulnerable to extinction on a National level from declining population trends, limited range, and/or continuing threats'. C. Nesting Birds Nesting birds, including raptors, are protected by the California Department of Fish and Game Code 3503, which reads, "It is unlawful to take, possess, or needlessly destroy the nest or eggs of any bird, except as otherwise provided by this code or any regulation made pursuant thereto." Passerines and non -passerine landbirds are further protected under the Federal Migratory Bird Treaty Act. As such, the CDFG typically recommends pre - construction surveys for potentially suitable nesting habitat that will be directly (actual removal of trees/vegetation) or indirectly (noise disturbance) impacted by construction - related activities. D. California Environmental Quality Act Some species that are otherwise not protected by the ESA or CESA and do not have a special CDFG or Fish and Game Code designation (e.g., fully protected) may still, under CEQA, be determined to be significantly impacted by a project. For example, if a project were to destroy or disturb a roosting site for either a bat maternity colony or a wintering monarch butterfly colony it could significantly impact the local and/or regional population of either species. Although loss of an individual bat or monarch butterfly would likely be considered an insignificant impact, loss of a roost site where multiple individuals are present may be considered significant. This is because roost sites may be limited in availability and often have very specific habitat and/or microclimate conditions. When a roost site is lost, individuals may not be able to find an alternate roost in sufficient time for protection from the elements before expiring. However unless a roost site has already been ' This is no longer an official U.S. Fish and Wildlife Service category, but is still considered in this document because it contains many species that could become threatened or endangered 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 13 studied and the local population of the subject species is well known, the significance of the loss cannot be readily evaluated. In order to avoid a potential finding of significant impact to species such as roosting bats or monarchs, all potential habitats should be seasonally avoided or field surveys should be completed to determine presence/absence. E. California Native Plant Society and CEQA The California Native Plant Society (CNPS) has developed a rating system for the state's rare, threatened and endangered plants. Plants rated by CNPS are subject to protection under CEQA, and may also be protected by state and federal endangered species laws if they are listed by the state or federal government. F. Regulated Waters Impacts to stream channels (bed and bank) are regulated by the California Department of Fish and Game Code §§1600 et seq., and may require a DFG Streambed Alteration Agreement. Impacts to wetlands and streams may also fall under the jurisdiction of the Clean Water Act §404 permit process and the Porter -Cologne Water Quality Control Act. The U.S. Army Corp of Engineers (USACE) enforces permit provisions of the Clean Water Act regulating dredge and fill operations. The USACE also exerts jurisdiction over "waters of the U.S." which include territorial seas, tidal waters, and non tidal waters in addition to wetlands and drainages that support wetland vegetation, exhibit ponding or scouring, show obvious signs of channeling, or have discernible banks and high water marks. The State of California Regional Water Quality Control Board (RWQCB) enforces permit provisions of the Porter -Cologne Water Quality Control Act. Projects that may potentially impact wetlands in the state of California require a 401 Certification permit. Each 401 Certification is decided on a case-by-case basis, and is guided by the applicable requirements of the CWA, Porter -Cologne and the regulations. G. Stormwater Control Requirements In urbanized areas, stormwater runoff is the largest source of pollution to waters in creeks, ponds and lakes. Pollution caused by stormwater runoff can be controlled through obtaining and complying with a municipal stormwater permit from the National Pollutant Discharge Elimination System (NPDES). Controls set forth in the permit offer an opportunity for development and redevelopment projects to reduce impacts to water quality. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 14 H. Town of Los Altos Hills Heritage Tree Designation Title 12, Chapter 2 of The Town of Los Altos Hills Municipal Code (Section 101), defines a Heritage Tree as "any tree that, due to age, size, location, visibility, historic nature, or other unique attribute, has been deemed by the Town to be a heritage tree and accordingly deserves special consideration for preservation and protection." A Heritage Oak is defined as "any tree of the genus Quercus, including, but not limited to, Valley Oak (Quercus lobata), California Live Oak (Quercus agrifolia), Black Oak (Quercus kelloggii) and Blue Oak (Quercus douglasii) that has a trunk or multiple trunk thirty-six (36) inches in circumference (approximately twelve (12) inches in diameter) at a point four (4) feet above the root crown". A permit is required to remove or destroy a Heritage Oak. No person shall remove, purposefully damage, or purposefully cause to die any Heritage Oak on private or public property within the Town of Los Altos Hills without first having obtained a removal permit from the Town. A removal permit is not required when: (a) The Heritage Oak has been identified for removal on an approved tentative subdivision map or an approved site development permit; or (b) The City Manager (or designee) has determined that the Heritage Oak presents an immediate danger to persons or property. Persons believing a Heritage Oak presents an immediate danger should call Town Hall during normal business hours and 911 at all other times. (§ 3 (part), Ord. 332, eff. June 1, 1990). Application for a Heritage Oak removal permit shall contain the number, size, and location of the Heritage Oak(s) requested to be removed, and a brief explanation of the reasons for the requested removal. Such reasons may include, but not be limited to, the fact that the Heritage Oak is dead, diseased beyond reclamation, hazardous, or crowded and that good horticultural practices dictate its removal. If there is a disagreement regarding the condition of the Heritage Oak between the applicant and the Town, an arborist's opinion must be obtained at the expense of the applicant. No heritage trees are proposed for removal as part of this project. L Santa Clara Valley Water District Streamside Standards and Guidelines In their publication User Manual: Guidelines and Standards for Land Use Near Streams, the Santa Clara Valley Water Resources Protection Collaborative (SCVWRPC 2006)2 emphasizes the vital role of riparian vegetation in "maintaining stream stability, providing valuable wildlife habitat, and moderating downstream flooding", as well as regulating 2 Chapters 2 and 3 of the Guidelines contain the adopted requirements of the Town of Los Altos Hills for construction near a stream. Chapter 4 contains detailed specifications for use by architects, engineers and other project designers. Chapters 5-11 do not contain adopted requirements; these chapters are provided as reference material and background information for homeowners and developers. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 15 water quality by filtering pollutants from stormwater, such as oil and grease from roadways, fertilizer runoff from lawns, and excess sediments from upstream. Specifically, the stream -side environment supports riparian vegetation and the functions riparian vegetation provides. Riparian vegetation benefits terrestrial species, as well as semi - aquatic amphibians and reptiles and fish. Such habitat functions include: • Sediment stabilization: provided by riparian trees, shrubs, and grasses; • Shading and water temperature moderation: provided by mature riparian shrubs and trees; • Overhanging escape cover: provided by shrubs and grasses near the stream edge; • Coarse particulate organic matter: organic material dropping into the stream in the form of leaves, insects, etc., that provide input for aquatic food webs; • Bird breeding and foraging habitat: provided by mature native riparian species, such as cottonwoods and willows, oaks, other trees, shrubs, forbs, grasses, and the stream banks; • Foraging, refugia, aestivation, and breeding habitat for semi -aquatic amphibian and reptile species: provided by low vegetation, rocks, downed materials, and the stream banks; • Foraging, breeding, hibernacula, and dispersal habitat for mammals: provided by the riparian vegetation and the stream bank substrate. J. Significance Criteria The significance criteria are based in part on the Environmental Checklist (CEQA Guidelines Appendix G [Title 14 CCR, Section 15000-15387]). These criteria are used to determine the extent to which the proposed project would impact sensitive biological resources. The threshold of significance may vary for each species or habitat, and is determined by the lead agency. Using these guidelines, the Project would result in a significant impact if it would: • Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special -status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service. • Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 - Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 16 • Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means. • Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites. • Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance. • Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan. VIII. SPECIAL STATUS PLANTS, ANIMALS, AND NATURAL COMMUNITIES The California Department of Fish and Game (CDFG) Natural Diversity Data Base (CNDDB) maintains records of reported occurrences of sensitive plant, animal and natural plant communities of concern. CNDDB records provide useful information about what species have been found in a given project area, and what species may be expected in similar habitat types. An area that has not been surveyed or visited may support sensitive species that have not been discovered and reported, and may require site-specific surveys to rule out special status species occurrences. The U. S. Fish and Wildlife Service (USFWS), Sacramento, also maintains lists of listed species and other species of concern that may occur in or be affected by projects in a given USGS topographic quadrangle. CNDDB records for the Palo Alto 7.5 minute topographic quadrangle and eight surrounding quadrangles were reviewed for sensitive element occurrences on the project site (CDFG 2010a). Review of the US Fish and Wildlife Service list of endangered and threatened species for the nine 7.5 minute quadrangles, and the CNPS on-line Inventory of Rare and Endangered Plants (CNPS 2010) was also conducted. Special status species that were identified in the region as having at least some minimal potential for occurrence based on proximity to the site, or similar habitat utilization were included in Appendix B. Special -status species that have a higher probability for occurrence onsite, based on habitat types and/or recorded observations within 5 miles of the property are discussed in greater detail below. Special status species found exclusively within habitats not present on the property (i.e. sand dune, serpentine grassland, salt marsh, freshwater marsh and/or marine habitats, etc.) were excluded from analysis due to the lack of these habitats on or adjacent to the property. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 17 • There is potential for one federally listed species, the California red -legged frog, (Rana aurora draytonii) and one state fully protected species, white-tailed kite (Elanus leucurus) to utilize the project area. One non -listed special status species was found to occur within the trail alignment, the San Francisco dusky -footed woodrat (Neotoma fuscipes annectens). Four additional non -listed special status wildlife species were identified as having potential for presence within the project area, Cooper's hawk (Accipiter cooperii), loggerhead shrike (Lanius ludovicianus), western red bat (Lasiurus blossevillii) and pallid bat (Antrozous pallidus),. Eight species on various watch lists that also have potential for presence within the project area include fringed myotis (Myotis thysanodes), long-legged myotis (Myotis volans), hoary bat (Lasiurus cinereus), Yuma bat (Myotis yumanensis), long-eared bat (Myotis evotis), California thrasher (Toxostoma redivivum), Nuttall's woodpecker (Picoides nuttallii) and oak titmouse (Baeolophus inornatus). • Two special status plant species: western leatherwood (Dirca occidentalis) and San Francisco collinsia (Collinsia multicolor) were identified as having potential to occur within the project area. One rare plant community, Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance) was identified within Matadero Creek, adjacent to the trail alignment. Three additional federally and/or state listed species are a high priority for conservation and are included in the discussion. These are San Francisco garter snake (Thamnophis sirtalis tetrataenia), California tiger salamander (Ambystoma californiense) and steelhead (Oncorhynchus mykiss irideus). Though these species are not expected to occur on site, a discussion of each is provided because they are federally listed species and have been detected in the region (CDFG 2010a). A. California Red -legged Frog The California red -legged frog (CRF) is a federally listed Threatened species and a California Species of Special Concern. Red -legged frogs are known to occur in slow -flowing streams, and marshes with heavily vegetated shores for breeding as well as grasslands, riparian woodland, oak woodland and coniferous forests. These frogs stay near the shore hidden in vegetation rather than in open water. Seasonal bodies of water are frequently occupied by red -legged frogs, and in some areas these may be critical for persistence. It is speculated that California red -legged frogs may lie dormant during dry periods of the year or during drought. California red -legged frogs are thought to disperse widely during autumn, winter, and spring rains. Juveniles use the wet periods to expand outward from their pond of origin and adults may move between aquatic areas. Frogs disperse through many types of upland vegetation and use a broader range of habitats outside of breeding season. CRF have been observed to move extensively 1072 Geneva Avenue, San Francisco CA 94112 -.Ph: 415-404-6757 . Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 18 and travel up to 2 miles or more between breeding ponds without apparent regard to topography, vegetation type, or riparian corridors (Bulger in litt.1998, in USFWS, 2002). The breeding season for CRF generally begins in January and lasts through March. Minimum breeding age appears to be two years in males and three years in females (Jennings and Hayes 1985). Females lay 750-4000 eggs in clusters attached to aquatic vegetation, two to six inches below the water surface. Eggs hatch in two to three weeks. Once hatched, the tadpoles generally take between 11 and 20 weeks to metamorphose, doing so between May and August. Although most tadpoles are expected to transform in the summer, they can also over -winter, so transformation can take from about 4 to 13 months. CRF typically require a permanent water source with a minimum depth of 0.7 meters (2.5 feet) (USFWS 2004). Successful breeding has been observed in sub -optimal habitats with little or no emergent vegetation present (USFWS 2004). In the absence of vegetation CRF will attach their eggs to rocks, wood or other debris. CRF has been extirpated from 70 percent of its former range and now is found primarily in coastal drainages of central California, from Marin County, California, south to northern Baja California, Mexico. Potential threats to the species include elimination or degradation of habitat from land development and land use activities and habitat invasion by non-native aquatic species (USFWS 2002). The project area is outside of CRF Critical Habitat (USFWS 2005). The nearest recorded observation of CRF (Occ. #230 ; 2001) is located at Matadero Creek, approximately 1.0 miles northeast of the project site (CDFG 2010a). Both adults and tadpoles were observed at this site between 1997 and 2001. There are several more observations of CRF that have been recorded within 5 miles of the project area including sightings in Bear Creek and San Francisquito Creek (CDFG 2010a). There are also several additional creeks and ponds within the Los Altos Hills, Woodside and Portola Valley area that provide potential habitat for CRF. There is potential habitat for CRF to occur within the section of Matadero Creek that is adjacent to the project area. Because CRF can utilize upland habitats and travel up to 2 miles when dispersing from breeding areas, there is potential that CRF to occur within the trail alignment when dispersing in the rainy season. Avoidance and minimization measures should be followed to insure CRF are not impacted by the proposed trail project. B. California Tiger Salamander California tiger salamander (Ambystoma californiense; hereafter referred to as CTS) is a large, terrestrial salamander with a black body and white to yellow spots and bars (Stebbins 2003). The Central California Distinct Population Segment (DPS) is state and federally -listed as Threatened (USFWS 2010b; CDFG 2010b) and is designated as a California Species of Special Concern. California tiger salamanders are distributed throughout the Central Valley and Central Coast ranges from Colusa County south to San Luis Obispo and Kern counties from sea level to 1054 meters (3,460 feet) in elevation. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 19 Two disjunct populations are located within Sonoma County and Santa Barbara County, which are geographically isolated from the Central Valley population. California tiger salamanders inhabit lowland grasslands, oak savannah, and mixed woodland habitats, and require vernal pools, seasonal ponds, or semi-permanent calm waters that pond water for a minimum of three to four months in duration for breeding and larval maturation, and adjacent upland habitat with small mammal burrows for aestivation (Storer 1925, Barry and Shaffer 1994, Stebbins 2003). California tiger salamanders begin migrating to breeding sites following the onset of autumn rains typically in November, and have been documented traveling distances up to 1.6 km (Austin and Shaffer 1992). Eggs are laid singly or in small clusters on the pond bottom or attached to individual strands of vegetation (Storer 1925, Shaffer and Fisher 1991, Barry and Shaffer 1994, Jennings and Hayes 1994). Metamorphosis occurs a minimum of ten weeks following hatching and young migrate in mass when temporary pools begin to dry in late spring or early summer (Feaver 1971, Jennings and Hayes 1994, Stebbins 2003). Juveniles and adults aestivate through the summer and fall typically in small mammal burrows, most frequently created by California ground squirrel (Spermophilus beecheyi) or pocket gopher (Thomomys spp.) (Shaffer, et al. 1993, Barry and Shaffer 1994; Jennings and Hayes 1994, Stebbins 2003). California tiger salamanders are at risk of extinction due to loss of habitat from development of agriculture and grazing lands, habitat fragmentation, and introduction of predatory exotic species such as mosquitofish (Gambusia affinis), bullfrogs (Rana catesbeiana), and Louisiana red swamp crayfish (Procambarus clarkii) (Zeiner, et al. 1988, Shaffer, et al. 1993, and Jennings and Hayes 1994). Critical habitat for the Central California DPS of CTS was designated in 2005 (USFWS 2005) and there are ten critical habitat units within Santa Clara County. The project area does not overlap with any critical habitat unit for CTS. The nearest CNDDB record of CTS (Occ. #63; 2005) is from Lake Lagunita, approximately 2.3 miles northeast of the project site (CDFG 2010a). CTS have also been documented using restored ponds on the west side of Junipero Serra Boulevard near Lake Lagunita, approximately 2.1 miles northeast of the project site. CTS have not been detected at Felt Lake (pers. comm. Dr. Alan Launer). No breeding or suitable summer aestivation habitat is present on site or in the immediate project vicinity and CTS is not expected to occur within or adjacent to the project area. C. San Francisco Garter Snake The San Francisco garter snake (SFGS) is federally and state listed as endangered and is a fully protected species under §5050 of the California Fish and Game Code. A highly aquatic subspecies of the common garter snake endemic to the San Francisco Bay Area, San Francisco garter snakes are distributed along the western San Francisco Peninsula from the southern San Francisco County border south to Waddell Lagoon south of Ano Nuevo and as far west as Crystal Springs Reservoir. It occurs sympatrically with its 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 o Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com o www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 20 primary prey species, the California red -legged frog (Rana aurora draytonii); however, it will opportunistically prey on a variety of species including frogs, tadpoles, egg masses, newts, small fish, salamanders, reptiles, small mammals, birds and their eggs and several small invertebrates (Stebbins 2003). San Francisco garter snakes prefer densely vegetated habitats close to water where they can retreat when disturbed (Stebbins 2003). The species often occurs near ponds, marshes, streams and other wetlands associated with cattails (Typha spp.), bulrushes (Amphiscirpus, Bolboschoenus, Isolepis, Schoenoplectus and Trichophorum spp.) and rushes (Juncus and Eleocharis spp.). Mating occurs shortly after they leave their winter retreats in May and females give birth to live young between June and September. Species may hibernate near the coastal areas in fossorial mammal burrows and other refuges, or remain active year- round, weather permitting. San Francisco Garter snakes are usually found around ponds and marshes that support large populations of Pacific tree frog (Hyla reg lla) and California red -legged frog, both of which serve as prime food sources. Recent research conducted by Sean Barry of Essex Environmental documents that SFGS will also prey on bullfrog (Rana catesbiana). Critical habitat has not been designated for this species. The nearest recorded observation of SEGS is located near the Stanford Linear Accelerator, approximately 4.0 miles west of the project area (CNDDB 2010a). The only other occurrence within the region is located approximately 5.1 miles northwest of the project site on a private property on Portola Road. The closest aquatic habitat that could potentially support SFGS within the vicinity of the project area is Matadero Creek. This habitat, though it has been documented to support the California red -legged frog which is an important prey species of the San Francisco garter snake, is unlikely to support San Francisco garter snakes due to a lack of suitable marsh and/or pond habitat associated with the creek. No other potentially suitable habitat for this species exists within the vicinity. This species is not expected to occur on within the project area. D. Steelhead Steelhead (Oncorhynchus mykiss irideus) within the Central California Coast ESU was federally -listed as threatened on August 18, 1997. The Central California Coast ESU Ecologically Significant Unit (ESU) includes all naturally spawned populations of steelhead (and their progeny) in California streams from the Russian River to Aptos Creek, and the drainages of San Francisco and San Pablo Bays eastward to the Napa River (inclusive), excluding the Sacramento -San Joaquin River Basin (NOAA 2005a). Critical habitat, designated on February 16, 2000, is designated to include all river reaches and estuarine areas accessible to listed steelhead in coastal river basins from the Russian River to Aptos Creek, California (inclusive), and the drainages of San Francisco and San Pablo Bays. Also included are adjacent riparian zones, all waters of San Pablo Bay westward of 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project --February 2012 Page 21 the Carquinez Bridge, and all waters of San Francisco Bay from San Pablo Bay to the Golden Gate Bridge (NOAA 2005b). Excluded is the Sacramento -San Joaquin River Basin of the California Central Valley, as well as tribal lands and areas above specific dams or above longstanding, naturally impassable barriers (i.e., natural waterfalls in existence for at least several hundred years). Major river basins containing spawning and rearing habitat for this ESU comprise approximately 6,516 square miles in California. The following counties lie partially or wholly within these basins (or contain migration habitat for the species): Alameda, Contra Costa, Marin, Mendocino, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma. Steelhead are anadromous fish that migrate from the ocean into fresh water streams to spawn (Moyle 2002). Rainbow trout refers to the resident form of the species that inhabits lakes or streams and does not migrate to the ocean. Steelhead build redds (i.e., spawning beds) at the head of riffles where water is well oxygenated and nearby pools with deeper water provide safe refuge for juveniles. Optimal temperatures for growth are 15-18°C. While in freshwater streams, steelhead feed on drifting aquatic organisms, terrestrial insects and bottom dwelling invertebrates (Moyle 2002). Migratory steelhead smolts migrate to the ocean after spending 1-3 years in their natal freshwater streams. Adults remain in the ocean for 1-4 years prior to returning to their natal streams, or occasionally to neighboring streams, to spawn. Unlike salmon, steelhead often return to spawn more than once. The Santa Clara Hydrologic Unit includes South Bay creeks from San Francisquito Creek in Palo Alto eastward to Coyote Creek (NOAA 2005b). Matadero Creek occurs within this region, but is excluded from this critical habitat designation for Central California Coast steelhead ESU. Matadero Creek watershed probably supported a small steelhead run in the past and steelhead continue to enter the system from San Francisco Bay, according to local residents (SCBWMI 2001). Channelization, flood control projects, and barriers such as culverts have drastically reduced fish habitat (SCBWMI 2001). Currently this watershed is not expected to support a steelhead population (Leidy, et al, 2005). Deer Creek, a small tributary to Matadero Creek on the east side of the trail alignment, is unlikely to support steelhead currently, or historically, due to the steepness and low flows of this small watershed (Leidy, et al, 2005). E. San Francisco Dusky footed Woodrat The San Francisco dusky -footed woodrat is a California species of special concern and is one of eleven recognized subspecies. The San Francisco dusky -footed occurs in the Santa Cruz Mountains and in the East Bay hills. The dusky -footed woodrat is generally a nocturnal mammal that occurs in a variety of brushy and wooded areas. They inhabit oak and riparian woodlands, coastal scrub, and chaparral habitats with a well-developed understory. The woodrat builds stick structures (`houses') for nesting up to 2 meters long and a meter in height that may last for tens of years. These stick houses are constructed on the ground, within shrubs and trees, tree hollows, rock crevices and sometimes in human 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 22 structures such as wood sheds. The elaborate stick houses help protect the woodrat from seasonal temperature extremes and predators. Woodrats exhibit high site fidelity and are highly arboreal. They are generalist herbivores and live in loosely -cooperative societies. The dusky -footed woodrat eats primarily woody plants, including leaves, flowers, nuts and berries. Coast live oak trees are an important food resource for this species. Several San Francisco dusky -footed woodrat nests are located near the trail alignment. All of these nest structures are outside of the project area however one nest is located within a Coast live oak tree located along Arastradero Road near Stirrup Way that is proposed for removal. F. Raptors and Nesting Birds No special status birds were observed on the property, however the property provides potential habitat for several special status birds. Three special status raptors, white tailed kite, Cooper's hawk, and sharp -shinned hawk have potential to utilize the property. White-tailed Kite This species potentially nests within grasslands and oak savannah habitats in the foothills of Woodside and Portola Valley. White-tailed kites forage over grassland and nest in shrubs and trees. The species is a year-round resident of Central and Coastal California. This species was not observed during biological surveys of the property however potential suitable foraging and nesting habitat is present along the trail alignment. Cooper's Hawk The species inhabits dense stands of oak woodlands, riparian deciduous forests, or other forest habitats often near water and suburban areas (Baicich & Harrison 2005). This woodland raptor hunts in broken woodlands, along forest edges and suburban areas for medium-sized birds and mammals. Typical nest site selection is characterized by mature trees with significant canopy cover; although, species will nest in suburban areas in a variety of trees (Curtis et al. 2006). One Cooper's hawk was observed flying near the eastern boundary of the property on November 29, 2010. There is potentially suitable foraging and nesting habitat for this species along the trail alignment. Loggerhead Shrike The loggerhead shrike is designated a California Species of Special Concern by the California Department of Fish and Game (CDFG 2010b). Loggerhead shrikes inhabit a variety of habitats from open grasslands and scrub to woodlands and riparian areas (Yosef 1996, Baicich & Harrison 2005). This species is a year-round resident throughout much of California; however, 'population declines have been observed in the San Francisco Bay Area in areas where oak savannah habitat has been lost (Shuford and Gardali 2008). Trees, shrubs, and fence posts are important habitat features, which serve as hunting perches and an announcement site for territory pair maintenance (Shuford and Gardali 2008). Breeding 1072 Geneva Avenue, San Francisco CA 94112 -.Ph: 415-404-6757 • Cell: 650-269-3894 - Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 23 begins in February and is double- to triple -brooded (Baicich & Harrison 2005). There is potentially suitable nesting and foraging habitat within the project area. Other Migratory Birds The native plant communities and ornamental vegetation on the property provide potential nesting habitat for a variety of native songbirds, raptors and other species. Species observed that may forage and nest within the project area include red-tailed hawk, American kestrel, oak titmouse, Nuttall's woodpecker, Bewick's wren, bushtit, scrub jay, Oregon junco, chestnut -backed chickadee, Anna's hummingbird, Stellar's jay, scrub jay, and spotted towhee, among others. G. Bats Potential bat roosting and foraging habitat is located on the property due to the habitats present within the project area and on adjacent properties (annual grassland, riparian, suburban forest). Two special status bat species were determined to have potential to occur within the project area, pallid bat and western red bat. Pallid Bat The pallid bat is a California Species of Special Concern and a U.S. Forest Service and Bureau of Land Management Sensitive Species, and a High Priority species by the Western Bat Working Group (CDFG 2010b). The pallid bat is found in a variety of habitats including all types of woodland especially oak savanna, grassland, riparian areas and wetlands, orchards, vineyards, and irrigated cropland if appropriate roosting sites are available. A very social bat, the pallid bat occupies a wide variety of habitats throughout California, including grasslands, shrublands, woodlands, and forests. The species is most common in open, dry areas with rocky areas necessary for roosting. Roosts in rock crevices, caves, mine shafts, under bridges, in buildings and tree hollows. It feeds on a variety of insects and arachnids. There is moderate potential for pallid bats to use the property for roosting and foraging. Trees proposed for removal were visually inspected for tree hollows and did not provide suitable roosting habitat for this species. Western Red Bat The western red bat is designated as a California Species of Special Concern by the California Department of Fish and Game and a High Priority species by the Western Bat Working Group (CDFG 2010b). The western red bat is easily distinguished by its distinctive reddish coloration. Roosting typically occurs individually in dense clumps of tree foliage in riparian areas, especially willows, cottonwoods and sycamores, and within orchards and suburban areas in trees and 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com e www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- Februmy 2012 Page 24 shrubs. Roosts are often hidden from view and only access from below (Bolster 2005). Red bats are primarily moth specialists, but individuals will forage for a variety of other insects. Individuals have been observed foraging around street lamps and flood lights in suburban areas (Bolster 2005). The western red bat migrates long distances, but has been reported to overwinter in the Bay Area with interspersed winter foraging bouts on warm days (Bolster 2005). The property provides habitat for additional species that are on watch lists including fringed myotis, long-legged myotis, long-eared myotis, Yuma myotis and hoary bat. Additional bats -within the region may utilize the property such as Mexican free -tailed bat (Tadarida brasiliensis), big brown bat (Eptesicus fuscus) and others. Though these species do not have protected status under ESA or CESA, impacting a roosting bat colony could be considered a significant impact under CEQA, due to the limited amount of suitable roosting habitat and the slow reproductive rate of bats. H. Monarch Butterfly Monarch butterfly is not a state or federally listed species, however due to its unique life history and habitat requirements it is given special consideration under the California Environmental Quality Act (CEQA) review process. Winter roost sites extend along the western coast from Mendocino in northern California, south to Baja California, Mexico. Roost habitat consists of wind -protected tree groves, typically eucalyptus (Eucalyptus globulus), Monterey pine (Pinus radiata) and Monterey Cypress (Cupressus macrocarpa), with nectar and water sources nearby. Roost sites consist of congregations of several hundred to several thousand adult butterflies. Along the Central California coast, monarch butterflies typically roost between October and February. The closest record of a monarch roost site is located at Ardenwood Farms Regional Preserve in Newark, approximately 13.3 miles northeast of the site (CDFG 2010a). The row of Eucalyptus trees along Arastradero Road provides potential habitat for monarchs, however monarch roost sites typically consist of groves of trees that are protected from the wind, with nectar and water sources nearby. These habitat components are not present within the project area. No Monarch butterflies were observed during biological surveys in November and December 2010, and trees proposed for removal along the trail alignment are unlikely to support monarch butterflies. L Special Status Plants and Rare Plant Communities No special status plant species were observed on the property, however the property was surveyed in the fall, when many plants, especially annuals, are past their bloom stage, and are less visible. Two special status plants were determined to have potential for presence on site based on habitat types. These are western leatherwood (Dirca occidentalis) and San Francisco collinsia (Collinsia multicolor). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com o www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 25 One rare plant community, Central Coast Riparian Scrub (Salix lucida ssp. lasiandra Alliance), was identified within the project area (Holland 1986; CDFG 2006; CDFG 2007). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 26 IX. Recommended Avoidance and Minimization Measures No impacts are anticipated to special status species or natural communities as a result of the proposed trail project. Potential impacts and recommended measures to mitigate impacts to special status species are provided below. A. California Red -legged Frog Potential impacts to California red -legged frogs can be avoided and/or minimized by implementing minimization and avoidance measures (USFWS 1999b). To the maximum extent practicable the applicant shall follow the following measures: • BIO -1 - All ground disturbance associated with trail building activities on site will be conducted during the dry season (April 15 — October 15). • BIO -2 - Staging areas and access routes to the work area will be delineated and inspected by the project biologist prior to establishment to avoid unnecessary impacts to California red -legged frogs and their habitat. • BIO -3 - Exclusion fencing will be erected around portions of the construction site adjacent to Matadero Creek and Deer Creek prior to the onset of project activities. Fencing will be a minimum of 3 feet in height and buried in the soil 4 to 6 inches to inhibit California red -legged frogs from entering the project area. • BIO -4 - Once the exclusion fence is installed, a pre -construction survey will be conducted to ensure that no California red -legged frogs are present in the project area. • BIO -5 - If California red -legged frogs are detected on site, the USFWS would be contacted for guidance on moving the animal(s) to a safe location. No CRF would be handled without permission from the USFWS. • BIO -6 - During project activities, all trash that may attract predators will be properly contained, removed from the work site and disposed of regularly. Following construction, all trash and construction debris will be removed from work areas. • BIO -7 - All practicable erosion control Best Management Practices (BMPs) will be implemented to minimize the potential of impacts to water quality of Matadero Creek and Deer Creek. • BIO -8 - No smoking except in vehicles will be permitted within vegetated areas. • BIO -9 - Trash dumping will be prohibited. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 27 B. San Francisco Dusky footed Woodrat BIO -10 - Woodrat nests within 100 feet of ground disturbing activities shall be surveyed and monitored to determine if nests are active. • BIO -11 - For woodrat nests that can be avoided, orange construction/ protective fencing will be placed between work areas and woodrat nests, and will include a 2 - foot buffer between the protective fencing and the nest. BIO -12 - For woodrat nests that cannot be avoided, woodrat nests shall be dismantled by a qualified biologist. Dismantling will be conducted during the time of year that would least impact breeding woodrats (i.e. late fall/ winter: November/December/January). Dismantling will be conducted slowly to avoid impacting neonate woodrats. If woodrat neonates are detected in the nest, dismantling will cease and the nests will be checked every 48 hours to determine if the neonates are still present. Dismantling will continue once it is determined that the neonates are no longer present and have either been weaned from their mothers, or the mothers have moved them from the nest. • BIO -13 - DFG shall be consulted if any San Francisco dusky -footed woodrats (adults, subadults or neonates) are harmed by project activities. C. Protection of Special Status Raptors The trees and shrubs on the property provide potential nesting habitat for birds including raptors such as Cooper's hawk and white-tailed kite. Ground disturbance and construction activities on the property could impact nesting birds, including raptors. • BIO -14 - If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for nesting birds including raptors such as white-tailed kite and Cooper's hawk, shall be conducted by a qualified biologist within 300 feet of the construction area, where access is available, within two weeks prior to construction. BIO -15 - If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical no -activity buffer zones are 300 feet for active raptor nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. D. Protection of Migratoiy Birds The native plant communities and ornamental vegetation on the property provide potential nesting habitat for a variety of native songbirds, raptors and other species. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 28 BIO -16 — If ground disturbance activities are proposed during the bird nesting season (February 1 — August 31), then preconstruction surveys for migratory birds, shall be conducted by a qualified biologist. For migratory raptors including red- tailed hawk, surveys shall be conducted within 300 feet of the project area where access is available. For non -raptor migratory bird species, surveys shall be conducted within 100 feet of the project area, where access is available. Surveys for migratory birds shall be conducted within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. BIO -17 -- If active bird nests are found, and project activities could potentially impact nesting success, appropriate no -activity buffer zones shall be established around active nest (s). Typical no -activity buffer zones are 300 feet for active raptor nests, and 100 feet for active migratory bird nests. If project activities would be conducted within these buffer zones, the US Fish and Wildlife Service Migratory Bird Treaty Office and the Department of Fish and Game will be consulted for guidance and all necessary permits would be obtained. E. Protection of Special Status and Non -Special Status Bats The property provides potential habitat for roosting bats. There are several trees on the property that may provide day and/or night roosts for special status and non -special status bat species. BIO -18 - To avoid impacts to roosting bats within the project area, including pallid bat and western red bat, pre -construction surveys for roosting bats shall be conducted by a qualified bat biologist within two weeks prior to any ground disturbance, tree removal and/or tree pruning activities within the project area. Any tree removal on site shall be done according to the recommendations of the qualified bat biologist. If active bat maternity roosts are detected (this season is typically between April and August) within a structure or tree that will be impacted by the project, the roost would need to be avoided until all young are volant, and the Department of Fish and Game will be consulted for permission in the use of any bat exclusion devices. F. Protection of Special Status Plants and Plant Communities BIO -19 — To avoid impacts to special status plant species, (San Francisco collinsia and western leatherwood), one or more preconstruction surveys shall be conducted by a qualified biologist prior to any ground disturbance and/or vegetation removal within the project area. The survey (s) should be timed to occur at the most suitable time of year (i.e. bloom period) to detect San Francisco collinsia and western leatherwood. 1072 Geneva Avenue, San Francisco CA 94112 - Ph: 415-404-6757 - Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com e www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 29 BIO -20 — If San Francisco collinsia and/or western leatherwood are identified within the project area, and one or more individual plants could potentially be impacted by project activities, the California Native Plant Society and the Department of Fish and Game will be consulted to develop appropriate mitigation measures. Mitigation measures may include seed/plant material collection, propagation and replanting in an appropriate restoration area(s). H. Protection of Regulated Waters and Wetlands While the proposed project does not include any in -channel work or grade alteration or construction below the top of bank, indirect effects on the aquatic environment of Matadero Creek and Deer Creek could result from project implementation. In addition, direct and indirect impacts to California red -legged frog habitat within Matadero Creek could be considered significant under CEQA guidelines. Project implementation could affect the regulated waters and wetlands in the following ways: • Erosion from the project site during construction could release sediments into the creek channels, adversely affecting the aquatic habitat and indirectly impacting aquatic species. • Inadvertent spills of cement, oil and grease, or other contaminants during construction could reach the creek channels, adversely affecting the aquatic habitat and indirectly impacting aquatic species. In order to avoid indirect impacts regulated waters and wetlands, the measures outlined below shall be implemented. With the incorporation of these measures, project implementation would not result in any inadvertent impacts on downstream water quality. BIO -21 - Under no circumstances shall spoils, gravel, paving materials or other construction materials or debris be placed, even temporarily, along or below the top of bank of the creek. • BIO -22 - Best Management Practices (BMPs) to prevent pollutants, construction materials or debris from entering the creek and storm drains shall be installed prior to the initiation of work and properly maintained. I. Exclusion of Invasive Species The following measure is recommended to avoid impacts from introduced invasive plant species: 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 30 • BIO -23 - The project proponent shall avoid planting ornamental species reported by the California Invasive Plant Council to have the potential to be invasive. Species on this list shall be prohibited from use in landscaping. J. Wildlife Corridors The proposed project would not create any impacts to wildlife movement or existing wildlife corridors through the project area. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradem Tr ail Improvement Project. -- February 2012 Page 31 XI. REFERENCES Austin, C. C. and Shaffer, H. B. 1992. Short-, Medium- and Long-term Repeatability of Locomotor Performance in the Tiger Salamander Ambystoma californiense. Funct. Ecol. 6, 145=153. Baicich, P.J. and C.J.O. Harrison. 2005. Nests, Eggs, and Nestlings of North American Birds. Second Edition. Princeton University Press. Princeton, New Jersey. 347 pp. Barry, S. J., and H.B. Shaffer.. 1994. The Status of the California Tiger Salamander (Ambystoma californiense) at Lagunita: a 50 -year Update. Journal of Herpetology 28:159-164. Beidleman, L.H., Kozloff, E. N. 2003. Plants of the San Francisco Bay Region. University of California Press, Berkeley, California. Beier, P. and S. Loe. 1992. A Checklist for Evaluating Impacts to Wildlife Movement Corridors. Wildlife Society Bulletin 20(4):434-440. Bildstein, Keith L. and Ken Meyer. 2000..Sharp-Shinned Hawk (Accipiter striatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.-birds.comell.edu/bna/species/482. Bogan, M. A., E. W. Valdez, and K.W. Navo. 2005. Yuma Myotis (Myotis evotis). Species Account. Western Bat Working Group. http://www.wbwg.org/speciesinfo/species accounts/vespertilonidae/myM.pdf. Bulger, J. 1998. Wet season dispersal and habitat use by juvenile California red -legged frogs (Rana aurora draytonii) in forest and rangeland habitats of the Santa Cruz Mountains. A research proposal submitted to the U.S. Fish and Wildlife Service, Sacramento, California. California Department of Fish and Game 2010a. California Natural Diversity Database (CNDDB). Database search for the Palo Alto 7.5 minute topographic quadrangle and eight surrounding quadrangles December, 2010. Data expiration January 3, 2011. . 2010b. Special Animals. California Natural Diversity Database. Wildlife and Habitat Data Analysis Branch. July. 2007. Vegetation Classification and Mapping Program, List of California Vegetation Alliances, October 22, 2007 2006. Rare Plant Communities, California Natural Diversity Database, March. Cal -IPC, 2010. California Invasive Plant Inventory Database. httT)://www.cal:ipc.oreip/inventory/weedlist.l)hT) 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 32 CNP S. 2010. Inventory of Rare and Endangered Plants (online edition, 8th Edition, released December. of 2010). California Native Plant Society. Sacramento, CA. Accessed from htti)://wwwirareplants. ceps. ori/ Cowardin, Lewis M., Virginia Carter, Francis Golet, and Edward LaRoe. 1988. Classification of wetlands and deepwater habitats of the United States. Office of Biological Services; US Fish and Wildlife Service, Washington, D.C. Curtis, Odette E., R. N. Rosenfield and J. Bielefeldt. 2006. Cooper's Hawk (Accipiter cooperii), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http: //bna.birds.comell. edufbna/species/075. Dunk, T R. 1995. White-tailed kite (Elanus leucurus). In The Birds of North America, No. 178 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The_ American Ornithologists' Union, Washington, D.C. Feaver, P.E. 1971. Breeding Pool Selection and Larval Mortality of Three California Amphibians: Ambystoma tigrinum californiense Gray, Hyla regilla Baird and Girard and Scaphiopus hammondi hammondi Girard. Master's Thesis, Department of Biology, Fresno State College, Fresno, California. 58 pp. Federal Interagency Committee for Wetland Delineation. 1989. Federal manual for identifying and delineating jurisdictional wetlands. U. S. Army Corps of Engineers, U. S. Environmental Protection Agency, U. S. Fish and Wildlife Service, and U.S.D.A. Soil Conservation Service, Washington, D.C. Cooperative Technical Publication. Hickman, James C., editor. 1994. The Jepson Manual. University of California Press, Berkeley, California. Holland, Robert F. 1986. Preliminary descriptions of the terrestrial natural communities of California. California Department of Fish and Game Nongame Heritage Program. Mimeographed report. October, 1986. Kunz, T: H., and R. A. Martin. 1982. Plecotus townsendii. American Society of Mammalogists, Mammalian Species, 175:1-6. Leidy, R.A., G. S. Becker, and B.N. Harvey. 2005. Historic Distribution and Current Status for Steelhead/Rainbow Trout (Oncorhynchus mykiss) in Streams of the San. Francisco Estuary, California. Center for Ecosystem Management and Restoration, Oakland, California. htti)://www.cemar.org/pdf/santaclara..pdf Jameson, Jr., E., H. Peeters. 2004. Mammals of California. Berkeley: University of California Press. 1072 Geneva Avenue, San Francisco CA 94112 , Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com e www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 33 Jennings, M.R. and Hayes, M.P. 1994. Amphibian and Reptile Species of Special Concern in California. Prepared for the Calif. Dept. of Fish and Game Inland Fisheries Div. Rancho Cordova, Calif. November 1. 255 pp. Jennings, M.R. and Hayes, M. P. 1985. Pre -1900 Overharvest of California red -legged frogs (Rana aurora draytonii); The inducement for bullfrog (Rana catesbeiana) introduction. Herpetologica 41(1):94-103. Macwhirter, R. B. and K. L. Bildstein. 1996. Northern Harrier (Circus cyaneus). The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.comell.eduibna/species/210. Moyle, P.B. 2002. Inland fishes of California. University of California Press, Berkeley, CA. 502 pp - National Oceanic and Atmospheric Administration (NOAA) 2005a. Endangered and Threatened Species: Final Listing Determinations for 16 ESUs of West Coast Salmon, and Final 4(d) Protective Regulations for Threatened Salmonid ESUs. Federal Register / Vol. 70, No. 123 / Tuesday, June 28, 2005. NOAA 2005b. Endangered and Threatened Species; Designation of Critical Habitat for Seven Evolutionarily Significant Units of Pacific Salmon and Steelhead in California; Final Rule. Federal Register 70 (170): 52488 - 52627. NOAA Fisheries Office of Protected Resources. hqp://www.nwr.noaa.gov/Publications/FR Notices/2005/upload/70FR52488.i3df, National Resources Conservation Service (NRCS), US Department of Agriculture. Web Soil Survey for San Mateo County. Website accessed December, 20010. http://websoilsurvey.nres.usda. Qoy/app/ San Francisco Regional Water Quality Control Board. 1995. Basin Plan. Santa Clara Valley Urban Runoff Pollution Prevention Program, 2008. Watershed Monitoring and Assessment Program Stream Survey and Impact Assessment -- Matadero Creek. September 15, 2008, Prepared by EOA, Inc. http://www.scvurppp-w2k.com/pdfs/0809/FINAL Matadero USA Rnt.ndf Santa Clara Valley Water District (SCVWD), 2006. Guidelines and Standards for Land Use Near Streams. Santa Clara Valley Water Resources Protection Collaborative. Revised July. http://www.vallpMater.org/media/i)df/Creekwise/Guidelines chapters/Title%20pase%20a nd%20aknowledgements.pdf. Sawyer, John, and Todd Keeler -Wolf. 1995. A Manual of California Vegetation. California Native Plant Society, Sacramento. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 34 Sawyer, J.O., T. Keeler-Wolf,:and J.M. Evans. 2009. A .Manual of California Vegetation (2nd edition). California Native Plant Society, Sacramento. 1300 pp. Shaffer, H.B., R.N. Fisher, S.E. Stanley. 1993. Status Report: The California Tiger Salamander (Ambystoma californiense). A Final report to the California. Department of Fish and Game, Inland Fisheries Division. Rancho Cordova, California. Under contracts FG9422 and FG 1383. SCBWMI.2001. Watershed management plan, Volume One unabridged, watershed characteristics report, Chapter 7: natural setting (amended December 2003). Santa Clara Basin Watershed Management Initiative. Shaffer, H. B., and R. Fisher. 1991. Final Report to the California Department of Fish and Game: California tiger salamander surveys, 1990 --Contract (FG9422). California Department of Fish and Game, Inland Fisheries Division, Rancho Cordova, CA. Shuford, W.D. and T.G. Gardali. Eds. 2008. California Bird Species of Special Concern. A Ranked Assessment of Species, Subspecies, and Distinct Populations of Birds of Immediate Conservation Concern in California. Studies of Western Birds No. 1. Western Field Ornithologists and California Department of Fish and Game. 450 pp. Stebbins, R.C. 2003. Field Guide to Western Reptiles and Amphibians, Third Edition. Peterson Field Guide Series. Houghton Mifflin Company, New York. Storer, T.I. 1925. A:Synopsis of the Amphibia of California. University of California Publications in Zoology 27:1-342. U.S. Fish and Wildlife Service (USFWS). 2010a. Federal Endangered and Threatened Species that Occur in or may be Affected by Projects in Santa Clara County. Threatened and Endangered Species System (TESS) printout. Database access December 29, at htta://www.fws.gov/sacramento/es/Up lists/auto list form.cfm. 2010b. Endangered and Threatened Wildlife and Plants; Endangered and Threatened Wildlife and Plants: Revised Designation of Critical Habitat for California Red -Legged Frog; Final Rule (50 CFR Part 17). Federal Register: Vol. 75, No. 51: 12816-12959. March 17. . 2005. Federal Register: Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the California Tiger Salamander (Ambystoma californiense), Central Population; Final Rule; 50 CFR. Part 17. Vol. 70. No. 162: pp. 49380 — 49458. 2002. Recovery plan for the California red -legged frog (Rana aurora draytonii). U.S. Fish ID and Wildlife Service, Portland OR. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: Cllecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project -- February 2012 Page 35 1999b. Programmatic Consultation for Section 404 Nationwide Permit Program that may Affect California Red -legged Frogs, January 26. Document No. 1-1-99-F-52. Yosef, Reuven. 1996. Loggerhead Shrike (Lanus ludovicianus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.comell.edu/bna/species/231. Zeiner, David C., William F. Laudenslayer, Jr., Kenneth E. Mayer, and Marshall White. 1990. California's wildlife, Volume I: amphibians and reptiles; Volume II: birds; and Volume III: mammals. California Statewide Habitat Relationships Program, CDFG, The Resources Agency, Sacramento, CA. Personal Communications Dr. Alan Launer, Campus Biologist, Stanford University. Telephone and email communications, January, 2011. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmaii.com • www.CRecology.com 211 pal tS'-xr r'�+ : 1"'�•"" q v.atz�eia, rs,,: �+�+'•�v�� "r .�. r � s Y ; BRA for Town of Los Altos Hills Ai-astradero Ti -ail Improvement Project Febl-iialy 2012 Pa, e A-3 - - - Figure A-5. View of trail alignment along Arastradero Road as it -crosses under 1-280. Photo date: 12/07/2010. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894: Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — Februaby 2012 Page B-1 Appendix B. Special Status Plant and Animal Species in the Vicinity of the Project Site In evaluating on-site habitat suitability for special status plant and wildlife species within the study area, relevant literature, knowledge of regional biota, and observations made during the field investigations were applied as analysis criteria. Criteria determinations for occurrence potential of special status species are divided into the five categories described below. These determination categories appear in the following table, which provides a summary of the status, habitat affinities, flowering phenology, habitat suitability and local distribution, and potential for occurrence for each of the target special status species. It should be noted that local distribution references refer to the CNDDB Element Occurrence Index (EONDX) number (CDFG 2009). The EONDX is an integer primary key (unique for each record) used within the CNDDB for GIS relational databases. Although the EONDX is assigned sequentially, gaps may appear as records are merged or updated. Factors influencing which determination criteria are applied to target species is detailed below. • None denotes a complete lack of habitat suitability, local range restrictions, and/or regional extirpations. • Not Expected denotes situations where suitable habitat or key habitat elements may be present but may be of poor quality or isolated from the nearest extant occurrences. Incompatible habitat suitability refers to elevation, geology, soil chemistry and type, vegetation communities, microhabitats, and degraded/significantly altered habitats. These factors create unsuitable ecological conditions for the consideration of even a low occurrence potential within the study area. • Absent indicates specified taxa not observed during field investigations and were consequently ruled out. This category also refers to diagnostic vegetative material of shrubby perennial species not observed on site. This category refers only to plant species. • Possible indicates the presence of suitable habitat or key habitat elements that potentially support a specific species or taxa. • Present indicates the target species was either observed directly or its presence was confirmed by diagnostic sign (i.e. tracks, scat, burrows, carcasses, castings, prey remains, etc.) during field investigations. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com �.` " � t 3 s :z �_�'�� Oc�ur�Or►s�fre .` _ : . ,� _� _�� INVERTEBRATES r Bay checkerspot Fed: FT The bay checkerspot butterfly is a medium-sized butterfly in None butterfly CA: none the Nymphalidae (brush -footed butterflies) family. The No suitable habitat Euphydryas editha species is restricted to grasslands with serpentine soils in present within the bayensis the San Francisco Bay area. Plantago erecta is the primary trail alignment. host plant, Castilleja densiflorus and C. purpurescens are secondary host plants. Nectar plants include Layia platyglossa and Lasthenia californica. The species is only known from the San Francisco peninsula and the south San Francisco Bay area. Declining populations have resulted from loss of grassland habitat to development and loss of host and nectar plants within grasslands from invasive weeds. The bay checkerspot was last observed at Jasper Ridge Biological Preserve in 1998. Ricksecker's water Fed: none Inhabits slow moving freshwater streams, side channel and Not Expected scavenger beetle CA: none backwater pools, ponds, marshes and lakes in Sonoma, Very little known Hydrochara rickseckeri SA Marin, Alameda, Contra Costa and San Mateo counties. about species. Has Little data is available regarding this species' natural history. not been observed since 1950's. Nearest record is located in San Mateo. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project February 2012 Page B-2 Specie ,yams S't`atus ` ,Habitat « � .rr San Francisco Fed: none Inhabits small, marshy ponds and ditches with emergent and None forktail damselfly CA: none floating aquatic vegetation. Has been recorded in San Mateo No suitable habitat Ischnura gemina SA and San Francisco Counties. on site, and species has not been recorded in Santa Clara County Monarch butterfly Fed: none Monarch butterflies require wind protected tree groves along Not Expected Danaus plexippus CA: none the California coast for nectaring, migratory roosting, and Monarch roosting SA wintering sites. Roosting sites are also located in isolated sites are typically locations bordering San Francisco Bay. Blue gum located within Y2 Eucalyptus (Eucalyptus globulus) is commonly used by mile of the coast, or monarch butterflies as nectaring and roosting sites. San Francisco Bay, Monterey pine (Pinus radiata) and Monterey cypress and the property is (Cupressus macrocarpa) groves may also provide roosting several miles inland. habitat for monarch butterflies. Myrtle's silverspot Fed: FE The Myrtle's silverspot butterfly is a medium sized butterfly None butterfly CA: none that is found in coastal dune or coastal prairie habitat. Species once Speyeria zerene Females lay their eggs in the debris and dried stems of their occurred in San myrtleae larval host plant blue violet (Viola adunca). Adults feed on Mateo County, but nectar from flowers including hairy gumweed (Grindelia now is believed to hirsutula), coastal sand verbena (Abronia latifolia), mints and be restricted to thistles. coastal areas of Populations were formerly found in dunes and bluffs from Marin County. No San Mateo County north to the mouth of the Russian River suitable habitat in Sonoma County. The adult flight season ranges from late present in project June to early September. area. Unsilvered fritillary Fed: none The Unsilvered fritillary butterfly is a medium-sized butterfly Not Expected Speyeria adiaste CA: none in the brush -footed butterfly family, Nymphalidae, with a No suitable habitat adiaste SA wingspan of approximately 2 inches. The spot pattern on the is present within the ventral hind wings is unsilvered and almost obsolete. The project area. Unsilvered fritillary butterfly occurs in grasslands, chaparral and oak woodland, where it's host plant (Viola sp.) are present. The species nectars on thistles and California buckeye (Aesculus californica). This species is uncommon and is thought to be declining in numbers. Steelhead Fed: FT, CH Steelhead are anadromous fish that migrate from the ocean Not Expected Oncorhynchus mykiss CA: none into fresh water streams to spawn (Moyle 2002). Rainbow Species has not irideus AFS: Th trout refers to the resident form of the species that inhabits been documented in central California lakes or streams and does not migrate to the ocean. the upper watershed Steelhead build redds (i.e., spawning beds) at the head of of Matadero Creek coast DPS riffles where water is well oxygenated and nearby pools with for several decades. deeperwater provide safe refuge forjuveniles. Optimal temperatures for growth are 15-18°C. While in freshwater streams, steelhead feed on drifting aquatic organisms, terrestrial insects and bottom dwelling invertebrates (Moyle 2002). Migratory steelhead smolts migrate to the ocean after spending 1-3 years in their natal freshwater streams. Adults remain in the ocean for 1-4 years prior to returning to their natal streams, or occasionally to neighboring streams, to spawn. Unlike salmon, steelhead often return to spawn more than once. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-3 SpeciesJda a Staff s �Habi at $i4MPHiB,iANS= SND R1=PTILES., _gip r;�`x��x�, California red -legged Fed: FT, CH A medium-sized frog that inhabits lowlands & foothills in or Possible frog CA: SSC near permanent sources of deep water with dense, shrubby No suitable breeding Rana aurora draytoni/ or emergent riparian vegetation up to 1,500 meters in habitat on the trail elevation (Stebbins 2003). Range extends from Redding to alignment, however Baja California, Mexico with hybridization occurring with the the trail alignment California red -legged frog from the Oregon border to Marin may provide County. Breeding occurs between November and April in nonbreeding standing or slow moving water at least 0.7 meters (2 %2 feet) dispersal habitat. in depth with emergent vegetation, such as cattails (Typha spp.), tules (Scirpus spp.) or overhanging willows (Salix spp.) (Hayes and Jennings 1988). Habitat for this species is located in several areas on the San Francisco Peninsula where suitable ponds, marshes, streams with adjacent uplands are present. This species has been detected in Matadero Creek, adjacent to the trail alignment. California tiger Fed: FT, CH The California tiger salamander is a large, terrestrial Not Expected salamander CA: ST, salamander distributed throughout the Central Valley and Species is unlikely Ambystoma SSC Central Coast ranges from Colusa County south to San Luis to utilize the trail californiense Obispo and Kern counties. California tiger salamanders alignment due to the inhabit lowland grasslands, oak savannah, and mixed lack of pond or woodland habitats, and require vernal pools, seasonal vernal pool habitats ponds, or semi-permanent calm waters that pond water for on or adjacent to the at least 3 to 4 months in duration for breeding, and adjacent project area. upland habitat with small mammal burrows for aestivation. Loss and degradation of vernal pools is a significant threat to the species. California tiger salamanders are at risk due to loss of habitat, habitat fragmentation, loss and degradation of vernal pools, and introduction of predatory exotic species such as mosquitofish (Gambusia affinis), bullfrogs (Rana catesbiena), and Louisiana red swamp crayfish (Procambarus clarkii), and poisoning of ground squirrels (Zeiner et al. 1988, Collins et al. 1988, Shaffer et al. 1993, and Jennings and Hayes 1994). High mortality of California tiger salamanders while crossing roads while migrating to and from breeding sites also adversely affects individuals and at -risk populations (Bang and Shaffer 1994). Foothill yellow- Fed: none A medium-sized frog that inhabits rocky, cascading streams None legged frog CA: SSC in woodland, chaparral and coniferous forests from the No suitable habitat Rana boylii USFS Oregon border to San Luis Obispo County and the western within or adjacent to foothills of the Sierra Nevada below 6000 feet. Frequents the trail alignment. shallow, slow, gravelly streams and rivers with sunny banks. San Francisco garter Fed: FE A highly aquatic subspecies of the common garter snake Not Expected snake CA: SE, FP endemic to the San Francisco Bay Area, San Francisco Species is unlikely Thamnophis sirtalis garter snakes are distributed along the western San to utilize the trail tetrataenia Francisco Peninsula from the southern San Francisco alignment due to the County border south to Waddell Lagoon south of Ano Nuevo lack of suitable pond and as far west as Crystal Springs Reservoir. The species and/or marsh often occurs near ponds, marshes, streams and other habitats on or wetlands associated with cattails, bulrushes, and rushes. adjacent to the Mating occurs shortly after they leave their winter retreats in project area. May and females give birth to live young between June and September. Species may hibernate in upland habitats near water in fossorial mammal burrows and other refuges, or remain active year-round weather permitting. Critical Habitat has not been designated for this species. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.corn BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-4 �Spec�es arae * " Shat s, �� x dt, 'tea NAM ' S t nt �Occ Onsi4e Western pond turtle Fed: none A moderate sized freshwater turtle that inhabits permanent Not Expected Emys marmorata CA: SSC or nearly permanent bodies of water and low gradient slow Species is unlikely marmorata USFS:S moving streams below 6000 feet elevation. Species to utilize the trail requires aquatic habitat with a minimum of 2 meters (6.5 alignment area due feet) of depth for escape cover and suitable basking sites, to the lack of and adjacent open upland habitats for nesting sites. Range suitable aquatic extends from Washington to the northern Bay Area counties habitats in adjacent along the Pacific slope drainages. Two recognized areas to support this subspecies include the northwestern pond turtle (E. m. species. marmorata) which ranges north of the American River and the southwestem pond turtle (E. m. pallida) which ranges from the coastal areas south of San Francisco. Subspecies interbreed within the gradation zone that defines the two subspecies. ilii 5 4 g .; _Irs""Kylk. Burrowing owl Fed: none Inhabits valley bottoms and foothills with low vegetation and Not Expected Athene cunicularia CA: SSC fossorial mammal activity. Listing includes wintering No suitable breeding (burrow sites & some BLM: S observations with/without a burrow in San Francisco, habitat. Marginally wintering sites) Ventura, Sonoma, Marin, Napa and Santa Cruz counties. suitable wintering Breeding begins in March; single -brooded (Baicich & habitat adjacent to Harrison 2005). the trail alignment. California thrasher Fed: none Inhabits chaparral, foothills, valley thickets and suburban Possible Toxostoma redivivum CA: none areas. Breeds in similar habitats throughout much of the Suitable nesting ABC coastal California and the western Sierra foothills south of habitat is present Redding. Breeds November through July; double -brooded adjacent to trail (Baicich & Harrison 2005). alignment. Cooper's hawk Fed: none Inhabits dense stands of oak woodlands, riparian deciduous Possible Accipiter cooperii CA: WL forests, or other forest habitats often near water & suburban Suitable nesting and (nesting) areas. Hunts in broken woodlands & along forest edges. foraging habitat is Breeding begins in April; single -brooded (Baicich & Harrison present within areas 2005). adjacent to trail alignment. Species was observed foraging in area during biological surveys. Northern harrier Fed: none Northern harrier is a year-round resident of coastal California Not Expected Circus cyaneus CA: WL and the Central Valley. Inhabits both freshwater and May forage saltwater marshes and adjacent upland grasslands. Nests infrequently over on the ground in tall grasses or clumps of tall vegetation in project area grasslands and meadows (Macwhirter and Bildstein 1996). Breeds from Late March through September; single -brooded (Baicich & Harrison 2005). Northern harriers forage on the wing in low flight in marshes, prairies, heavily grazed grasslands, and harvested fields primarily for voles (Microtus spp.), but also feeds opportunistically on other small mammals, reptiles, amphibians and small birds (Macwhirter and Bildstein 1996). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-5 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 - Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com W` ; ''� ".01 - �� d ,�x �OccurOns_ ife„ Golden eagle Aquila Fed: none A large diumal raptor that nests on cliffs and in large trees in Not Expected chrysaetos CA: SSC, open areas. Forages in open terrain including grasslands, Marginally suitable (nesting and wintering) FP, WL, deserts, savannahs and early successional stages of forest foraging habitat is BCC and shrub habitats. Breeding begins in February to late May; present for this single -brooded (Baicich & Harrison 2005). species. There are no known nesting sites for golden eagle within the region. May occasionally forage over open habitats and occur as a flyover due to large habitat range. Lawrence's goldfinch Fed: none Inhabits and oak/pine woodlands, foothills and chaparral Not Expected Carduelis /awrencei CA: none from northern California west of the Sierra Nevada south to Marginally suitable (nesting) ABC, BCC Baja California, Mexico. Breeding begins in March; double- habitat in project brooded (Baicich & Harrison 2005). area. This species is rarely detected in Santa Clara County, and typically does not breed in coastal habitats. Loggerhead shrike Fed: none Inhabits a variety of habitats from open grasslands and Possible Lanius ludovicianus CA: SSC scrub to woodlands and riparian areas. Species typically Suitable foraging (nesting) BCC uses fenceposts, shrubs and small trees for perching while and marginal foraging in open habitats. Year-round resident of California. nesting habitat Breeding begins in February; double to triple -brooded present within oak (Baicich & Harrison 2005). savannah in project area. Long-eared owl Fed: none Inhabits riparian and live oak woodlands near meadows and Not Expected Asio otus CA: SSC forested habitats. Occurs in dense conifer stands at higher No suitable habitat (nesting) elevations. An uncommon species in the San Francisco Bay present for this Area. Breeds from March to July. species within the project area. Merlin Fed: none Winters throughout California, breeds in northern states, Not Expected Falco co/umbadus CA: WL Canada and Alaska. Wintering habitat included open forests, Marginal winter (wintering) grasslands, agricultural fields, mud flats and urban areas. foraging habitat in Feeds primarily on small birds. Breeding begins in May; the project area. single -brooded Baicich & Harrison 2005). Nuttall's woodpecker Fed: none Inhabits oak woodland and mixed riparian woodlands. Present Picoides nuttallii CA: none Forage along bark of trees for insects; also feeds on acoms. Suitable nesting (nesting) ABC Cavity nester. Breeding begins in March; single -brooded habitat is present (Baicich & Harrison 2005). within oak savannah and ornamental trees within project area. Oak titmouse Fed: none Primarily an oak obligate species, the oak titmouse inhabits Present Baeolophus inornatus CA: none oak woodlands, oak savannahs, pinyon and juniper Suitable nesting and (nesting) ABC woodlands and occasionally suburban areas with oaks. foraging habitat is Year-round resident throughout much of California. Breeding present in the begins in March; single -brooded Baicich & Harrison 2005. project area. Bank swallow Fed: noneNone Colonial nester, nests primarily in riparian and other lowland Riparia riparia CA: FT habitats west of the desert. Requires vertical banks/cliffs No suitable open (nesting) with fine-textured/sandy soils near streams, rivers, lakes, bank habitat for this and/or ocean to dig nesting hole. species within the trail alignment. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 - Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project —February 2012 Page B-6 peaes� ne stills H bitat `RM Ot NIS ccur�Onsitel Black -crowned night Fed:none Colonial nester, usually in trees, occasionally in tule patches. Not Expected heron CA: none Rookery sites located adjacent to foraging areas: lake No suitable nesting (Nycticorax nycticorax) BLM: S margins, mud -bordered bays, marshy spots. habitat for this (rookery site) species within the trail alignment. Sharp -shinned hawk Fed: none Inhabits north -facing slopes in conifers, including ponderosa Not Expected Accipiter striatus CA: WL pine, black oak, & Jeffrey pines, preferably in riparian areas. Suitable foraging (nesting) Forages primarily for small birds along woodland edges & habitat is present in openings, hedgerows, brushy pastures, & shorelines. project area. Breeding begins in April; single -brooded (Baicich & Harrison Species is not 2005). expected to nest in project area. White-tailed kite Fed: none Inhabits grasslands, agriculture fields, oak woodlands, Possible Elanus leucurus CA: FP savannah and riparian habitats in rural and urban areas. Suitable foraging (nesting) Other: Feeds primarily on California voles. Forages over grassland habitat is present and nests in shrubs and trees. Year-round resident of within the open Central and Coastal California. Breeding begins in February; habitats in the sometimes double -brooded (Baicich & Harrison 2005). project area. Great blue heron Fed: none Colonial nester in tall trees, cliffsides, and sequestered spots None Ardea herodias CA: none on marshes. Rookery sites in close proximity to foraging No suitable habitat (rookery site) Other: areas: marshes, lake margins, tide -flats, rivers and streams, for rookeries. May CDF: S wet meadows. forage within project area. Snowy egret Fed: none Colonial nester, with nest sites situated in protected beds of None Egretta thu/a CA: none dense tules. Rookery sites situated close to foraging areas: No suitable habitat (rookery site) SA marshes, tidal -flats, streams, wet meadows, and borders of for rookeries. May lakes. forage within project area. Saltmarsh common Fed: none Resident of the San Francisco bay region, in fresh and salt Not Expected yellowthroat Geothlypis trichas CA: SSC BCC water marshes. Requires thick, continuous cover down to Suitable marsh water surface for foraging; tall grasses, tule patches, willows habitat not present sinuosa for nesting. in project area. Northern harrier Circus cyaneus Fed: none CA: SSC Inhabits coastal salt and fresh -water marsh. Nests and Not Expected. forages in grasslands, from salt grass in desert sink to Species utilizes mountain bogs/swamps. Nests on ground in shrubby coastal grasslands vegetation, usually at marsh edge; nest built of a large typically near water. mound of sticks in wet areas. May forage within project area infrequently. Yellow -breasted chat Fed: none A large, secretive wood warbler that inhabits riparian Not Expected Icteria virens CA: SSC thickets, pond margins, marshes, hedgerows, old pastures Dense thickets not (nesting) and edge habitats in forests especially regenerating burned present in Matadero and logged areas (Eckerle and Thompson 2001, Baicich & Creek in project Harrison 2005). Distributed throughout northern California area. and the Central Valley. Nests in dense shrubs up to eight feet in height; breeding begins in early April; double -brooded (Baicich & Harrison 2005). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 - Cell: 650-269-3894 - Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-7 y r g Potential to ° k' n ffiInhabits San Francisco Fed: none chaparral, coastal scrub, oak woodland, and Present dusky -footed CA: SSC riparian woodland in the San Francisco Bay Area. They Species was woodrat exhibit high site fidelity and may live in the same nest detected on site Neotoma fuscipes community for generations. Nest structures are key indicator within the oak annectens of their presence and are easily identified by their large, savannah and within conical appearance. Species is typically not associated with ornamental urban areas due to lack of suitable native woodland plants vegetation. used for foraging, and increased predation pressure from feral and domestic cats. Typically does not nest in human structures, unless suitable foraging habitat is adjacent. American badger Fed: none A large mustelid that inhabits open areas with friable soils Not Expected Taxidea taxus CA: SSC within woodland, grassland, savannah and desert habitats. A Marginal habitat fossorial mammal that preys predominately on ground present in squirrels (Ammospermophilus and Spermophilus spp.) and grasslands, but pocket gophers (Thomomys spp.). Mating occurs in late limited available summer; young are born in March and April. open habitat within the trail alignment. Species rarely observed in Santa Clara County. Big free -tail bat Fed: none Big free -tail bat ranges from most of South America Not Expected (Nyctinomops CA: SSC northward to include Mexico, Arizona, New Mexico, southern Rare migrant in macrotis) WBWG - MH and western Texas, southern California and southeastern Santa Clara County. Nevada, southern Utah, and north to central Colorado. The species is migratory, and the known elevational range is from near sea level to about 8,500 ft (2,600 meters). Big free -tail bats appear to mainly inhabit rugged, rocky habitats in and landscapes. The species has been found in a variety of plant associations, including desert shrub, woodlands, and evergreen forests. Fringed myotis Fed: none Exhibits a strong roosting preference for large trees and Possible Myotis thysanodes CA: none snags, but will use buildings, caves, rock crevices, etc. if Potential roosting WBWG-H necessary. Inhabits a variety of woodland, scrub and and foraging habitat grassland habitats up to 2,850 meters throughout California along Matadero except for Central Valley and southern deserts. Forages Creek. great distances and is active during winter months. Highly sensitive to human disturbance. Western red bat Fed: none The western red bat is primarily riparian obligate species Possible Lasiurus blossevillii CA: SSC with a widespread distribution extending from British Species is a fall WBWG-H Columbia to Argentina (Bolster 2005). They are ubiquitous migrant. Suitable USFS: S throughout most of California except the northern Great roosting habitat Basin region. The red bat is easily distinguished by its present within distinctive reddish coloration. Roosting typically occurs Matadero Creek. individually in dense clumps of tree foliage in riparian areas, especially willows, cottonwoods and sycamores, and within orchards and suburban areas in trees and shrubs. Roosts are often hidden from view and only access from below (Bolster 2005). Red bats are primarily moth specialists, but individuals will forage for a variety of other insects. Individuals have been observed foraging around street lamps and flood lights in suburban areas (Bolster 2005). The western red bat migrates long distances, but has been reported to overwinter in the Bay Area with interspersed winter foraging bouts on warm days Bolster 2005). 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-8 � S ec ffi"N ine P WOW S a"tus g * �� a Habitat. { ---------------- ".Potentia Ao �:- Occur _ nsite Long-eared bat Fed: none The long-eared myotis bat ranges across western North Possible Myotis evotis CA: none America from Canada to Baja California, Mexico and Potentially suitable BLM: S eastward to the western Great Plains (Bogan et al. 2005). roosting and WBWG-M Long-eared myotis bats primarily inhabit coniferous and to a foraging habitat in lesser extent semi -arid shrublands, sage, chaparral, and project area agricultural areas (Bogan et al. 2005). Roosts are located in tree cavities and under exfoliating bark in dead trees; however, pregnant females may use rock crevices, tree stumps and fallen logs. Young are born in June; females form small nursery colonies (Jameson and Peeters 2004). They forage for large prey such as beetles and moths by gleaning from foliage, rocks and other substrate, while hovering (Bogan et al. 2005). Hoary bat Fed: none Ubiquitous throughout California. A solitary foliage rooster Possible Lasiurus cinereus CA: none that prefers evergreens, but will use deciduous trees in Unlikely to breed WBWG-M forested habitats, particularly in edge habitat (Bolster 2005). within project area. May forage in small to large groups. Feeds primarily on Potentially suitable moths, but will eat a variety of other insects. Migrates great roosting and distances. foraging habitat is resent. Yuma myotis Fed: none The Yuma myotis bat ranges throughout western North Possible Myotis yumanensis CA: none America from British Columbia, Canada to Mexico, and is Potentially suitable BLM:S ubiquitous throughout California. Typical habitat includes breeding habitat, WBWG-LM riparian corridors and edge habitat in forested canyons, but foraging and also inhabit and shrublands, deserts and forests (Bogan et roosting habitat al. 2005). They are colonial roosters and are typically found within Matadero in manmade structures such as bridges or building, but will Creek also use caves, mines and old cliff swallow nests (Jameson and Peeters 2004). They also roost in a variety of habitats and forage above the water in riparian corridors and along the forest edge. Yuma myotis bats form matemity colonies of several thousand and give birth from April through July depending on latitude (Bogan et al. 2005). Long-legged myotis Fed: none Long-legged myotis bats inhabit brushy woodlands and Possible Myotis volans CA: none coniferous forests up to 2,800 meters throughout California Potentially suitable WBWG-H except the Central Valley and deserts. They roost in a roosting and variety of habitats including exfoliating bark, tree hollows, foraging habitat in caves, rotten stumps, snags, cliff crevices and bridges. They the project area. are foliage gleaners that require nearby water. Pallid bat Fed: none Inhabits rocky terrain in open areas in lowlands, foothills and Possible Antrozous pallidus CA: SSC mountainous areas near water throughout California below Potential roosting USFS: S 2,000 meters. Roost in caves, rock crevices, mines, hollow and foraging habitat WBWG-H trees, buildings and bridges in and regions in low numbers in the project area. (<200). Active from March -November; migrates in some areas, but may hibernate locally. Preys on large beetles and scorpions. This species is typically found in dry grasslands and oak savannah habitats, and currently can be detected in the south and east San Francisco Bay area. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 - Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — Februmy 2012 Page B-9 �' � • �-��'' Speeies� afne�WON'& s� z � �P=otentialkto Habitat ��,. z� OC_CUfi �i1SitL' Townsend's big- Fed: none A cave rooster and moth specialist. Inhabits caves and Not Expected eared bat CA: SSC mines, but may also use bridges, buildings, rock crevices Marginally suitable Corynorhinus USFS: S and tree hollows in coastal lowlands, cultivated valleys and habitat present townsendi WBWG-H nearby hills characterized by mixed vegetation throughout within the project California below 3,300 meters. Exhibits high site fidelity and area. The species is is highly sensitive to disturbance. Forages along edge a rare rooster on the habitats near water; may travel long distances during San Francisco foraging bouts. It is a moth specialist with over 90% of its peninsula. diet composed of lepidopterans. This species has been detected in the north and east San Francisco Bay area. Alkali milk -vetch Fed: none Alkali playa, valley and foothill grassland, vernal pools. None Astragalus tener var. CA: none Low ground, alkali flats, and flooded lands in annual No suitable habitat tener CNPS 1 B.2 grassland or in playas or vernal pools. 1-170m. Flowers present. March — June Anderson's Fed: none Evergreen shrub that occurs in openings and edges of None manzanita CA: none broadleaved upland forest, chaparral, and north coast No suitable habitat Arctostaphylos CNPS 113.2 coniferous forest. Flowers from November — April. present. andersonii Arcuate bush mallow Fed: none An evergreen shrub that occurs ultramafic chaparral, None Malacothamnus CA: none gravelly alluvium. Flowers from April — Sep. No suitable habitat arcuatus CNPS 1B.2 present. Bent -flowered Fed: none Cismontane woodland, valley and foothill grassland. 50- Not Expected fiddleneck (Amsinckia CA: none 500M. Flowers from March — June. Low potential for lunaris) CNPS 16.2 occurrence in ruderal grasslands near project area. No suitable habitat along trail alignment. Caper -fruited Fed: none Valley and foothill grassland. Alkaline clay. 0-455m. Flowers Not Expected tropidocarpum CA: none March — April. Low potential for Tropidocarpum CNPS 16.1 occurrence in capparideum ruderal grasslands near project area. No suitable habitat along trail alignment. Choris's popcorn- Fed: none Annual herb that occurs in chaparral, coastal scrub, coastal None flower CA: none prairie, mesic sites. Flowers from March — June. No suitable habitat Plagiobothrys CNPS 1 B.2 present. chorisianus var. chorisianus Coastal marsh milk- Fed: none Coastal dunes, coastal salt marshes. None vetch CA: none Mesic sites in dunes or along streams or coastal salt No suitable habitat Astragalus CNPS 1 B.2 marshes. 0-30m. Flowers April — October present. pycnostachyus var. pycnostachyus Congdon's tarplant Fed: none Valley and foothill grassland. Alkaline soils, sometimes Not Expected Centromadia parryi CA: none described as heavy white clay. 1-230m. Flowers May to Low potential for ssp. congdonii CNPS 1B.2 November. presence within ruderal grasslands near project area. No alkaline soils in project area. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 - Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-10 S ec�es ame St tms bitat�� '`� P.�otental�Eo Crystal Springs Fed: none Annual herb found in grassy slopes in valley/foothill None lessingia CA: none grasslands or coastal sage scrub on serpentine soil. Flowers No suitable habitat Lessin is arachnoidea CNPS 113.2 from Jul — Oct. present. Davidson's bush Fed: none Deciduous shrub that occurs in sandy washes in coastal None mallow CA: none scrub, riparian woodland, or chaparral. Flowers from June — No suitable habitat Malacothamnus hallii CNPS 113.2 Jan. present. Dudley's lousewort Fed: none Perennial herb that occurs in chaparral, cismontane None Pedicularis dudleyi CA: none woodland, north coast coniferous forest, and valley and No suitable habitat CNPS 1 B.2 foothill grassland. Flowers from April — June. resent. Fountain thistle Fed: FE Valley and foothill grassland, chaparral. Serpentine seeps None Cirsium fontinale var. CA: CE and grassland. 90-180m. Flowers from May — October. No suitable habitat fontinale CNPS 16.1 present. Fragrant fritillary Fed: FSC Bulbiferous herb found in moist areas, often ultramafic, open None Fritillaria liliacea CA: none hills, in valley and foothill grasslands. Flowers from Feb. — No suitable habitat CNPS 113.2 Aril. present. Franciscan onion Fed: none Bulbiferous herb found in cismontane woodland, valley and Not Expected Allium peninsulare var. CA: none foothill grassland. Clay soils, often on serpentine. Dry Low potential for franciscanum CNPS 1 B.2 hillsides. Flowers from May — June. occurrence in annual grasslands near project area. No suitable habitat along trail alignment. Franciscan thistle Fed: none Perennial herb found in coastal bluff scrub, broadleaved None Cirsium andrewsii CA: none upland forest, and coastal scrub, sometimes on serpentine No suitable habitat CNPS 113.2 seeps. Flowers from March — July. present. Hall's bush mallow Fed: none Evergreen shrub found in primarily ultramafic chaparral. None Malacothamnus hallii CA: none Flowers from May -Sep. No suitable habitat CNPS 16.2 present. Hickman's cinquefoil Fed: FE Perennial herb found in open pine forests in marshy areas None Potentilla hickmanii CA: SE and on coastal bluffs, prairies, and grassy meadows. No suitable habitat CNPS 113.1 Flowers from April — Aug. present. Hoover's button- Fed: none Vernal pools. Alkaline depressions, vernal pools, roadside Not Expected celery CA: none ditches and other wet places near the coast. 5-45m. Flowers Low potential for Eryngium anstulatum CNPS 113.1 July. occurrence in var. hooveri roadside ditch near project area. No suitable habitat along trail alignment. Indian bush mallow Fed: none Deciduous shrub that occurs in cismontane woodland and None Malacothamnus CA: none chaparral, on granitic outcrops and sandy bare soils. No suitable habitat aboriginum CNPS 1 B.2 Flowers from April — Oct. present. Kings Mountain Fed: none Broadleaved upland forest, chaparral, north coast coniferous None manzanita CA: none forest. Granitic or sandstone outcrops. 305-730m. Flowers No suitable habitat Arctostaphylos CNPS 113.2 from January — April. present. regismontana Marin western flax Fed: FT Chaparral, valley and foothill grassland. In serpentine None Hesperolinon CA: CT barrens and in serpentine grassland and chaparral. 30- No suitable habitat congestum CNPS 113.1 365m. Flowers from April — July. present. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project —February 2012 Page 8-11 p�ec�e atrt� at Robust monardella Fed: none A rhizomatous herb that occurs in chaparral openings, None Monardella villosa ssp. CA: none cismontane woodland, and coastal scrub. Flowers from June No suitable habitat globosa CNPS 113.2 — July. present. Round -leaved filaree Fed: none Cismontane woodland, valley and foothill grassland. Clay Not Expected California macrophylla CA: none soils. 15-1200m. Flowers March — May. Low potential for CNPS 1 B.1 occurrence in ruderal grasslands near project area. Most recent record for species from region is over 100 years old (CNDD13 2010). Saline clover Fed: none Marshes and swamps, valley and foothill grassland, vernal None Trifolium CA: none pools. Mesic, alkaline sites. 0-300m. Flowers from April to No suitable habitat depauperatum var. CNPS 113.2 June. present. hydrophilum San Francisco Bay Fed: none Coastal bluff scrub, coastal dunes, coastal prairie, coastal None spineflower CA: none scrub. Closely related to C. pungens. Sandy soil on terraces No suitable habitat Chorizanthe cuspidata CNPS 113.2 and slopes. 5-550m. Flowers April — August. present. var. cuspidata San Francisco Fed: none Perennial herb that occurs in coastal scrub, valley and None campion CA: none foothill grassland, coastal bluff scrub, chaparral, coastal No suitable habitat Silene verecunda ssp. CNPS 1 B.2 prairie. Often on mudstone or shale. Flowers March — present. verecunda August. San Francisco Fed: none Annual herb that occurs in moist shady woodland, Possible collinsia CA: none associated with California buckeye, honeysuckle, ferns, Potential habitat Collinsia multicolor CNPS 1B.2 coast live oak, poison oak. Flowers from March — May. present within shady banks of Matadero Creek, however not expected within trail alignment. San Francisco owl's- Fed: none Coastal prairie, valley and foothill grassland. On serpentine Not Expected clover CA: none and nonserpentine substrate (such as at Pt. Reyes). 10- Low potential for Triphysaria floribunda CNPS 1B.2 160m. Flowers April — June. occurrence in ruderal grasslands near project area. No suitable habitat along trail alignment. San Joaquin Fed: none Chenopod scrub, alkali meadow, valley and foothill None spearscale CA: none grassland. In seasonal alkali wetlands or alkali sink scrub No suitable habitat Atriplex joaquiniana CNPS 113.2 with Distichlis spicata, Frankenia, etc. 1-250m. Flowers from present. April — October. San Mateo thorn -mint Fed: FE Annual herb that occurs in serpentinite vertisol clays; in None Acanthomintha duttonii CA: CE relatively open areas. Flowers from April — June. No suitable habitat CNPS 1 B.1 present. San Mateo woolly Fed: FE Cismontane woodland. Often on roadcuts; found on and off None sunflower CA: CE of serpentine. 45-150m. Flowers from May to June. No suitable habitat Eriophyllum latilobum CNPS 1B.1 present. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — February 2012 Page B-12 species ame at s. Nab tat '� Fit nf�al�o ' ... State listed as Endangered FT Oeclar<fl_ns_%tem _ — Western leatherwood Fed: None Deciduous shrub that occurs on mesic sites in broadleaved Possible Dirca occidentalis CA: none upland forest, closed -cone coniferous forest, chaparral, Potential habitat SCT CNPS 1 B.2 cismontane woodland, North Coast coniferous forest, present within SCD State candidate for delisting riparian scrub, and riparian woodland. Flowers from January Matadero Creek, SSC California Species of Special Concern — April. however species FP Fully Protected CH was not observed WL Watch List during field surveys. White -flowered rein Fed: none Perennial herb that occurs in broadleafed upland forest, None orchid CA: none lower montane coniferous forest, North Coast coniferous No suitable habitat Piperia candida CNPS 1 B.2 forest, sometimes on serpentine. Flowers from May — Sep. present. R�►R FCA -,NT COMMUNITIES -- Fed: none Central Coast Riparian Scrub (Salix lucida ssp, lasiandra Present CA: G3S3/ Alliance) Central Coast G4S3? Riparian Scrub is present along Matadero adjacent to the trail alignment. Explanation of State and Federal Listing Codes Federal listingcodes: California listing codes: FE Federally listed as Endangered SE State listed as Endangered FT Federally listed as Threatened ST State listed as Threatened RE Federally proposed for listing as Endangered SCE State candidate for listing as Endangered FPT Federally proposed for listing as Threatened SCT State candidate for listing as Threatened FPD Federally proposed for delisting SCD State candidate for delisting FC Federal candidate species (former Category 1 candidates) SSC California Species of Special Concern SC Species of Concern (NMFS regulated species only) FP Fully Protected CH Critical Habitat (Proposed or Final) is designated WL Watch List SSC Species of Special Concern designated by the Marine Mammal Commission FSC Federal Species of Concern —No longer maintained by USFWS Sacramento Regional Office SLC Species of local concern or conservation importance — No longer maintained by USFWS ABC The American Bird conservancy maintains a Green List of all the highest priority birds for conservation in the continental United States and Canada. Based off the species assessments prepared by Partners in Flight (PIF) and has been expanded to include shorebirds, waterbirds and waterfowl. AFS American Fisheries Society identifies marine, estuarine and diadromous fish species that are at risk of extinction in North America. The AFS has designated the following four classifications in order of conservation importance E — Endangered, T— Threatened, V — Vulnerable, and CD — Conservation Dependent. Audubon Audubon Watchlist: *RED: species in this category are declining rapidly, have very small populations or limited ranges and face major conservation threats. These typically are species of global conservation concern. Q' YELLOW: this category includes those species that are also declining but at a slower rate than those in the red category. These typically are species of national conservation concern. *GREEN: species in this category are not declining, have unknown trends, or have very large population sizes; and are not included on the Watchlist. BCC U.S. Fish and Wildlife Service Birds of Conservation Concern. List of migratory and nonmigratory bird species (beyond those already designated as federally threatened or endangered) that represent the Service's highest conservation priorities. BLM Bureau of Land Management. Species designated as "Sensitive Species" are treated with the same level of protection that is given to federal candidate species. CNPS California Native Plant Society. CNPS 1B = California Native Plant Society: rare or endangered in CA or elsewhere. 0.1: Seriously endangered in California; 0.2: Fairly endangered in California, CNPS 2 = California Native Plant Society: rare or endangered in CA but more common elsewhere., CNPS 3 = California Native Plant Society: more information is needed to determine degree of sensitivity, CNPS 4 = California Native Plant Society: plant of limited distribution. CDFGC California Department of Fish and Game Code: §3503 prohibits the taking, possession or needless destruction of the nest or eggs of any bird; §3503.5 prohibits the taking, possession or destruction of any bird in the order Falconiformes or Strigiformes (birds -of -prey) or the taking, possession or destruction of the nest or eggs of any such bird; §3511 outlines protection for fully protected birds; and §3513 prohibits the taking or possession of any migratory non -game bird as designated in the Migratory Bird Treaty Act. FS USDA Forest Service designates species as "sensitive" that are not listed or proposed for listing by the federal Endangered Species Act for which population viability is a concern, as evidenced by significant current or predicted downward trends 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com BRA for Town of Los Altos Hills Arastradero Trail Improvement Project — Februa y 2012 Page B-13 in population numbers or density, or significant current or predicted downward trends in habitat capability that would reduce a species' existing distribution. MBTA Migratory Bird Treaty Act. Species of migratory birds protected by the Migratory Bird Treaty Act (16 U.S.C. 703-711) and subject to the regulations on migratory birds contained in this subchapter B of title 50 CFR. MNBMC Migratory Nongame Bird of Management Concern: Considered to be of concern in the U.S. due to documented or apparent population decline, small or restricted population, or dependence on restricted or vulnerable habitat. SA "Special Animals" is a general term that refers to all of the taxa the CNDDB is interested in tracking, regardless of their legal or protection status. This list is also referred to as the list of "species at risk" or "special status species". The Department of Fish and Game considers the taxa on this list to be those of greatest conservation need. USBC The United States Bird Conservation Watch List. Includes the Partners in Flight (PIF) Watch List, the United States Shorebird Conservation Plan Watch List and the Waterbird Conservation for the Americas Watch List. WB WG The Western Bat Working Group. H — High Priority indicates species that are imperiled or are at high risk of imperilment based on available information on distribution, status, ecology and known threats; M — Medium Priority indicates a lack of information to assess the species' status; L— Low Priority indicates relatively stable populations based on available data. The WB WG also uses intermediary designations including MH — Medium -High and LM — Low -Medium priorities. Xerces Xerces Society for Invertebrate Conservation. Red List identifies endangered, threatened or at -risk pollinator species. PE — Possibly Extinct indicates species only known from historical occurrences; CI— Critically Imperiled indicates species at very high risk of extinction; I — Imperiled indicates species at high risk of extinction; V — Vulnerable indicates species at moderate risk of extinction; DD — Data Deficient indicates lack of information to sufficiently assess status. GLOBAL RANKING The global rank (G -rank) is a reflection of the overall condition of an element throughout its global range. SPECIES OR NATURAL COMMUNITY LEVEL G 1 = Less than 6 viable element occurrences (Eos) OR less than 1,000 individuals OR less than 2,000 acres. G2 = 6-20 Eos OR 1,000-3,000 individuals OR 2,000-10,000 acres. G3 = 21-80 Eos OR 3,000-10,000 individuals OR 10,000-50,000 acres. G4 = Apparently secure; this rank is clearly lower than G3 but factors exist to cause some concern; i.e., there is some threat, or somewhat narrow habitat. G5 = Population or stand demonstrably secure to ineradicable due to being commonly found in the world. SUBSPECIES LEVEL Subspecies receive a T -Tank attached to the G -rank. With the subspecies, the G -rank reflects the condition of the entire species, whereas the T -rank reflects the global situation of just the subspecies or variety. For example: Chorizanthe robusta var. hartwegii. This plant is ranked G2TI. The G -rank refers to the whole species range i.e., Chorizanthe robusta. The T -rank refers only to the global condition of var. hartwegii. STATE RANKING The state rank (S -rank) is assigned much the same way as the global rank, except state ranks in California often also contain a threat designation attached to the S -rank S1 = Less than 6 viable Eos OR less than 1,000 individuals OR less than 2,000 acres S 1.1 =very threatened S 1.2 = threatened S 1.3 = no current threats known S2 = 6-20 Eos OR 1,000-3,000 individuals OR 2,000-10,000 acres S2.1 = very threatened S2.2 = threatened S2.3 = no current threats known S3 = 21-80 Eos or 3,000-10,000 individuals OR 10,000-50,000 acres S3.1 = very threatened S3.2 = threatened S3.3 = no current threats known S4 = Apparently secure within California; this rank is clearly lower than S3 but factors exist to cause some concern; i.e. there is some threat, or somewhat narrow habitat. S5 = Demonstrably secure to ineradicable in California. NO THREAT RANK. Notes: 1. Other considerations used when ranking a species or natural community include the pattern of distribution of the element on the landscape, fragmentation of the population/stands, and historical extent as compared to its modern range. It is important to take a bird's eye or aerial view when Tanking sensitive elements rather than simply counting Eos. 2. Uncertainty about the rank of an element is expressed in two major ways: By expressing the rank as a range of values: e.g., S2S3 means the rank is somewhere between S2 and S3. By adding a ? to the rank: e.g., S2? This represents more certainty than S2S3, but less than S2. 3. Other symbols GH All sites are historical; the element has not been seen for at least 20 years, but suitable habitat still exists (SH = All California sites are historical). GX All sites are extirpated; this element is extinct in the wild (SX = All California sites are extirpated). GXC Extinct in the wild; exists in cultivation. GIQ The element is very rare, but there are taxonomic questions associated with it. T Rank applies to a subspecies or variety. 1072 Geneva Avenue, San Francisco CA 94112 • Ph: 415-404-6757 • Cell: 650-269-3894 • Fax: 415-404-6097 E-mail: CRecology@gmail.com • www.CRecology.com C CORNERSTONE EARTH GROUP Type of Services Project Name Location Client Client Address Project Number Date Geotechnical Investigation Arastradero Trail Improvement Project Arastradero Road Los Altos Hills', California Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, CA 441-1-1 December 2, 2011 2nd DRAFT Prepared by Laura C. Knutson, P.E., G.E. Principal Engineer Geotechnical Project Manager C. Barry Butler, P.E., G.E. Principal Engineer Quality Assurance Reviewer 125.9.Oakmead Parka;:ay i Sunnyvale, CA 94085 -r'4082454600 I F4082454620 wwwxornerstoneearth. com 2737 North MainStreet, Suitel0 i Walnut .Creek, CA. 94597 3 925 988 9500 I F.9259889501 j�CORtHERST.ONE EARTH-GROUP- TABLE ARTH GROUP TABLE OF CONTENTS SECTION1: INTRODUCTION ..................:..:......................................................................:...........1 1.1 Project Description----------------------------------------------------------------------------------------1 1.2 Scope of Services---------------------------------------------------------------------------------=---------1 1.3 Exploration Program--------------------------------------------------------------=-----------------------1 1.4 Laboratory Testing Program ------ ----------------------------------- ------------------------------- ----- 2 1.5 Environmental Services ------------- =------------------------------------------------------------ --------- 2 SECTION 2: REGIONAL SETTING............:...................................................................................2 2.1 Regional Seismicity--------------------------------------------------------------------------------=------- 2 SECTION 3: SITE CONDITIONS................:...................................................:...............................3 3.1 Site Reconnaissance and Air Photo Review--------------------------------------------=--=------- 3 3.2 Surface Description--------------------------------------------------------------------------------------- 3 3.2.1 Retaining Wall Vicinity..................................................................................................3 3.2.2 Arastradero Road Pavement Sections........................................................................3 Table 1: Arastradero Road — Existing Shoulder Structural Sections...................................4 3.3 Subsurface Conditions----------------------------------------------------------------------------------- 4 3.3.1 Plasticity/Expansion Potential......................................................................................5 3.3.2 In -Situ Moisture Contents...................................................................................:.........5 3.4 Ground Water----------------------------------------------------------------------------------------------- 5 SECTION 4: GEOLOGIC HAZARDS...................................................................................:.........5 4.1 Fault Rupture --------- ------------------------------------ —---------------- —----------------------- -------- 5 4.2 Estimated Ground Shaking ---- —--- --------------------------------------------------------------------- 5 4.3 Liquefaction Potential------------------------------------------------------------------------------------- 5 4.4 Lateral Spreading------------------------------------------------------------------------------------------- 5 4.5 Seismic Settlement/Unsaturated Sand Shaking -------------------------------------------------- 6 4.6 Landsliding-------------------------------------------------------------------------------------------------- 6 ARASTRADERO TRAIL IMPROVEMENT PROJECT Page i 441-1-1 ED. CORNERSTONE.. EARTH GR`O.UP' SECTION5: CONCLUSIONS:.........................................................:....................................:.........6 5.1 Summary--=-----------------------------------------------------------=--------------------------=-------- 6 5.1.1' Existing Shallow Landslide..........................................................................................6 5.1.2. Expansive Soils.....:.........................................................................::............................7 5.2 Plans and -Specifications Review------------------------------=--=-----------------------------=------ 7 5.3 Construction Observation and Testing -- - 7 SECTION6: EARTHWORK..........................:s................................................................................7 6.1 Site Demolition, Clearing and Preparation------------------ ------ 7 6.1.1 Site Stripping........:.........................................................................:.:...........................7 6.1.2 Tree and: Shrub Removal .............. .......7 6.1.3 Demolition of Existing Site Improvements .................. 6.1.4. Abandonment of Existing Utilities.......................................................:.......................8 6.1.5 Removal of Existing Landslide.......................................................:..............................8 6.2 Temporary Cut and Fill Slopes—, 8 6.3 Subgrade Preparation--- -------------------------- 6.4 Subgrade Stabilization Measures,--. -------------------------------------------=----------- ------ 9 6.4.1 Scarification and Drying ................................................... .........9 .................................... 6.4.2 Removal and Replacement............................................................:..............................9 6.4.3 Chemical Treatment...........................................................................:..........................9 6.5 Material for Fill----------------------------------------------------------------------------------------=-----10 6.5.1 Re -Use of On-site Soils...............................................................................................10 6.5.2 Re -Use of On -Site Site Improvements.......................................................................10 6.5.3 Potential Import Sources.....................................:......................................................10 6.6 Compaction Requirements -------- –--------------------------- ----------------------------- -----------10 Table 2: Compaction Requirements......................................................................................11 6.6.1 Construction Moisture Conditioning..............................................:..........................12 6.7 Trench Backfill------------------------=-----------------------------------------=-------------------12 6.8 Permanent Cut and Fill Slopes------------------------------------------------------------------------12 6.9 Site Drainage ------------ –--------- --=-------------------------------------- ------ –------- –--- --------12 6.10 Permanent Erosion Control Measures ----- –------------- ----------- –------------------- -----�-13 SECTION 7: RETAINING WALLS........................................................................:.......................13 7.1 Summary. of Recommendations--------------------------------------------------------------------13 ARASTRADERO TRAIL IMPROVEMENT PROJECT Page H 441-1-1 C CORNERSTONE EARTH GROUP 7.2 Lateral Earth Pressures----------------------------------------------------------------------------------13 Table 3: Recommended Lateral Earth Pressures..................:....................................:.........14 7.3 Seismic Lateral Earth Pressures----------------------------------------------------------------------14 7.4 Wall Drainage-----------------------------------------=------------------------------------------------------14 7.5 Backfill ------------------ -- 7.6 Foundations--------------------------------------------------------------------------------------------------15 7.6.1 Seismic Design Criteria..............................................................................................15 7.6.2 Drilled Piers...............................:..................................:...................................:.::........15 7.6.3. Vertical Capacity and Estimated Settlement.............................................................15 7.6..4 Lateral Capacity — L -Pile Parameters.........................................................................16 Table 4: Recommended L -Pile Parameters .............................................................................16 7.6.5 Construction Considerations.....................................................................................16 7.7 Soil Nails --------------- =--------------------------------------------------------------------------------------- 16 Table 5: Recommended Soil Nail Parameters ........................................ SECTION 8: PEDESTRIAN PAVEMENTS.............................................................................:.....17 8.1 Pedestrian Trail------==-----------------------------=-------------------------------------------------------17 SECTION 9: LIMITATIONS..........................................................................................................17 SECTION 10: REFERENCES......................................:................................................................18 FIGURE 1: VICINITY MAP FIGURES 2A TO 2C: SITE PLAN APPENDIX A: FIELD INVESTIGATION APPENDIX B: LABORATORY TEST PROGRAM ARASTRADERO TRAIL IMPROVEMENT PROJECT Page iii 441-1-1 � CORNERSTONE Ise EARTH GROUP Type of Services Project Name Location SECTION 1: INTRODUCTION Geotechnical Investigation Arastradero Trail Improvement Project Arastradero Road Los Altos Hills, California: This geotechnical report was prepared for the sole use of the Town of Los Altos Hills for the Arastradero Trail Improvement project in Los Altos Hills, California. The location of the site is shown on the Vicinity Map, Figure 1. For our use, we were provided with the following documents: ■ Electronic copies of the civil plan set titled, "Los Altos Hills Trail, Segments A — K, Los Altos Hills, California," prepared by BKF Engineers, dated August 24, 2010 1.1 PROJECT DESCRIPTION The project will consist of rehabilitating an existing path and constructing a new multi use path alongside Arastradero Road beginning just north of Highway 280 and continuing west to the Santa Clara County line. A portion of the pedestrian/equestrian path on the south side of Arastradero Road will require a 5 to 8 -foot -high retaining wall to support the path width. The location of the proposed retaining wall is shown on Figure 2B. 1.2 SCOPE OF. SERVICES Our scope of services was presented in our proposal dated March 26 and April 19, 2007, and January 18, 2011 and consisted of field and laboratory programs to evaluate physical and engineering properties of the subsurface soils, engineering analysis to prepare recommendations for site work and grading, retaining walls and their foundations, asphalt concrete paths, and preparation of this report. Brief descriptions of our exploration and laboratory programs are presented below. - -1.3 EXPLORATION PROGRAM Field exploration for the proposed retaining wall consisted of five borings drilled with truck- mounted, hollow -stem auger and limited -access, Minuteman drilling equipment on April 4 and ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 1 441-1-1 C CORNERSTONE EARTH GROUP May 15, 2007. The borings were drilled to depths of 15 to 19 feet. The borings were backfilled with cement grout in accordance with local SCVWD requirements. In addition, in 201"0 we cored the shoulder pavements of Arastradero Road in several locations to provide information for the planned bike lanes. Coring of the Arastradero Road pavement shoulders was performed at 12locations, with coring and power auger equipment on June 7, 2010. The cores were extended through the pavement structuralsection into the underlying subgrade. The cores were patched with cement grout. The approximate locations of our previous exploratory borings and pavement cores are shown on the Site Plan, Figures 2A.through 2C. Details regarding our field program, are included in Appendix A. 1.4 LABORATORY TESTING PROGRAM In addition to visual classification of samples, the previous and current laboratory programs focused on obtaining data for foundation design and seismic ground deformation estimates. Testing included moisture contents, dry densities, washed sieve analyses, and Plasticity Index tests. Details regarding our laboratory program are included in Appendix B. 1.5 ENVIRONMENTAL SERVICES Environmental services were. not requested for this project. If environmental concerns are determined to be present during future evaluations, the project environmental consultant should review our geotechnical recommendations for compatibility with the environmental concerns. SECTION 2: REGIONAL SETTING 2.1 REGIONAL SEISMICITY The San Francisco Bay area is one of the most seismically active areas in the Country. While seismologists cannot predict earthquake events, the U.S. Geological Survey's Working Group on California Earthquake Probabilities 2007 estimates there is a 63 percent chance of at least one magnitude 6.7 or greater earthquake occurring in the Bay Area region between 2007 and 2036. As seen with damage in San Francisco and Oakland due to the 1989 Loma Prieta earthquake that was centered about 50 miles south of San Francisco, significant damage can occur at considerable distances. -Higher levels of shaking and damage would be expected for earthquakes occurring at closer distances. The faults considered capable of generating significant earthquakes are generally associated with the well-defined areas of crustal movement, which trend northwesterly. The retaining wall site is located about 0.6 miles north of the Monte Vista Fault and about 3 miles northeast of the San Andreas Fault. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 2 441-1-1 n CORNERSTONE EARTH GROUP SECTION 3: SITE CONDITIONS 3.1 SITE RECONNAISSANCE AND. AIR PHOTO REVIEW_ Our certified engineering geologist conducted a reconnaissance -level investigation of portions of the Arastradero Trail that were considered to have possible geologic constraints. This included the area along Arastradero Road where the retaining wall is planned, which is in an area considered by the California Geological Survey to be prone to earthquake -induced landsliding (CGS, 2006). Pampeyan (1993) and Brabb et al. (2000) show this area underlain by Monterey Formation bedrock striking west-northwest and dipping gently (10-35 degrees) to the south. Matadero Creek cuts through the Monterey Formation hills nearly at right angles to strike, flowing through a flat alluvial terrace floor nearly 600 feet wide. Aerial photographs listed in the "References" section show these parts of the trail alignment at eight times during the period from 1939 to 1981. Until the photographs of 1974, Arastradero Road crossed near the central part of the valley floor north of its present location. The hilislopes above the road were smooth, covered with grass, and did not show landslide morphology other than a possible scarp area near the top of the slope seen on the 1963 photos. The portion of Arastradero Road adjoining the Arastradero Trail alignment was relocated to the south when Highway 280 was built sometime between the aerial photos of 1965 and 1974. This involved excavating the road cuts to the south. 3.2 SURFACE DESCRIPTION 3.2.1 Retaining Wall Vicinity The retaining wall area is along the south side of Arastradero Road between Stirrup Way on the east and about 500 feet west of Stirrup Way on the west. The existing cut slope on the south side of the road in the area of the proposed retaining wall is inclined at about 1'/2:1 (horizontal:vertical) and is covered with grass, but appears to be mostly planar and stable, since construction occurred more than 30 years ago. A few small depressions were seen that could mark landslide scarps; however, lobes of accumulated debris were not observed except at the northwestern end of the retaining wall alignment. Here from about the location of our Boring EB -4, and for about 50 feet to the east, the hillside at the toe extends out about 1 foot relative to the rest of the cut. A fairly sharp scarp nearly at the top of the cut/grade break shows a drop of about 3 feet at the head. This landslide is located at one end of the road cut so probably involves soil or deeply weathered Monterey Shale. It appears to be less than 5 feet thick. No other signs of slope instability were seen along Arastradero Road; however, desiccation cracks in the clayey soils indicate creep or expansive soils may have to be considered. 3.2.2 Arastradero Road Pavement Sections We cored the shoulders of both sides of Arastradero Road at a total of 12 locations to measure the existing pavement structural sections. Our findings are shown in the table below. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 3 441-1-1 CORNERSTONE . EARTH :GROUP Table 1: Arastradero Road Existing Shoulder Structural Sections Core Location Asphalt Concrete (inches) Aggregate Base (inches) . C-1* I 4 15 C-2* 4 15 C-2** 31/ 151/2 C-3* 6 12 C-3** 3 13 C-4* 4 14 C-5* 3 Culvert C-6* 6 13 C-6** 21/ 141/2 C-7* 5 13 G-8* 5 14 C-9* 51/ 131/2 C-10* 41/ 141/ C-11* 4. 13 C-12* 4 15 * Core through Arastradero Road section ** Core through water line patch section on north side of road 3.3 SUBSURFACE CONDITIONS A field reconnaissance of the above mentioned portions of the Arastradero Trail was performed on April 4, 2007. Drilling was occurring at that time so the cuts for two drill pads that exposed bedrock (Borings EB -2 and EB -3) were examined as well. These exposures were located at the base of the highest road cut along Arastradero Road. These revealed gray, closely fractured siltstone, -locally weathered brown. The rock had low hardness and was weak. Bedding orientation was measured as N70W 34S at EB -2 and N80W 38S at EB -3. These are concordant with strike and dip shown by Pampeyan (1993) to the west and dip into the hillslope. Pampeyan identifies the unit as Monterey Shale of upper and middle Miocene age. Joint set orientations were variable but a dominant set measured as N83W 61N and N17E 75E at'EB-2 and N73E 56N at EB -3. Since the cut slope was measured sloping at 34 degrees, these joints would not daylight in the cut. Bedrock at the base of the cut was overlain by 0.6 to 1.5 feet of moderately plastic silt that appeared to be colluvium. Our Boring EB -5 was performed about 6 feet above the road grade within the slope break adjacent to the existing v -ditch. About 7 feet of colluvium overlying bedrock was encountered to the terminal depth of 19 feet. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 4 441-1-1 CC_ORNERStbNE EART14 G.WOU.P 3.3.1 .Plasticity/Expansion Potential We performed one Plasticity Index (PI) test on a representative sample. Test results were used to evaluate expansion potential of surficial soils. The results of the surficial PI tests indicated a PI of 24, indicating moderate expansion potential to wetting and drying cycles. 3.3.2. In -Situ Moisture Contents Laboratory testing indicated that the in-situ moisture contents within the upper 10 feet range from about 3 to 10 percent over the estimated laboratory optimum moisture.. 3.4 GROUND WATER Ground water was not encountered in any of our borings during drilling along Arastradero Road; however, the borings were not left open but were immediately backfilled when the boring was completed. As predominantly clays were encountered; the borings were not left open long enough for water, -if present, to seep into the boring holes. We anticipate that perched water conditions could be experienced seasonally due to underground drainage patterns. SECTION 4: GEOLOGIC HAZARDS 4.1 FAULT RUPTURE As discussed in Section 2 above, several significant faults are located near the site. The site is not located within a State -designated Alquist Priolo Earthquake Fault Zone, or a Santa Clara County Fault Hazard Zone. As no known surface expression of fault traces is thought to cross the site, fault rupture hazard is not a significant geologic hazard at the site. 4.2 ESTIMATED GROUND SHAKING As discussed, the site is located in a highly seismically active region of Northern California, and the San Andreas and Monte Vista -Shannon faults are located less than 3 and 0.3 miles from the site, respectively. Moderate to severe (design -level) earthquakes can cause strong ground shaking, which is the case for most sites within the Bay Area. 4.3 LIQUEFACTION POTENTIAL The retaining wall area is not located within a State -designated Liquefaction Hazard Zone (CGS, Palo Alto Quadrangle, 2006) nor is it in a Santa Clara County Liquefaction Hazard Zone (Santa Clara County, 2003). As the site consists of thin soils overlying soft bedrock, liquefaction is not considered a site hazard for the planned retaining wall. 4.4 LATERAL SPREADING Lateral spreading is horizontal/lateral ground movement of relatively flat -lying soil deposits towards a free face such as an excavation, channel, or open body of water; typically lateral ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 5 441-1-1 CORNERSTONE EARTH GR -OUP spreading is associated with liquefaction of one or more subsurface layers near the bottom of the exposed slope: As failure tends to propagate as block failures, it is difficult to analyze and estimate where the first tension crack will form. There are no open faces within.200 feet of the retaining wall are where lateral.spreading could occur; therefore, in our opinion, the potential for lateral spreading to affect the retaining wall is low. 4.5 -SEISMIC SETTLEMENT/UNSATURATED SAND SHAKING Loose unsaturated sandy soils can settle during strong seismic shaking. As the unsaturated soils encountered: at the retaining wall were predominantly stiff to _very stiff clays or stiff. to very stiff silts overlying soft bedrock, in our opinion, the potential for significant differential seismic settlement affecting the proposed improvements is low. 4.6 LANDSLIDING As discussed above, a few small .depressions were observed in the cut slope along Arastradero Road that could mark landslide scarps; however, lobes of accumulated debris were not observed except at the west end of the retaining wall. Here from about the location of our Boring EB -4 and for about 50 feet to the. east, the hillside at the toe extends out about 1 foot relative to the rest of the cut. A fairly sharp scarp nearly at the top of the cut shows a drop of about 3 feet at the head. This landslide is located at one end of the road cut so probably involves soil or deeply weathered Monterey Shale. It appears to be a slump probably less than 5 feet thick. SECTION 5: CONCLUSIONS 5.1 SUMMARY From a geotechnical viewpoint, the project is feasible provided the concerns listed below are addressed in the project design. Descriptions of each concern with brief outlines of our recommendations follow the listed concerns. a Existing shallow landslide ■ Presence of moderately expansive soils 5.1.1 Existing Shallow Landslide As discussed above, there appears to be a shallow landslide/slump located near Boring EB -4 and for about 50 feet to the east. Likely the slump is about 5 feet thick or less. We recommend that the landslide be removed during construction of the retaining wall. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 6 441-1-1 L CORNERS:TO.NE LE: EARTH GROUP 5.1.2 Expansive Soils The surficial soils are moderately expansive. Care should be taken by the contractor during grading to keep the surface materials in a moist condition prior to placement of the trail aggregate base and asphalt sections, and compact the native expansive soils. at the compaction and moisture levels recommended. 5.2 PLANS AND SPECIFICATIONS REVIEW We recommend that we be retained to review the geotechnical aspects of the project structural, civil, and landscape plans and specifications, allowing sufficient time to provide the design team with any comments prior to issuing the plans for construction. 5.3 CONSTRUCTION OBSERVATION AND TESTING As site conditions may vary significantly between the small -diameter borings performed during this investigation, we also recommend that a Cornerstone representative be present to provide geotechnical observation and testing during earthwork and foundation construction. This will allow us to form an opinion and prepare a letter at the end of construction regarding contractor compliance with project plans and specifications, and with the recommendations in our report. We will also be allowed to evaluate any conditions differing from those encountered during our investigation, and provide supplemental recommendations as necessary. For these reasons, the recommendations in this report are contingent of Cornerstone providing observation and testing during construction. Contractors should provide at least a 48-hour notice when scheduling our field personnel. - SECTION 6: EARTHWORK 6.1 SITE DEMOLITION, CLEARING AND PREPARATION 6.1.1 Site Stripping The site should be stripped of all surface vegetation, and surface and subsurface improvements within the proposed development area. Demolition of existing improvements is discussed in detail below. A detailed discussion of removal of the existing landslide is provided later in this report. Surface vegetation and topsoil should be stripped to a sufficient depth to remove all material greater than 3 percent organic content by weight. Based on our site observations, surficial stripping should extend about 2 to 4 inches below existing grade in vegetated areas. 6.1.2 Tree and Shrub Removal Trees and shrubs designated for removal should have the root balls and any roots greater than 'h -inch diameter removed completely. Mature trees are estimated to have root balls extending to depths of 2 to 4 feet, depending on the tree size. Significant root zones are anticipated to extend to the diameter of the tree canopy. Grade depressions resulting from root ball removal ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 7 441-1-1 CORNERSTONE fes: EARTH GROUP should be cleaned of loose material and backfilled in accordance with the recommendations in the "Compaction" section of this report. 6.1.3 Demolition of Existing Site Improvements The existing pavements within'the trail alignment should be completely removed. Alternatively, if feasible, the pavement may be pulverized and mixed with the underlying base section and reused within the trail base section. 6.1.4 Abandonment of Existing Utilities Any utilities to be. abandoned may be left in place provided the ends are plugged with concrete, they do not conflict with planned improvements, and that the trench fills do not pose significant risk to the planned surface improvements. The risks associated with abandoning utilities in place include the potential for future differential settlement of existing trench fills, and/or partial collapse and potential ground loss into utility lines that are not completely filled with grout. The risk for each issue are relatively low for single utility lines less than 4 inches in diameter and increase with increasing pipe diameter. 6.1.5 Removal of Existing Landslide The existing landslide/slump (shown on Figure 2B) should be removed down to competent bedrock. We estimate that the slump is less than about 5 feet thick. We understand from preliminary cross sections that the landslide will likely be removed as part of the planned slope contouring and excavation for the western end of the retaining wall. Our representative should confirm that the landslide is fully removed prior to retaining wall foundation construction: The excavated material may be reused as engineered fill during construction of the wall. 6.2 TEMPORARY CUT AND FILL SLOPES The contractor is responsible for maintaining all temporary slopes and providing temporary shoring where required. Temporary shoring, bracing, and cuts/fills should be performed in accordance with the strictest government safety standards. On a preliminary basis, the upper 10 feet at the site may be classified as OSHA Site B materials. A Cornerstone representative should be retained to confirm the preliminary site classification. Provided the trail is constructed during the summer/early fall months, we do not anticipate perched water conditions affecting the proposed: cuts. 6.3 SUBGRADE PREPARATION After site clearing and demolition is complete, and prior to backfilling any excavations resulting from landslide removal or demolition, the excavation subgrade and subgrade within areas to receive additional site fills, slabs -on -grade and/or pavements should be scarified to a depth of 6 inches, moisture conditioned, and compacted in accordance with the "Compaction" section below. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 8 441-1-1 LC1. CORNtgstoNE EARTH GROUP 6.4 SUBGRADE STABILIZATION MEASURES Soil subgrade and fill materials, especially soils with high fines contents such as clays and silty soils, can become unstable due to high moisture content, whether from high in-situ moisture contents or from winter rains.As the moisture content increases over the laboratory optimum, it becomes more likely the materials will be subject to softening and yielding (pumping) from construction loading or become. unworkable during placement and compaction. As discussed in the "Subsurface" section in this report, the insitu moisture contents are about 4 to 10 percent over the estimated laboratory optimum in the upper 10 of the soil profile in the area of the retaining wall and the depth to.ground water is on the order of 5 feet below grade adjacent to the creek. The contractor should anticipate drying the soils prior to reusing them as fill. In addition, repetitive rubber -tire loading or other repetitive loads will likely de -stabilize the soils. There are several methods to address potential unstable soil conditions and facilitate fill placement and trench backfill. Some of the methods are briefly discussed below. Implementation of the appropriate stabilization measures should be evaluated on a case-by- case basis according to the project construction goals and the particular site conditions. 6.4.1 Scarification and Drying The subgrade may be scarified to a depth of 9 to 12 inches and allowed to dry to near optimum conditions, if sufficient dry weather is anticipated to allow sufficient drying. More than one round of scarification may be needed to break up the soil clods. 6.4.2 Removal and Replacement As an alternative to scarification, the contractor may choose to over -excavate the unstable soils and replace them with dry on-site or import materials. A Cornerstone representative should be present to provide recommendations regarding the appropriate depth of over -excavation, whether a geosynthethic (stabilization fabric or geogrid) is recommended, and what materials are recommended for backfill. 6.4.3 Chemical Treatment Where the unstable area exceeds about 5,000 to 10,000 square feet and/or site winterization is desired, chemical treatment with quicklime (CaO), kiln -dust, or cement may be more cost- effective than removal and replacement. Recommended chemical treatment depths will typically range from 12 to 18 inches depending on the magnitude of the instability. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 9 441-1-1 n CO0NEF2STONE EARTH GROUP 6.5 MATERIAL FOR FILL 6.5.1 Re -Use of On-site Soils On-site soils with an organic content less than 3 percent by weight may be reused as general fill. General fill should not have lumps, clods or cobble pieces larger than 6 inches in diameter; 85 percent of the fill should be smaller than 21/2 inches in diameter. Minor amounts of oversize material (smaller than 12 inches in diameter) may be allowed provided the oversized pieces are not allowed to nest together, and .the compaction method will allow for loosely placed lifts not exceeding 12 inches. Based on our observations, the bedrock in the retaining wall area should breakdown under equipment loads to meet the size requirements. 6.5.2 Re -Use of On -Site Site Improvements We anticipate that some asphalt concrete (AC) grindings and aggregate base (AB) will be generated during site demolition along Arastradero Road. If the AC grindings are mixed with the underlying AB to meet Class 2 AB specifications, they may be reused within the new trail structural sections. Laboratory testing will be required to confirm the grindings meet project specifications. 6.5.3 Potential Import Sources Imported and non -expansive material should be inorganic with a Plasticity Index (PI) of 15 or less. To prevent significant caving during trenching or foundation construction, imported material should have sufficient fines. Samples of potential import sources should be delivered to our office at least 10 days prior to the desired import start date. Information regarding the import source should be provided, such as any site geotechnical reports. If the material will be derived from an excavation rather than a stockpile, potholes will likely be required to collect samples from throughout the depth of the planned cut that will be imported. At a minimum, laboratory testing will include PI tests. Material data sheets for select fill materials (Class 2 aggregate base, %-inch crushed rock, quarry fines,etc.) listing current laboratory testing data (not older than 6 months from the import date) may be provided for our review without providing a sample. If current data is not available, specification testing will need to be completed prior to approval. Environmental and soil corrosion characterization should also be considered by the project team prior to acceptance. Suitable environmental laboratory data to the planned import quantity should be provided to the project environmental consultant; additional laboratory testing may be required based on the project environmental consultant's review. The potential import source should also not be more corrosive than the on-site soils, based on pH, saturated resistivity, and soluble sulfate and chloride testing. 6.6 COMPACTION REQUIREMENTS All fills, and subgrade areas where fill, slabs -mon -grade, and pavements are planned, should be placed in loose lifts 8 inches thick or less and compacted in accordance with ASTM D1557 ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 10 441-1-1 LCll CORNERSTONE EARTH GROUP (latest. version) requirements as shown in the table below. In general, clayey soils should be compacted with sheepsfoot equipment and sandy/gravelly soils with vibratory equipment; open - graded materials such as crushed rock should be placed in lifts no thicker than 18 inches consolidated in place with vibratory equipment. Each lift of fill andallsubgrade should be firm and unyielding under construction equipment loading in addition to meeting the compaction requirements to be approved. The contractor (with input from a Cornerstone representative) should evaluate the in-situ moisture conditions, as the use of vibratory equipment on soils with high moistures can cause unstable conditions. General recommendations for soil stabilization are provided in the "Subgrade Stabilization Measures" section of this report. Where the soil's PI is 20 or greater, the expansive soil criteria should be. used. Table 2: Compaction Requirements Description Material Description Minimum Relative' Compaction (percent) Moisture Content (percent) General Fill (within upper 5 feet) On -Site Expansive Soils . 87-92 >3 Low Expansion Soils 90 >1 General Fill (below a depth of 5 feet) On -Site Expansive Soils 95 >3 Low Expansion Soils 95 >1 Retaining Wall Backfill Without Surface Improvements 90 >1 Retaining Wall Backfill With Surface Improvements 954 >1 Trench Backfill On -Site Expansive Soils 87-92 >3 Trench Backfill Low Expansion Soils 90 >1 Trench Backfill (upper 6 inches of subgrade) On -Site Low Expansion Soils 95 >1 Crushed Rock Fill '/-inch Clean Crushed Rock Consolidate In -Place NA Non -Expansive Fill Imported Non -Expansive Fill 90 Optimum Trail Subgrade On -Site Expansive Soils 87-92 >3 Trail Subgrade Low Expansion Soils 90 >1 Trail Aggregate Base Class 2 Aggregate Base 90 Optimum Pavement Subgrade On -Site Expansive Soils 87-92 >3 Pavement Subgrade Low Expansion Soils 95 >1 Pavement Aggregate Base Class 2 Aggregate Base 95 Optimum Asphalt Concrete Asphalt Concrete 95 (Marshall) NA i — Reiative compaction based on maximum density determined by ASTM D1557 (latest version) 2— Moisture content based on optimum moisture content determined by ASTM D1557 (latest version) 3 — Class 2 aggregate base shall conform to Caltrans Standard Specifications, latest edition, except that the relative compaction should be determined by ASTM D1557 (latest version) 4 — Using light -weight compaction or walls should be braced ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 11 441-1-1 CORNERSTONE EARTH. GROUP 6.6.1 Construction Moisture Conditioning Expansive soils can undergo significant volume change when dried then wetted. The contractor should keep all exposed expansive soil subgrade (and also trench excavation side walls) moist until protected by overlying improvements (or trenches are backfilled). If expansive soils are allowed to dry out significantly, re -moisture conditioning may require several days of re -wetting (flooding is not recommended)., or deep scarification,_ moisture conditioning, and re -compaction. 6.7 TRENCH BACKFILL Utility lines constructed within public right-of-way should be trenched, bedded and shaded, and backfilled in accordance with the local or governing jurisdictional. requirements. Utility lines in private improvement areas should be constructed in accordance. with the following requirements unless superseded by other governing requirements. All utility. lines should be bedded and shaded to at least 6 inches over the top of the lines with crushed rock ('/-inch-diameter or greater) or well -graded sand and gravel materials conforming to the pipe manufacturer's requirements. Open -graded shading :materials should be consolidated in place with vibratory equipment and well -graded materials should be compacted to at least 90 percent relative compaction with vibratory equipment prior to placing subsequent backfill materials. General backfill over shading materials may consist of on-site native materials provided they meet the requirements in the "Material for Fill" section, and are moisture conditioned and compacted in accordance with the requirements in the "Compaction" section.: 6.8 PERMANENT CUT AND FILL SLOPES All permanent cut and fill slopes in soil and engineered fill should have a maximum inclination of 2:1 (horizontal:vertical) for slopes up to 10 feet high; slopes greater than 10 feet should be inclined at no greater than 2.5:1. Fill slopes should be overbuilt and trimmed back, exposing engineered fill when.complete. Refer to the "Erosion Control" section of this report for a discussion regarding protection of slope surfaces. Based on the plans reviewed, there doesn't appear to be any planned fills where keyways and benches would be required. 6.9 SITE DRAINAGE Surface runoff should not be allowed to flow over the top of or pond at the top or toe of engineered slopes or retaining walls. Ponding should also not be allowed on or adjacent to pavements or the trail. Surface drainage should be directed towards suitable drainage facilities such as lined v -ditches or drain inlets. Lined v -ditches should be included at the top of slopes behind retaining walls, and at the toe of open space adjacent to planned trails. All v -ditches and drain inlets should be sized to accommodate the design storm events for the upslope tributary area. Concrete -lined v -ditches should be reinforced as required and have adequate control and construction joints, and should be constructed neat in excavations; backfill around formed ditches should not be allowed. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 12 441-1-1 List CORNERSTONE EARTH GROUP 6.10 PERMANENT. EROSION CONTROL MEASURES Hillside grading will require periodic maintenance after construction to reduce the potential for erosion and sloughing. At a minimum all slopes should be vegetated by hydroseeding or other landscape ground cover. The establishment of vegetation will help reduce runoff velocities, allow some infiltration and transpiration, trap sediment within runoff, and protect the soil from - raindrop impact. :Depending on the exposed material type and the slope inclination, more aggressive erosion control measures may be needed to protect slopes for one or more winter seasons while vegetation is establishing. For slopes with inclinations of 2:1 '(horizontal:vertical) or greater, erosion control may consist of jute netting, straw matting,or erosion. control blankets used in combination with hydroseeding. Both construction and post -construction Storm Water Pollution Prevention Plans (SWPPPs) should be prepared for the project -specific requirements. We recommend that final grading plans be provided for our review. SECTION 7: RETAINING WALLS 7.1 SUMMARY OF RECOMMENDATIONS As discussed previously, walls up to about 5 to 8 feet high are planned to support the planned cuts along Arastradero Road. In our opinion due to the planned cuts and existing slope inclinations, a shallow foundation design would result in excessive cut and fill during construction with the exception of the existing landslide/slump area, where removal of the landslide is recommended. Likely the proposed retaining walls will most cost-effectively be supported on either a drilled pier with shotcrete lagging wall or a soil nail wall. We have presented design criteria for these two wall types. 7.2 LATERAL EARTH PRESSURES The structural design of any site retaining wall should include resistance to lateral earth pressures that develop from the soil behind the wall, any undrained water pressure, and surcharge loads acting behind the wall. Provided a drainage system is constructed behind the wall to prevent the build-up of hydrostatic pressures as discussed in the section below, we recommend that the walls be designed for the following pressures:. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 13 441-1-1 LC1. CORNERSTONE EARTH GROUP Table 3: Recommended Lateral Earth Pressures Sloping Backfill Inclination (horizontal:vertical) Lateral Earth Pressure* Unrestrained — Cantilever Wall Restrained — Braced Wall Level 45 pcf 45 pcf + 8H 3:1 55 pcf 55 pcf + 8H 21/2:1 60 pcf 60 pcf + 8H 2:1 65 pcf 65 pcf + 8H 11/2:1, 90 pcf 90 pcf + 8H Additional Surcharge Loads 1/3 of uniform vertical loads at top of wall % of uniform vertical loads at top of wall Lateral earth pressures are based on an equivalent fluid pressure " H is the distance in feet between the bottom of footing and top of retained soil If adequate drainage cannot be provided behind the wall, an additional equivalent fluid pressure of 40 pcf should be added to the values above for both restrained and unrestrained walls for the portion of the wall that will not have drainage. Damp proofing or waterproofing of the walls may be considered where moisture penetration and/or efflorescence are not desired. 7.3 SEISMIC LATERAL EARTH PRESSURES Section 1802A.2.7 of the 2007 and 2010 CBC states that lateral. pressures from earthquakes should be considered in the design of basements and retaining walls. We reviewed the seismic earth pressures for the proposed basement using procedures generally based on the Mononobe-Okabe method for the retaining wall along Arastradero Road. Because peak ground accelerations are greater than 0.40g, even though the walls are less than 10 feet in height, we checked the result of the seismic increment when added to the recommended active earth pressure against the recommended cantilevered wall earth pressures. Because the wall will be designed for 65 to 90 pcf (equivalent fluid pressure) due to the sloping conditions above the wall, based on current recommendations for seismic earth pressures (Lew et al., SEAOC 2010), it appears that active earth pressures plus a seismic increment do not exceed the cantilevered wall earth pressures. Therefore, an additional seismic increment above the design earth pressures is not required as long as the walls are designed for the restrained wall earth pressures recommended above. 7.4 WALL DRAINAGE Adequate drainage may be provided by a subdrain system behind the walls. This system should consist of Miradrain or Geotech Drainage Panels placed in vertical strips of at least 24 inches wide and spaced no more than 6 feet on center. The vertical drainage strips should be connected per manufacturer's recommendations to a horizontal drainage strip (TotalDrain or equivalent) placed at the base of the wall. The horizontal drainage strip should be connected to the storm drain. Where the path alignment grade slopes at least 1 percent, a connection should ARASTRADERO TRAIL IMPROVEMENT PROJECT Paae 14 441-1-1 - C CORNERSTONE EARTH GROUP be placed at the low point. If the path grade will be relatively level, connections should be spaced no more than 50 feet on center. Drainage panels should terminate 12 to 18 inches from final exterior grade and should be capped with relatively low permeability soils to reduce the potential for surface water infiltration. 7.5 :BACKFILL Where surface improvements will be located over the retaining wall backfill, backfill placed behind the walls should be compacted to at least 95 percent relative compaction using light compaction equipment. Where no surface improvements are planned, backfill should be compacted to at least 90 percent. If heavy compaction equipment is used, the walls should be temporarily braced. Based on the current plans, we understand that v -ditches are planned behind the retaining walls, which we highly recommend. 7.6 -FOUNDATIONS The proposed retaining wall along Arastradero Road may be supported on drilled pier foundations, as discussed below. Alternatively, the wall may be designed as a soil nail wall as discussed in Section 7.7. 7.6.1 Seismic Design Criteria We understand that the project structural design will be based on the 2010 California Building Code (CBC), which provides criteria for the seismic design of structures in Chapter 16. The "Seismic Coefficients" used to design structures are established based on a series of tables and figures addressing different site factors, including the soil profile in the upper 100 feet below grade and mapped spectral acceleration parameters based on distance to the controlling seismic source/fault system. Based on our borings, the Arastradero Trail site is underlain by shallow soft bedrock with SPT "N" values greater than 50 blows per foot; therefore, we have classified the site as Site Class C. Site coordinates are Latitude 37.38490 and Longitude - 122.165°. 7.6.2 Drilled Piers The proposed retaining walls may be supported on drilled, cast -in-place, straight -shaft friction piers. Alternatively, the site retaining wall may be designed as a soil nail wall, which is discussed in Section 7.7 of this report. The piers should have a minimum diameter of 16 inches and extend to a depth below the adjacent path grade equal to I Y2 times the retained height or greater depending on the lateral load resistance requirements. Adjacent piers centers should be spaced at least three diameters apart. 7.6.3 Vertical Capacity and Estimated Settlement The vertical capacity of the piers may be designed based on an allowable skin friction of 650 psf for combined dead plus live loads based on a factor of safety of 2.0; dead loads should not exceed two-thirds of the allowable capacities. The allowable skin friction may be increased by ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 15 441-1-1 MCORNERSTONE EARTH GROUP one-third for wind and seismic loads. Frictional resistance to uplift loads may. be developed along the pier shafts based on an ultimate frictional resistance of 1,000 psf; the structural engineer should apply an appropriate factor of safety (such as 1.5) to the ultimate uplift capacity. Total settlement of individual piers or pier groups of four or less should not exceed'/4-inch to mobilize static capacities. 7.6.4 Lateral Capacity — L -Pile Parameters The structural engineer may design the piers using the computer program L -Pile based on the parameters below. The upper 12 inches of pier embedment should be neglected when determining lateral capacity. The structural engineer should apply an appropriate factor of safety to the ultimate shear and moments for design. Table 4: Recommended L -Pile Parameters *Elastic silt layer should be used for the Segment 7 .wall only 7.6.5 Construction Considerations The excavation of all drilled shafts should be observed by a Cornerstone representative to confirm the soil/bedrock profile and that the piers are constructed in accordance with our recommendations and project requirements. The drilled shafts should be straight, dry, and relatively free of loose material before reinforcing steel is installed and concrete is placed. If ground water cannot be removed from the excavations prior to concrete placement, drilling slurry or casing may be required to stabilize the shaft and the concrete should be placed using a tremie pipe, keeping the tremie pipe below the surface of the concrete to avoid entrapment of water or drilling slurry in the concrete. 7.7 SOIL MAILS As an alternative to soldier beam and lagging walls, the cuts along Arastradero Road may be supported by soil nail walls, designed with the Caltrans soil nail wall computer design program SNAILZ. Based on our explorations, the slope consists of soft bedrock with a thin mantle of soil. The following table may be used to design the wall. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 16 441-1-1 Total Unit Effective Undrained Soil Soil Layer LPILE Soil Weight Friction Shear Stiffness E50 Description Model (pcf) Angle Strength (k) (percent) (degrees) (psf) (pci) Elastic Silt* Stiff Clay 125 0 1,500 500 0.007 0 to 5 feet from FG w/o water Siltstone Stiff Clay 125 0 2,500 :750 0.006 w/o water *Elastic silt layer should be used for the Segment 7 .wall only 7.6.5 Construction Considerations The excavation of all drilled shafts should be observed by a Cornerstone representative to confirm the soil/bedrock profile and that the piers are constructed in accordance with our recommendations and project requirements. The drilled shafts should be straight, dry, and relatively free of loose material before reinforcing steel is installed and concrete is placed. If ground water cannot be removed from the excavations prior to concrete placement, drilling slurry or casing may be required to stabilize the shaft and the concrete should be placed using a tremie pipe, keeping the tremie pipe below the surface of the concrete to avoid entrapment of water or drilling slurry in the concrete. 7.7 SOIL MAILS As an alternative to soldier beam and lagging walls, the cuts along Arastradero Road may be supported by soil nail walls, designed with the Caltrans soil nail wall computer design program SNAILZ. Based on our explorations, the slope consists of soft bedrock with a thin mantle of soil. The following table may be used to design the wall. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 16 441-1-1 LC CORNE; TONE EARTH GROUP Table 5: Recommended Soil Nail Parameters *Determined from charts in FHWA Soil Nail Design Manual **Elastic silt layer should be used for the Segment 7 wall only SECTION 8: PEDESTRIAN PAVEMENTS 8.1 PEDESTRIAN TRAIL The pedestrian trail subject to pedestrian and/or occasional light pick up loading should consist of at least 2 inches of asphalt concrete and be supported on at least 4 inches of Class 2 aggregate base overlying subgrade prepared in accordance with the "Earthwork" recommendations of this report. SECTION 9: LIMITATIONS This report, an instrument of professional service, has been prepared for the sole use of the Town of Los Altos Hills specifically to support the design of the Arastradero Trail Improvement project in Los Altos Hills, California. The opinions, conclusions, and recommendations presented in this report have been formulated in accordance with accepted geotechnical engineering practices that exist in Northern California at the time this report was prepared. Nc warranty, expressed or implied, is made or should be inferred. Recommendations in this report are based upon the soil and ground water conditions encountered during our subsurface exploration. If variations or unsuitable conditions are. encountered during construction, Cornerstone must be contacted to provide supplemental recommendations, as needed. The Town of Los Altos Hills may have provided Cornerstone with plans, reports and other documents prepared by others. The Town of Los Altos Hills understands that Cornerstone reviewed and relied on the information presented in these documents and cannot be responsible for their accuracy. Cornerstone prepared this report with the understanding that it is the responsibility of the owner or his representatives to see that the recommendations contained in this reportare presented to other members of the design team and incorporated into the project plans and specifications, and that appropriate actions are taken to implement the geotechnical recommendations during construction. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 17 441-1-1 Total Unit Effective *Ultimate Soil Layer Description Weight Friction Cohesion Bond (pc{) Angle (psq Stress (degrees) (psf) Elastic Silt** first 20 feet of nail length 125 28 0 1,500 Siltstone 125 30 0 2,200 *Determined from charts in FHWA Soil Nail Design Manual **Elastic silt layer should be used for the Segment 7 wall only SECTION 8: PEDESTRIAN PAVEMENTS 8.1 PEDESTRIAN TRAIL The pedestrian trail subject to pedestrian and/or occasional light pick up loading should consist of at least 2 inches of asphalt concrete and be supported on at least 4 inches of Class 2 aggregate base overlying subgrade prepared in accordance with the "Earthwork" recommendations of this report. SECTION 9: LIMITATIONS This report, an instrument of professional service, has been prepared for the sole use of the Town of Los Altos Hills specifically to support the design of the Arastradero Trail Improvement project in Los Altos Hills, California. The opinions, conclusions, and recommendations presented in this report have been formulated in accordance with accepted geotechnical engineering practices that exist in Northern California at the time this report was prepared. Nc warranty, expressed or implied, is made or should be inferred. Recommendations in this report are based upon the soil and ground water conditions encountered during our subsurface exploration. If variations or unsuitable conditions are. encountered during construction, Cornerstone must be contacted to provide supplemental recommendations, as needed. The Town of Los Altos Hills may have provided Cornerstone with plans, reports and other documents prepared by others. The Town of Los Altos Hills understands that Cornerstone reviewed and relied on the information presented in these documents and cannot be responsible for their accuracy. Cornerstone prepared this report with the understanding that it is the responsibility of the owner or his representatives to see that the recommendations contained in this reportare presented to other members of the design team and incorporated into the project plans and specifications, and that appropriate actions are taken to implement the geotechnical recommendations during construction. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 17 441-1-1 CORNERSTONE 01 EARTH GROUP Conclusions and recommendations presented in this report are valid as of the present time for the development as currently planned. Changes in the condition of the property or adjacent properties may occur with the passage of time, whether by natural processes or the acts of other persons. In addition, changes in applicable or appropriate standards may occur through legislation or the broadening of knowledge. Therefore, the conclusions and recommendations presented in this report may be invalidated, wholly or in part, by changes beyond Cornerstone's control. This report should be reviewed by Cornerstone after a period of three (3) years has elapsed from the date of this report. In addition, if the current project design is changed—then Cornerstone must review the proposed changes and provide supplemental recommendations, as needed. An electronic transmission of this report may also have been issued. While Cornerstone has taken precautions to produce a complete and secure electronic transmission, please check the electronic transmission against the hard copy version for conformity. Recommendations provided in this report are based on the assumption that Cornerstone will be retained to provide observation and testing services during construction to confirm that conditions are similar to that assumed for design, and to form an opinion as to whether the work has been performed in accordance with the project plans and specifications. If we are not retained for these services, Cornerstone cannot assume any responsibility for any potential claims that may arise during or after construction as a result of misuse or misinterpretation of Cornerstone's report by others. Furthermore, Cornerstone will cease to be the Geotechnical - Engineer -of -Record if we are not retained for these services. SECTION 10: REFERENCES Literature Brabb, E.E., Graymer, R.W., and Jones, D.L., 2000, Geologic map and map database of the Palo Alto 30' X 60' quadrangle, California: U.S. Geological Survey Miscellaneous Field Studies Map MF -2332, map scale 1:100,000, 30 p., hftp://pubs.usgs.gov/mf/2000/mf-2332/ California Building Code, 2010, Structural Engineering Design Provisions, Vol. 2. California Department of Conservation Division of Mines and Geology, 1998, Maps of Known Active Fault Near -Source Zones in California and Adjacent Portions of Nevada, International Conference of Building Officials, February, 1998. California Geological. Survey, 2006, State of California Seismic Hazard Zones, (Palo Alto 7.5 - Minute Quadrangle, Santa Clara County), California: Seismic Hazard Zone Report 111. Pampeyan, Earl H., 1993, Geologic Map of the Palo Alto and Part of the Redwood Point 7-1/2' Quadrangles, San Mateo and Santa Clara Counties, California, U. S. Geological Survey, Miscellaneous Investigation Series, Map 1-2371. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 18 441-1-1 C"0RNEl2ST0.NE EARTH GROUP Schwartz, D.P. 1994, New Knowledge of Northern California Earthquake Potential: in Proceedings of Seminar on New Developments in Earthquake Ground Motion Estimation and Implications for Engineering Design Practice, Applied Technology; Council 35-1. Townley, S.D. and M.W. Allen, 1939, Descriptive Catalog of Earthquakes of the Pacific Coast of the United States, 1769 to 1928: Bulletin of the Seismological Society of America, Vol. 29, No. 1, pp. 1247-1255. USGS, 2011, Earthquake Ground Motion Parameters, Version 5.1.0, revision date February 10, 2011 - A Computer Program for determining mapped ground motion parameters for use with IBC 2006 available at http://earthquake.usgs.gov/research/hazmaps/design/index.php. Working Group on California Earthquake Probabilities, 2007, The Uniform Earthquake Rupture Forecast, Version 2 (UCRF 2), U.S.G.S. Open File Report 2007-1437. Aerial Photographs Date Flight Frames Scale Type August 1, 1939 CIV- 286-65,-66 1:20,000 black & white October 5, 1943 DDB -1 B 28,29 1:20,000 black & white August 15, 1960 GS-VACY 2-107,-108 1:30,000 black & white June 19, 1963 CIV -1 DD 34,-35 1:20,000 black & white May 11, 1965 SCL 2-177,-178 1:12,000 black & white June 25, 1974 Area 9 9-46,47 1:20,000 color April 8, 1981 GSVEZR 4-86 1:24,000 black & white ARASTRADERO TRAIL IMPROVEMENT PROJECT Page 19 441-1-1 N, I", "V, -W t Ni 1V �j v� G3 x 11j. -A 1., J"! 7 FIr YLT 0 E-7-7- LAI] � jujt: i I'd IRA _nN , 5r z J, 91 r l2 At 4,- 74 X 7 r77 r. XN` i't 7 7 v I-' y YWZE Rn .2 L -V -M %V N 7 W 4 3 w Mf Vicinity Map Project Number 441-1-1 Arastradero Trail Improvement Project Figur I e Number Los Altos.Hills, CA Figure R. T GROUP LC E H Late December 2011 1 Drawn By FLS _ K 1 !n A. .'..Q Izill s �° c ftte Cn r" t 3. 0C T. VAR a ': �: , ` amt• l � • Si - i ,J ;;s�; j{ , i4i T �•��+��t'� i i ) c f'i � 0) Wim Y Site Plan Mix CORNERSTONE 441-1-1 EARTH GROUP Arastradero Trail Improvement Project ` "°° `�"° Figure 2A Los Altos Hills, CA Dar December ?011 Dn,m 9, FLL t ! x yrs �d '91. wur•k„�, C-3 �I• .d w��-Wi''`t .+wr '(��.: - t'>'� t t 'tt ii tt 1 ' t ttl •1P t ::. • l 1 1 .k tri n lttt t 1 L: t �+�w�d �fC -• t : It � �6 � _.. t t It tll 11'5 t y, .,,,,. ~�_3cn. .M +r � w� �`x`ht'+"��j 3�,.7 ��is,�� rtoi w�l awrYN 1•. .�'��i+f� �5it I- �'4+p p 4 r, rARASTR ? 109MA�31 �,n�,l�}t TvY� X44-`` "w.�M�-{"`'4' � �'Y � � t:� tlr'-»:--1 UC • f F�B-4 EB•3 , „��. ,EB 2 _•. � Q Pro osed retal� nij wwall 5 ' +,,� �� MI S t5 � i - � 1 1 p� r _ y � U 7}.. C O Iq S t1 f � CL a E to Approximate location of + I °` ° ebt {' " Y":Cf`i ►M existln shallow landslide , �, � " `�� 'G j Y A Q 1 Y: ;✓' t i .✓^- ' !:i$ df♦ Ctt'$=' nV'`L��e n f�L /� Q Q O ,t A 'M y M" R J 2F' G 1 8hgot ti�, ro.,. 1 - •! 1° :k n,.• Y}*; .,mak .," 1" .rte _ 9 .K..rk n f. V J Base b BKF dated 0-24-2010 see F1 ure 2A for Legend - pF �'e 1'- ':t{�w ,y -.p. � ,�+4 '�" a• 4 =/.,' -�. ,�'-$^ '.i t � r t xnn"�'''�' t-f��s'�7r g` U) 1'f YU' 4 Q 1 pc, k ;x '{ ?" T3 � °1"!' -• r ��,�. � Y� °'`.,r� �`" r �� 5k 5 ! '�'" r � � r f e iMT vSw .'4.V.-•..- - '� *�d1 r., ! x.� `"��+e"� �y„2 � � � ,�\•tt`e`b °« ! "1� p� tlll'''.`i '' S4 •M. C r Rgl'w�3' `4'. , K n� ^j t '�'`�"�,� n's s 0.0 r`,.L'd4y� Mei . ?k � h + t 1 'S°". t , E°i. " oow F: 4A T'^ ,t a w'9 w • • j � t C � f Ki � � �� : r� �r ?N• � .�...._.�� , ,'Y- 1,'�tt ht 5 . �r p t, t tvn('E? ` �/ • % x ' '� Y j (� F ,e.w} Yr ",... ^ Na s i . r x ;� 'v w•m,-W17A$jt 1 Sir �4f 1 r rj. - r 1 - t� 2i B.� 3S�S r f , � !� 1 ° 'ta � � { ,' ... a - 11y�,'+•,•,,,; ,�� rs Y ""'t iii 14 •O V t' 1 j S t'r?{t ,;F �•t� It g nZi yi r�} t t� W fy„t �'`�►� -y=x`� `� Aa .eilylu-�•�...,.:.rc.t.r'_!,,} ;�'�. µeft` �� ti .1 iZ;� l� xi�';:y�'' r .zr;l :a.{f ,arwr-•' OU v. f�isrs, - •�iwm.,.�A3.:..,. ;.,�.,#�,. • us;. rte. :t. `i. C CORNERSTONE EARTH GROUP Site Plan Arastradero Trail Improvement Project Los Altos Hills, CA 441-1-1 Figure 2C Om mbe 2011 '7' FLL CORNERSTONE EARTH. GROUP APPENDIX A: FIELD INVESTIGATION The field investigation consisted of a surface reconnaissance and a subsurface exploration program using truck -mounted and track -mounted, hollow -stem auger and limited -access, "Minuteman" drilling equipment. Four 4 -inch -diameter exploratory borings were drilled on April 4, 2007 to depths of approximately 15 feet. One 8 -inch -diameter exploratory borings was drilled on May 15, 2007 to a depth of 19 feet. Twelve pavement cores were performed on June 7, 2010. The approximate locations of exploratory borings and cores are shown on the Site Plan, Figures 2A through 2C. The, soils and bedrock encountered were continuously logged in the field by our representative and.described in accordance with the Unified Soil Classification System. (ASTM D2488). Boring logs, as. well as a key to the classification of the soil and bedrock, are included as part of this appendix. Boring and core locations were approximated using existing site boundaries and other site features as references. Boring elevations were based on interpolation of plan contours. The locations and elevations of the borings should be considered accurate only to the degree implied by the method used. Representative soil samples were obtained from the borings at selected depths. All samples were returned to our laboratory for evaluation and appropriate testing. The standard penetration resistance blow counts were obtained by dropping a 140 -pound hammer through a 30 -inch free fall. The 2 -inch O.D. split -spoon sampler was driven 18 inches and the number of blows was recorded for each 6 inches of penetration (ASTM D1586). 2.5 -inch 1. D. samples were obtained using aModified California Sampler driven into the soil with the 140 -pound hammer previously described. Unless otherwise indicated, the blows per foot recorded on the boring log represent the accumulated number of blows required to drive the last 12 inches. The various samplers are denoted at the appropriate depth on the boring logs. Field tests included an evaluation of the unconfined compressive strength of the soil samples using a pocket penetrometer device. The results of these tests are presented on the individual boring logs at the appropriate sample depths. Attached boring logs and related information depict subsurface conditions at.the locations indicated and on the date designated on the logs. Subsurface conditions at other locations may differ from conditions occurring at these boring locations. The passage of time may result in altered subsurface conditions due to environmental changes. In addition, any stratification lines on the logs represent the approximate boundary between soil types and the transition may be gradual. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page A-1 441-1-1 UNIFIED SOIL CLASSIFICATION (ASTM D-2487=10) MATERIAL TYPES CRITERIA FOR ASSIGNING SOIL GROUP NAMES GROUP SOIL GROUP NAMES & LEGEND with Clay ® SYMBOL ® Sandy Silt Well Graded Gravelly Sand - - GRAVELS CLEAN GRAVELS Cu>4AND 1<Cc<3 GW WELL -GRADED GRAVEL •�. o J >50% OF COARSE <5%FINES Cu>4 AND 1>Cc>3 GP POORLY -GRADED GRAVEL c Qo °o p Z FRACTION RETAINED with S(It . SWELL TEST CN - CONSOLIDATION TC - GRAVELS WITH FINES FINES cLASSIFrasMLORCL GM SILTY GRAVEL u o oow ON NO 4. SIEVE LU w LU QQ UNCONFINED COMPRESSION >12% FINES FINES CLASSIFY AS CL OR CH GC CLAYEY GRAVEL (3.0) - (WITH SHEAR STRENGTH IN KSF) _ IN KSF) RV - R -VALUE UU UNCONSOLIDATED SA - SIEVE ANALYSIS: :% PASSING _ UNDRAINED TRIAXILL C7w� SANDS CLEAN SANDS Cu>6 AND 1<Cc<3 SW WELL -GRADED SAND UJI -g z <5% FINES Cu>6 AND 1>Cc>3 SP POORLY -GRADED SAND a0 A >50% OF COARSE SANDS AND FINES FINES CLASSIFY AS ML OR CL SM SILTY SAND v FRACTION PASSES ON NO 4. SIEVE >12%FINES FINES CLASSIFY AS CL OR CH SC ] CLAYEY SAND SILTS AND CLAYS PI>7AND PLOTS>•A•LINE CL LEAN CLAY J INORGANIC PI>4AND PLOTS<•A•LINE ML SILT 0 LIQUID LIMIT<50 w LuLu ORGANIC LL (oven dnedyLL (not dned)<0.75 OL ORGANIC CLAY OR SILT — w w U) U) zao -- <o N SILTS AND CLAYS PI PLOTS LINE CH FAT CLAY w � z INORGANIC PI PLOTS <•A' LINE MH ELASTIC SILT Z LIQUID LIMIT>50 ORGANIC LL(oven driedyLL (not dned)<0.75 OH ORGANIC CLAY OR SILT HIGHLY ORGANIC SOILS PRIMARILYORGANIC MATTER;DARK IN COLOR, AND ORGANIC ODOR PT PEAT OTHER MATERIAL SYMBOLS Poorly Graded Sand i Sand ® with Clay ® Clayey Sand Silt ® Sandy Silt Well Graded Gravelly Sand - - I Artificial/Undocumented Fill Gravelly.Silt ® Poorly -Graded Gravelly Sand Asphalt '—''- Topsoil Boulders and Cobble ADDITIONAL TESTS 0-4 Well -Graded Grave( • with Clay PLASTICITY INDEX Well -Graded Grave( • with S(It . SAMPLER TYPES PENETRATION RESISTANCE (RECORDED AS BLOWS l FOOT) ® SPT ® Shelby Tube ® Modified Califomia (2.5" I.D.) ® No.Recovery ® Rock Core ® Grab Sample ADDITIONAL TESTS 0-4 CA - CHEMICAL ANALYSIS (CORROSIVITY) PI - PLASTICITY INDEX CD - CONSOLIDATED DRAINED TRIAXIAL SW SWELL TEST CN - CONSOLIDATION TC - CYCLIC TRIAXIAL CU - CONSOLIDATED UNDRAINED TRIAXIAL TV - TORVANE SHEAR DS - DIRECT SHEAR UC - UNCONFINED COMPRESSION PP - POCKET PENETROMETER (TSF) (1.5) - (WITH SHEAR STRENGTH (3.0) - (WITH SHEAR STRENGTH IN KSF) _ IN KSF) RV - R -VALUE UU UNCONSOLIDATED SA - SIEVE ANALYSIS: :% PASSING _ UNDRAINED TRIAXILL #200 SIEVE PLASTICITY CHART - WATER LEVEL ISI 60 70 60 w 50 0 z 40 U y 30 g 0 20 10 0 NUMBER OF BLOWS OF 140 LB HAMMER FALLING 30 INCHES TO DRIVEA2 INCH O.D. (1-3A8 INCH I.D.) SPLIT -BARREL SAMPLER THE LAST 12 INCHES OFAN 1B4NCH DRIVE (ASTM -1588 STANDARD PENETRATION TEST). 0 10 20 30 40 50 ' 60 70 80 90 100 110 120 •• UNDRAINED SHEAR STRENGTH IN KIPSISO. FT AS DETERMINED BY LABORATORY LIQUID LIMIT I%) TESTING ORAPPROXIMATED BY THE STANDARD PENETRATION TEST, POCKET PENETROMETER..TORVANE, OR VISUAL OBSERVATION. �:( E -TONE LEGEND TO SOIL Figure Number EAR,T-H G.R C U P DESCRIPTIONS A-1 PENETRATION RESISTANCE (RECORDED AS BLOWS l FOOT) - - SAND & GRAVEL SILT & CLAY RELATIVE DENSITY BLOWSIFOOT' CONSISTENCY BLOWSIFOOT' STRENGTH" (KSF) .VERYLOOSE 0-4 VERY SOFT 0-2 0-0.25 LOOSE 4-10 SOFT 2-4 025-0.5 MEDIUM DENSE 10-30 MEDIUM STIFF 4-0 0.5-1.0 DENSE 30-50 STIFF B-15 1.0-2.0 VERY DENSE OVER 50 VERYSTIFF 15-30 2.0-4.0 HARD OVER 30 OVER 4.0 NUMBER OF BLOWS OF 140 LB HAMMER FALLING 30 INCHES TO DRIVEA2 INCH O.D. (1-3A8 INCH I.D.) SPLIT -BARREL SAMPLER THE LAST 12 INCHES OFAN 1B4NCH DRIVE (ASTM -1588 STANDARD PENETRATION TEST). 0 10 20 30 40 50 ' 60 70 80 90 100 110 120 •• UNDRAINED SHEAR STRENGTH IN KIPSISO. FT AS DETERMINED BY LABORATORY LIQUID LIMIT I%) TESTING ORAPPROXIMATED BY THE STANDARD PENETRATION TEST, POCKET PENETROMETER..TORVANE, OR VISUAL OBSERVATION. �:( E -TONE LEGEND TO SOIL Figure Number EAR,T-H G.R C U P DESCRIPTIONS A-1 HARDNESS Soft = Reserved for plastic material alone. Low hardness — Can be gouged deeply or carved easily with a knife blade. Moderately hard — Can be readily scratched by a knife blade: scratch leaves a heavy trace of: dust and is readily visible after the powder has been blown away. Hard.— Can be scratched with difficulty: scratch produces little powder and is often faintly visible. Very hard — Cannot be scratched with knife blade: leaves a metallic streak. STRENGTH Plastic or very low strength. Friable:— Crumbles easily by rubbing with fingers. Weak - An unfractured specimen of such material will crumble under light hammer blows. Moderately strong — Specimen will withstand a few heavy hammer blows before breaking. Strong— Specimen will withstand a few heavy ringing blows and will.yield with difficulty only dust and small flying fragments. Very strong — Specimen will resist heavy ringing hammer blows and will yield with: difficulty only dust and small flying fragments. WEATHERING —The physical and chemical disintegration and decomposition of rocks and minerals by natural processes such as oxidation, reduction, hydration, solution, carbonation, and freezing and thawing. Deep _ Moderate to complete mineral decomposition: extensive disintegration: deep and thorough discoloration: many fractures, all extensively coated or filled with oxides, carbonates and/or clay or silt. Moderate —_Slight change or partial decomposition of minerals: little disintegration: cementation little to. unaffected. Moderate to occasionally intense discoloration. Moderately coated fractures. Little — No megascopic decomposition of minerals: little or no effect on normal cementation. Slight and intermittent, or localized discoloration. Few stains or fracture surfaces. Fresh - Unaffected by weathering agents. No disintegration or discoloration. Fractures usually . less numerous than joints. FRACTURING Intensity Very little fractured Occasionally fractured Moderately fractured Closely fractured Intensely fractured Crushed BEDDING OF SEDIMENTARY ROCKS Splitting Property Massive Blocky Slabby Flaggy Shaly or Platy Papery Min EARTH GROUP Thickness Greater than 4.0 feet 2.0 to 4.0 feet 0.2 to 2.0 feet 0.05 to 0.2 feet 0.01 to 0.05 feet less than 0.01 feet Size of Pieces in Feet Greater than 4.0 1.0 to 4.0 0.5 to 1.0 0.1 to 0.5 0.05 to 0.1 Less than 0.05 Stratification verythick-bedded thick -bedded thin -bedded very thin -bedded laminated thinly laminated Physical Properties of .figure Number Rock Descriptionsa-i I-. BORING NUMBER EB -1 PAGE 10F1 OCORNERSTONE C EARTH GROUP PROJECT NAME Arastadero Trail Improvement Project PROJECT NUMBER 116-1-1 PROJECT LOCATION Los Altos Hills, CA DATE STARTED 4/4/07 DATE COMPLETED 4/4/07 GROUND ELEVATION 329 FT +/_ BORING DEPTH 15.5 ft. DRILLING CONTRACTOR Access Soil Drillino LATITUDE LONGITUDE " DRILLING METHOD Minuteman GROUND WATER LEVELS: LOGGED BY LCK AT TIME OF DRILLING Not Encountered NOTES TAT END OF DRILLING Not Encountered This log is a part of a report by Comersone Earth Group, and should not be used as a standaltme document. This description applies only to the location of the a M F- F; o\ (9 UNDRAINED SHEAR STRENGTH, ` eVloration at the time of drilling. Subsurface conditions may differ at other locations and may change at ata location with tune. The description presented is a m m o w GO(7 2 Z w ~ X w Z m j k5f O HAND PENETROMETER Z _ m simplification of actual conditions encountered. Transitions between spit types may be $ m ] - Z t11 m O O �> rn w a N > (L _gradual. �m �Z LL Za F7 -W ~ Zo TORVANE W p N o, m< z U w `� * UNCONFINED COMPRESSION W Z EL o O g a 2 UUNNCIAOINSSOLIDATED-UNDRAINED DESCRIPTION a AL 329.0 0 �.0 2.0 3.a . a.o Elastic Silt (MH) . hard, moist, brown with orange and gray mottling, trace of fine sand 34 MC -1 94 28 Q Is 326.0 Claystone [Monterey Shaie (TM)] .. soft, severely weathered, moist, brown with 84 MC -2B 95 27 Q orange and gray mottling, some fractures 5 88 SPT -3 22 321.0 Sandstone [Monterey Shale (TM)] moist, severely weathered, brown with some orange staining, fine to very fine with silt 54 SPT -4 19 10 soMG-5thin 5" seams of slightly cemented siltstone 15 75 SPT -6 24 313.5 Bottom of Boring at 15.5 feet. 20- 25- BORING NUMBER EB -2 CORNERSTONE PAGE IOFI E /rk R T H G R O U n PROJECT NAME. Arastadero Trail Improvement Project CIO" PROJECT NUMBER 116-1-1 PROJECT LOCATION Los Altos Hills. CA DATE STARTED 4/4/07 DATE COMPLETED 414/07 GROUND ELEVATION 326 FT +/- BORING DEPTH 15 ft. DRILLING CONTRACTOR Access Soil Drilling LATITUDE LONGITUDE DRILLING METHOD Minuteman GROUND WATER LEVELS: LOGGED BY LCK �Z AT TIME OF DRILLING Not -Encountered NOTES S AT END OF DRILLING Not Encountered This log is apart of a report by Cornerstone Earth Gmup, and should not be used as a UNDRAINED SHEAR STRENGTH, a standalone documenL This description applies only to the location of the v F F O ksf a loration at the time of dulling. Subsurface conditions maydiferat other locations and may change at this location with time. The description presented is a m m o W S 0 z W X W Z CO j O HAND PENETROMETER z O " : simplification of actual conditions encountered. Transitions between sol types may be o 0 W ❑ z W 3 Q Z Z < W <� m gradual. o m ? —r �° u- Fa W O HO Fo 0 TORVANE rL W uai 'm 3 < < j < W r w `� ® UNCONFINED COMPRESSION w ❑ , o m rn a z F W it z S UNCONSOLIDATED -UNDRAINED DESCRIPTION Z d a X1.0 AXIAL2.0 326.0 0 3.0 4.0 Claystone [Monterey Shale (TM)] soft, severely weathered, moist, brown with rust and gray mottling, fractured, slightly cemented siltstone and silty sandstone s1 11. MC -1B 98 24 » 54 SPT -2 24 5 52 SPT -3 26 65 SPT -4 21 10 67 SPT -5 311.0 i 15 Bottom of Boring at 15.0 feet. i i i I i 20 i i i 25 i t BORING NUMBER EB -3 PAGE 1 OF 1 CORNERSTONE C ■ EARTH GROUP PROJECT NAME Arastadero Trail Improvement Project (( PROJECT NUMBER 116-1-1 PROJECT LOCATION Los Altos Hills. CA DATE STARTED 4/4/07 DATE COMPLETED 414/07 GROUND ELEVATION 318 FT +/- BORING DEPTH 15 ft. DRILLING CONTRACTOR Access Soil Drilling LATITUDE LONGITUDE DRILLING METHOD Minuteman GROUND WATER LEVELS: LOGGED BY LCK Q AT TIME OF DRILLING Not Encountered NOTES ZAT END OF DRILLING Not Encountered This log is a part of a report by Comerstone Earth Group, and snoWd not be used as a standalone document This description applies only to the location of the a F F oUNbRAINED C7 SHEAR STRENGTH, e�lorabon at the lime of drilling. Subsurface conditions may differ at other locations and may change at alis location with time. The description presented is a m m o W = t7 Z w X w Z m j k51 O. HAND PENETROMETER Z O JO simplification of actual conditions encountered. Transitions between wil types may be W m Z W 3 Q Z Z 4 W = m gradual. m ay � LL O HW a w TORVANE > W > > .MZ < Za ZQ UNCONFINED COMPRESSION J Wq p _ c. z W o Z j o F g U o a Z - UNCONSOLIDATED -UNDRAINED DESCRIPTION a AL 1.0 2.0 3.0 4.0 318.0 0 Siltstone [Monterey Shale (TM)] soft, severely weathered, moist, brown with orange to gray mottling, closely jointed, slight cementation 26. MC -1B 90 27 87 11." MC -2 71 30 5 39 SPT -3 44 -SPT -4 10 seams of fine sandstone siltstone 76 : SPT -5 303.0 15 Bottom of Boring at 15.0 feet. 20: i i 25 BORING NUMBER EB -4 CORNERSTONE PAGE 1OF1 ■ PROJECT NAME Arastadero Trail Improvement Project EARTH GROUP PROJECT NUMBER 116-1-1 PROJECT LOCATION Los Altos Hills. CA DATE STARTED: 4/4/07 DATE COMPLETED 4/4/07 GROUND ELEVATION 309 FT +/- BORING DEPTH 15 ft'. DRILLING CONTRACTOR Access Soil Drilling LATITUDE LONGITUDE .DRILLING METHOD Minuteman GROUND WATER. LEVELS: LOGGED BY LCK -VAT TIME OF DRILLING Not Encountered NOTES T AT END OF DRILLING Not Encountered This log is a part of a report by Cornerstone Earth Group, and snould not be used as a UNDRAINED SHEAR STRENGTH, a stand-alone document This description applies only to the location of the eksf xploration at the time of drilling. Subsurface wnditions may differ at other locations location description m c K W {_ M O F.: Z W X W O Z W j O- HAND PENETROMETER ZO and may change at this with time. The presented is a simpfdication of actual conditions encountered. Transitions between sod types may be m o —0 `m W W 3 QQ ?> d Q _ a tip gradual v Wim. - Z iZ LL C O to Q TORVANE W rn o N a Z(L 1=-W Z Y F U Z w `r 19 UNCONFINED COMPRESSION W IJ31 mG a > H N K2 . UNCONSOLIDATED -UNDRAINED DESCRIPTION Z ° 0 a a TR1.[ALz.O 3.0 4.0 309.0 0 Elastic Silt (MH) very stiff, moist, brown with orange to gray mottling 22 MC -1 92 30 .24 305.5 Siltstone [Monterey Shale (TM)] Q Mczs 102. 24 soft, severely weathered, moist, brown with 5 orange to gray mottling, closely jointed 32 SPT -3 30 softer, color to bluish green harder, color back to brown with orange to 39 MC -4B 10 gray mottling siltstone i 32 SPT -5 31 294'0 I i 15 Bottom of Boring at 15.0 feet. 1 's i 20 1 i i i i 25 i BORING NUMBER EB -5 PAGE 1 OF 1 CORNERSTONE R PROJECT NAME Arastadero Trail Improvement Project EARTH O� r n GROUP V 1 C L.J r PROJECT NUMBER 116-1-1 PROJECT LOCATION Los Altos Hills. CA DATE STARTED 5/15/07 DATE COMPLETED 5/15/07 GROUND ELEVATION 283 FT+I- BORING DEPTH 19 ft.: DRILLING CONTRACTOR Exploration Geoservices, Inc. LATITUDE LONGITUDE :DRILLING METHOD Mobile B-53, 8 inch Hollow -Stem Auger GROUND WATER LEVELS: LOGGED BY . PAFAT TIME OF DRILLING Not Encountered NOTES TAT END OF DRILLING Not Encountered . This log is a part of a report by Cornerstone Earth Group, and should not be used as a standalone document This description applies only to the location of the = e UNDRAINED SHEAR STRENGTH, e)ploraton at the tine of drilling. Subsurface conditions may differ at other locations and may change at this location with time. The description presented is a m m o ul M = 0 Z > w ? w m ksf O HAND PENETROMETER Z simplification of actual conditions encountered. Transitions between sod types may he W 10 3: aw W° <O Q S.m d gradual. m �a �Z 2° Ha Ha O r0 d to Q TORVANE W p U) o N¢ j Zit : v mo w UNCONFINED COMPRESSION W > a a �. ° F o y zUNCONSOLIDATED-UNDRAINED a �. TRWxIAL DESCRIPTION z a 283.0 0 .1.0 20 3.0 4.0 Elastic Silt (MH) very stiff, dry to moist, dark gray, trace sand and fine gravel 221 Mal 95 13 Q 27 MC -2 87 29 Q 48 MC -3 88 34 276.0 Sandstone [Monterey Formation (Tm)] 90' low hardness, weak to moderately strong, 10" MG` 101 22 gray, mottled, massive, fine grained, angular to sub -angular, silty, moderately weathering 48 SPT 10.:;: -522 271.0 Siltstone [Monterey Formation (Tm)] x x x x x x low hardness, weak to moderately strong, x x gray, mottled, iron stained fractures, little to 50 SPTm6 26 3" X x moderate weathering, monterey formation 15 x x x x x x x x x x x X x x x x 264'0 x x 50 SPT Bottom of Boring at 19.0 feet. 8„ 20- 0253035 25- 30- 351 EC CORNERSTONE EARTH GROUP APPENDIX B: LABORATORY TEST PROGRAM The laboratory testing program was performed to evaluate the physical and mechanical properties of the soils retrieved from the site to aid in verifying soil classification. Moisture Content: The natural water content was determined (ASTM D2216) on 21 samples of the materials recovered from the borings. These water contents are recorded on the boring logs at the appropriate sample depths. Dry Densities: In place dry density determinations (ASTM D2937) were performed on 11 samples to measure the unit weight of the subsurface soils. Results of these tests are shown on the boring logs at the appropriate sample depths. Plasticity Index: One Plasticity Index determination (ASTM D4318) was performed on samples of the subsurface soils to measure the range of water contents over which these materials exhibit plasticity. The Plasticity Index was used to classify the soil in accordance with the Unified Soil Classification System and to evaluate the soil expansion potential. Results of these tests are shown on the boring logs at the appropriate sample depths and are attached to this appendix. Unconfined Compression: The unconfined compressive strength was determined on four relatively undisturbed samples by unconfined compression testing (ASTM D2166). The results of these tests are included as part of this appendix. ARASTRADERO TRAIL IMPROVEMENT PROJECT Page B-1 441-1-1 Plasticity Index (ASTM D4318) Testing Summary 60 50 .., CH 0 x 40 m a ; 30 .2 CL w to to IL 20 OH or MH OL 70 80 90 100 _ _ C `=ML=� Liquid: Limit (%) 00 10 20 30 40 50 60 c. � cc Boring No. Depth (t{) Natural Water Content .Liquid Limit plastic .Limit plastic) Index passing No. 200 Group Name (USCS.-ASTM D2487) . -�- EB-4. 2.0 30 60 36 24 — Elastic Silt (MH) C_0R:N.E.R.STON E: ECam A R T H G ROUP Plasticity Index Testing Summary ""°""""°° 4 41-1-1 -- Arastradero Trail Improvement Projec Los Altos Hills, CA F1Q.. N.- g Figure 61 ob.��nro 'Dommbe,2ml OL r ML _ _ C `=ML=� �''' 00 10 20 30 40 50 60 Unconfined Compressive Strength ASTM D2166 15000 i --0 Samplel -f- Sample2 12000 --Sample3 --X Sample4 U, N I P 9000 w .N N a 6000 F O U 3000 0 0:00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 Strain, % Sample No.: 1 2 3 4 Unconfined Compressive Strength, psf 6672 8056 -. 11956 10917 Unconfined Compressive Strength, psi 46.3 55.9 83.0 75.8 Undrained Shear Strength, psf 3336 4028 5978 5458 Failure Strain, % 3.2 2.3 1.9 1.9 Strain Rate, % per minute 1.0 1.0 1.0 1.0 Strain Rate, inches/minute 0.05 0.05 0.05 0.05 Moisture Content, % 28.0 26.7 24.2 24.1 Dry Density, pcf . 93.7 95.3 97.7 F 102.0 Saturation, % 94.7 93.8 90.1 99.7 Void Ratio 0.799 0.769 0.725 0.653 Specimen Diameter, inches 2.414 2.425 .2.430 2.425 Specimen Height, inches 5.01 5.00 5.03 5.03 Height to Diameter Ratio 2.1 2.1 2.1 2.1 Assumed Specific Gravity 2.70 2.70 2.70 2.70 Sample Location , -__.--Bo.rin ___Sample_ Depth -ft. _..______ ______Soil_ Description_____ 1 EB -1 1B 1-2.5 Brown CLAY 2 EB -1 2B 4 Brown CLAY 3 EB -2 1 B 2 Brown CLAY 4 EB -4 2B 4 Brown CLAY Job No.: 640-011 Type of Sample Jundisturbed Client: Cornerstone Earth Group , Project: C-2 Trail - 116-1-1 Remarks: Date: 4/16/2007 By: MD/RU 11_1% . C 2 A -0- M11 :a u I�EI(AdON T.kHASPORTATIONCONSUITANT�, December 19, 2011 Mr. Richard Chiu Public Works Director Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, CA 94022 Subject: Pedestrian, Bicycle, and Equestrian Recounts for the Arastradero Road Trail Project Dear Mr. Chiu: Hexagon Transportation Consultants, Inc. has completed updated counts of potential usage of the proposed Arastradero Road Trail. The purpose of the update was to see whether the newly -opened Stanford S1 trail has changed the usage on Arastradero Road. The updated study counted existing pedestrians, equestrians, and bicycles in the corridor. The count along Arastradero Road included a survey of users to determine where they are coming from and going to. The study included a count of parking for the Arastradero Preserve, both in the preserve parking lot and along nearby streets. Hexagon also counted parking at the Page Mill Road park-and-ride lot. The results of the study are discussed below. Pedestrian and Bicycle Counts At all three count locations, the March 2011 counts were higher than the June or December 2011 counts. (see Table 1). In all cases the counts were done on a Saturday from 10 AM to 2 PM. The weather was clear and sunny on all count days. The counts.do not show any obvious pattern of increasing or decreasing bicycle, pedestrian, and equestrian usage. Pedestrian and Bicycle Survey Hexagon also conducted a survey of the pedestrians, equestrians, and bicyclists using Arastradero Road to determine where they are coming from (see Table 2). The highest number of respondents occurred in the December 2011 survey. As noted above, this doesn't mean there were more users of the road; it means that more people were willing to stop and answer the question about trip origin. In terms of pattern of trip origin, the survey results are similar. Only about 7-9% of users were found to reside in Los Altos Hills. Parking Count Parked cars were counted at:the Arastradero Preserve, and nearby streets, and also at the Page Mill Road park-and-ride lot. Table 3 shows that the number of parked cars at the Arastradero Preserve in June and December was less than or equal to the previous count in March 2011. Of the cars on the street during all surveys, a maximum of one vehicle was parked on Tracy Court or Liddicoat Drive, and the rest were parked on Arastradero Road. The 46 -space Page Mill Road park-and-ride lot was counted in June and December (see Table 4). A comparison of the counts indicates that the lot was over 2/3 full during the entire period of the June count and over 2/3 full during the entire period of the December count except for the last 1/2 hour: Both counts showed that the lot.was close to capacity during a period of the day. However, the peak parking occurred earlier in the day during the June count and about midday during the December count. The change in the time for the peak parking demand is probably due to the difference in June and December temperatures. 111 W. St. John Street, Suite 850 S San Jose, California 95113 phone 408.971.6100 6 fax 408.971.6102 • www.hextrans.com M -0.1 ID Nl- 010 11 Mr. Richard Chiu December 19, 2011 Conclusions With the pedestrian, bicycle, equestrian, and parking counts Hexagon could find no evidence that opening of the Stanford S1 trail has increased usage of other trails and roads in the area. The March 2011 counts occurred before the trail opened. However, the June 2011 counts actually were lower than the March 2011 counts, and the December 2011 counts were lower or similar to the March 2011 counts. It is not logical to assume that the trail opening would lead to lower usage of other facilities. The most logical conclusion is that the trail opening has had no effect on usage of other nearby roads and trails. Thank you for allowing us the opportunity to prepare this recount study. Please feel free to contact us if you have any questions about this study. Sincerely, HEXAGON TRANSPORTATION CONSULTANTS, INC. Gary Black President Table 1 Existing Bicycle and Pedestrian Count (count conducted from 10 AM to 2PM) 'Location e Bicycles Frernont'Road_ ned�r -Town:=Hall �.::68 Arastradero Road at Stirrup Way) 372 304 292 std%oad_ 2IPa a Mi11 Road (near AraR�;`511r y Pedestrians .. .6 Fcemont�Road near;:.Towr�:Hall Arastradero Road at Stirrup Way) 14 13 5 Pa a MiIIM6o id nearAras"t WWRoad _ d.. _ - �.:_6 ".' E uestrians _--w� Arastradero Road 7ai Stirrup Way) 0 0 4 Pa - e 1�7till ' M& ATas'fr6cId Road PPIM u Wexaoon Transportation (onsultants. Inc. 2 1 Page WIWI WE C 010 Mr. Richard Chiu December 19, 2011 Table2 Trip Origins on Arastradero Road Number of .. Origin March June December Los Altos Htlls �l 13-_ , 9,/0 ` 4 16x z. 8°/D * 19 M Palo Alto 29 20% 33 16% 47 17% Portola=Valle 0� ° C40 Los Altos 10 7% 19 9% 32 12% MenloPark Mountain View 33 23% 28 14% 45 17% Sunnyvale 11f 8% 10 5% 16 6% _ _ Sa�ta�Clara?.�.,t �'��' �10��. t 7�% ��4 �� ,y 4``— �-' � ° �: � �1��{ �x 0%r• San Jose j11 8% 27 13% 28 10% �� Belmont 2 1% 0 0% 2 1% Other 7 5% 32 15% 55 20% "' ��''s�- NZ <`:3 `not all users were survey participants Table.3 Existing Parking -Count — Arastradero Preserve On-StreetTime Parking Lot - 3/12/2011 6/11/2011 12/10/2011 3/12/2011 6/11/2011 12/10/2011 2, s -11Z z - r� x es rte, _> Noone 33 ._ �=3.1. � 32 t.� ��_b �3 8:_a _ u. 4 L � 9gx, 'OO�*.T. 335 _22x i173OLk' u Hexagon Transportation Consultants. Inc. 3 1 P e g e 9 ODE a 4 5 Mr: Richard Chiu December 19, 2011 Table 4 Existing Parking.Count — Page Mill Road Park -and -I Time- -Park-an&Ride Lot 6/11/2011 12/10/2011 10 30,A 4 R 11:0.0=" . 38! 35 'T�3'=sem 12,30' 00 - hexagon Transportation Consultants. Inc. Ride Lot 4 1 Page a 11 r—; fl . 9 1a 9 u HUMN TRANSPORTATION CONSULTANTS, INC. June 17, 2011 Mr. Richard Chiu Public Works Director Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, CA 94022 Subject: Pedestrian, Bicycle, and Equestrian Recounts for the Arastradero Road Trail Project Dear Mr. Chiu: Hexagon Transportation Consultants, Inc. has completed updated counts of potential usage of the proposed Arastradero Road Trail. The purpose of the update was to see whether the newly -opened Stanford S1 trail has changed the usage on Arastradero Road. The updated study counted existing pedestrians, equestrians, and bicycles in the corridor. The count along Arastradero Road included a survey of users to determine where they are coming from and going to. The study included a count of parking for the Arastradero Preserve, both in the preserve parking lot and along nearby streets. Hexagon also counted parking near Arastradero Road at Purissima. Road and at Horseshoe Lane. The results of the study are discussed below. Pedestrian and. Bicycle Counts At all three count locations, the June 2011.counts were lower than the March 2011 counts (see Table 1). In both cases the counts were done on a Saturday from 10 AM to 2 PM. The weather was clear and sunny on. both count days. Hexagon can offer no obvious explanation for why the counts differed on the two count days. Pedestrian and Bicycle Survey Hexagon also conducted a survey of the pedestrians, equestrians, and bicyclists using Arastradero Road to determine where they are coming from (see Table 2). In the June 2011 survey there were more respondents. As noted above, this doesn't mean there were more users of the road; it means that more people were willing to stop and answer the question about trip origin. In terms of pattern of trip origin, the survey results are similar. Only about 8% of users were found to reside in Los Altos Hills. Parking Count Parked cars were counted at the Arastradero Preserve, and nearby streets, and also near the intersection of Arastradero Road and Purissima Road, which is the trailhead for the new Stanford S1 trail. Table 3 shows that the number of parked cars at the Arastradero Preserve .was less than for the previous count in March 2011. Of the cars on the street, one was parked on Tracy Court, and the rest were parked on Arastradero Road. None was parked on Liddicoat Drive. Hexagon can offer no obvious reason for why there were fewer cars parked at. the Preserve in the June count. During the parking count, there were no cars parked on Arastradero Road, Purissima Road, or Horseshoe Lane near the S1 trailhead. Conclusions With the pedestrian, bicycle, equestrian, and parking counts Hexagon could find no evidence that opening of the Stanford S1 trail has increased usage of other trails and roads in the area. The June 2011 counts actually were lower than the March 2011 counts, before the trail opened. It is not logical to assume that the trail opening would lead to lower usage of other facilities. Therefore, the most logical conclusion is that the trail opening has had no effect on usage of other nearby roads and trails. 111 W. St. John Street, Suite 850 • San Jose, California 95113 phone 408.971.6100 • fax 408.971.6102 • www.hextrans.com 40. PA NIP) 0 r-� s ITS Mr. Richard Chiu June 17, 2011 Thank you for allowing us the opportunity to prepare this recount study. Please feel free to contact us if you have any questions about this. study. Sincerely, HEXAGON TRANSPORTATION CONSULTANTS, INC. Gary Black President Table 1 Existing Bicycle and Pedestrian Count (count conducted from 10 AM to 2PM) Location i3icycles -t 3/12/2011 6/11/2011 3/12/2011 6/11/2011 3/12/2011 6/11/2011 ;FremgAt Roach: nearovn Hall) : .. �,., a'a�.r :. 68..x T2s Arastradero Road (at Stirrup Way) 372 304 14 13 : 0 0 Page ,Mill:RoadnearaAr..-astradero-Road) _r< ., { rsL,: 708 _i Table 2. Trip Origins on Arastradero Road "not all users were.suney participants P� - � �Iexagon Transportation (onsultants. Inc. 2 1 P a g e lr 0 0 21 -1 -0 - Me Me Mr. Richard Chiu June 17, 2011 Table 3 Existing Parking Count—Arastradero Preserve On-StreetTime Parking Lot. 3112/2011 6/11/2011 3/12/2011 6/11/2011 �`" 11.00�33�27�7g7£ uWexa9on Transportation Consultants, Inc. 3 1 Page HEXAM TRANSPORTATION CONSULTANTS, IN(. April 4, 2011 Mr. Richard Chiu Public Works Director Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, CA 94022 Subject: Pedestrian, Bicycle; and Equestrian Study for the Proposed Arastradero Road Trail Dear Mr. Chiu: Hexagon Transportation Consultants, Inc. has completed a study of potential usage of the proposed Arastradero Road Trail. The proposed trail consists of a roadside trail and bike lanes along Arastradero Road and Page Mill Road from Purissima Road to the Arastradero Preserve (see Figure 1). To estimate the potential usage of the trail by pedestrians, equestrians, and bicycles, Hexagon counted existing use in the corridor, and we counted a fully -completed trail on Fremont Road in front of the Town Hall. The count along Arastradero Road and at the Arastradero Preserve included a survey of users to determine .where they are coming from and going to. The results of the study are discussed below. Pedestrian and Bicycle Counts Hexagon counted pedestrians, equestrians, and bicycles at three locations along the proposed corridor on Saturday March 12 from 10:00 AM to 2:00 PM. This time period was chosen because past experience has shown that this is the busiest time of the week for use of recreational facilities. The count locations were on Arastradero Road near Stirrup Way, Page Mill Road near Arastradero Road, and at the Arastradero Preserve (see Figure 1). Hexagon also counted Fremont Road in front of the Town Hall for comparison purposes :since that location has had a trail for many years. Bike lanes do not exist along Arastradero Road or Page Mill Road. Nevertheless, the counts show significant bicycle usage (see Table 1). The riders appeared to be almost exclusively experienced bicyclists out for recreational or training rides. Arastradero Road does not have a pedestrian path, and the number of pedestrians was low. However, Page Mill Road does have a pedestrian path, and the number of pedestrians was even lower than on Arastradero Road. The number of pedestrians on Fremont Road was much higher. This is probably because Fremont Road traverses an area with a lot more houses nearby than Arastradero Road or Page Mill Road. Based on Hexagon's observations, it appears that most pedestrians on the trails are people out for recreational walks. The number of bicycles on Fremont Road was much less than on the other roads. This is probably because Fremont Road does provide a direct connection.to the roads that go into the hills, which are preferred by serious cyclists. Pedestrian and Bicycle Survey Hexagon also conducted a survey of the pedestrians, equestrians, and bicyclists using Arastradero Road and using the Arastradero Preserve to determine where they are coming 111 W. St. John Street, Suite 850 San Jose, California 95113 16 10 qW Phone 408.971.6100 Fax 408.971.6102 Mr. Richard Chiu April 4, 2011 " Page 2 of 4 from (see Table 2). People were asked if they would answer a couple of questions as they were passing by. Some users were not willing to participate. Of the pedestrians and bicyclists that answered the questions, some were found to reside in Los Altos Hills, but most came from other communities. This is not a surprising result because most of the people surveyed were bicyclists. Arastradero Road, Page Mill Road, and the Arastradero Preserve are a regional attraction, and serious bicyclists can easily reach them from surrounding communities, even from miles away. Almost all of the survey respondents walking on Arastradero Road, which wasn't many, were from Los Altos Hills. The survey also checked where cars were parked to use the Preserve. At the start of the survey, 10 AM, there were 33 cars parked in the Preserve lot, 20 cars parked on the street on Arastradero Road, and two cars parked on Liddicoat Drive. Later in the day, the number of cars parked on -street diminished, but the Preserve parking lot remained full. It appeared that most hikers in the Preserve drove to the site and parked in the lot or on the street. Most bicyclists rode to the Preserve, although some drove cars and parked. Trail Usage Estimate It is likely that providing a pedestrian trail along Arastradero Road would increase the number of pedestrians in that corridor. The existing conditions are such that pedestrians sometimes must walk in the street, which would discourage some potential users. On the other hand, it is unlikely that the Arastradero Road trail would get as many users as the Fremont Road trail. The number of homes in the vicinity of Arastradero Road is less, and the trail would not really lead to a concentration of destinations. The Arastradero Preserve is an obvious destination that residents might walk to. However, from most of Los Altos Hills the walk to the Preserve would be very long indeed. For example, from Town Hall to the Preserve is a distance of over three miles. Hexagon would expect that the trail would result in an increase of pedestrians to maybe 30 in the busiest four-hour period compared to 14 pedestrians today. We certainly would expect fewer than the 65 pedestrians that were counted on Fremont Road. Bike Lane Usage Estimate The count showed a lot of bikes already using Arastradero Road, and even more using Page Mill Road, even though no bike lanes exist today. Experienced riders are comfortable riding on roads without bike lanes, and bike lanes probably would not increase their usage. The benefit of bike lanes is that they allow less -experienced riders to feel comfortable, and they make drivers more aware of bikes, which can increase safety. The presence of bike lanes on Arastradero Road and Page Mill Road leading to the Arastradero Preserve could encourage more Los Altos Hills residents to ride bikes to the Preserve. However, our survey at the Preserve showed that only 4% of Preserve users were from Los Altos Hills. Most of these people drove to the Preserve. If all these people switched to bikes, the increase in total riders on Arastradero Road would be about 8%, or 31 riders during the peak 4 -hour period. �® Mr. Richard Chiu April 4, 2011 ®® Page 3 of 4 Hexagon understands that the proposed bike lanes on Page Mill Road cannot be continuous because the road crosses a narrow bridge. We do not believe that this presents a hazardous condition provided the bike lane termination is properly signed and striped. We do not believe the termination would discourage use of the bike lanes. Most bicycle riding is done on roads without bike lanes. Hexagon believes bike lanes are beneficial wherever they can be installed, but they don't need to be on every road and at every location to have a good system. Thank you for allowing us the opportunity to study the proposed Arastradero trail system. Please feel free to contact us if you have any questions about this study. Sincerely, HEXAGON TRANSPORTATION CONSULTANTS, INC. Gary Black President Mr. Richard Chiu April 4, 2011 Page 4 of 4 Table 1 Existing Bicycle and Pedestrian Count . (count conducted Saturday, March 12, 2011 from 10 AM to 2 PM) Location i3icycles Pedestrians Equestrians Arastradero Road (at Stirrup Way) 372 14 0 Mage M###r:Roadz(near A_ rastradero Raa;) _ r 7708 Arastradero Preserve* 600 182 3 *total Preserve users; hikers came by car, most bicyclists rode Table 2 Trip Origins Based on Survey* PeopleNumber of Arastradero Origin Preserve •... Los.Altos"{fCfs 6..5 4°l°3:: pn Palo Alto 32 24%� 29 20% u Pavia#a Valleys' '2 n r:IZ0 D_.lcr— i. :12 6a Los Altos 0 0 10 7% hlteryfa Pyr Mountain View w 14 11% 33 23% Redwood G�ty - 2°�QT;' j ° Sunnyvale 6 4% 11 7% Sat GI r M' 13' 1D°�D_ E San Jose 18 14% 111 7% Belmont 2 2% 2 1% Other 7 5% 7 5% *not all users were survey participants Pedestrian, B LEGEND e and Equestrian Study for the Proposed Arastradero Road Trail = Count Locations ....... = Proposed Trail Location �� iJ[FA40tl TQAHSDOQTAil01iCONSBl1AH1S.�fl[. Figure 1 nt Locations 1A, D NORTH N'I to Scale Attachment 2 Debbie Pedro From: Chrisandanitra [chrisandanitra@yahoo.co.uk] Sent: Friday, March 30, 2012 10:07 AM To: Debbie Pedro Subject: Safer biking for our kids - Arastradero Rd project Debbie, As residents of Baleri Ranch Rd we received the notice regarding the proposal to improve the Arastradero Rd bike path. We'd like to voice our strong support for the project as it appears any possible objections are far outweighed by the advantages. What could be more important than safety on the road, both for the many cyclists and walkers who use this route, and also for the cars that share the road. We are fortunate to live in an area where many a school and working commute can be accomplished by bike, with great advantage for road congestion, health and the environment. The proposal can only increase these opportunities, and further improve the quality of the neighborhood. Given rising gas prices, the increase in health problems due to lack of exercise, and the increasing concern regarding pollution of the environment, we are delighted to see a proposal that will benefit all three. The Arastradero Rd Trial Project for safer driving and cycling in the stretch around the Turman school area appears to continue to receive the support of drivers and cyclists alike. We hope for the same approval of this project. Anitra Bowers 14210 Baleri Ranch Road Sent from my iPhone 1 Debbie Pedro From: Karen Matthys [karen@matthys.com] Sent: Friday, March 30, 2012 10:28 AM To: Debbie Pedro Cc: 'Mike Matthys' Subject: Support for Safe Bicycle Path on Arastradero Hi Debbie, I wanted to express my support (and the support of my husband and children) for the safe bicycle/walking path that LAH is considering on Arastradero between Page Mill and Purissima. I really appreciate the town taking steps to make this happen for several important reasons: 1. For all the children in the northern part of Los Altos Hills, they currently do not have a safe route to get to Terman and Gunn, and to the Purissima ballfields. The Arastradero "saddle road" is very narrow in parts and most parents I know would not allow their children to ride on this stretch. Hence our children are stuck in cars, or on buses to school almost every day. FYI, the Palo Alto school district may end the bus route next year due to expenses. We just received a letter to this effect from Cathy Mak, Chief Business Officer at the PAUSD school district. This action would make it even more critical for our children to be able to bicycle to school. 2. As we all know, obesity is a very serious issue among children in the US. Our children are the first generation in a long time that are expected to live FEWER years than their parents. Sadly, less than 1 in 3 California children meet the state fitness targets: http://www.mercurynews.com/california/ci 19443974 . To combat obesity, the American Academy of Peditricians recommends that our children get more exercise — at least 60 minutes per day — which the safe route on Arastradero will provide. 3. The benefits of the bicycle and walking path on Arastradero are not just for children. I lived with my family in the Netherlands several years ago, and I saw the amazing benefits from having safe bicycle routes all over a community. Even 80+ year olds rode bicycles there and were in excellent shape. No wonder the average life span in the Netherlands is 2.4 years more than in the US. (world bank 2009 data) Thanks for considering our thoughts. I plan to attend the hearing next Thurday; but fyi many parents who support the safe bicycle route on Arastradero will be out of town for Palo Alto school spring break next week. Best, Karen and Mike Matthys 14230 Baled Ranch Road Los Altos Hills Debbie Pedro From: Sandra Viarengo [sandra viarengo@sbcglobal.net] Sent: Friday, March 30, 2012 11:30 AM To: Debbie Pedro Subject: Support of Arastradero bike path I am writing to support bike path, we have lived on Baleri Ranch Road for 15 yrs. Our children attend Gunn, Terman and play baseball at Purissima fields. A safe bike path is way overdue. In addition, today my children take the bus to school. There is some discussion at PAUSD that the school bus service may be discontinued. A safe bike path would be needed for the children to get to school. Regards, Sandra Viarengo 6502243391 Sent from my iPhone 1 Debbie Pedro From: steinber@law.ucla.edu Sent: Friday, March 30, 2012 11:01 AM To: Debbie Pedro Subject: Arastradero Bike Path Project Dear Debby, I strongly support the Arastradero Bike Path Project, which will be good for the schoolchildren of our town, those in northern LAH who wish to bike to work or events at Stanford, and those in northern LAH who are recreational cyclists and do not have the skill or outfits to ride roadbikes dressed in spandex. I hope to be able to attend next Thursday's meeting. Yours truly, Richard H. Steinberg 28226 Radcliffe Lane Sent from my Verizon Wireless B1ackBerry Debbie Pedro From: Allison Deeter [alli.deeter@gmail.com] Sent: Friday, March 30, 2012 11:32 AM To: Debbie Pedro Subject: Support of arastradero bike paths Hi Debbie, I'm unable to attend the meeting next week because we will be out of town, but I wanted to weigh in with my support of the bike paths. I have 3 children (6th, 4th and 2nd grade).who would greatly benefit from these paths in getting to Terman, as well as their many activities at Purissima fields. Please help us protect our kids and provide them safe ways to get around town. Best, Alli and Byron Deeter Moon Lane 1 March 29, 2012 Re: April 5th Planning Commission Public Hearing Dear Planning Commission, As you know, the 1 mile Stanford Trail Project has been opposed in it's entirety by an overwhelming majority of local homeowners. On behalf of United STOP concerned homeowners, we reviewed the revised project plan with Debbie Pedro and Richard Chiu on March 28th, 2012. Key Points: 1. Bike lanes will be striped or restriped to allow 5' bike lanes in each direction from Arastradero at Purrissima/280 to Arastradero at Tracy Court with the exception of the Page Mill bridge area. At the Page Mill bridge area, the bike lanes will share the traffic lanes. Comments: We defer to the effected homeowners from Purrisima to Tracy to review and comment to the Planning Director and Town Council as appropriate. 2. The centerline of the traffic lanes on Arastradero between -Stirrup and the Park.and Ride will be pushed toward the freeway and the lanes narrowed to accommodate a 5' wide bike lane in each direction and a 5' pedestrian path. The wall height was thereby reduced from the original plan. Comments: Based on proximity, we defer to local homeowners to review and comment to the Planning Director and Town Council as appropriate. 3. The Arastradero Wall will be approx 450' in length. The wall will begin on the corner of Stirrup. The wall starting at the corner of Stirrup will be 3.9' to 2.1' in height for approx 30'. Thereafter, the wall will range from 2.4' to 2.1' in height for approx 120'. Finally, the wall range from 1.2' to .5 in height for the remaining 300'. Five euchalyptus trees near park and ride will be removed. Please note : All measurements are approximate. Please consult engineering plans for detailed measurements. Comments: Although the height of the wall has been reduced, we question if a 2' to 4' wall will still attract graphetti. We defer to local homeowners to review and comment as appropriate. 4. Existing 2b pedestrian pathways from Arastradero at Purrissima/280 to Page Mill Road at Berry Hill Court will be redressed. Thereafter, the Page Mill Road at Berry Hill Court native pathway will be converted to a 2b pathway. The newly converted 2b pathway will curve a few feet behind the Matadero Creek and then merge into native creek and hillside trails. Comments: Based on later physical review, we found that existing 2b pathways donot exist except for a short length of pathway to the right and left of Twin Oaks Court and_ along the back of one home that is located between Park and Ride and Berry Hill. It appears that the majority of the pathway from Purrissima to Matadero Creek is native pathway. Therefore, the reference to "only redressing existing 2b pathways" may not -be -entirely accurate; For-the-most----- part, native pathways will be converted to 2b pathways and not simply "redressed". Personally speaking, we believe that our native pathways: are best aligned with our rural environment and should remain so. Much objection to the. project was due to concerns about the existing wildlife riparian corridor, environmentally sensitive creek area and homeowner safety including fire and burglary concerns. These concerns are due to the over -abundant trails running behind and alongside out homes that connect the Berry Hill, Baleri Ranch, Stirrup and Saddle Mountain residential areas. Having said this, the Page Mill native trail that will be converted to a 2b pathway at Berry Hill .will dead end into native creek and hillside :trails behind Matadero Creek. This is of greatest concern. If possible, this pathway should be left a native trail. Regardless the case, the pathway along Page Mill -from Berry Hill should not curve left in.its final few feet to dead end into the native trail along the sensitive creek area and local trails. Instead, it should curve right in its: final few feet to the pathway along the side of the Page Mill bridge. Pedestrians to and from Arastradero Road would tend to use this shorter route anyway and it will reduce.environmental impact concerns to the native creek trail and wildlife corridor as well as area isafety concerns. 5. A flashing pedestrian cross walk will be installed across Page Mill Road at the western corner of Baleri Ranch Road. Comments: Residents are looking to preserve the rural feel of the area, not create an urban environment. It was felt that this was unnecessary and perhaps could cause a false sense of security to pedestrians crossing Page Mill Road. Pedestrians and equestrians may be safer relying on their own good senses and judgement for safe passing not- blinking lights. Such a blinking crosswalk can be seen across San Antonio Road in Los Altos. In this location, it was understandably installed as a high-density residents crossing into town proper. Los Altos Hills. has many crossings, hills and blind turns. There are no such blinking crosswalks anywhere in the hills. Having said this, a blinking crosswalk would be preferable to other alternatives. A 4 way stop or traffic light would be dangerous due to the limited line of sight. 6. Mitigated Negative Declaration. Comments: We have received a hard copy of the Mitigated Negative Declaration. Soft copies were not available due -to the file size. We have not reviewed the report in its entirety. The Mitigated Negative Declaration states that although the proposed project could have significant impact to the environment, due .to significant revisions in the project, .an environmental impact report will not be required. There are other areas of concern beyond those stated in points 3 through 5. Due to the steep slope and moderately expansive soil; an area of landslide/slump instability 5' thick_ has been noted in the Geotechnical Investigation on the Arastradero hillside near Park and Ride. Removal of the landslide to bedrock is recommended as well as other stabilizing methods to address unstable soil conditions during construction. As stated, actual site conditions may vary from the small -diameter borings, geotechnical observation and -testing during_ earthwork and foundation construction has been recommended. Concerned residents backing Arastradero have long cited similar instabilities near Stirrup that have not been noted or addressed. These are our initial comments until we have an opportunity to review the Mitigated. Negative Declaration in its entirety. Summary : While the project has been downscaled significantly, concerns regarding the conversion from native to 2b pathways especially near Matadero Creek, slope instability at Arastradero and possibly wall grapphiti still remain in question. A full environmental impact report and OSHA review may be appropriate. We are encouraged that the scale of this project has been significantly reduced and hope that all remaining concerns will be properly addressed. Sincerely, United STOP Concerned Homeowners Attachment 3 TOWN OF LOS ALTOS HILLS December 1, 2011 Staff Report to the Planning Commission SUBJECT: STUDY SESSION ON THE RETAINING WALL DESIGN FOR THE ARASTRADERO TRAIL IMPROVEMENT PROJECT; File# 269-11- MISC. FROM: Debbie Pedro, Planning Director RECOMMENDATION: That the Planning Commission: Discuss the retaining wall design options, take testimony from the public, and make a recommendation on the retaining wall design for the Arastradero Trail Improvement Project. BACKGROUND: In February 2006, the Board of Trustees of Leland Stanford Junior University and the County of Santa Clara entered into an Agreement for Trail Easements, Construction, Management and Maintenance and Grant of Trail Easements. This Trail Agreement obligated Stanford to offer to fund improvements to an existing trail within the Town of Los Altos Hills. The purpose of the Arastradero Trail Improvement project is to complete missing segments of the Town's pathways system and to provide a safe and convenient pedestrian/bicycle connection between the residential neighborhoods to the north and south of I-280. The project area begins at the intersection of Arastradero Road and Purissima Roads; continue along Arastradero Road under the I-280 freeway to Page Mill Road; continue along Page Mill Road to the intersection of Baleri Ranch Road/Arastradero Road; and ends at the Los Altos Hills Town boundary west of Tracy Court. The project site encompasses approximately one lineal mile and all improvements are located within existing Town of Los Altos Hills pedestrian and equestrian path easements and road Right -Of -Way. DISCUSSION: The Project includes a retaining wall along the south side of Arastradero Road, west of Stirrup Way. The approximately 475 feet long retaining wall with heights ranging from 3 to 10 feet tall is necessary to accommodate the new Type IIB roadside path. On October 24, 2011, the Pathways Committee reviewed four retaining wall options and recommended the Shotcrete Wall with Boulderscape (Faux Rock) Finish. Planning Commission Study Session Retaining Wall Design for Arastradero Trail Improvement Project December 1, 2011 Page 2 -Stacked Crib Wall (aka Living Wall) Open face allows landscaping. Higher1. • due to larger arn6unt• excavation (2,3 )00 cubic yards) required behind thewall Tr , 11 - 2. Soldier BeamWall withTimberLacraina Vertical wall face Minimal excavation and backfill required -dcal 3. Soil Nail Shoterete Wall with Stone Facin- !r Vertical or slightly slanted wall face e } JaM. i O ��•� S.l,, Non structural stone veneer -T Little or no excavation and backfill kAW behind wall 4. Soil Nail ShotcreteI +e"' n_ Bbulderseape (Faux Rock) Finish W�W ' $INNI Slightl facep Y ''- r slanted wall 4 JaL Vine pockets installed in the wall face for vine plantings • ! Little or no excavation and backfill sH -2¢ �` behind 'all Planning Commission Study Session Retaining Wall Design for Arastradero Trail Improvement Project December 1, 2011 Page 3 Since the proposed retaining wall is in an easily accessible location, residents have expressed concerns that it will attract graffiti and become a public nuisance. Although the Pathways Committee did not recommend the Stacked Crib Wall (Living Wall), it remains a possible alternative because the landscaping and vegetation growing on the wall makes it a less likely target for graffiti. In addition to the Soil Nail Shotcrete Wall with Boulderscape Finish and the Stack Crib Wall, a variation on the Boulderscape (Faux Rock) wall is included for Planning Commission consideration. The option of a Two -Tiered Soil Nail Shotcrete Wall with Boulderscape (Faux Rock) Finish is essentially the same as the one recommended by the Pathways Committee except a planter strip between the walls would allow additional vines or small plants to be installed. The cost for the Stacked Crib Wall and Two -Tiered Soil Nail Shotcrete Boulderscape Wall alternatives would exceed the original project budget and requires the Town's contribution of $350,000 to $500,000. An updated matrix with details on the optional retaining wall designs is included in Attachment 2. ATTACHMENTS 1. Draft Pathways Committee meeting minutes (excerpt) dated October 24, 2011 2. Matrix for Retaining Wall Alternatives 3. Schematic Wall Sections and photos of Wall Alternatives TOWN OF LOS ALTOS HILLS Staff Report to the City Council March 17, 2011 SUBJECT: INITIAL STUDY AND NEGATIVE DECLARATION FOR THE LOS ALTOS HILLS/STANFORD TRAIL IMPROVEMENT PROJECT FROM: Debbie Pedro, Planning Director APPROVED: Carl Cahill, City Manager RECOMMENDATION: That the City Council: 1. Continue the project to a date uncertain in order to complete further study on potential impacts. BACKGROUND In December 2000, and the County of Santa Clara Board of Supervisors granted the Stanford University Board of Trustees a General Use Permit that allowed for more development on Stanford lands. The Permit came with a host of conditions including that Stanford agree to construct certain trail improvements within San Mateo and Santa Clara Counties. After years of discussions Stanford and County Planners agreed on the current trail route configuration through the Lands of Stanford. However, the approved trail on Stanford lands falls short by a mile in connecting with the Arastradero Preserve. So Stanford also agreed with the County to offer funding to the Town for safety oriented improvements to specific roadside paths in Los Altos Hills. These existing paths along Arastradero and Page Mill Roads complete the connection from new and existing public trails on Stanford lands to Palo Alto's Arastradero Preserve. However, the existing path through Town does not meet Town specifications in all locations. On November 18, 2010, the City Council voted unanimously to pass Resolution No. 61-10 approving the Agreement between Stanford and the Town and formed a subcommittee to develop a path improvement plan. The plan is intended to provide a safe and convenient pedestrian/equestrian/bicycle connection between public trails on the Lands of Stanford, Town residential neighborhoods to the north and south of I-280 and Arastradero Preserve. The project consists of the rehabilitation of existing Town pathways according to Town specifications, the completion of a missing pathway link along Arastradero Road adjacent to I-280, crosswalk improvements and the installation of new bike lanes on portions of Arastradero and Page Mill Road. A foot bridge is also proposed as an option near Page Mill and Baleri Ranch Roads. The paths to be improved are for routes shown on the Town's Master Path Plan. The Town General Plan Pathway Element states that "The Pathway System of the Town is intended primarily for the use of Town residents but it should be connected to the path and trail systems of neighboring jurisdictions". The project spans one lineal mile, beginning at the intersection of Arastradero and Purissima Roads, and ends at Arastradero Road near Tracy Court. Staff Report to the City Council March 17, 2011 Page 2 of 3 DISCUSSION On March 3, 2011, the Planning Commission voted (4-0-1, Partridge abstained) to recommend that the City Council consider the following: • Identify current and forecast usage of the trails, parking, and their impact on local neighborhoods • The potential safety impacts of additional bicycle traffic at the Page Mill Road vehicular bridge. • The impacts of increased foot traffic that may result from upgrading the existing native paths to Type IIB paths • The impacts of non residents accessing local LAH pathways from the proposed trail. In addition, the Commission also directed staff to route the project plans to the Pathways and Open Space Committees for input. Four residents spoke at the March 3, 2011 Planning Commission meeting. The majority of the concerns are related to potential increase in traffic and parking problems in and around the project area. Specifically, neighbors are concerned that the improved trail would connect the Stanford S-1 Trail with the Arastradero Preserve and create a significant increase in the number of users, exacerbating weekend parking and bicycle traffic problems that already exist in the surrounding neighborhoods. There are also neighbor concerns that the proposed pedestrian and equestrian bridge near Baleri Ranch Road will invite non-residents to explore the Town's pathways, causing potential safety and privacy impacts. The bridge was intended to divert pedestrians and equestrians away from the Baleri Ranch Road vehicle bridge. However the footbridge is optional and can be removed from the project scope. To summarize, here are the benefits and concerns associated with this project: Benefits Concerns The project will benefit residents by providing The project will provide an improved connection safer pedestrian, equestrian and bicycle routes between the public trails on Stanford lands and between the northeast and northwest parts of Palo Alto's Arastradero Preserve. This could Town as well connections with regional trails result in a potential increase of non-resident and open space. users of Town paths. The project will improve the safety of an The project could increase traffic and parking in existing trail section shown on the Town's and around the neighborhoods, exacerbating a Master Path Map. problem that already exists near the Arastradero Preserve. The paths will be constructed in compliance with the Town's Type IIB or native path standards. The project could result in increased bicycle usage that may cause safety hazards or New bike lanes will improve public safety inconvenience to motorist, particularly over the narrow bridge section of Page Mill Road. Oa Staff Report to the City Council March 17, 2011 Page 3 of 3 As of the date of this report, the Town received three emails commenting on the project. (Attachment 3) CONCLUSION It is recommended that the Council continue the project to a date uncertain to allow staff additional time to research the issues discussed by the Planning Commission. It will also allow the Open Space and Pathways Committees to review the plans at their next regular monthly meeting and provide comments to staff. Continuing the project allows time for redesign or additional mitigation in response to resident comments and concerns. The project will be re -noticed prior to any future hearings. Additional information regarding this project is included in the March 3, 2011 Planning Commission staff report. (Attachment 2) ATTACHMENTS 1. Project area map 2. Planning Commission staff report dated March 3, 2011 3. Emails from Jitze Couperus, 13680 Page Mill Road, dated March 10, 2011, Tasneem Ismail. i, 14240 Berry Hill Court, dated March 9, 2011, and Edwina Cioffi, 14250 Baleri Ranch Road, dated March 6, 2011 4. Project plans TOWN OF LOS ALTOS HILLS March 3, 2011 Staff Report to the Planning Commission SUBJECT: INITIAL STUDY AND NEGATIVE DECLARATION FOR THE LOS ALTOS HILLS/STANFORD TRAIL IMPROVEMENT PROJECT FROM: Debbie Pedro, Planning Director RECOMMENDATION: That the Planning Commission: Review and forward a recommendation that, based on the Initial Study, the City Council adopt the attached Mitigated Negative Declaration for the Los Altos Hills/Stanford Trail Improvement project. BACKGROUND In February 2006, the Stanford University Board of Trustees and the County of Santa Clara entered into a Trail Agreement that obligated Stanford to fund improvements to an existing trail within the Town. On November 18, 2010, the City Council voted unanimously to pass Resolution No. 61-10 approving the Agreement between Stanford and the Town regarding the Trail Project. The Los Altos Hills/Stanford Trail Project includes the restoration and construction of pathways and bike lanes that spans approximately one lineal mile. The Trail incorporates existing paths and begins at the intersection of Arastradero and Purissima Roads, follows Arastradero Road under I-280 westerly to Page Mill Road, then south along Page Mill Road to the intersection of Baleri Ranch and Arastradero Roads. DISCUSSION The proposed project includes three types of trail improvements: 1. Restoration of existing pathways. A number of Type 2B and native paths already exist within the project area. These paths will be restored to the Town's pathways standards and top dressed with gravel/quarry fines. 2. Construction of new pathways. All new paths will be constructed according to the Town's Type 2B Roadside Path requirements including: • 5 -feet width with 2 -feet wide shoulders where possible • Surface, 6 -inches of Stevens Creek Quarry Crusher Fines • 2 -inch x 6 -inch wood headers where necessary New paths to be constructed include an approximately 445 foot long section along Arastradero Road that begins at Stirrup Way. This section will require the construction of a concrete retaining wall of up to 8' to allow edge widening for the new path. The Staff Report to the Planning Commission Los Altos Hills/Stanford Trail Project March 3, 2011 Page 2 of 3 retaining wall will have a simulated natural stone finish. At this wall location, a second, native path will be constructed at the top of the adjacent slope. In addition, an approximately 70 foot long pre -fabricated pedestrian and equestrian bridge will be installed at the trail crossing at Matadero Creek near Baleri Ranch Road. 3. Bile lanes striping and road widening. Bike lanes will be striped on existing asphaltic concrete ("AC") paved roadways. In some areas the existing AC surface will require edge widening to accommodate the bike lanes. The bike lanes on Arastradero from Purissima to Page Mill Road, and on Page Mill to Berry Hill Court will be constructed in a Class II configuration (separate, striped lanes in both directions). Portions of the roadway along the stretch of Arastradero Road between Stirrup Way and the Park and Ride lot will be widened by 3'-5'. On Page Mill between Berry Hill and Baleri Ranch Roads, the bike lanes will be Class III (bikes merge with vehicular traffic in both directions). No road widening is proposed for this area. On Arastradero Road from Liddicoat Drive to Tracy Court, the roadway on the south side of Arastradero will be widened by 6"-18". Tree Removal Thirteen trees are proposed to be removed as part of this construction project. They include three Eucalyptus trees on the west side of Arastradero (east of Page Mill Road) to accommodate the eastbound bike lanes, seven Coast live oaks on Arastradero Road at Stirrup Way to accommodate the new retaining wall and bike lane, one Peruvian pepper tree west of the retaining wall to accommodate slope improvements, and two Coast live oaks adjacent to Matadero Creek near Baleri Ranch Road to accommodate path improvements. No heritage oak trees (oaks over 12" in trunk diameter) are proposed to be removed. Environmental Review In conformance with the California Environmental Quality Act (CEQA), staff has prepared an Initial Study/Mitigated Negative Declaration for the project. The Initial Study identified potential impacts relating to air quality, biological resources, cultural resources, and hydrology and water quality. Based on the analysis contained in the study, these impacts will be reduced to a less than significant level with mitigation. A detailed analysis of the potential impacts and mitigation measures are discussed in the Initial Study. (Attachment 1) A Notice of Intent to adopt a Mitigated Negative Declaration was published in the Town Crier on February 9, 2011. The notice was also submitted to the Santa Clara County Clerks Office for a 30 day public review period which began on February 17 and will end on March 17, 2011. As of this date, the Town has received written comments from resident Edwina Cioffi expressing concerns about the project's safety impacts on local residents and environmental impacts on animals including deer and rabbits. (Attachment 3) 2 Staff Report to the Planning Commission Los Altos Hills/Stanford Trail Project March 3, 2011 Page 3 of 3 CONCLUSION The Trail improvement project will provide a safe and convenient pedestrian/equestrian/bicycle connection between the residential neighborhoods to the north and south of I-280. The proposed project is consistent with the Town of Los Altos Hills General Plan Pathways Element (2008) and Open Space and Recreation Element (2007). The proposed project will be designed and constructed in compliance with the Town of Los Altos Hills Municipal Code. The project is designed to accommodate non -motorized modes of travel, including biking, horseback riding, jogging, hiking and walking. Based on the Initial Study, staff concluded that the proposed project, as mitigated, will not have a significant effect on the environment. The Negative Declaration identifies specific mitigation measures intended to mitigate for any potential significant environmental impacts as described in the Initial Study. The Initial Study and Negative Declaration are included in this report. ATTACHMENTS 1. Initial Study/Negative Declaration 2. Biological Assessment prepared by Coast Ridge Ecology 3. Email from Edwina Cioffi, 14250 Baleri Ranch Road, dated February 24, 2011 4. Project plans 3