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3.2
ITEM 3.2 TOWN OF LOS ALTOS HILLS March 10, 2016 Staff Report to the Planning Commission SUBJECT: TENTATIVE PARCEL MAP FOR A TWO-LOT SUBDIVISION OF A 2.61 ACRE PARCEL; LANDS OF YIU; 25700 BASSETT LANE; FILE #370-14- TM-IS-ND. FROM: Steve Padovan, Consultant Planner 4g APPROVED: Suzanne Avila, AICP, Planning Director RECOMMENDATION That the Planning Commission do one of the following: 1. Forward a recommendation to the City Council for approval of the requested Tentative Parcel Map, based on the findings in Attachment 1 and the conditions of approval in Attachment 2; or 2. Continue the project pending a request for additional informationon issues relevant to the project; or 3. Forward a recommendation to the City Council to deny the requested Tentative Parcel Map. Findings for denial will be provided at the next available Planning Commission meeting. TENTATIVE MAP REVIEW In order to approve a subdivision, the Planning Commission must determine that the project is consistent with the General Plan, Subdivision and Zoning Regulations, and that no findings for denial can be made, as specified in Section 66474 of the State Subdivision Map Act. Staff has prepared findings for approval of the project (Attachment 1). Comments on the Tentative Parcel Map have been received from the following: • Town Geotechnical Consultant; • Engineering Department; • Santa Clara County Fire Department; • Santa Clara County Department of Environmental Health; • Purissima Hills Water District; • Environmental Design and Protection Committee; • Open Space Committee; and • Pathways Committee. These comments are included in the current and previous staff reports and incorporated into the conditions of approval as appropriate. Neighboring residents and property owners within 500 feet of the site have been notified of the public hearing. Tentative Map for Lands of Yiu March 10, 2016 Page 2 of 12 BACKGROUND The tentative map was initially reviewed by the Planning Commission on October 1, 2015. At that meeting, residents raised the following concerns: - Development on the new lot will require a large amount of tree removal in order to accommodate a driveway and building area; - The significant removal of trees and other vegetation will reduce the existing landscape screening of future development; - The proposed footprint of the new residence substantially impacts the existing drainage swale and the proposed setback from the drainage may not be adequate depending on the amount of runoff that feeds into that drainage; - The proposal does not appear to be consistent with the General Plan regarding development on slopes greater than 30%. Following a thorough discussion of the issues raised at the meeting, the Planning Commission voted 5-0 to continue the map off-calendar (see Attachment 3). The Commission requested that the applicant address the following: - Clarify the location of the pathway easement; - Move the footprint of the proposed development out of the drainage swale; - Substantially reduce the number of heritage trees slated for removal; - Identify how utilities will be provided to the site; - Clarify the construction method for the new residence that will protect the steep slopes and the open space easement; - Confirm the status of the drainage swale based on the amount of runoff in the basin. PROJECT DESCRIPTION The applicant is requesting approval of a subdivision of the 2.61 gross acre parcel into two lots of 1.07 net acres (Parcel 1) and 1.51 net acres (Parcel 2) with Lot Unit Factors (LUF) of 1.003 and 1.078 respectively. Existing Development Gross Net Ave Slope LUF ,MDA 'MFA , _Acreage Acreage'' (%) (sq. ft.) (sq.. ) Existing 2.612 2.579 19% 2.081 24,192 11,550 Site * Existing site data is calculated prior to proposed right-of-way dedications. Proposed Development Parcel Gross Net Ave Slope LUF MDA MFA Acreage Acreage (%) (sq ft). (sq.ft.) 1 1.070 1.070 12.93% 1.003 13,943 5,871 2 1.541 1.509 23.31% 1.078 10,789 5,751 Tentative Map for Lands of Yiu March 10, 2016 Page 3 of 12 The proposed lots meet all of the minimum requirements in the Town's Subdivision Ordinance with regard to the following: • Each lot is a minimum of one net acre; • Each lot has a minimum LUF of 1.0; • Each lot contains a 160-foot diameter building circle within the proposed parcel boundaries thereby indicating that the parcel contains a viable building site; • Each lot contains an area of at least one net acre within a 350-foot diameter circle that encompasses each parcel; • Each lot meets the minimum slope density requirement based on the proposed average slope of the lots (Parcel 1 requires 1.067 net acres; Parcel 2 requires 1.398 net acres) Additional background and site development information is available in the October 1, 2015 Planning Commission staff report(see Attachment 4). DISCUSSION General Plan Consistency The Town's General Plan includes policies related to land use development and the preservation of the Town's semi-rural character and natural resources. Policy 1.1 of the General Plan Land Use Element states the following: "Uses of land shall be consistent with the semi-rural atmosphere of the community, minimize disturbance to natural terrain, minimize removal of natural vegetation, and create the maximum compatibility of development with the natural environment through site design and landscaping". In addition, Land Use Element Policy 2.5 states: "Steep slopes, canyons, and ravines generally in excess of 30% slope, as well as natural swales and drainage channels, and geologic hazard areas within areas designated for residential development shall be left undisturbed and preserved in their natural condition to the maximum extent feasible. " Under the Conservation Element, Goal 2 states that the Town should protect native and naturalized trees and plants through policies that include minimizing disturbance of natural terrain and vegetation, preserving and protecting native plants and heritage trees and avoiding development of environmentally sensitive areas. Additionally, the Open Space and Recreation Element contains policies that encourage the preservation of open space on parcels within Open Space Conservation Areas, have slopes of 30% or more, contain heritage trees, or contain sensitive habitat areas Based on the current lot configuration, Parcel 1 has a development area that is relatively flat, is outside of the fault trace, and can accommodate a new residence with minimal grading and tree Tentative Map for Lands of Yiu March 10, 2016 Page 4 of 12 removal (would replace an existing residence). Parcel 2 also has a large flat area with minimal vegetation. However, this area is located within a fault zone and cannot accommodate any habitable living space. In order to compensate for this, the applicant has proposed to locate the driveway, parking, garage, and usable outdoor recreation areas (pool and patio) within the fault zone. The residence will be located within a useable development area directly abutting the northern edge of the fault zone and outside of all yard setbacks. This area consists of slopes ranging from under 10% to over 40% and there are clusters of oaks, buckeyes, and bay trees on the steeper portions of the site. The applicant has proposed an open space easement over the drainage on the eastern portion of the site which will be added to an existing storm drain and equestrian trail easement. Staff is presenting the revised map and easement to the Open Space Committee at its March 10, 2016 meeting and will provide comments at the Planning Commission meeting. The location of the development area will impact several heritage oak trees and encompass some steeper portions of the property. In order to protect the steeper slopes and the native vegetation, the Planning Commission may want to consider expanding the open space/conservation easement area to include areas that exceed 40% slope and include the heritage oaks along the west side of the drainage (the applicant has proposed only a five foot easement from the centerline of the drainage). Proposed easement language is included under Condition No. 6 in Attachment 2. Tree Removal The subject property contains approximately 280 trees of varying sizes. The previous driveway and house design on Parcel 2 proposed removing up to 37 trees, a large number of which are heritage oaks (over 12 inch diameter trunk). Based on the concerns raised at the last meeting, the applicant has redesigned the driveway by moving it slightly to the south and adding several turns (see revised tree study under Attachment 5). This results in a significant reduction in the number of trees being removed for the driveway and fire truck turnaround (from 19 trees down to six trees). The applicant's conceptual designs for a residence, garage and outdoor recreation area on each parcel continue to show a large number of trees being removed to accommodate the future development. As these designs are only conceptual, the approval of the tentative map does not grant any site development approvals for new residences. However, at the previous hearing, the Planning Commission did raise concerns regarding impacts to trees on a property after it is subdivided. The Commission does not typically review new single family dwellings and the number of trees removed may change if the property is sold and developed by a new owner. Based on the dense forest canopy on these lots and the concerns raised by the public to preserve screening and heritage trees as much as possible, the Commission may want to consider adding a condition that requires Planning Commission review of all new development on the properties. Construction Methods and Utilities Based on the soils report and the topography of the site, the applicant has stated that any new residence on the lots will be constructed with a pier and beam type foundation which generally Tentative Map for Lands of Yiu March 10, 2016 Page 5 of 12 minimizes disturbance to areas outside of the proposed building footprints. Utilities will be placed underground within the driveway. This type of construction along with required fencing and monitoring of impacted trees by an arborist should minimize impacts to the remaining trees. Drainage swale There is an existing drainage swale that collects water from the properties above Rhus Ridge Road and transmits the water to a storm drain at the end of Bassett Lane. The drainage appears to have been altered in the past with the channel diverted further to the east. Last year, the Public Works Department asked the owner (and applicant) to improve the storm drain inlet based on complaints received by the neighbors regarding overflowing water and erosion issues. Since that time, the applicant has redirected the channel back into the former swale and constructed improvements to the storm drain inlet on Bassett Lane to address those concerns. The Commission asked the applicant to provide additional information on the volume of runoff into the drainage swale and to delineate the location of the centerline of the swale. The revised map has been amended to show the correct location of drainage down the middle of the swale. According the calculations provided by the applicant's engineer (the revised Hydrology Study reviewed by Town staff is included as Attachment 6), the volume of runoff in the drainage basin from a 100-year storm can be accommodated within the existing swale and the applicant has proposed a five foot open space easement from the centerline of the swale to maintain adequate flow during storm events. The conceptual residence design includes a cantilevered portion of the building over the easement. The Town does not allow these types of encroachments into open space easements. The Planning Commission should discuss this issue and specify in the conditions of approval whether or not to allow a cantilevered structure to extend into the easement. As for clarification on whether or not the drainage is defined as a creek, Town staff has reviewed the U.S. Geological Survey maps, Town drainage maps and county watershed maps. The maps do not name or define the drainage nor show a blue line to delineate a creek. In addition, the drainage swale maintains no riparian habitat, contains water only during storm events, and has minimal volume based on the small drainage basin. Based on these criteria, the drainage swale is not considered a creek. However, it should be noted that the Town's General Plan policies specifically reference natural swales and drainage channels when considering the protection of natural resources. This drainage swale clearly meets that definition, therefore, the Commission can choose to enlarge the open space easement over the swale to a width that it deems appropriate. CONCLUSIONS The applicant has modified the map to show the correct location of the drainage and included a five foot easement, provided hydrology information on 100-year storm flow volumes, and significantly reduced the number of trees being removed for the driveway location. The property has substantial site constraints due to the location of a fault trace, a drainage swale and areas with slopes over 30% that limit the amount of buildable area. However, the parcels will provide adequate developable areas to accommodate residential development and the incorporation of Tentative Map for Lands of Yiu March 10, 2016 Page 6 of 12 easements over the drainage swale and steeper slopes will minimize visual impacts to surrounding properties. As documented in the recommended findings of approval, the proposed subdivision is in compliance with the General Plan and Subdivision Ordinance, and would allow development to occur that generally meets the provisions of the Zoning and Site Development Ordinances. The Tentative Parcel Map is also consistent with the State Subdivision Map Act. ATTACHMENTS 1. Recommended Findings for Subdivision Approval 2. Recommended Conditions of Approval 3. Excerpt from the October 1, 2015 Planning Commission Meeting Minutes 4. October 1, 2015 Planning Commission Report 5. Tree Survey 6. Hydrology Study dated Revised February 11, 2016 7. Tentative Map plan set (Commission only) Tentative Map for Lands of Yiu ATTACHMENT 1 March 10, 2016 Page 7 of 13 ATTACHMENT 1 RECOMMENDED FINDINGS FOR THE TWO LOT SUBDIVISION OF A 2.61-ACRE PARCEL LANDS OF YIU (Assessor's Parcel Number 336-43-013) FILE#370-14-TM-IS-SD 1. The subdivision as proposed would create two lots that meet all of the minimum requirements in the Town's Subdivision Ordinance with regard to the following: minimum lot area of one acre; minimum Lot Unit Factor of 1.0; the location of a 160-foot diameter building circle within the proposed parcel boundaries thereby indicating that the parcel contains a viable building site; a minimum of one net acre within a 350-foot diameter circle that encompasses each parcel; and the lots meet the minimum slope density requirement based on the proposed average slope of the lots. 2. The proposed subdivision would create two lots that are compatible with the permitted density on the Land Use Map for the Town and consistent with the Land Use and Conservation Elements in the General Plan which include policies to preclude development on slopes of greater than 30% to the maximum extent feasible, minimize disturbance of natural terrain and vegetation, and preserve heritage oaks through the dedication of open space easements over the drainage swale and over the steeper portions of the property to maintain the open space in perpetuity. 3. Access to the proposed lots will be provided from a public road. Adequate services including water, sewer, gas and electric, telephone, fire protection and police protection are available to serve the subdivision as described in the staff report 4. All lots as proposed on the Tentative Parcel Map are physically suitable for the proposed future development. The Town Geotechnical Consultant has indicated that stated concerns can be addressed by adherence to the Project Geotechnical Report and conditions of approval for the project. 5. All potentially significant environmental effects can be reduced to a less than significant impact. The design of the subdivision and the proposed improvements are not likely to cause substantial environmental damage or to substantially and unavoidably injure fish or wildlife or their habitat. 6. The design of the subdivision and the proposed improvements are not likely to cause serious public health problems. It has been determined that each of the proposed lots contains a suitable building site, and that the proposed density is consistent with the General Plan. Tentative Map for Lands of Yiu March 10, 2016 Page 8 of 13 7. The Town Engineer has reviewed the project and has determined that the design of the subdivision and the improvements will not conflict with easements, acquired by the public at large, for access through or use of the property within the proposed subdivision. Tentative Map for Lands of Yiu ATTACHMENT 2 March 10, 2016 Page 9 of 12 ATTACHMENT 2 RECOMMENDED CONDITIONS FOR THE TWO-LOT SUBDIVISION OF A 2.612-ACRE PARCEL LANDS OF YIU (Assessor's Parcel Number 336-43-013) FILE #370-14-TM-IS-ND GEOTECHNICAL/EARTHWORK 1. Geotechnical Engineering investigations shall be completed for new residential structures on Parcels 1 and 2. Recommended geotechnical design parameters shall be provided for all proposed improvements based on site-specific investigation and testing. In addition the consultant shall address the likely performance of detached garages constructed above the identified Berrocal Fault and the level of disruption to the driveway crossing the fault. With respect to Parcel 2, the Consultant shall discuss the potential benefits and alternative alignments for utilities to serve the residence that do not cross the fault trace. 2. Site development plans shall be prepared considering the results of design-level geotechnical engineering investigations requested above. Consideration shall be given to minimizing damages from potential surface fault rupture by strategic placement of site improvements and utility design. LAND AND EASEMENT DEDICATION 3. Payment of park and recreation dedication fees, pathway in lieu fee, and all other applicable fees shall be required prior to recordation of the Final Map. The park and recreation dedication fees shall be provided in accordance with sections 9.1.1403 and 9.1.1404 of the Los Altos Hills Municipal Code. 4. The applicant shall relocate or abandon existing public utility easements and grant new public utility easements where needed to all utility companies for utility construction and maintenance, including but not limited to: AT&T Telephone Company, Pacific Gas and Electric Company, Comcast Cable Television, and Purissima Hills Water District. The dedications shall all be completed in conjunction with Final Map approval, to the satisfaction of the City Engineer. 5. The applicant shall dedicate additional right of way easement to create 30' wide half width right of way over Rhus Ridge Road. The dedications shall be completed in conjunction with the Final Map approval, to the satisfaction of the City Engineer. 6. An open space/conservation easement shall be granted to the Town of Los Altos Hills over the drainage swale on Parcel 2 and on slopes over 30% that contain heritage oaks and are outside of the building development areas. Within the easement, no structures, Tentative Map for Lands of Yiu March 10, 2016 Page 10 of 12 grading, stormwater detention systems, or retaining walls will be permitted. Native vegetation may be planted within the easement. The Open Space Committee will review the easement language and easement boundary prior to recordation of the Final Map. IMPROVEMENTS 7. A Subdivision Improvement Plan which includes an Erosion and Sedimentation Control plan shall be submitted for review and approval by the City Engineer as part of the Subdivision Improvement Plans. This plans shall conform to all standards adopted by the Town of Los Altos Hills and shall comply with all appropriate requirements of the Town's NPDES Permit relative to grading and sediment erosion control including but not limited to: a) restricting grading during the moratorium from October 15 to April 15; b) protecting all finished graded slopes from erosion using such techniques as hillside benching, erosion control matting and/or hydroseeding; c) protecting downstream storm drainage inlets from sedimentation; d) appropriate use of sediment rolls to retain sediment on the project site; e) any other suitable measures outlined in the ABAG Manual of Standards. 8. All lots within the subdivision shall be connected to the public water system to the satisfaction of the City Engineer and Purissima Hills Water District. Services shall be installed to the property lines or be bonded for prior to recordation of the Final Map. An encroachment permit shall be required to be issued by the Public Works Department for all work proposed within the public right of way. Any necessary fees shall be paid prior to the recordation of the Final Map. 9. All existing and proposed utilities located within the subdivision that serve the subdivision shall be placed underground, in accordance with Subdivision Ordinance, Sec. 9-1.1105. Cable television, gas, electric, and telephone services, to the property lines are included in this requirement. Plans for the location of all such utilities are to be included in the improvement plans for the subdivision. Improvements shall be installed or bonded for prior to recordation of the Final Map. 10. All lots within the subdivision shall be connected to the public sanitary sewer system. An encroachment permit must be obtained from the Public Works Department for all work proposed within the public right of way. Services shall be installed to the property lines or bonded for prior to the recordation of the Final Map. 11. A Grading and Construction Operation plan shall be submitted by the subdivider for review and approval by the City Engineer and Planning Director prior to issuance of any permits for subdivision improvements. The Grading/Construction Operation plan shall address truck traffic issues regarding dust, noise, and vehicular and pedestrian safety on Rhus Ridge Road and Bassett Lane; storage of construction materials; placement of sanitary facilities; parking for construction vehicles; and parking for construction personnel. A debris box (trash dumpster) shall be placed on site for collection of construction debris. Arrangements must be made with the GreenWaste Recovery, Inc. Tentative Map for Lands of Yiu March 10, 2016 Page 11 of 12 for the debris box, since they have a franchise with the Town and no other hauler is allowed within the Town limits. 12. The subdivider shall construct a native path within the existing pathway easement on the eastern border of Parcel 2, meandering around trees and away from creek. The subdivider must stake the proposed path route for review by the Pathway Committee and Town Engineer prior to constructing the path. 13. Improvement plans for the subdivision shall be submitted for review and approval by the Town Engineer prior to commencement of improvement work. 14. All subdivision improvements shall be constructed to the satisfaction of the Town Engineer or bonded for prior to recordation of the Final Map. 15. All subdivision conditions of approval and subdivision improvements shall be constructed and approved by the Town Engineer prior to issuance of any site development or building permits. 16. Any, and all, wells on the property shall be shown on the Improvement Plans, shall be properly registered with Santa Clara Valley Water District (SCVWD), and shall be abandoned, capped in accordance with the SCVWD standards. 17. All existing structures located within the future building setback lines shall be removed prior to recordation of the Final Map. PLANNING AND ZONING 18. Payment of park and recreation dedication fees, path in lieu fee and all other applicable fees shall be required prior to recordation of the Final Map. The park and recreation dedication fees shall be provided in accordance with Sections 9.1.1403 and 9.1.1404 of the Los Altos Hills Municipal Code. 19. The applicant shall inform the Town of any damage and shall repair any damage caused by construction of the subdivision improvements to pathways, private driveways and public and private roadways prior to final acceptance of the subdivision by the Town. The applicant shall provide the Town with photographs of the existing conditions of the roadways and pathways prior to recordation of the Final Map. 20. The applicant shall defend, indemnify, and hold harmless the Town of Los Altos Hills and its agents, officers, and employees from any claim, action, or proceeding against the Town of Los Altos Hills or its agents, officers, or employees to attack, set aside, void, or annul an approval of the project to the extent such actions are brought within the time period required by Government Code Section 66499.37 or other applicable law; provided, however, that the Applicant's duty to so defend, indemnify, and hold harmless shall be subject to the Town's promptly notifying the Applicant of any said claim, action, Tentative Map for Lands of Yiu March 10, 2016 Page 12 of 12 or proceeding and the Town's full cooperation in the defense of such actions or proceedings. 21. Prior to beginning any grading, construction or demolition operations, all significant trees shall be fenced with chain link type material at the dripline. Town staff must inspect the fencing and trees to be fenced prior to starting demolition, grading or construction. The fence must remain in place throughout the course of construction. No storage of equipment, vehicles or debris shall be allowed within the drip lines. All large and heritage oak trees shall be retained to the greatest extent feasible. 22. The applicant shall ensure that noise generating construction activities are limited to Monday through Saturday between the hours of 8:00 am and 5:30 pm. No heavy noise generating equipment is allowed to be used on Saturdays and no construction is allowed on Sundays or holidays as noted per Chapter 7, Sec.5-7-01 of the Los Altos Hills Municipal Code. 23. The addresses for the two parcels shall be assigned and approved by the Town as required by the Santa Clara County Fire Department and in accordance with Town policies. 24. The new residences on Parcels 1 & 2 shown on the Tentative Map Conceptual Development Plan are conceptual only, and no approval of any residence is indicated by approval of the Tentative Map. Site development applications for the new residences shall be submitted to the Planning Department for review and approval by the Planning Commission. 25. At such time as development on each of the new parcels is proposed, the applicant shall submit a detailed drainage improvement plan for review and approval by the Engineering Department. Peak discharge shall not exceed the existing pre-development peak discharge value of the property. Detention storage must be incorporated into the project to reduce the predicted peak discharge to the pre-development value. The applicant's engineer shall provide data and peak discharge hydrologic model(s) utilized, as well as, the calculations of the peak discharge value prior and post development. FIRE DISTRICT REQUIREMENTS 26. Plans for new residences shall be reviewed and approved by the Santa Clara County Fire Department at the time of site development permit application. Conditions that may be applied at that time include, but are not limited to, providing an acceptable water supply based on the size of the new residences, providing an emergency vehicle turnaround, placement of property address signs that are clearly visible from the right-of-way, and providing an approved access system if the lots are fenced and gated. ATT- rti'iT`3 Chair Couperus asked if the Town could ask a carrier to add an antenna i-,'dne part of Town if they are requesting a project in another part. Mr. Padov • aid it would not hurt to suggest but the Town could not demand it. Tom Johnson, applicant,AT&T,answered questions posed by t .4 ommission. Seeing no one else wishing to speak Chair Couperu:, osed the PUBLIC HEARING. Commission discussion ensued. MOTION MADE AND SECONDED: issioner Partridge moved to forward a recommendation to the City Co ,o''" that the Conditional Use Permit for modifications to an existing wireless co ` 'cation facility be approved, subject to the fmdings in Attachment 1 and c tau l itions of approval in Attachment 2. The motion was seconded by Commiss'di'er Abraham. AYES: Co . sf.oner Abraham, Commissioner Mandle., Co•,Iir•issioner Partridge, Commissioner Tankha, Chair >'li perus NOES: None • ABSENT: None ABST° r' : None 4 ION CARRIED 5-0. 3.2 LANDS OF YIU; 25700 BASSETT LANE (APN 336-43-013) File # 370-14-IS- TM-ND; A request for a two lot subdivision of an existing 2.612 (gross) acre parcel. CEQA review: Categorically Exempt pursuant to Section 15315, Minor Land Divisions; (Staff-C. Richardson). Ex parte disclosures: Commissioner Partridge said he had spoken with neighbor Peter Nieh. Commissioner Tankha said she had spoken with the applicant as well as neighbor Sharon Nieh. Commissioner Mandle said she had spoken with Roger Spreen and neighbor Wendy Wilson. Commissioner Abraham said he did not recall the names of those he had spoken with. Chair Couperus said he had spoken with Roger Spreen, Sue Welch, and Peter Nieh. Commissioner Tankha noted corrections to the staff report. Chair Couperus opened the PUBLIC HEARING. Consultant Planner Steve Padovan presented the staff report on behalf of Consultant Planner Cynthia Richardson. 2 Regular Planning Commission Meeting Minutes October 1,2015 Approved December 3,2015 Commission asked questions of staff. The Commission, as a collective, expressed concern with the amount of tree removal proposed for the hypothetical development. Commissioner Partridge asked questions pertaining to the right of way dedication, as well as the amount of lot coverage. Simon Yiu,Applicant, spoke on behalf of his project. Commission asked questions of the applicant. Peter Carlino, Lea and Braze Engineering, answered questions posed by the Commission Steven Stept, Architect, spoke to the possible house designs, and presented exhibits. Peter Nieh, Los Altos Hills, said that too many trees were proposed for removal and did not support this development. Wendy Wilson, Los Altos Hills, also expressed concern with the amount of tree removal and how the development would alter the topography of the hillside. She said she was not opposed to putting a house on the lot, but the screening and trees would need to be maintained. Diana Su, Los Altos Hills, spoke on behalf of resident Charles Knowles who could not attend. She expressed Mr. Knowles' opinion that he did not think it was unreasonable to subdivide the property, but could not support the removal of the trees and how development would affect the roots of those being preserved. He was also concerned with how the development would affect a swale on the property during flooding season. This concern was echoed by Ms. Wilson from the audience. Roger Spreen, Los Altos Hills, said this looked like an attempt to shoehorn a house into a lot where there should not be one. He mentioned aspects of the General Plan that the proposal was not in conformance with, and said he was not in support of this development. Sue Welch, Member of the Open Space/Pathways Committees, spoke to the location of the pathway easement, and that the open space easement location was requested to be contiguous with the pathway easement to assist with maintaining clear vegetation. At the request of the Commission, Ms. Wilson answered questions about the mention of the flooding of the swale she shares with the property in question. 3 Regular Planning Commission Meeting Minutes October 1,2015 Approved December 3.2015 Nigel Belton, arborist, spoke to the proposed tree removals. Chair Couperus closed the PUBLIC HEARING. Commission discussion ensued. Commissioner Abraham said that he shared many of the concerns discussed this evening, and while the applicant is "cutting it pretty thin" with the Lot Unit Factor (LUF), it did meet the minimum standard. He expressed concern with the trees, but said that a large number would survive still leaving heavily wooded parcels. The proposal is in compliance with Town rules, and said that while he does not want this development, he did not see any justification for denial. Commissioner Mandle said that she suspected the swale was really a creek, but at the least it was a watercourse with a substantial amount of water. She requested staff to hire a hydrologist to make the determination. The proposed building envelope comes too close to the swale should it overflow, but to divert the water course would go against Town Policies. She requested the proposal be modified and brought back to the Commission. Commissioner Tankha agreed this development would be constrained and fitting two parcels on this lot was a tight fit. She said the determination of the swale/creek could cause the applicant to reconsider where they want to subdivide the lot, and asked if the Commission should allow them to reexamine this before they proceed. She also expressed concern over the amount of trees to be removed, but she would like to take another look before making a decision. Commissioner Partridge said that approving this proposal could cause the very same issues with constrained lots that the Commission has been dealing with over the last year, considering the fault, water course, steep slopes, and extensive tree removal. He expressed concern over the size of the Open Space Easement, as he was not sure it was large enough, and that a building could not be put on the site without impacting the water course. He said he did not see a valid solution to the issues as proposed. Chair Couperus said that a subdivision consists of no less than one acre lots when the lot is reasonably flat, clear, and there are not too many constraints. There are two (2) one acre lots here but there are multiple constraints. This part of Town was steep and heavily wooded, and with possible hydrology issues, and the installation of utilities, the area left over was too constrained. The subdivision as proposed was not consistent with the General Plan, and pushed the threshold more closely than he was comfortable with. Commission and staff discussion ensued. The Commission then asked the architect how he would like them to proceed, as they were not comfortable with approving the subdivision as presented. 4 Regular Planning Commission Meeting Minutes October 1,2015 Approved December 3,2015 Mr. Stept said that he did not know how to proceed at this point. He assured the Commission that a sensitive design that meets all the requirements could be achieved on these lots, and that his team had spent a lot of time analyzing the site. He said the applicant was sensitive to the amount of tree removal and the concern the Commissioners had, but this lot had been allowed to sit for many years unkempt, while other lots were able to develop before their lots had reached this point. MOTION MADE AND SECONDED: Commissioner Mandle moved that the Commission continue discussion of the tentative parcel map for a two lot subdivision, Lands of Yiu, and ask the applicant to clarify the location of the pathway easement, move the foot print of the proposed development out of the swale, substantially reduce the number of heritage trees slated for removal, identify how the utilities will be installed without impacting tree roots, and clarify the construction method for the steep slopes and maintaining the open space easement. Furthermore, the Commission requests the applicant confirm the status of the water course as a creek or a swale. The motion was seconded by Commissioner Partridge. AYES: Commissioner Abraham, Commissioner Mandle, Commissioner Partridge, Commissioner Tankha, Chair Couperus NOES: None ABSENT: None ABSTAIN: None MOTION CARRIED 5-0. Chair Couperus called for a recess at 9:07 P.M The meeting resumed at 9:19 P.M. 4. OLD BUSINESS - none 5. NEW BUSINESS µyr•' ' 5.1 Introduction to the Wate ient Landsca•e Ordinance WELO Staff- S. Padovan). ,0-P' e00 - Consul .1.0 anner Steve Padovan presented the staff report. onunission asked questions of staff. 5 Regular Planning Commission Meeting Minutes October 1,2015 ATTACHMENT 4 TOWN OF LOS ALTOS HILLS October 1, 2015 Staff Report to the Planning Commission RE: TENTATIVE PARCEL MAP FOR A TWO-LOT SUBDIVISION: LANDS OF YIU, 25700 BASSETT LANE. FILE#370-14-TM-IS-SD-ND. FROM: Cynthia Richardson, Consulting Planner 0)g. APPROVED BY: Suzanne Avila, Planning Director 0� c RECOMMENDATION That the Planning Commission: Forward a recommendation that the City Council to approve the Tentative Parcel Map, based on the findings in Attachment 1 and subject to the conditions of approval in Attachment 2. TENTATIVE MAP REVIEW In order to approve a subdivision, the Planning Commission must determine that the project is consistent with the General Plan, Subdivision and Zoning Regulations, and that none of the findings for denial can be made, as specified in Section 66474 of the State Subdivision Map Act. Staff has prepared findings for approval of the project (Attachment 1).=-Comments on the Tentative Parcel Map have been received from the Town Geotechnical Consultant, the Town Engineer, Santa Clara County Fire Department, the Environmental Design and Protection Committee, the Open Space Committee and the Pathways Committee; and are attached for the Planning Commission's review. Neighboring residents and property owners within 500 feet of the site have been notified of the public hearing. BACKGROUND The subject property was originally part of Lot 1 of Tract No. 4169, Rhus Ridge Ranchos, which was recorded in January 1971. A subsequent Parcel Map was recorded in August 1971 which modified the original parcel to create the subject lot which is 2.61 gross acres. There is an existing single family residence on the property. PROJECT DESCRIPTION The applicant is requesting approval of a two-lot subdivision of a 2.612 gross acre parcel located on Bassett Lane. The property is surrounded by residential properties developed with a mix of one and two story dwellings. The site is gently to moderately sloping with an average 19% slope that descends from Rhus Ridge Road to the terminus of Bassett Lane. A trace of the potentially active Berrocal Fault extends through the southern portion of the property. A drainage swale runs from Rhus Ridge to Basset Lane along the eastern property line. This drainage swale is not located on any map as an official creek. Parcel 1 contains an older home that is proposed to be demolished. Lands of Yiu October 1, 2015 Page 2 of 10 Existing Development Gross NetAve.,Slope ' MDA MFA , Acreage ' Acreage (%) LUF (sq. ft) (sq.ft) Existing 2.612 2.579 19% 2.081 24,192 11,550 Site * Existing site data is calculated prior to proposed right-of-way dedications. Proposed Development • Parcel Gross Net Ave. Slope LUF ' MDA MFA Acreage Acreage (%) _ .(sq.ft) (sq. ft) 1 1.070 1.070 12.93% 1.003 13,943 5,871 2 1.541 1.509 23.31% 1.078 10,789 5,751 Lot Design and Building Sites Parcel 1 is 1.070 net acres with an average slope of 12.93%; Parcel 2 is 1.541 net acres with an average slope of 23.31%. The Tentative Parcel Map includes a 160-foot diameter building circle on each parcel, showing that each contains a viable building site. The Tentative Parcel Map shows conceptual site design, building footprints, driveways, and drainage installations. This development is conceptual only and is intended to demonstrate that all parcels can be developed to meet Town standards. Once the Tentative Parcel Map is recorded individual site development applications can be made for each parcel. The site specific design of the proposed home will be evaluated through the appropriate public review process where specific conditions can be included. In addition landscape screening will be required for each home site to soften the effect of the new construction. Staff evaluated both parcels to determine that enough area is free of encumbrances (open space easements, slopes over 30%, fault trace and property line setbacks) for development. Parcel 1 has an existing home that will be demolished. This lot is the flatter of the two lots and maintains enough space for a new home. Parcel 2 has steeper slopes and a drainage swale along the eastern portion of the property. Roughly 10,481 square feet of area is unencumbered and available for development. The lower portion of the property near Bassett Lane has steep slopes including some that exceed 30%. If these steep slopes are also removed from the developable area the unencumbered area is reduced to 7,812 square feet. The applicants have designed a home for Parcel 2 that appears to meet the Zoning and Site Development Ordinance with no requests for exceptions or variances. Staff performed a preliminary review and found the home design to be acceptable however staff has not performed a comprehensive review of all plans and documents associated with this conceptual design. The garage which is a non-habitable structure, overlays the fault line setback area. The Town Geotechnical Consultant's email (Attachment 3) states that the revised garage location meets with his approval. There are no trees being removed with the subdivision improvements. Future site development requests may result in some tree removal for development of a new driveway and home. Lands of Yiu October 1, 2015 Page 3 of 10 Access Driveway access for Parcels 1 and 2 will be from Bassett Lane, a private road. The City Engineer has conditioned the project such that the applicant shall dedicate additional right-of-way easements to create a 30 foot wide half street on Rhus Ridge Road which is also a private road. Utilities Water supply will be provided by Purissima Hills Water District. PG&E will provide gas and electric services, Pacific Bell will provide telephone service and Comcast will provide cable service. All utilities are required to be placed underground. The City Engineer has required that all parcels tie into the Town's sanitary sewer system. An encroachment permit must be obtained from the Public Works Department for all work performed within any public right-of-way. Geotechnical Review The Town's Geotechnical Consultant, Cotton, Shires and Associates has reviewed the proposed Tentative Map and Geologic Investigation provided by the applicant. Cotton, Shires and Associates reported that the Project Geotechnical Consultant has adequately characterized site conditions and recommended appropriate geotechnical design criteria for future residential developmenton the proposed Parcels (see Attachment 4). A trace of the Berrocal Fault trace runs East-West on the upper portion of the property. The future homes are constrained by surface fault rupture, potentially expansive soils, strong to violent seismic ground shaking. Therefore fault setbacks have been established for future all habitable structures. These setbacks are offset 25 feet from the edge of identified faulted ground and are depicted on the Tentative Map The applicant originally showed a garage on Parcel 2 within the fault setback zone because it is a detached nonhabitable structure. The Geotechnical Consultant had some concerns about with the exact location of the garage and therefore the garage has been located such that the Geotechnical Consultant does not have any objections. The Geotechnical Consultant noted that secondary ground cracking could occur within the setback area and the garage may not be free of damage in the event of a major local earthquake. In addition, the lap pool extending over the fault could be extensively damaged. The Town has permitted pools across fault trace constrained ground as long as potential water discharge does not appear to present a hazard to a neighboring residence. In this case the Geotechnical Consultant does not see an obvious water discharge issue. Drainage All proposed parcels naturally drain over the site and will be required to maintain the existing flow patterns, using surface flow designs whenever possible. Subdivision improvement plans will be submitted with the final map. Lands of Yiu October 1, 2015 Page 4 of 10 COMMITTEE REVIEW Environmental Design and Protection Committee The Committee has concerns to the subdivision based on future home sites being located on steep slopes with heavy vegetation and that the home has a detached garage (Attachment 5). Pathways Committee The Pathways Committee recommends the owner construct a native path within the existing pathway easement on the eastern border of Parcel 2, meandering around trees and away from the creek. The Committee would like to see the owner stake the proposed path route for review by_the Pathways Committee prior to construction of the path. Additionally the Committee has requested an easement for the public use over Bassett Lane and Rhus Road. The Engineering Department does not support this request because the applicant does not own the road right-of-way (see Attachment 6). Open Space Committee The Open Space Committee recommends that the owner place a 25 foot riparian setback (from the top of bank) and open space easement along the drainage (small tributary of Adobe Creek) that runs from Rhus Ridge Road down to Bassett Lane near the eastern border of Parcel 2. The applicant has placed an open space easement over the existing drainage easement and has widened it in some locations. The applicant believes that this swale is not a creek as shown on any official map and that the following section of the Municipal Code should not apply to this project(see Attachment 7). Municipal Code Section 10-2.702(e). Creek Protection. Structures shall be set back a minimum of twenty-five (25) feet from the top of bank of all creeks. Greater setbacks may be required along major creeks in the Town; however, lesser setbacks may be allowed where approved by the Planning Commission. ENVIRONMENTAL REVIEW In compliance with the California Environmental Quality Act (CEQA), Categorically Exempt.Section 15315, Minor Land Divisions. CEQA specifically allows projects to be exempt which consists of the division of property in urbanized areas zoned for residential use into four or fewer parcels when the division is in conformance with the General Plan and Zoning Ordinance, no variances or exceptions are required, all services and access to the proposed parcels to local standards are available, the parcel was not involved in a division of a larger parcel within the previous two years, and the parcel does not have an average slope greater than 20 percent. CONCLUSIONS Staff has concluded that, as documented in the recommended findings of approval, the proposed subdivision is in compliance with the General Plan and Subdivision Ordinance, and would allow development to occur that meets the provisions of the Zoning and Site Development Ordinances. Lands of Yiu October 1, 2015 Page 5 of 10 ATTACHMENTS 1. Recommended Findings for Subdivision Approval 2. Recommended Conditions of Approval 3. Cotton, Shires and Associates, Ted Sayre email dated September 23, 2015 4. Cotton, Shires and Associates report,November 12, 2014 5. Environmental Design and Protection Committee comments,November 20, 2014 6. Pathways Committee minutes,November 24, 2014 7. Open Space Committee comments,November 13, 2014 8. Arborist report prepared by Nigel Belton, Certified Arborist dated April 20, 2015 9. Tentative Map plan set (Commission only) Lands of Yiu October 1,2015 Page 6 of 10 ATTACHMENT 1 RECOMMENDED FINDINGS FOR THE TWO LOT SUBDIVISION OF A 2.612-ACRE PARCEL LANDS OF YIU (Assessor's Parcel Number 336-43-013) FILE#370-14-TM-IS-ND-GD 1. The subdivision as proposed would create three lots: Lot 1 would be 1.07 acres in size, with a Lot Unit Factor of 1.003; Lot 2 would be 1.541 acres in size, with a Lot Unit Factor of 1.078; Each parcel would provide a viable building site. In this and all other respects, the lots conform to the Los Altos Hills Subdivision Ordinance. 2. The proposed subdivision would create two lots that would meet the General Plan guidelines for land with an average slope between 10 and 30 percent, and in all other respects will be consistent with the General Plan. 3. Access to the proposed lots will be provided from a public road. Adequate services including water, gas and electric, telephone, fire protection and police protection are available to serve the subdivision as described in the staff report. Future development on the two parcels will require connection of each parcel to the sanitary sewer system. 4. All lots as proposed on the Tentative Map are physically suitable for the proposed future development. The Town Geotechnical Consultant has indicated that stated concerns can be addressed by adherence to the Project Geotechnical Report and conditions of approval for the project. It has been determined that each of the proposed lots contains a suitable building site, and that the proposed density is consistent with the General Plan. 5. The design of the subdivision and improvements will not cause serious public health problems. Future development on the two parcels will require connection of each parcel to the sanitary sewer system. 6. The Town Engineer has reviewed the project and has determined that the design of the subdivision and the improvements will not conflict with easements, acquired by the public at large, for access through or use of the property within the proposed subdivision. Lands of Yiu October 1,2015 Page 7 of 10 ATTACHMENT 2 RECOMMENDED CONDITIONS FOR THE TWO-LOT SUBDIVISION OF A 2.612-ACRE PARCEL LANDS OF YIU (Assessor's Parcel Number 336-43-013) FILE#370-14-TM-IS-ND-GD GEOTECHNICAL/EARTHWORK 1. Geotechnical Engineering investigations shall be completed for new residential structures on Parcels 1 and 2. Recommended geotechnical design parameters shall be provided for all proposed improvements based on site-specific investigation and testing. In addition the consultant shall address the likely performance of detached garages constructed above the identified Berrocal Fault and the level of disruption to driveway crossing the fault. With respect to Parcel 2, the Consultant shall discuss the potential benefits and alternative alignments for utilities to serve the residence that do not cross the fault trace. 2. Site development plans shall be prepared considering the results of design-level geotechnical engineering investigations requested above. Consideration shall be given to minimizing damages from potential surface fault rupture by strategic placement of site improvements and utility design. LAND AND EASEMENT DEDICATION 3. Payment of park and recreation dedication fees, pathway in lieu fee, and all other applicable fees shall be required prior to recordation of the Final Map. The park and recreation dedication fees shall be provided in accordance with sections 9.1.1403 and 9.1.1404 of the Los Altos Hills Municipal Code. 4. The applicant shall relocate or abandon existing public utility easements and grant new public utility easements where needed to all utility companies for utility construction and maintenance, including but not limited to: AT&T Telephone Company, Pacific Gas and Electric Company, Comcast Cable Television, and Purissima Hills Water District. The dedications shall all be completed in conjunction with Final Map approval, to the satisfaction of the City Engineer. 5. The applicant shall dedicate additional right of way easement to create 30' wide half width right of way over Rhus Ridge Road. The dedications shall be completed in conjunction with the Final Map approval,to the satisfaction of the City Engineer. IMPROVEMENTS Lands of Yiu October 1, 2015 Page 8of10 6. A Subdivision Improvement Plan which includes an Erosion and Sedimentation Control plan shall be submitted for review and approval by the City Engineer as part of the Subdivision Improvement Plans. This plans shall conform to all standards adopted by the Town of Los Altos Hills and shall comply with all appropriate requirements of the Town's NPDES Permit relative to grading and sediment erosion control including but not limited to: a) restricting grading during the moratorium from October 15 to April 15; b) protecting all finished graded slopes from erosion using such techniques as hillside benching, erosion control matting and/or hydroseeding; c) protecting downstream storm drainage inlets from sedimentation; d) appropriate use of sediment rolls to retain sediment on the project site; e) any other suitable measures outlined in the ABAG Manual of Standards. 7. All lots within the subdivision shall be connected to the public water system to the satisfaction of the City Engineer and Purissima Hills Water District. Services shall be installed to the property lines or be bonded for prior to recordation of the Final Map. An encroachment permit shall be required to be issued by the Public Works Department for all work proposed within the public right of way. Any necessary fees shall be paid prior to the recordation of the Final Map. 8. All existing and proposed utilities located within the subdivision that serve the subdivision shall be placed underground, in accordance with Subdivision Ordinance, Sec. 9-1.1105. Cable television, gas, electric, and telephone services, to the property lines are included in this requirement. Plans for the location of all such utilities are to be included in the improvement plans for the subdivision. Improvements shall be installed or bonded for prior to recordation of the Final Map. 9. All lots within the subdivision shall be connected to the public sanitary sewer system. An encroachment permit must be obtained from the Public Works Department for all work proposed within the public right of way. Services shall be installed to the property lines or bonded for prior to the recordation of the Final Map. 10. A Grading and Construction Operation plan shall be submitted by the subdivider for review and approval by the City Engineer and Planning Director prior to issuance of any permits for subdivision improvements. The Grading/Construction Operation plan shall address truck traffic issues regarding dust, noise, and vehicular and pedestrian safety on Rhus Ridge Road and Bassett Lane; storage of construction materials; placement of sanitary facilities; parking for construction vehicles; and parking for construction personnel. A debris box (trash dumpster) shall be placed on site for collection of construction debris. Arrangements must be made with the GreenWaste Recovery, Inc. for the debris box, since they have a franchise with the Town and no other hauler is allowed within the Town limits. 11. The subdivider shall construct a native path within the existing pathway easement on the eastern border of Parcel 2, meandering around trees and away from creek. The subdivider Lands of Yiu October 1,2015 Page 9 of 10 must stake the proposed path route for review by the Pathway Committee and Town Engineer prior to constructing the path. 12. Improvement plans for the subdivision shall be submitted for review and approval by the Town Engineer prior to commencement of improvement work. 13. All subdivision improvements shall be constructed to the satisfaction of the Town Engineer or bonded for prior to recordation of the Final Map. 14. All subdivision conditions of approval and subdivision improvements shall be constructed and approved by the Town Engineer prior to issuance of any site development or building permits. 15. Any, and all, wells on the property shall be shown on the Improvement Plans, shall be properly registered with Santa Clara Valley Water District (SCVWD), and shall be abandoned, capped in accordance with the SCVWD standards. 16. All existing structures located within the building setback lines shall be removed prior to recordation of the Final Map. PLANNING AND ZONING 17. Payment of park and recreation dedication fees, path in lieu fee and all other applicable fees shall be required prior to recordation of the Final Map. The park and recreation dedication fees shall be provided in accordance with Sections 9.1.1403 and 9.1.1404 of the Los Altos Hills Municipal Code. 18. The property owner shall grant an Open Space Easement to the Town as shown on the Tentative Map. No structures or fencing are permitted and no grading or fill shall be permitted. 19. The applicant shall inform the Town of any damage and shall repair any damage caused by construction of the subdivision improvements to pathways, private driveways and public and private roadways prior to final acceptance of the subdivision by the Town. The applicant shall provide the Town with photographs of the existing conditions of the roadways and pathways prior to recordation of the Final Map. 20. The applicant shall defend, indemnify, and hold harmless the Town of Los Altos Hills and its agents, officers, and employees from any claim, action, or proceeding against the Town of Los Altos Hills or its agents, officers, or employees to attack, set aside, void, or annul an approval of the project to the extent such actions are brought within the time period required by Government Code Section 66499.37 or other applicable law; provided, however, that the Applicant's duty to so defend, indemnify, and hold harmless shall be subject to the Town's promptly notifying the Applicant of any said claim, action, Lands of Yiu October 1,2015 Page 10 of 10 or proceeding and the Town's full cooperation in the defense of such actions or proceedings. 21. Prior to beginning any grading or construction operations, all significant trees shall be fenced with chain link type material at the dripline. Town staff must inspect the fencing and trees to be fenced prior to starting grading or construction. The fence must remain in place throughout the course of construction. No storage of equipment, vehicles or debris shall be allowed within the drip lines. All large and heritage oak trees shall be retained to the greatest extent feasible. 22. The applicant shall ensure that noise generating construction activities are limited to Monday through Saturday between the hours of 8:00 am and 5:30 pm. No heavy noise generating equipment is allowed to be used on Saturdays and no construction is allowed on Sundays or holidays as noted per Chapter 7, Sec.5-7-01 of the Los Altos Hills Municipal Code. 23. The addresses for the three parcels shall be assigned and approved by the Town as required by the Santa Clara County Fire Department and in accordance with Town policies. 24. The new residences on Parcels 1 & 2 shown on the Tentative .Map Conceptual Development Plan are conceptual only, and no approval of any residence is indicated by approval of the Tentative Map. Site development applications for the new residences shall be submitted to the Planning Department for review and approval. 25. At such time as development on each of the new parcels is proposed, the applicant shall submit a detailed drainage improvement plan for review and approval by the Engineering Department. Peak discharge shall not exceed the existing pre-development peak discharge value of the property. Detention storage must be incorporated into the project to reduce the predicted peak discharge to the pre-development value. The applicant's engineer shall provide data and peak discharge hydrologic model(s) utilized, as well as, the calculations of the peak discharge value prior and post development. FIRE DISTRICT REQUIREMENTS 26. Plans for new residences shall be reviewed and approved by the Santa Clara County Fire Department at the time of site development permit application. Conditions that may be applied at that time include, but are not limited to, providing an acceptable water supply based on the size of the new residences, providing an emergency vehicle turnaround, placement of property address signs that are clearly visible from the right-of-way, and providing an approved access system if the lots are fenced and gated. Cynthia Richardson From: Ted Sayre <tsayre@cottonshires.com> Sent: Wednesday, September 23, 2015 8:18 AM To: Cynthia Richardson Cc: Genevieve Fernandez Subject: RE: Geotechnical Report for Parcel 2-27500 Bassett Lane, LAH Follow Up Flag: Follow up Flag Status: Flagged Hi Cynthia- The revised garage position at Parcel 2 on Bassett Lane is a large improvement over the previous position that extended over the actual fault. The proposed position is much more prudent and I do not object to approval from a geotechnical perspective as long as this building is retained as a non-habitable structure. The applicant should be aware that secondary ground cracking could occur within the setback area and the garage may not be free of damage in the event of a major local earthquake. In addition, the applicant should be aware that the lap pool extending over the fault could be extensively damaged. My understanding is that pools have been permitted across fault constrained ground within the Town in the past as long as potential water discharge does not appear to present a hazard to a neighboring residence (I do not see an obvious water discharge issue in this case). Ted Sayre----Cotton, Shires and Associates, Inc. (please let me know if a formal letter is needed) From: Cynthia Richardson [mailto:crichardson@ losaltoshills.ca.gov] Sent: Tuesday, September 22, 2015 4:39 PM To: Ted Sayer (tsayre@cottonshires.com) Cc: Genevieve Fernandez Subject: FW: Geotechnical Report for Parcel 2-27500 Bassett Lane, LAH Hi Ted, Can you let me know if the revised garage works now that it is relocated. Thanks so much. CL,vi.thisi T21G�IarGsov c, PLawvJCovsuLtav°t Towv„of Los Altos f-ftLts Pho:n.e E50_941-7-222 T .sect 050_947-2505 c.rLckaro(sovL@LoscLtosl^LLLs.ca.a�ov office Hours: Tuesda j avwl Thursda j www.losaltoshills.ca.gov From:Steven Stept [mailto:sstept@feldmanarch.com] Sent:Tuesday, September 22, 2015 4:09 PM To: Cynthia Richardson <crichardson@losaltoshills.ca.gov> Cc: 'John Stillman' <iohn@murrayengineers.com>; Pete Carlino <pcarlino@leabraze.com>; Gabriel Aczon • . re, COTTON, SHIRES AND AssOCIATES,.INC. CONSULTING ENGINEERS AND GEOLOGISTS . RECEIVED November 12,2014 L5121B NOV 1 201 TOWN OF LOS ALTOS HILLS TO: Nicole Horvitz Planner TOWN OF LOS ALTOS HILLS 26379 Fremont Road Los Altos Hills, CA 94022 SUBJECT: Supplemental Geotechnical Peer Review RE: Yiu Two Lot Subdivision 370-14-TM-IS-SD-ND 25700 Bassett Lane At your request, we have completed a supplemental geotechnical peer review of the subject Tentative Map application using: • Tentative Map (4 sheets) prepared by Lea & Braze Engineering, Inc., dated October 3,2013; • Subdivision Feasibility Yiu Property (report) prepared by Murray Engineers, Inc., dated September 25,2014; • Revised Site Geologic Map (letter) prepared by Craig S. Harwood, dated December 6,2012; • Geologic Evaluation - Proposed Building Site Parcel 2 (report) prepared by Craig S. Harwood, dated June 25,2012; and • Geotechnical Investigation (report) prepared by Hark_ Kasunich. and Associates, dated June 25,2012. In addition, we have reviewed pertinent technical documents from our office files. DISCUSSION We understand that the applicant proposes to subdivide the subject property (approximately 2.58 acres) into 2 parcels. An existing residence is located on the property within the limits of proposed Parcel 1. Proposed Parcel 2 (the eastern property) is vacant. We understand that access for Parcel 2 would be provided by a new driveway extending from Rhus Ridge Road. We have `previously reviewed a different site Northern California Office Central California Office Southern California Office 330 Village Lane 6417 Dogtown Road 550 St.Charles Drive,Suite 108 Los Gatos,CA 95030-7218 San Andreas,CA 95249-9640 Thousand Oaks,CA 91360-3995 (408)354-5542•Fax(408)354-1852 (209)736-4252•Fax(209)736-1212 (805)497-7999•Fax(805)497-7933 www.cottonshires.com Nicole Horvitz November 12,2014 Page 2 L5121B subdivision plan (letter dated January 8, 2013) and provided comments pertinent to the future development of Parcel 2. CONCLUSIONS AND RECOMMENDED ACTION The proposed subdivision and future residential development is constrained by potential surface fault rupture, potentially expansive soils, areas of steep slopes, a central drainage swale within Parcel 2, and strong to violent seismic ground shaking. Fault setbacks restricting the future habitable residential development are illustrated on the Tentative Map. These setbacks are offset 25 feet from the edge of identified faulted ground. Based on review of referenced reports and inspection of site exploratory excavations, we conclude that completed geologic studies and recommended fault setbacks are consistent with prevailing professional practice. We note that Tentative Map Sheet TM-3 illustrates detached conceptual garages on top of the identified Berrocal Fault trace for both Parcels 1 and 2. The conceptual driveway for Parcel 2 also crosses the fault trace. It should be understood that depicted garages may be subject to collapse in the event of local fault rupture and that the driveway to Parcel 2 may be impassible to vehicles. If utilities are to follow driveway alignments, then all underground utilities to Parcel 2 may be severed by fault rupture within the property. We suggest that consideration be given to alternative garage locations not located above the fault trace when future site development plans are prepared for both parcels. We also suggest that the Project Geotechnical Consultant consider alternative alignments for Parcel 2 utilities that do not cross the fault trace within the property. We recommend geotechnical approval of the Tentative Map application with the following items to be addressed during the detailed site development design of Parcels 1 and 2. 1. Design-Level Geotechnical Engineering Investigations - Geotechnical Engineering investigations should be completed for new residential structures on Parcels 1 and 2. Recommended geotechnical design parameters should be provided for all proposed improvements based on site-specific investigation and testing. In addition, the consultant should address the likely performance of detached garages constructed above the identified Berrocal Fault and the level of disruption to driveways crossing the fault. With respect to Parcel 2, the Consultant should discuss the potential benefits and alternative alignments for utilities to serve the residence that do not cross the fault trace. 2. Individual Site Development Plans - Site development plans should be prepared considering the results of design-level COTTON,SHIRES AND ASSOCIATES, INC. • Nicole Horvitz November 12,2014 Page 3 L5121B geotechnical engineering investigations requested above. Consideration should be given to minimizing damages from potential surface fault rupture by strategic placement of site improvements andutility design. Appropriate documentation to address the above two items should be submitted to the Town for review by the Town Engineer and Town Geotechnical Consultant prior to approval of specific individual lot site development plans. LIMITATIONS This geotechnical peer review has been performed to provide technical advice to • assist le'Tcwm with.. discretionary permit decisions. Our services have been limited to review of the documents previously identified, and a visual review of the property. Our opinions and conclusions are made in accordance with generally accepted principles and practices of the geotechnical profession. This warranty is in lieu of all other warranties,either expressed or implied. Respectfully submitted, COTTON,SHIRES AND ASSOCIATES,INC. TOWN GEOTECHNICAL CONSULTANT Ted Sayre Principal Engineering Geologist CEG 1795 David T. Schrier Principal.Geotechnical Erigmeer GE 2334 DTS:TS:kd COTTON,SHIRES AND ASSOCIATES, INC. COTTON, SHIRES AND ASSOCIATES, INC. CONSULTING ENGINEERS AND GEOLOGISTS RECEIVED November 12,2014 L5121B NOV 1-A- 2014 TOWN OF LOS ALTOS HILLS TO: Nicole Horvitz Planner TOWN OF LOS ALTOS HILLS 26379 Fremont Road Los Altos Hills,CA 94022 SUBJECT: Supplemental Geotechnical Peer Review • RE: Yiu Two Lot Subdivision 370-14-TM-IS-SD-ND 25700 Bassett Lane At your request, we have completed a supplemental geotechnical peer review of the subject Tentative Map application using: • Tentative Map (4 sheets) prepared by Lea & Braze Engineering, Inc., dated October 3,2013; • Subdivision Feasibility Yiu Property (report) prepared by Murray Engineers,Inc.,dated September 25,2014; • Revised Site Geologic Map (letter) prepared by Craig S. Harwood, dated December 6,2012; • Geologic Evaluation - Proposed Building Site Parcel 2 (report) prepared by Craig S. Harwood, dated June 25,2012; and • Geotechnical Investigation (report) prepared by Ham; Kasunich and Associates, dated June 25, 2012. In addition, we have reviewed pertinent technical documents from our office files. DISCUSSION We understand that the applicant proposes to subdivide the subject property (approximately 2.58 acres) into 2 parcels. An existing residence is located on the property within the limits of proposed Pixcel 1. Proposed Parcel 2 (the eastern property) is vacant. We understand that access for Parcel 2 would be provided by a new driveway extending from Rhus Ridge Road. We have `previously reviewed a different site Northern California Office Central California Office Southern California Office 330 Village Lane 6417 Dogtown Road 550 St.Charles Drive,Suite 108 Los Gatos,CA 95030-7218 San Andreas,CA 95249-9640 Thousand Oaks,CA 91360-3995 (408)354-5542•Fax(408)354-1852 (209)736-4252•Fax(209)736-1212 (805)497-7999 •Fax(805)497-7933 www.cottonshires.com Nicole Horvitz November 12, 2014 Page 2 L5121B subdivision plan (letter dated January 8, 2013) and provided comments pertinent to the future development of Parcel 2. CONCLUSIONS AND RECOMMENDED ACTION The proposed subdivision and future residential development is constrained by potential surface fault rupture, potentially expansive soils, areas of steep slopes, a central drainage swale within Parcel 2, and strong to violent seismic ground shaking. Fault setbacks restricting the future habitable residential development are illustrated on the Tentative Map. These setbacks are offset 25 feet from the edge of identified faulted ground. Based on review of referenced reports and inspection of site exploratory excavations, we conclude that completed geologic studies and recommended fault setbacks are consistent with prevailing professional practice. We note that Tentative Map Sheet TM-3 illustrates detached conceptual garages on top of the identified Berrocal Fault trace for both Parcels 1 and 2. The conceptual driveway for Parcel 2 also crosses the fault trace. It should be understood that depicted garages may be subject to collapse in the event of local fault rupture and that the driveway to Parcel 2 may be impassible to vehicles. If utilities are to follow driveway alignments, then all underground utilities to Parcel 2 may be severed by fault rupture within the property. We suggest that consideration be given to alternative garage locations not located above the fault trace when future site development plans are prepared for both parcels. We also suggest that the Project Geotechnical Consultant consider alternative alignments for Parcel 2 utilities that do not cross the fault trace within the property.. We recommend geotechnical approval of the Tentative Map application with the following items to be addressed during the detailed site development design of Parcels 1 and 2. 1. Design-Level Geotechnical Engineering Investigations - Geotechnical Engineering investigations should be completed for new residential structures on Parcels 1 and 2. Recommended geotechnical design parameters should be provided for all proposed improvements based on site-specific investigation and testing. In addition, the consultant should address the likely performance of detached garages constructed above the identified Berrocal Fault and the level of disruption to driveways crossing the fault. With respect to Parcel 2, the Consultant should discuss the potential benefits and alternative alignments for utilities to serve the residence that do not cross the fault trace. 2. Individual Site Development Plans - Site development plans should be prepared considering the results of design-level COTTON, SHIRES AND ASSOCIATES, INC. Nicole Horvitz November 12,2014 Page 3 L5121B geotechnical engineering investigations requested above. Consideration should be given to minimizing damages from potential surfacefault rupture by strategic placement of site improvements and utility design. Appropriate documentation to address the above two items should be submitted to the Town for review by the Town Engineer and Town Geotechnical Consultant prior to approval of specific individual lot site development plans. LIMITATIONS This geotechnical peer review has been performed to provide technical advice to ° assist the'Town with discretionary permit decisions. Our services have been limited to review of the documents previously identified, and a visual review of the property. Our opinions and conclusions are made in accordance with generally accepted principles and practices of the geotechnical profession. This warranty is in lieu of all other warranties,either expressed or implied. Respectfully submitted, COTTON, SHIRES AND ASSOCIATES,INC. TOWN GEOTECHNICAL CONSULTANT Ted Sayre Principal Engineering Geologist CEG 1795 ( Ja.,)-celT ,‘ David T. Schrier Principal Geotechnical Engineer GE 2334 DTS:TS:kd COTTON, SHIRES AND ASSOCIATES, INC. RECEIVED as 100 r2a55e}- keit9- ENVIRONMENTAL DESIGN and PROTECTION COMMITTEE NOV 212014 Application for: �j� Applicant Name: • • Applicant Address: ;Lrac_ti •• Reviewed by: Y..o- r , �� • Date: --------------_--- COMMENTS Site Impact e er�Zi�. $ r afV-1 aa-- • ?,..,(-rn ...-- _ - -- - LUQ1c6,e.J1 - .f •' Noise )"()WI_ .14.) cda) 5hcoV.X6)---- Creaks ,: /La 3E0 C7311- Drainage.---- - - - - 31� 1y� t�v� tc, Easements Existing Vegitation ------------------- --------------- Mitigation— - _ Los Altos Hills Pathway Committee FINAL Minutes of Regular Meeting of Monday,November 24,2014 1. ADMINISTRATIVE Chairman Ann Duwe called the meeting to order at 7:05 PM Members present: Weegie Caughlan,Nick Dunckel,Ann Duwe,Vic Hesterman,Joe Kleitman,Sue Welch,Tim Warner(arrived 7:10 pm),Denise Williams Members/absent: Eileen Gibbons(excused),Breene Kerr,Rachelle Mirkin,Bob Stutz(Associate) Council Members present: Courtney Corrigan(PWC Council Liaison;arrived 7:30 pm) Members of public present: Heather Rose(Chair,LAH Education Committee) Bob Elson(Miranda Drive) Les Earnest(Dianne Drive) Liz Hitchner(26370 Ginny Lane) 2. APPROVAL OF AGENDA AND MINUTES Chair AD called the meeting to order at 7:05 pm.Agenda was approved as amended to move item 5C to top. (AD moved,WC seconded,and vote was unanimously in favor(WC,ND,AD,VH,JK, SW,DW).Minutes from the October 27,2014 meeting were approved with amendments. 3. PROPERTIES FOR REVIEW The following property was reviewed for pathway recommendations: A. 25750 Moody Road(File 379-14-ZP-SD). Reason for pathway review is remodel and construction of an addition.The developer was not present.The parcel is on the south side of Moody Road(public road)at the intersection with Rhus Ridge Road(private road)and has frontages on both roads.The roadside pathway map ("bubble map)shows an existing roadside path along the Moody frontage.The developers' site plans do not show any pathway easements,although a IIB roadside path in good condition has been constructed on the Moody frontage,probably in the road ROW.This pathway was constructed and paid for by the Town and VTA in 2005-06 as part of the Moody Road path upgrade.Developers are to restore the roadside path along Moody to IIB standards after construction is completed.WC moved that: 1)Town staff should confirm whether pathway easements exist along both the Moody Road and Rhus Ridge frontages and if so,whether they are in the road ROW or on the property in question;2)if pathway easements exist and are in the road ROW,request the developers to pay a pathway in lieu fee;3)if pathway easements do not exist,request these easements and do not require developers to pay a pathway in lieu fee.JK seconded and the vote was unanimously in favor(WC,ND,AD,VH,JK,TW,SW,DW). B Bassett(File 370-14-TM-IS-SD-ND).Reason for pathway review is a two-lot subdivision.The developer was not present.The subdivision is on the east side of Bassett Lane,a winding cul-de-sac that serves six residences and it has frontage on both Bassett and Rhus Ridge Road(both private).The roadside pathway map(i.e., "bubble map")shows the preferred roadside pathway in the roadway on both Basset and Rhus Ridge. Development plans show an existing off-road pathway easement along the eastern border of Parcel 2 that is 30 feet wide at the higher southern end (Rhus Ridge Road)and 60 feet wide at the lower northern end where it meets Bassett Lane and connects to the emergency access road to Summitwood.This easement has sufficient space to allow the path to meander through the trees and away from the creek.AD moved that the subdivider construct a native path within the existing pathway easement on the eastern border of Parcel 2, meandering around trees and away from creek. Developers must stake the proposed path route for review by the PWC prior to constructing the path.Staff should also request an easement in conferring access for the public over Bassett Lane and Rhus Road adjacent to the subdivision.WC seconded and the vote was unanimously in favor(WC,ND,AD,VH,JK,TW,SW,DW). C. 25800 Vinedo Lane(File 383-14-ZP-SD-GD).Reason for pathway review is construction of a new residence,a pool,and sports court.The developer was not present.The parcel is a flag lot on the south side of Vinedo, which is a private road.The 2005 Master Path Plan shows an off-road path running along the western border of this parcel and the adjacent parcels to the west(25830 and 25810 Vinedo)that connects Vinedo to Altamont Road.This path includes the shared driveway for 25800 and 25802,and 25560 Vinedo and is open and accessible.The roadside pathway map(i.e.,"bubble map")shows the opposite side of Vinedo is preferred for a roadside path along Vinedo.JK moved that the Town ask the developers of 25800 Vinedo to pay a pathway in'lieu fee.Staff should confirm that easements have been granted on the shared driveway and/or the adjacent parcels(25830 and 25810 Vinedo)for passage on the existing off-road pathway segment leading from Vinedo to Altamont.WC seconded and the vote was unanimously in favor(WC, ND,AD,VH,JK,TW,SW,DW). FINAL PWC Mine 14-1124 2/2/15 1 Nicole Horvitz From: Deborah Padovan Sent: Wednesday, December 17, 2014 10:23 AM To: Susan Welch; Nicole Horvitz Cc: Nancy Couperus Subject: RE: OSC review of 27500 Bassett two-lot subdivision Thank you. From: Susan Welch [mailto:skwelch@earthlink.net] Sent: Wednesday, December 17, 2014 10:21 AM To: Deborah Padovan; Nicole Horvitz Cc: Nancy Couperus Subject: OSC review of 27500 Bassett two-lot subdivision Hi Deborah and Nicole, Here is the OSC recommendation for the subdivision. Sorry I had forgotten that the OSC Chair,Roger Spreen(who has been out of Town and who I was waiting to hear from)had recused himself for proximity. So I did not need to wait for his input after all. Sorry for the delay. Sue At the November 13,2014 Open Space Committee meeting, a recommendation was made that the subdivider place a 25-ft riparian setback(from top of bank)and open space easement along the drainage(small tributary of Adobe Creek)that runs from Rhus Ridge Road down to Bassett Lane near the eastern border of Parcel 2.This area is a steeply sloped with many large oaks. This approach is consistent with the Land Use Element of the General Plan,Goal 2-Policy 2.5: "Steep slopes,canyons and ravines generally in excess of 30%slope,as well as natural swales and drainage channels, and geologic hazard areas within areas designated for residential development shall be left undisturbed and preserved in their natural condition to the maximum extent feasible." There is an existing pathway and equestrian easement along this eastern border of Parcel 2 that is about 30-ft wide at the top (Rhus Ridge Road end)and 60-feet wide at the bottom(Basset Lane end)and the PWC recommended a native path be constructed on this easement, meandering around the trees and avoiding the creek.Roger Spreen,who lives within 500 feet of this subdivision,recused himself from the discussion. 1 A SURVEY OF THE SIGNIFICANT TREES JUN 2 LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO -I®MES ` 2015 AT 25700 BASSETT LANE—LOS ALTOS HILLS I /N0, l�s wAlrosts Prepared at the request of: Simon Yiu Progressive Capital LLC P.O. Box 32686 San Jose, CA 95152 simonyiu2001@yahoo.com Site inspection by: Nigel Belton ISA Certified Arborist WE-0410A April 20, 2015 Job—Bassett Lane 4-15 TABLE OF CONTENTS: Background 1 Assignment 1 Summary 1 Limiting Conditions 4 Observations and Discussion 4 General Recommendations for Tree Protection during Construction 5 -Tree Protection Zone Fencing 5 - Utility, Sewer and Drainage Trenching Requirements 6 -Grade Changes within Tree Canopy Drip lines 6 -Tree Pruning guidelines 7 Recommended Tree Removal within the Construction Footprint on Parcel One 7 Recommended Tree removal within the Construction Footprint on Parcel Two 9 Recommendations for Tree Removal because of Poor Condition Ratings 14 Recommendations for The Removal of California Bay Laurels for Sanitation Reasons 23 Recommendations for Tree Protection Fencing on both Parcels 26 Preliminary Recommendations for the Installation of Underground services 26 - Recommendations for Parcel One 27 - Recommendations for Parcel Two 28 Inspection Schedule 29 A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Background: Aaron Lim and Steven Stept of Feldman Architecture contacted me concerning the provision of a tree survey and an arborist's report pertaining to the proposed development of two new homes at 25700 Bassett Lane, Los Altos Hills. I met with them on site to discuss the proposed development and the scope of work concerning the preparation of a tree survey and an arborists report. Aaron Lim provided me with a topographic survey map which showed the locations of the two proposed homes which will be built on adjoining parcels. The majority of the trees on this site had been previously surveyed with numbered tags attached to their trunks, however many of the trees were not numbered sequentially and other trees had not identified with any tags. Assignment: This assignment entails the provision of a tree survey and an arborist's report concerning all of the native trees that exceed six inches diameter measured at 54 inches above grade. The subject trees are identified by numbered tags affixed to their trunks. These numbers correspond with the numbering utilized in the arborist's report and on the accompanying tree survey chart and tree location map. The tree survey chart documents tree dimensions and tree conditions (tree health and structure ratings). The survey chart also identifies those trees that are suitable for preservation and trees that are recommended for removal. The arborist's report includes observations regarding tree and site conditions and qualifies why specific trees must be removed because of their conditions and/or locations. The report makes recommendations pertaining to tree protection measures during both the design and construction phases of this project and also includes an inspection schedule for the construction period. This report also makes recommendations concerning appropriate pruning work to improve the appearance and structural integrity of those trees that will remain. Summary: The tree survey site comprises of two separate parcels which are being developed for single family homes. One of these parcels has an existing home on it that will be demolished. The development site comprises of mature native woodland and smaller areas of open grassland. The trees on this location include Coast Live and Valley Oaks, California Bay Laurel and California Buckeye. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 1 This document must be considered as being a preliminary report based on initial information concerning the proposed development of Parcel One and Parcel Two. The final locations of the sewer services, underground utilities and retention areas are yet to be determined but conceptual locations were provided for my review. This report makes general recommendations regarding the least impactful locations of these services concerning the protection of the critical root zones of these trees. The report recommends that where possible such services must be situated within driveway and infrastructure footprints. Where these services cannot be routed within driveway and infrastructure footprints they must be routed in the least impactful locations possible. The project arborist must provide further guidance concerning the actual locations of these services and utilities in an addendum to this report. This addendum must also make recommendations pertaining to root protection procedures required for individual trees. Total of 278 protected trees with trunk diameters over six inches diameter measured at 54 inches above grade were surveyed on both parcels. A total of 166 of these trees are designated for preservation and protection during the construction period. A total of 112 trees are recommended for removal. These trees are to be removed because of their locations concerning proposed construction footprints, their condition ratings or for sanitation reasons (concerning the potential for the spread of Sudden Oak Death Disease). Sixty three of these trees are located in close proximity to or within construction footprints (house, driveway and other infrastructure locations). Twenty four trees are recommended for removal due to their poor health and/or structure condition ratings. Thirty two California Bay Laurel Trees are also recommended for removal for sanitation reasons. Some of these California Bay Laurels also have poor condition ratings. Note that the California Bay Laurel is noted as being the primary vector regarding the spread of Sudden Oak Death disease in native woodlands. I noted a number of Coast Live Oaks within this survey area that were expressing symptoms consistent with an infection by this pathogen. Other California Bay Laurels which are setback further away from these native oaks have been recommended for preservation as they serve to provide valuable screening from the road and adjacent properties. Eighty three trees were surveyed on Parcel One (the western parcel). Fifty seven of these trees are designated for preservation and twenty six trees are recommended for removal. One hundred and ninety five trees were surveyed on Parcel Two (the eastern parcel). One hundred and five trees are designated for preservation and ninety trees are recommended for removal. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 2 Tree protection zone fencing must be installed as prescribed in this report before any equipment comes on site and the demolition work proceeds. This fencing must remain in place throughout the entire demolition and construction periods and must not be dismantled or moved without the written consent of the project arborist. Care must be taken to protect the critical root zones of the trees to be preserved. Critical root zones are generally defined as the areas near or within the drip lines of tree canopies. These areas are vulnerable to damage during grading work, trenching work for utilities and the demolition and construction periods of this development. Damage to tree roots can include root cutting during trenching and grading work, soil compaction from equipment operations, root suffocation from the addition of fill soils. Roots can also be damaged by the disposal of toxic substances such as chemicals and concrete washings. The trees designated for preservation should be pruned by a State Licensed tree service provider under the supervision of an ISA Certified arborist to improve their structural integrity and appearance. The project arborist must inspect the site and provide supervision at the following times: 1—Meet with the tree removal and pruning contractor to identify trees designated for removal and discuss the scope of pruning work. 2—Inspect this site when the Tree Protection Zone (TPZ)fences have been installed after the tree removal and pruning work has been completed and before any demolition,grading and construction work proceeds. 3—Inspect the site any time utility, sewer line or drainage trenches encroach within Critical Root Zones (under the drip lines of protected trees). Provide guidance and supervision regarding root protection procedures. 4—When excavations for the construction the houses and surrounding infrastructure such as the driveways, turnaround areas and retention areas encroach within the canopy drip lines of the protected trees. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 3 Limiting Conditions: The inspections of these trees were made from the ground and no trees were climbed to examine any above ground structures nor were any roots below the soil grade examined. The inspections of tree structures and defects were limited to visual examinations only. The observations and recommendations made in this report must considered as being limited to information provided by these visual inspections only. Recommendations concerning the utilization of pruning work or other means to improve the structural integrity and safety of trees must not be considered as a guarantee against partial or whole tree failure. Trees can and do fail unexpectedly and these events can occur even after such recommended remedial work has been undertaken. Note that I reviewed preliminary plans for new underground utilities, drains and sewer service lines on both parcels. This report makes general recommendations pertaining to alternative routes for these underground services in order to reduce the number of encroachments within the critical root zones of the protected trees. The report also makes general recommendations regarding required root protection and pruning procedures during trenching work but does not provide specific recommendations for the protection of individual trees during these procedures.Such recommendations should be provided as an addendum to this report after the final locations of these services are determined. Discussion and Observations: The project site entails two adjoining parcels. The most western parcel has an existing structure on it and is bordered by Bassett Lane (Parcel One). The existing house will be demolished in order to build a new home within the same general proximity. This house will be serviced by a new driveway entering off Bassett Lane. The eastern parcel is bordered by Basset Lane and Rhus Ridge Road (Parcel Two). A new house will be built on this undeveloped site and it will accessed with a new driveway entering from Bassett Lane. The two hundred and seventy eight trees surveyed on the project site comprised of the following species: - 160 Coast Live Oaks (Quercus agrifolia) - 21 Valley Oaks (Quercus lobata) - 73 California Bay Laurels (Umbellularia Californica) -24 California Buckeye (Aesculus californica) - 1 Wild Plum (Prunus ssp) A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 4 The majority of the Coast Live Oaks generally have good to fair health ratings and exhibit fair structures. I noted that a large number of California Bay Laurels are growing within close proximity to many of these oaks. The California Bay Laurel is noted as being the principal vector regarding the transmission of Sudden Oak Death Disease (Phytophthora ramorum)to adjacent Coast Live Oaks. A number of Coast Live Oaks on the project site exhibited bleeding areas on their lower trunks which appear to be consistent with the symptoms of this disease. It is important to note that this pathogen has the potential to cause significant damage and mortality but it does:not spread readily from Oak to Oak. The disease does not appear to cause significant harm to infected California Bay Laurels. The more desirable Coast Live Oaks can be treatedprophylactically with a chemical application (using the material Agrifos)which should serve to reduce the risk of infection. This treatment is an important consideration concerning the protection of the most significant and attractive oak trees situated in closer proximity to these new homes. I recommended that many of the California Bay Laurels are removed for sanitation reasons in order to reduce the potential for the spread of this disease which is established in areas of the Los Altos Hills. The other California Bay Laurels that are recommended for preservation in this report are generally set back further from the vulnerable oaks and they serve to provide vegetative cover and valuable screening from the adjacent streets and properties. General Recommendations for Tree Protection During the Construction Period: 1-Tree Protection Zone Fencing Requirements: Tree Protection Zone (TPZ)fencing must be installed around the trees identified for preservation before any equipment comes on site (before demolition and grading work proceeds). These fences must be inspected by the City of Los Altos Hills before the commencement of any grading(as mandated in the Municipal Code—Section 12-2.502). Note that the City Code specifies that the Tree Protection Zone fencing must be placed at tree canopy drip lines. In the event that tree canopies encroach over construction areas,fencing shall be located as close possible to this location while allowing enough space for construction activities to occur. Municipal Code dictates that these fences must consist of minimum five foot high chain link fencing material attached to two inch diameter galvanized posts, driven 24 inches into the ground and spaced no more thanl0 feet apart. The TPZ fences must not be removed, moved or partially dismantled at any time during the construction period without the written consent of the Project Arborist. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 5 No grading work and trenching, nor equipment or vehicle encroachment may occur within these defined Tree Protection Zones. Construction materials and waste (including chemicals and concrete washings) must not be stored or disposed of within these areas. Attach tree protection notices to these fences at a distance of every ten feet (these notices must be laminated in plastic). See the attached sample notice. 2- Utility, Sanitary Sewer Services and Drainage Trenching Requirements: Note that all new underground utilities and drains and sewer services (including septic systems) must be routed around the outside the canopy drip lines of the protected trees wherever possible in order to protect these Critical Root Zone areas from excessive damage. In the event that utilities and drains must be routed under tree canopies they must be setback as far as possible from tree trunks to reduce the potential for root loss and damage. In the event that trenching work for utilities (including sanitary sewer lines, electrical, gas, telephone, cable services) or storm drains and irrigation lines must encroach within the defined Tree Protection Zones,the project arborist must provide guidance regarding appropriate root protection and preservation strategies in order to minimize root loss and disturbance. Recommended root protection strategies may include tunneling the under significant roots (roots over 1.5 inches diameter)to insert services underneath them or entail root pruning work contingent on the proximity of the services to the trunks of the affected trees. Root pruning work entails the use of a sharp saw to cut cleanly cut significant sized roots at the edge of the excavation in order to avoid tearing damage (a sawzall is recommended for this work). In most cases the encroaching trenches must be hand dug or an initial soil cut must be made in the service trench at between 12 and 16 inches outside of the final edge of excavation line in order to locate any significant roots. These larger roots must then be hand dug back to the final excavation line and pruned with a saw before the trenching work is completed. The project arborist must be on site to supervise all root protection and pruning work within tree canopy drip lines before it proceeds in order to ensure that it is done correctly. 3 - Notes Regarding Grade Changes Within The Canopy Drip Lines of Protected Trees: Grade changes must be avoided wherever possible and when unavoidable they must be minimized to protect critical root zones (CRZ) near or within the canopy drip lines of the protected trees. Grades should not be altered (cut or filled) by more than two inches within critical root zones where at all possible. In the event that deeper soil fills are planned near or within critical root zone areas,the use of tree wells to maintain an adequate area of the existing soil grade to protect tree health is recommended. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 6 4-Tree Pruning Guidelines: I recommend that the trees designated for preservation are pruned to improve their structures and appearance. Some pruning may also be required to provide adequate setbacks between tree canopies and structures. All pruning work must comply with International Society of Arboriculture (ISA) standards and be undertaken by a State Licensed tree service provider. This work must be performed under the supervision of an ISA Certified Arborist (see the attached ISA Pruning Standards). Pruning work should entail the removal of conspicuous dead wood and any damaged, crowded or crossing branches. Avoid over thinning the interiors of tree canopies. Utilize thinning cuts when pruning to achieve end weight reduction on heavy limb structures or for canopy size reduction purposes.Thinning cuts entail the removal of limb and branch ends back to side branches which are large enough to assume the terminal role as the new limb end (also known as drop crotch pruning). Cut the limb/branch end back to a side branch that is generally no smaller than one third the diameter of the portion removed. Note that the pruning of the Coast Live Oaks should be avoided during the wet winter months as this is the most likely period for the transmission of Sudden Oak Death Disease. The optimal months for the pruning of these oaks will be from May through September. Recommended Tree Removal within the Construction Footprint on Parcel One: The following 12 trees must be removed because they are situated within the footprints of the proposed home, driveway and infrastructure areas: #104—23 inch DBH Coast Live Oak #110—23 inch DBH Coast Live Oak #111—10/13 inch DBH Valley Oak #112—14/13 inch DBH Valley Oak #113—6 inch DBH Valley Oak #114—10 inch DBH Valley Oak #115—6.inch DBH Valley Oak #116—15 inch DBH Coast Live Oak #117—12 inch DBH Coast Live Oak #118—18 inch DBH Coast Live Oak #134—24 inch DBH Coast Live Oak #141—17 inch DBH Coast Live Oak A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 7 The following two trees must be removed because they will be located within close proximity to the driveway and surrounding infrastructure: #136—22 inch DBH Coast Live Oak (also poor condition rating due to decay in base of trunk) T---,-9•4--rt , ,t. /.1C::-.11.Z.:' ti * w.r t?: t „,'1,".4.-.., v r ¢3 nary s �`f jxilSt t�. �' `- ! ,ay+',}-.. 7 S> r� ,,. tic, 4,',4`2,;*$;;A,..,... ti.fik.R.--1,, 'WW1. •e 'rz01.-;`,*'--..,,' ' .r. ' d r .Vt `l�yF'4t 'i i 4 j� �' ,.,w r f` s v^ 4,} .c tat ,/d '. x..4.rC `i:", 2k,-' r4.t "4i '�� y it ' '"a< '' 'S ;�1 • y I it" A �Y SY ''';'..f.,"4Ate FF r s{ .-"b'µ'��' g+�}^ f a.fv yip 4 1t� i''x f'{Y F S��H'',„4,-tit‘''',....-r�' 9, �' *+ e, '!+ per` (' f� xexft"i,' , .,1, rift s:;:.--* ":',.....'4. q y ...,•-,' iVF . •a is t ("ki �'�- 4x a+c. '� 4 i "zj e4t st t e e-P7 .. t. '�' Srik ,A,-,4_,_,i, ,, ,,..,..„,,,,, -r+'ala 'n r li`F '�r1' .+j'yt-',° t '',,, i' 'bt' ti l ,._ tr . 'r 1 it -.P 9 t Y '!: f,s{ Di). Yds 1.';,1.;;,,J, k -i 4 - +.. ,-t !t r 6 f 3tr"N'1:Ay ',-�' W4 ,t11 t'&l VRIO tAig,1:1:t$Iz--- +�,9 �? � h� ,� I i v '1' > Jy ' 22-';~�f,Qr 4 d t z 4 .� ,�qlg{�tJ{�� 11.ri" � tush g� k 7 �f`,[3 •%-r40% � a'"F7 4 5� t a`u teM .VA VI P. y�q �1 Pati 14K +Y+ 34 KOr e ` ,, . 7r �'�S ''jai 1>r4 F{&; \a 1i a ! 'a, Y rU' ,n t7. L 3+Ad y'k,,r y•C r'"J_ t1 ." �4 g-v+�'r . i 1 ,"i vete 0 'y t4`. kit tail, ` r r4 r'- v.el, 0�;;f' �1`�', ';`.'4W$%`1 fit. -moi"t '. ^ .Aa ' a �� 55 liTif;'' ,si x F N a fr 1 '3-xtA % ' ,4,,,W4:,/,,,,` .'•-`1\,;,k #138—16 inch DBH Coast Live Oak A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 8 Recommended Tree Removal within the Construction Footprint on Parcel Two: The following 37 trees must be removed because they are situated within the footprints of the new home and driveway area: #13—9 inch DBH Coast Live Oak #14—15 inch DBH Coast Live Oak #18—12/11 inch DBH California Bay Laurel #18A—7 inch DBH California Bay Laurel #18B—7 inch DBH Coast Live Oak #19—13/13 inch DBH California Buckeye #20- 12/7/13 inch DBH Coast Live Oak #21—22 inch DBH Valley Oak #22-9 inch DBH California Bay Laurel #22A-6 inch DBH California Buckeye #23—9/13 inch DBH Valley Oak #24—12 inch DBH Coast Live Oak #24A—8/8 inch DBH California Bay Laurel #24B—16 inch DBH Coast Live Oak #25—10/11 inch DBH Coast Live Oak #26- 18 inch DBH Coast Live Oak #27-7 inch DBH Coast Live Oak #36—14 inch DBH Coast Live Oak #47—13 inch DBH Coast Live Oak #48—17 inch DBH California Bay Laurel (also decayed in lower trunk) ,9 Xi, -;r ..1- .'Iet�°.Tei.iiV.:4 t'`i.7 f k'. "-vr.'r� 42 "A).4., 7 .-1:141144^,,‘, ` 5 t h 1-rays 1. 7 S %it. � ;° 3' a�' cy L s t G. r P ... s I gyp `., t {ter; t '1^S' :. rcn �' w ' t # f . , „,-:..V _ 4.1,,, t' `fic �`:-,1/ , '. , x, 4 '. ?...17.....04A1, p �,, . , e r ., ,;' , 1/40 iy y..rs.; .f�f'a`rt' „i'- ey V.‘-'",i' ' 'a 4 ®• A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 9 #49—20 inch DBH California Bay Laurel (also decayed in trunk) #67—16 inch DBH Coast Live Oak #73—11 inch DBH Coast Live Oak #75—16 inch DBH Coast Live Oak #76—17 inch DBH Coast Live Oak #77—17 inch DBH Valley Oak #180—8/12 inch California Bay Laurel #182—22 inch DBH Coast Live Oak #183—6/6/15 inch DBH California Bay Laurel #184—14 inch DBH Coast Live Oak #185—8 inch DBH California Bay Laurel #186—16 inch DBH Coast Live Oak #187—14 inch DBH Coast Live Oak #188-8 inch DBH California Bay Laurel #189—13 inch DBH Coast Live Oak #190 14 inch DBH Coast Live Oak #191—14 inch DBH Coast Live Oak A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 10 The following 14 trees must be removed because they are situated within close proximity to the footprints of the new home and infrastructure: #15-20 inch DBH California Bay Laurel #17-17 inch DBH California Bay Laurel #17A-7 Inch DBH California Buckeye #28-27 inch DBH Coast Live Oak '' i',. ,e' ...1,41:4,,,.4,A.,.:ax ,,o.:,1-44-,....s.,,,;0, jr„..ii,..k.,,7,,,?,..„,-.;‘,.)::.-..---„?:1,:ii.:,.•;,,,,,t,i ' 4., -.44'4,02.4,`4*.v. e V...:,-.,..:-.:0.,,,,-1.i.,;‘, , -. e.,..4; ., ,,,,,f ,..kr:,..t,...tw, ..,t .A. „t,u.sof ,,,-,---,ty;..,-/-.#1. •;::.0-n? Illf -- --..-okr,,,ihIg-...:,m,,,,,:ri;I',:ti.:,,i,h ,_...,r,i.i., .,,,.....--...it trj".... 7 ki..-Y,,,...,41L-te.g...„1,-;7,1L,g,-;---, x,'-e.x.,.:f f."Xii.trs: 1;•4:1-.4'i.-741'5,71.f.ft:..-,6;,;,'4;4131,-: 4. ...,zr.v....1,......,..,.zeiiri:::,;0, k....-;p4,-4,,,r _,..',..,.,..;-.;,-,.--4 g.:,-x,-..,......1--„52,'.1 Ili ky .- _ . ,..„*,..1...,,-- ,--, . ,‘,.. .-__:..; „,, ,,,,.,-.,„„„,,..,,,, .i , ,..., .......,,, .,..,:. ,.....,:,,,,_,,, _..„......,..„.„ ,.,,...:::‘,„. . ......,,,,,.....„... ..„,,,..,:,..,. .,..1...144.7,.3+ .•,,,'. ,••••••••„„. .. -' ••-•.' --:*•'-'; — �4� � `���� ~ ~0~.~.-~ - _^-~_~_°� ^ -“1``' = ' A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE-LOS ALTOS HILLS Site visit by Nigel Belton ISA Certified Arborist WE-0410A-April 20,2015 Page 11 #29—8 inch DBH California Bay Laurel #30-25 inch DBH Coast Live Oak(also has internal decay in trunk) 4. ,.,..,;,,,,.,..e.....„„.., ,.,,1,,,, __,. ..... .: .., ,„.., ,..,.. •IN'' 41, _ 154.:..14-..-7,,,,,,,,.:-.:4,-v),..<4.--4„,- .,,,,,..„g. ..;* rer.:-•1:1 -,.-t.-. F.:,.,.. z.,...q.„-, .„,t i camn���-`- / �,v #37-8inch DBHCoast Live Oak A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton |lACe�ifiedArborist VVE-04IOA'April ZU'ZO1S Page 12 #40-8/7/6/8 inch DBH California Buckeye (also has internal decay in base of trunks) ,,,,--4 '404.-- ....„..... .,,,,,. „,„,„, .....,:.,„.. .„ A,..,,, ,,,./......:„.. . _-„,,,,, .4. . , ... )4.e:-...le-4,-4 -.,..-- 7 A-. , :tv....--; - '1,-.-4.:Tri•--:,., .c,-: :fi., - , ,v._,' ', - ••'••:=-4'• -r-):;-..:,•riptl,-.; k.-if'," .5*,•-r,', r,14-1;4,5,:k;:.--::134%7,i7.1i,‘f-1'',f*.-1.'II:, ';' :c'-, sr: m ` #46—lI/l3inch OBHCalifornia Bay Laurel #73-1IinchDBHCmastLh/eC>a� .••-•J‘0Y.,3{9,14r "'s.':' .—.4.4 .'.'gei ' ?Chi' ''.4`...A`'.,'-;AT it,%;, .,,,ri 4,--,---fr -.0,------ . 4) -;ty....:.:.::-4-/ridi,,,,v t fey .$1,,i.4„,:,‘,../c.. ,,,,, -:-..4.,, -\ _, „,......v,,,.....„ , .1.1 ,,,, :„4:.1, Iti .='t. '19'.•P I 4 '', ." )5`,..,/,'7.-7,'-igW•t4,- .fr.,...4 ...„.. ,, 4,k) ,'14,',1 '4•;.••,:lt.V.I' '• • :"),V,11--"';'•r';' •"."•Z•4--, •11, ‘,..1-^- J-.'`•.4-.'",'- 6 c r_*•,.,:'43-*:•-,':•t.siKr*,0•1'-'5r;tf',.4,;_T-1 a;"7-1r1.- . ',:;.;'';.t.--,4'''e -'-""'--*-'-'14.4 titi?...t7*,.4.i., Vfr').,Aw,:w15.7.**.ola„.N.,,,-.1.,,14,_ .4t,) i, ./:,.,,,1:,,,r,i. 6.1:.,,I.,..,t.„3 -ei.Isi, , vi.v...i,i;„-,,,v,,x,„1...14iiri,A4.*: ,.. 4e,- .,.a,teo:71,-3.).i.,.,.11,i,,,,,..6 .4.,. .-ki;Axifer.me.,, ,.54..,..4414, 0 kt, 2-''',::T•-,:r, :zrick,1-44,,..4:7,.'1" ...,:t,::-:.:,:4*. 4;"41'`':?.?;g', '41,e-:':;;".'''''ER"40 ;i::.,e.:_,',11:1.-......t.t,:;.',%`-..ile..fiNtgt1...,,t`I'IL,A••--Z::',*„,-"•110..-.' r$1.,:Af• .;PW47,141114, _•!.6'....'•:.:t. 1.:t•?,..t r••••;;••3•4!;1).•••• ..lx•-mej.,001•,, , '-'-::"'7-,AVIZ:.-?,;„'"-%--- -,‘":k_r,i;:"•.,3.•;:,..,•5;,•-11%-:"-f-ti/;'''':,,,,*-,f-,--:"-fi;-:••i-r• „„A f�� _, ^^ v�x ��^�sr�� r� r���,�� �� ASURVEY OFTHE 8GN|FK]\NTTREE3LOCATEDVV�H|NTHE PROX|KXRYOFTHE CONSTRUCOONTVVOHO;NES ATZ57DO8ASSETrLANE—LO5A[[O�H|�� �tevisit byNigel Belton'ISA Cer�OedArbohstVVE�41OA'Aph|ZO'ZD1S Pagel3 #78—7 inch DBH Coast Live Oak #179—22 inch DBH Valley Oak #179A—19 inch DBH California Bay Laurel #192—16 inch DBH California Bay Laurel Recommendations for the Removal of Trees Because of Poor Condition Ratings: Twenty five significant trees located on both parcels are recommended for removal because of poor health or structure ratings. Note that some of these trees have also been designated for removal because of their locations. #34—17/20/18 inch DBH Coast Live Oak- Poor health/structure ratings and S.O.D. symptoms ttk.t av'"—t9 t".-6 !e t t4-r i�'}, ly).i5 , -S. 74.4` 3s Y ''t ss t ti`P.(y 4 S l ,M V . ' .4. ,4 t.s_ln. .a mi N IT,a s ,, ani,,,, , µ $ j 777,,,777,�� fes- g� p.���,,ts s � ,, €.j �' !';-leo�,Y 5 *34r't� -. 4:,fly. g7 JP Yavtte.," a 1 if ro } f° °'_6 f '! �'', a ti.� '-r ` {ry"` 3 5;I>rt �y �Po, ; 5, '. j ter.•.. 7 L� Ssy{Y '��S .,, t�.�.�"� 'i�.i y1�riGY il SQA r._ Fs.. pi .: p'� +� V., YN.p_c". � C f 1_._ {+ 5s y1p S7 .i• 1c. fsal b -,,.1,''t ..l -,y t .. #40—8/7/6/8 inch DBH California Buckeye—Decay in the base of the trunk #53A—8 inch DBH Coast Live Oak—Killed by S.O.D. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 14 #55—7 inch DBH Coast Live Oak—Poor health / �r r . fr. ' ., y q 41'2 i �^S1, x, - cr IC I. :Vrd "� ' t *> , 'f4";.,"",.'''' ' ✓1.-fi is in i 1 Os, *,r- . t b , %'+YM+i j ,y7 . i.'. ,t. f .-r< U_ .y ,,--!. tit �`,<.rt �: t }' `,} ..- 1.-ta 41..-.:1,: ,f '>t ..k.. G'e. ,rai„ 1;- ` tea, r T* :k t ,•1 1 7,.' S ^Tit ." }} i$"frit..q *..-..i '.� T ' r' .w i ! t,t+ Y 14, ; �!7 s` -1,t v i� ' >dr : � , ; --A' e. i „"zc[ 4. ift .f + i t _ -, ,, :- . ,t 4 .`4. {' Ss '- si ` a -:n¢r-7r T, l k' #57—15 inch DBH Valley Oak—Dying tree ��4'1 • 4 i 4 r YVC^tel' ,Y rte�t+;;.0-4,-S sp ye? t 4 _i� .,; z� �, h4jt , r vw P C= . ys bAs r t{Nc< t_,ma �a . Fr y VV.- y , 8� dP1 !i-4 N�� t r ti f+� i �t 4 45*-P-u^j .s '40/..1,:a.--41.1.3.Yt` i ` K \ Sd .JtP G�+ yse4 Wmr f^g-.�l+ �i 9 C 1-.:T'**:'*' + tit .�,K:i+ii F4, kAf e 4- 4fir% ;'X s` i'. 1r/ `k'. +'1yi ,1 ,in w, . s. f A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 15 #71— inch DBH California Bay Laurel—Poor structure rating #78—7 inch DBH Coast Live Oak—poor structure supported by an adjacent tree #83A- 1linch D8HCoast Live Oak—Poor hea|th/structureratings—Severe beetle infestation 11?1,e3? ' 1 '',141''' ..\gi,2 4 ,, -A1,71..-g'etul f .... ..71:.1..w. . • , , , . _.: . ..., ,,,fet._., _ 0 #94A—9 inch DBH Coast Live Oak—Poor condition rating : .op ev,,,i5,:r-...:44,4,-.3 ,f.• ..i...."'-' ,;E.,,,,,--k,„,--,0"'.,* k•.Ts4,.,--•-. vp .?4 T-,5j.:":-.4.,,,,,,,-,4e.a0:',1,,X..--slricS";7-.7.11*s,,i---*:1----71-Agt.o. )\ A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Pa��l6 3�e�sitbyNige|De|ton |IACerbOedA/bo�tVVE�4l0A'Aph|8lZO1S #104-23 inch DBHCyyoast Live Oak(beetle damage and declining health) „4„.. .,...\,_,.,,,,..,.....,.....„,:,„‘„.,,,,,,,,A4P,..0-.,,e,02.5trgiu.'-)&te.. " ,� ,•te-�'1A'`.: h 107,7;k ,'tom � ,1 yi ri `q.3.;�. .''' ..,;-%•.:., y I,xY JC `t n J,,.t kitiit r }t(F� { +.; / X I -1-.-., .,4%-41".-.'.'''.42'•;,`; -4 1— S3 Y� t s J,�IC•t tit, r�'i'�,�e .•: 4 � ..dr �lmi )) a r 1...."A:,: it., 3.r.kl �.Cj l y. , r�1 3 1.. 1.M ('i , J --,:,-..,. :.--...v,".-. ' III s tel" \l. #106—13/15/18 inch DBH California Bay Laurel—Decay in the lower trunk �} r x ;f ,; , f.,-- . .4z. „mu...,..... .491 s#�.,..,..,,. :: f , fix ..,.;_,i..i. .,,,z,- .i., ; ,.. _.. 6, ,..,„1_ • ._ -,.... __ r Y6y i"; t ,� �3?n 'YPtT'��`� it } 41 ,8 ,',1,{1. t ` x�'. iF mit+� ,r Y ,,pry i, k�, u"-'.,{`i° I gym' rirA If 4,i Y syr �i i$i r. 4� Z "1 .i XGA 1 ,Ro, LlnR 4� 7 R7"Ft�Y{f r '!%1r a x `� f4 1 47r 'SSS i'A V(..,-"'4 '7I.t` F,p T F f 1 i rp-..-,,-,:,.. , %.4.,- v, ...\ „........ ,... t1-... \ t r ' � te r* �3fi" •• r i � r�' 1 »�,i.# . r 0-. ' .,.,...:t:.-,%---.,r Yr _ '..� A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 17 #121—6/7/13 inch DBH California Bay Laurel—Decay in base of trunk #139—23 inch DBH Valley Oak—Decay in base of trunk and leans heavily towards building footprint ei. �`- 1,4 y,- . x 7f''ak 1/ ,17,;-,%0•,,,,r, / till, 'r'' 1 �i �_ 11,101: t, t '' 1,v''"e x4i e ti0¢ yrr ting''-- 't� 'r d/�' sy-t�l:Spe r"'t� � ���'tJ, l J k' r p� K hi f,Y�31 j' 1', ` ' `Viii �40t 2 P1 id s I. �'rit�.+s�?a o• i{14,X-,4'' '• • ''` t[`ia' ; �i ro -,i�y�j��r...++'J`; v`a�t•�,��ti'd"� °�j j''������� rUJ '4 air ,,.t1,e,-- .!:':'1,,;'7,,',.,f..e 5�i t ;1 ° f"•� ; ( r y• .f{I$�� r� +vg e r Sry� ,41::i r 4C,,, •74t,-- 3,‘, i '„.+;,.--e.) ;.fir' �, �,.• dl'( to D!� r 4 1-+. `1 d'��1 no r v YYY ;L��',Y`f , «'K'��1yN t �r 1 ! uTjdY .,S `tlt'a1*7 51- �,+•. xili f1t,,Ok-_ 1,•f"(0.10'4,40 a riir2t `;4 yk((p'fti4.4r4• .:Pe 6.#;•-ti c5tro,s 1 „;,1 si Y "E�r`�C'� Agri rl i 1�4t1TiF 4j di'r s°'a,y1..�'" �- _4-A.,... '* a !` X r a fJ r 1 ['1 a. ,R r"as ST e .e ir: y '!1'h... '�FItS t6Mg..v .' ,� 5t`o}L 4p ` rl,f+ '` r iii tgit.,tifiz„I t.,-;,.!,.., ...5 A. ‘... . ',....1,1„Trp.I.' .-3 --_--4:-. , . el, �, f a ,.err f� �� 1 i.r� s� ''� ,.,,,,,...„„.,„,,,,„„,,,,.._,,,,,;„.,,, ,_,,. . --,, ,,,...„, if .:'P'S" P•'/Ii r `,. rt J{ L"fit 1'1°jt'�k 343s fit; ,• S3/ TH,,j F..'. ''^ 1.'ijVl .Y A • ''''l ' Lv. y` .. s ,r 1 ' Y \4 .nj Ok i 1r1 1lrtJ1x #146—8/7/11 inch DBH California Bay Laurel—Decay in base of trunk(and sanitation reasons) A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASS ETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 18 #163-12/7 inch DBH CoasLive Oak *-> `� ' #164-13 inch DBH Coast Live Oak It ,„...;,...,-)1,-...,,t-?,*t„,,,s,-, -,-!.. :txt , � � ' � �ov^ ~ A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Page19 5itevisitbyN�e| Be|ton'|SACerb�edAdbohstVVE'O41UA'Aph|IC\2O15 • p�y4 a . , './ 'F AIS _,, Y 1i if i ti`s.4, j 14+4 i," F f t n �' \a 3{. r y y_ -+'y q9i ,sof,•_,;;3 e ,uy��i y3 ti r T.e r f• r1...„.W... It E-^h ' j: • g. L;1µ '• .,,... 4. r :h_r -f...,,,,,-..-tz i '4$rr.. •rl rkFk <?a 3 .'x.'.' •� #169—10 inch DBH Coast Live Oak—Previously topped and compromised _ y F 'I it*.- •'ril +�' �,; '�• 1 �at' r�. r.+. i,/llw�t v `"� + '�r�+A- t .4':1,s4'11; i �yNr � `)r d ^s ' e "i .ig r qv', � s :� T - lit. - ) �•y ,...±$:,.i....:,:'- ‘7.'"':•; 'ti � \ :1 rj,� , 7LirFVY } .i4 ✓ t^ i§ " ` � •' Ok1Y1 , la - ' 1 i .0 ' .F ,( • • 1�k ; ,, yqy 1,rkr f . d rr r z.y.c r Lrr °� y�'t' '6 y'1 9•,,,..,....15.64:. • Ht �,f-y x t ..,,,.. ..,...•••,, a, .. of{ u Y, r �- rt?• t,�-)� !,fid-fop �eS SY4y ''')...'•.;"1,jY ,r., '''' XthaL., ,. %kli.Q, -rte`µ-4i'-,$,E an, c-, _/ , ,:. ��-+'. -•.4 45$ •:- r�icee: : .r `V., r4r A- -1 r ',.,, yl-$Vry_,a>4-i' Ett Y!' r * r i. J a 1 '-‘T,14'4•••=1,'''''Er •7 • r� r �qs- D'� ie• r ,A tJ���/ti°fit>.J �' rt.r �"""‘-•;-1'.&•f•.-`,..,ar 9•J • 104, "� -•"5 Vfte,.44.•,-.T, 'fr¢• - f bl i § T°� 1 t ft IY,, -"4— .a.t,`•:.: y'f ri'C • '.f f;,it.- v.R+. F_'� �� ± A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 20 #178—9 inch DBH California Bay Laurel—Dead Tree #181—9 inch DBH California Bay Laurel—Poor specimen leans towards house footprint #193—15/17 inch DBH California Bay Laurel—Decay in the base of the trunk #196—10 inch DBH California Bay Laurel—Poor health and a strong lean #215—20 inch DBH California Bay Laurel—Decay in the lower trunk and a strong lean #219—22 inch DBH Coast Live Oak—Significant decay in lower trunk and target area (adjacent to road) � •tet, k-!.:-.:R.,1',',...t...di , '.'.1-4�`.tirt. ....„,,...„...,, , .,.... -.3 t 1 ' '10-4,t.i: ' Av il• I '1(hIV:Ai,. liki: : 4P4:411i: t . .,---,41;r0,4,, f,... '. 'lit,11V4Z4-t:3)/..'11 ' 4.! triS (Kitt `t �t 1.:( - iii 1 S�� s ti., 'i ...1,,, ,,...L.411V.I.7., t,1.-.1,0.41.§, . ):6%',. F44.:4S . „F-73.'. .• ' A y -).42SS of'10 (t' 5{tif :, l vr.Nn4 4.' (lee 4 }y'rf'S7::',4 -C 6`..W-14-::= ":4,7;8/;' ., r a a+r, 4 ' �i�''1'4,:/:::fS ,,' f 1f vi i v7 X1(1 A 4.10:•Nf -9 L !,-key,./4'4•12.,4.0— 4r4:2 4,li s' `. 000,: . �gs��y, of q,fP� tc. t4 fi f ` ,ff, _( .kto' `;T+�Ey' C4 Skin t,�(N[ J !i}a Sr .1,,b,'L y- .(,y,;..-3,` ! ;. n+)'. . , N,,. Glx t ,t. ;�T:11 1 ii, �`�3S'° ••: ri'' �.,, 4�rl{ya S,.... r 'ltv, t(, f{t a ', ' *y,p'v;.}� +. v L fad Wy r r� lY' I �y, • ° 14 iiia r ki t = r\� .. m % ay.; .t.,\,.....ef r:?E : tt,�lii —,... f y,_ s Vit. i . t ��.` .. . .iw� 'i. ', `*-.� i , ` - 'r • '., T4s f f{�l “- Y *.,-1-•7. 1 ..*4,.:."-..,4 .�-:�, "'y ��•�' �'. � .kms ,'.�qc,�..'r�- 0jq S'-; .ry''p''wy`, . r`r ,10.p.:: i '. 31 1" 5�' `tit.rfa,.`lg ,els A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE-LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 21 #238-22 inch DBH California Bay Laurel—Significant decay in lower trunk and new house will be potential target (also for sanitation reasons) °+ H ( x -.� s' it k 3 ' { d /a ',ry 0,./i F} ...;:i;;;',1: y. s • w '.,a iX27 A, xyS t44.4,----- ":"•; ° -;x t -. +r t�a Dti. r .R-.-,i.2, ., . - ti +J�`'_.. �L{ r:t ark -fY•C`c - : Recommendations for the Removal of California Bay Laurel Trees for Sanitation Reasons: Thirty three California Bay Laurel trees located on both parcels are recommended for removal in order to reduce the risk of transmission of Sudden Oak Death Disease to the desirable Coast Live Oaks on this site. Some of these California Bay Laurel trees also have decay in their lower trunks and root collars that could predispose failure (see the tree condition notes in this report and in the tree survey chart concerning those trees): #16—12/15 inch DBH tree #35—17 inch DBH tree #44—17 inch DBH tree #66—8 inch DBH tree #71—14/8/8/7/11 inch DBH tree #85—9/6 inch DBH tree #97—15/9/10 inch DBH tree #99—15 inch DBH tree #106—13/15/18 inch DBH tree #121—6/7/13 inch DBH tree i r ." , k "e1. ./� \t1 k4 �'+ t \ 1 11 . 1 -,-,,..--:-.0. `' , . A. �A -,r-, ..-L,,,,, .~'•fie scr. \`l� J / s', :::-.7-- i 1 � �`i C� 7 w , )k.�e�ti�� .,+t w. t L • 7f r 3.{ M t Y� ..lc,F�.%-.:: ft� ..ti �l''�fy�e„cy --',i',,;1.4.14:?:-: !t Ea /°%1 n ,,><~. r r,:t,4 t,�;r ck &'I 4 ,..._,\ cz".-4,:ziets ..; -. 1. 710,,-.... .,,,,.!-!.,:.2.ri:P ':'7.-e,.• :.:,-V 6 - c 1 p + M #126—16/16 inch DBH tree #132—12 inch DBH tree #146—8/7/11 inch DBH tree #152—8 inch DBH tree A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 23 #l6I-8/9/8inch DBHtree ,...3...,...5:;,,,....,,,:,.::..?„..i ..,.„.../.e,;,„„..v..., , ,47.....„,..,„....„,;,;.... .....,.. t:......i. ' #168—7/12/9 inch DBH tree * W. ;,,.,...,,,c,..,,34..,k::-..k.;1„,-.,ii‘qt1:2,e.g. . t. .7z-ris,'.4!...,.;tk-0,,",,.---,..-.9.,:f1.,':' ..1-3•14,1424,,i6e41_,,z;fr.'ft,,..'", ' — 1. #173—8 inch DBH tree #l79A—l9inch D8Htree #193—15/17 inch DBH tree #18S—lOinch O8Htree #I96- l0inchD8Htree #199—10 inch DBH tree #212-8inch D8Htree A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 24 #2I3-7inch DBHtree #2l6-2Dinch DBHtree (and signiDcantdeuoyintnunk) T'' ;:,uiwa,v.,. 1, :07-:',..'.4,1,0,1,11,t 0 ..xyl.01.4.,0,4 ,4 ...;''i'f,-:`,1,,,j‘ 44 ( t :.,A....irLit,5..b"--;-•;:.:'.;-!,tf;-/A\ .i.',.,,,,i0%4`.::::,.*;:ic,:;,`:-n.,t..*:-I'f;i:17.,'.4:.V„ if - _to _ j * 4 , _• .....*, ir-- "Ittv,smot,...,rt,_,-.Kt,l'-;%,-'r,,,,,•,.."4':'- -•:.'41:7\e''":$,.....1.-: ' �����;rJ �������� ' ������ �m������.��� #216—10 inch DBH tree #220—11/17 inch DBH tree #222—11 inch DBH tree #Z3O-6/8inch DBHtree #257—16/17 inch DBH tree #Z68—Qinch DBHtree #259—10/8 inch DBH tree #261 10/16/12 inch DBH tree ASURVEY OFTHE 3IGN|RCANTTR[E LOCATEDVV�H|NTHE PROXrNnY0FTHE[ONSTRUCT0NTVVOHOK4B ATZS7OOBASSETTLANE —LOS�O�SH|�� visitSite byNige| Be|ton'|�A[e�� ed ArohWE-0410A PaQ�ZS Recommendations for Tree Protection Fencing on both Parcels: Tree Protection fencing must be installed as specified on page five before any site work proceeds and equipment comes on site. Install fencing as shown on the attached Tree Location map. Provide a 36 inch setback distance for the fence from both sides of the driveways and the parking/turn around areas to allow enough space for construction and the installation of required form work. Provide eight foot setback distances between the locations of the foundation footprints of the houses and garages and the Tree Protection Zone fence Locations where tree canopies encroach within this space. Where the protected tree canopies are located further away from this minimum setback distance, place the TPZ fencing at the edge of the canopy drip lines in order to provide both adequate tree protection and enough space for construction work and the storage of materials. The project arborist must mark out the TPZ fence locations with the contractor before this fencing is installed. The arborist must then inspect and document the installation all TPZ when installation is completed. Note that the town of Los Altos Hills must be notified three days in advance of any demolition and grading work in order to inspect and approve the TPZ fence installations before any site work commences. Preliminary Recommendations for the Installation of Underground Services: Note that I reviewed the preliminary plans for new underground utilities, drains and sewer service lines on both parcels (Proposed Tentative Lot Improvement Plans—Sheets TM3A and TMB3—Prepared by Lea & Braze Engineering, Inc. —3/10/2015). This report makes general recommendations pertaining to alternative routes for these underground services in order to reduce the number of encroachments within the critical root zones of the protected trees. The report also makes general recommendations regarding required root protection and pruning procedures during trenching work, but does not provide specific recommendations for the protection of individual trees during these procedures. Such recommendations should be provided as an addendum to this report after the final locations of these services are determined. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 26 Recommendations for Parcel One: 1—Cable Television Service Trench: The preliminary plans show that the Critical Root Zones of four trees will likely be encroached upon by this trench which will access the west side of the house (Tree's#95,#96,#101 and #119). I recommend that this service is routed within the driveway footprint and turning area to avoid trees locations. 2 &3—Sanitary Sewer Service and Gas Lines: Both of these services are shown as being located in close proximity to each other on the east side of the driveway and parcel. The preliminary plans show that the Critical Root Zones of eight protected trees will likely be encroached upon by the trench required for these services (Tree's#88, #84,#81,#108, #109,#107,#80 and#87. A number of these trees are large established Coast Live Oaks. I recommend that these services are routed within the driveway footprint and turning area to avoid trees locations. 4—Electrical Service: This service accesses the west side of the house and will encroach within the Critical Root Zones of four trees as shown on the preliminary plans (Tree's#144, #145,#143 and 3142A). I recommend that this service is routed within the driveway footprint and turning area to avoid trees locations. 5—Water Service: This service also accesses the west side of the house and will encroach within the Critical Root Zones of four trees(Tree's#131, #129,#124 and#125). I recommend that this service is either routed within the driveway footprint and turning area to avoid trees locations or the route is changed to go between Tree's#125 and#127. The final location to be determined on site. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 27 Recommendations for Parcel Two: 1 &2—Cable TV Service and Sanitary Sewer Services: These services are shown as being in close proximity to each other on the preliminary utility plans. They both enter from the street and access the house from the north side of the proposed driveway on this parcel. The Critical Root Zones of nine trees will likely be encroached upon (Tree's#87,#83, #79, #79A, #43,#45,#42,#41 and#12). I recommend that these services are routed up the driveway and through the turnaround area to avoid as many trees as possible. 3—Gas Service: This service is shown on the preliminary plans as being routed from Rhus Ridge Road to connect to the south east side of the new house. The Critical Root Zones of five or more trees will likely be encroached upon by this service (Tree's#211,#202,#201, #203 and#204). I recommend that if at all possible this service should be routed within the driveway and turnaround area on the west side of the house. Otherwise care must be taken to mark out the route of this service trench with the project arborist to avoid encroaching too far within the Critical Root Zones of protected trees. 4—Electrical Service: This service is shown on the preliminary plans as entering Parcel One off Bassett Lane and proceeding east parallel to the cul de sac. The service then enters Parcel Two from near the street and connects with the north side of the house. The Critical Root Zones of 11 protected trees will likely be encroached upon by the trench required for this service (Tree's#147, #148, #151,#155, #158,#166,#165,#4,#5,#3 and#2). I recommend that if at all possible this service is routed within the driveway and turnaround footprints on the west side of the new house. Otherwise,another option could be to enter directly off the street near Tree#259 and staying at least 10 feet east of Tree#172 to connect with the north or east side of the structure. This option will also serve to minimize potential impacts. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 28 5—Water Service: This service is shown on the preliminary plans as entering Parcel Two from north of the end of the cul de sac and proceeding southwards to terminate at the east side of the new house. The Critical Root Zones of about 15 protected trees will likely be encroached upon by this service as shown (Tree's#264, #262,#260,#263,#256,#255,#251,#252,#250,#254,#253,#249,#246, #245 and#244). A number of large oaks are situated in this area. I recommend that if at all possible this service is routed within the driveway and turnaround footprints on the west side of the new house. Otherwise,another option could be to enter directly off the street near Tree#259 and staying at least 10 feet east of Tree#172 to connect with the north or east side of the structure. This option will also serve to minimize potential impacts. Inspection schedule: This development site must be inspected by the project arborist before and during the construction period at the following times: 1—Meet with the tree removal and pruning contractor to identify trees designated for removal and discuss the scope of pruning work. 2—Inspect this site when the Tree Protection Zone (TPZ)fences have been installed after the tree removal and pruning work has been completed and before any demolition,grading and construction work proceeds. 3—Inspect the site any time utility,sewer line or drainage trenches encroach under the drip lines of protected trees. Provide guidance and supervision regarding root protection procedures. 4—When excavations for the construction the houses and surrounding infrastructure such as the driveways,turnaround areas and retention areas encroach within the canopy drip lines of the protected trees. A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 29 Please contact me if you have any questions or require further information. Respectfully submitted Nigel Belton Attachments: -Assumptions and Limiting Conditions -Tree Survey Charts -Tree Location Map -Sample Tree Protection Zone Notice - ISA Pruning Standards A SURVEY OF THE SIGNIFICANT TREES LOCATED WITHIN THE PROXIMITY OF THE CONSTRUCTION TWO HOMES AT 25700 BASSETT LANE—LOS ALTOS HILLS Site visit by Nigel Belton-ISA Certified Arborist WE-0410A-April 20,2015 Page 30 1 A s 111 FELDMAN ARCHITECTURE .T .....r7.1.''=-.-...'''',....,„. fix.42 7 �-• • • •• S''' : ( ,• ,,� �• :. ,� E1/4,. • ;� _ l / TREE PLAN LEGEND N D • .! :Ill / .x \ � I6..... ..%N.,.........,.......,•;;•/": ".`i 1x1 , --- PROPERTY EINE SETBACK , I MAT IINF\ jI /,... - . ...JET SETBACK .\ j )r �\w\ _ y S ' STORY E aEOIESRMI EASEMENT EARTHEN uF _ � IN,WADING l � _ 121 PAVED•RER 120 . ill n 41 1irliiiMI'... - fY :e. TREE. t� ti /(�L''� • IEI OM TREE TOM PRESERVED IfIf x)1 ' . e ' I t . TREE• az m • ,i,---- T- -_-_-. -` as f 1 •44 IEI TREE TO GE PRESERVED • ` I17/ •� _ 7/ I e TME• // 21 I 10: \1 n• / 'i �• I X vNDlti Tr io RPaoPoeE�O ORrvEwO ON 1 ( • TURNAROUND OR MOUSE EooTnnr l TREE wI �y�iwl ri )/ IE I TME TO EE REMOVED I • //I\ /• I X FOR ENRATION PURPOSES 1es u 14.2 = `• • 42r'. 1.41 • / .z. zi>\ 1 PROJECT ll M - Proposed Subdivision SI n al• n =F �•, a,n • //1 iEEIETIMO TREES • 05/00 Bassett Lane I \ I txe I / BOAK ER TELE Los Altos Hills,CA S .......... TOTAL: ITS / L ST 74 21 so T; axx =•x ,• \ n: 227 1 / Existing Tree Plan \ ? .: Pi • f...: .. ..`.. ..!z zaiMi •724 4 i RHUS RIDGE ROAD DAT E 1'�I,1 _Ed\�...� 0303 0016I� .7- y 1 #� ®�ELDMAN fry •RCMITIC TURi • 133 / ,,;;-=r,'-� \ TREE PLAN LEGEND f/ • - PROPERTY L. f • // (///l ,>, FAULT LINE //// / v/�i :. '^ I '.\ tlf EALAT SETBACK . / • pTMY DRNINIK a EQUESTRIAN EASEMENT —_ ,,:--I EARTHFnawA E /'• ;; 11\ I 1 IMI SDEDRN. / (/ %/ ' III x., RAVED AREA // / i It r / //"/ / 11! TREE/ j 11 / / /E .7 1i:n jJ; L • IEI OAR TREE TORE PRESERVED I 1 a / „ 11 1' / // 1 I 11 1• LREE• 11 1101// j // 243 + Il / I I I 1 • 1�// � r 1 TR TREE 10 pE PRESERVED I •i 11 ;. • ;/ ---/____ __- �` L•';'0iT •••;,////- it.o I LREE• i a 11 100 • / /// -rY fx• �•1 1 , 7 r / • - `- / 174//./'' X 1,TREE TO OE REMOVED BASED A• 1 --7.1.111111111111,41111 -7'7,. / 3131113.1311311 iO PROPOSED DRVFWAY I • 11 ( �/�:s TURNAROUND OR HOUSE et%ITPRHT 11 i•e • / `vrn,l-' r TREE/ I 71' al • • r IEI TREE TO eE REMOVED we ee I1 /// I /l� • • x MR...EATON PURPOSES I " II L._ // ri>\ / /�: ,;t,/ 164 PROJECT •'-�1 T-ir' �• 37''�� " Ito- i I ►PRpeRRd Subdivision 11 w- /L I e, II a •.".....'... >< -_-'_\ \ • /2'Ixl,l PROPOSED TINES TO KEEP L/oo Bassett Lane '•'�L'r�• • III �/ 1 j {iR!{► aos Altos Hills,CA 11 . 13 � _ moo _ j /1 n. I I n 1e r�jk- / 11 PARCEL 1_ i 11 . ". re I OAK.. ..O E, _ i M • 217.-----2:::;••;:"Z:,,,,,„‘, , 2.. • .K, ,.:,,,,I.,,,,...;..:... Lh /:' n v w I ! TIT-_ 0/ '/ st ex xn m• � ,07 �.�.s., a Di-THEIR oz Proposed Trim �.- -�'• 1\ TOTAL 1 �t __ . /• .3...69,, 20.1 • `` PROPOSED TREES TO REMOVE Driveways er /a r.l/ia ee /o s• • DRIVEWAY ra, .Ar=_ RMUS RIDGE ROAD `� .iE/� �x0e/' �•(i,+\\ PARCEL 1 __..__...... Removal Plan ` •`•• .' [[[ , t OAN _._'...—� o3 o9 aot6 1 7 \ OTH[R 0 /• •` }L\ PARCEL r 7... ..../.. ti OAR 6 j OTHER I 1 /• \ TOTAL. t 7 \ \ i 2 I � � rELDMAN •RCNIT•C TURK 44,0 Z(.113 • • :- J / ,, = TRE PLAN LEGEND )` j• 'a'• •••• a r `/M t•33-11p \[ •••••••' 41/'. .41/'.' eel PROPERTY LINE ' /r r.:••• e a fAULi LINE •\- /• p •• ei �' ° \ SMACK _• FAULT SETBACK • STORM DRNMAOE E COUEBTRIM.EASEMENT ta, 112 • • // t� aia''' : 174/1 %/' Vii/ MP; 114 I' PR N ti JaOMI • ' t. r ii �• I1. J PAVED AREA / im I71i // /I TREE• tt 7, ; • IFI OAK TREE TO RE PRESERVED I/ ii _,y. , L.. 1 • I 'F i r / ./ 2„4- TREE• '1.1 110 107 • • r• / ) ` • MEI TREE t0 BE PRESERVED .1 I—e•r_ r I.° • • • 11 ,Fe /ra T TREE • • I • t 1 1 _ ° ` �•.-(( 1 • X TURNAROUNDEPREONOUSE POOTPR+1 i ,• TURNAROUND ORNWSE fooiPR Ni • 11 1^ /• x / x TREE .11 I JF r/I r• ' Ft `Ei TREE TO BE REMOVED II I • •. X OR SANITATION PURPOSES + • . f/ • ao ' r i P° , , ,• T x/Y + 1 aa, ,s tea'• �_... ' .I I Proposed Subdivision a. : �� �../ a /_____~–\= /uimt) PROPOSED e57oo Bassett Lane �� �1� Los Altos Hills,CA If t I I t 'I t1 • '' IY`':'"-q rad _ 1e II GRR A - 7 n x ,> s-"�'J• ��a.,•. II OTHER 15 Ir 'a it eT •.s��� • N • arlrR TIT_I Iv sJ :aa• '•ono y.\ '11 OAK toe �� . 1' �•• \;0:1,,, ,n I=27 ' at_— Proposed Tree 22.117 PARCEL: '5„,.." ^a RemovRl Plan • .�A•• �.• TOTAL• me TLIn STDUnd1 17 •/•' '\••` t't V/ PROPOSED TREES TO REMOVE ._ as \ 444 — • t '•'>.a • • DRIVEWAY TURNAROUND TOTAL • RHOS RIDGE ROAD •, "aTPARCEL 1 '- eo e+ • / 6V 0 1 o a � OTHER 0 3 o3 1016 PARCEL S –... / J \ OTHER t _ 1 2• j•/ \5`\ TOTTAL'. /..-. * • 3 ELDMAN ,,\ B ARCHITECTURE ••••••••\\ ,4, %r • 1517 1.. 501,2 • m j / TREE �~ ,--; —ss:* PLAN LEGEND /• �•LNu • • • •/ y,I __� PROPERTY UNE '•\'• ii >< `` \ �b255 SETBACK MUT LIRE \• �%� !* max% ` u 1 I �•� FAME NTBACK � ',� z. ' //' _• // ' STORM ptNTµDEaeDUEETRUR EASEMENT _�_ ; 5•��,''. / ///' j:/' I '•e b. IRI EDEOeq / / " ] / 125,;//' ''' x.. ' // 11! I I PAVED AKEA %/1/j // / Ile f r // 175 11 i 11! TREES /1 1 ';I.1'4 i s /' Y ( 1. 1 1 175 if 1 (FI OM TREE TO KE PRESERVED IlL • ,s• K ' 15\K i z/i TREE. • / ', \� x ,0'• % ' I/'4:(''' l • (E.TREE TO SF PRESERVED lTREE• 11 I --�M� / I I IT/',./ E{�" x io PROPOSED DAvewav wl w II I / • x 14r TREE. t • 11 I ' 1T • 5511 ( /• r' `o1pRc�.oN REMOVED x i 1 X MOVED ilii w ,:/ P• I o l i r .bbl --.`z A_k_ u Jj'1„, Prop..Subdivision 142 l • iI 51 •,/ x ''. r'''' a,.. PROPOSED TREES TO KEEP SFE—• ,....•••••••••••••• � 1 KEEP .5]00 Bassen Lane 1 I I • ��—__— _ /r11 , Los Altos Hills.CA t I I z.l I COX 53.. OTIeR! S • . uz v , 11----4,-7.'„,,,• n . >2 ,,s II NOCK II TIT__ n \.>'' ,o ,, '' :,,.a,• �1.�EYI OTHER _ 85 S7 -_ Proposed IRU r.../�•.��••-�.�..�1.. xu • °$ �,o`e�333Sllll; Removal Plan 204 I lit - 40 54 \ Building Footplinta 67 \ 1 k as ~` •. V I MOPPED i TO IIWOYe \ V\ rz+: NRISREIIM 131MRROIRp MUMS TOTAL PATE RHOS RIDGE PO,irO xs. `� fOMPINR► • ••--�•. N.,.).,i;r40,/,' OPR 7 0 tt 73 \ PARCEL e o5o5.18 jOPOe / r b j %• •'\ OTHER1 t n M TOTAL: T e a M • .../ \. \ 4 FELDMAN ElARCMITRCTUR. P ,/ 0A. . f S ep F ,w . Fl,,x or u ' -- TREE .-::::::::',"::.'Ir. PLAN LEGEND j , T „ firi<,' z• 131 Yom' ••�'7�r.. PROPERTY LINE SETBACK .......... ' h. \` S✓' FAULT LINE •\`\•. f � W_ u, �N��Y�:— I STORM pINMAOE IEOUESIRIM EASEMENT ' v _�Tf f','. "— I EARTHEN aWAE Ili ///'� \� ' 'Y� /.1 ... INI.IIeDWO / M if 13/2,,,,, ; � / '� ,... I I PAVED AREA IjJJ a// / - • %%/j/ X ii�I.�„ I_% I i" ••—L. ..y •' TREE. I/ I i W ��/ IEI OM TREE TOLE PRESERVE° I /,,; .� tl j E,�7 TREE. i ac . 102 • ` W1' I.N ;le �'% • >� _. '. I :4714.„,, +'Me /w • (EI TREE TO 9E PRESERVED a P a i S ` -.�. ....Z.-..�.- /j/ s •tN4•Ye TREE F { N 11 IIA % . / \ �,�1��} 2• jl 11 // 44.1%..!.. r'2. X (E)TREE TO BE REMOVED BASED ON 11 1 /� /=�1 MO ,TY TO PROPOSE°ORVEWAN, i 1 1 / K 1 y'►� TURNAROUND OR NOUSE FOOTPRNT TREE 1 {• // `% Y4P, • IE)TREE TO BE rrcM°vED M I I - - // ,1 / Pv• X FOR 6M.TAlON PWPOSEE w "_.►1 .;,1. ...._,,.15/1 , '�.»"y `i:t'e� .i If Proposed Subdivision II ,.1 / ••-' `% PROPOSED TREES TO NEEP rr -II •N /x✓' „ Ct n. xN xJ, 257o°Bassett Lane 11 • aE - if '% ,;1b KEEP Los Altos Hills,CA u Gi-------A _ 1 • 11 // ,:„.:„...„...,......3,0,..... � x a, xl Ex A, OAK BI.. I~ �/� , x 7_...,_... +. /t MRCEL x TIT__ J} _ ♦ OAK -. IIV......".2"' yx ' • }0 IT•-Rm �. Y. 1i T r— x,1"';11 •11,1 I OTHER J7 Proposed Tree % y��•���••� 1,r ft♦ 30l r N Removal PIM xls{.,�� l; ,,.1 TOTAL MS ✓w �� • i -.�x _ Tree Removal Plan presented 16 E,1 /xi at tura Planning Commission .i, Hear I PROPOSE°TREES TO REMOVE 'ng '- • �xi. ' i NO ORNEWAY TURNAROUND o.... SANITATION TOTAL RHOS RIDGE ROAD as. FOOTPRINT DATE F ` •�� PARCEL 1 .l\� rOAK ___. D _. 11 . 17 o3 o3 aox6 Mme.•,. OTHER —.- D __. :- 507 E...._._ PARCEL 7 OAL S 1 21 OTHER1/AL: I x 11 Sr tt. • ` 5 \ III NFELDMAN A R C II I iii. 91194. Sgt •r titssktir .°;<4..._. ct w 1•i 31:7".„:„...........4,43.. rs "� 4.$.�. e :;.% '' x r:-.1)S> : 'l' EE S .K % A ,• TREE PLAN LEGEND tE1 14191 w i.f0:'Vi I` 4 1 x ' _- �� �;` faE.1.1A j�K �1 PROPERTY LINE IIn 'r��j �/ w ' `• '. se SET61 TI Ia fa r 1 IX N ` I % /'/ ;`` in 1.{..Y++ ,� psimimmilmo. FAULT UNE t rLr.rr _.. Rn, MO, /i We )J� ,dY�!a,�'• -•- FAULT SETBACK tLL999�� 1 " /-/ 1 `/' ��''''..?...•"..'''''T' `. n, y��t STORM DIW1NDE a EOUESTRAN EASEMENT S 1// LL♦ 4.-, xz swAlE T a /r';'„' nv ' I ' .. w a // 1i1�.rr .Rc 1.� a ii 1i1••❖ euaoma am lE. �// / MS $ •• i a ''i;4 � Pl•VI TREES /10. /1 1 a // 7 ,S •.L. 4.1 /�A • IE)OPX TREE TO BE PRESERVED all • II 11 1 / T% ' •.��.�lS �♦.' TREE• I Int Y• a/ W / 1 /ta (El TREE TO BE PRESERVED 11A.. ., EE. RE IE)TETOSEFEMOVED SAOEDOe ��„/•...1 1 �- I/�^ I I�J. 1M- 1 �� . k x TURNAROUND OR ROUSE FOOTPR Ni A.so 1 ' aR a R//,' / Y. %�7E. - 1/ • TREE S Is 1 - / - I % / EI TREE TO nE REMOVED / 1 // X FOR 0221107 ON PURPOSES \ 91 111 11 11 1 141 si II 37 .41 � sir _ - //.....17--,'Ll. .�' a la '1 ProVawd Subdivision n ee I �..�/••11 •s ' of % ay EltI PROPOSED TREES TO AOO BACK x5700 gassed Lane PROJECT ie _ • K .".1.1111 (1:1; 6 La DRIVEWAY Los Altos Hills,CA ..ir"' `YTe1 II xr 21 r« --- �-- :: - 1 OTHERLt i _. ; -/ .ef-`' el Sl! tall k OAK -- a t'l s/ u zz x • `��sw+• �1 OTHER [ �: 1l Er' uf' '-� it L PARCELS TIT__ 11 t" ,•sAa 1I OAK 10 ,I to x xxz -��io . ass ♦� • .. s r`.�-,,:":5-1'7,:, --zR2 1✓ el na ♦z♦ , OTHER s Proposed Tres v �/• �.. xs x„ al \� 41movJ Plea u a II s TOTAL: M. '" �� "' Revision n presented at&a Plan a - :o• :, ; Pan- ning Communion Hearing M '4171..7. SR x xi ,,..��6.... .i a a �F" RHUS RIDGE ROAD •` T •y:.,y' ti�' DAT e �, o3 D3 sox6 ' ''''‘..".."...."....'". ................N\ a �,'."S 1. /fI tom:-� 1 6 1 �o� FELDMAN '1,, ,,\•• B ARCHITECTURE r- �- ,./'•••/ �`� \` 1910 .. 133 K.''4', 7 / i,1;::63'x..=� ----../.' / j TREE PLAN LEGEND %• tb f�•u,.: x a...„6„...6.-5,31;::63-71•"..... ., ``''. ° \ ./r !al ____ PROP..,LAE •/ 11 Fes, \` _' SETBACK /• '�`/ . X' x /// I{ FALAI LIME `,•\••\•. ,%i� a FT /116 / '':1',Z....... �'f`\• 1 !�T . • FM�IT SETBACK •••••••••• •• � • / STORY DRNIU0E 6EOLESTMAN EASEMENT ------'"7:1 • . EMi1fA 6WALE • : 'y;','':` ;' %' I. '�' IMI HAP. 111 , // , / �� • 11 I I PAVED AREA �, / , ;xx X // f • ,e //; i // , li i}0� // / !/ II! TaEEF !/ r ••e y IX /r I 11! I! ; X ,;/'''' / Ie i)I r�OAA TIES TOSE PRESERVED It E• a ,e r X . I itis '11 xf TREE ` /! I I X /• / // X �,\ / • c,TREE TOW 1'llfaElN® • ,ee rr ‘1-, /d1 t l TI „g, ,,...„,,, °, I I MTREE 0 _ _ � f /! I TE)TREE TO EE aEYOVED M6EC ON 1 '��� / / �x_ ! / IPSO` X Mosuurtr T0816080E4-0 oRrvf v.r • • 1 I r I 11 TLIPxt,ouxo oA tout,FOOTPR M, I • I I l e 11, / �• x \ I I%j lxs I TREE' / el1 I 'Ill I .././ /! X I / /• I ' ICI TREE TO 9ERE6pvEo II 1 / "//// x I I'I`I • x FOR 6AF11IATON MYtNSE9 11 .:''•• I e , w as I .as al eI / 1: ! -AMP' .5 '' PROJECT • Propos sion II ;x ../ ;, A5700 Bassett ott Lane ax X.'' _____y_'__ K x PRO/MCD TREES TO BEEP a �,oj II] zs/oO Basset Lene I 11 — _____ ___ X_`�' • t II x I BEEP Loa Altos Rills,CA L1 _r�r,_�'�� ' IMC61 DTN�t lE ar w AWOL 1 .......69,�r • •.f 14 sI x!x 1 • 33 xI xx ne —ss-- I1 ' u 11 , ' xxx _ N I I 1 • '• sz .•• —xlr I x t de•- 1�. ° !, �i s' x,a a,axel ��+\I x OTIIfR PFopotad Tne u v s, �,.r••��.. "'.1. xIF x,. xsl 'dine 1\I' Wmevcl Plan • ' \`y/ Revision I • /•/ ~\,• ` \xx .+ PIIDPDEDD IRKS 10:1111111061 s . RHOS RIDGE ROAD —1.ORIYMAY ITDRRIIROUNO 9LIl DIMc SANITATION TOTAL FOOTPRINT DATE OW IN 66 •�•••��.. OM o 11 2 5 0303 mt6 F • ORAE D 0 0 0 —C �3'FiG'FW” .._.. PARCEL f _ OAK e 1 ;• TOTAL: 1 it 47 2 / 7 ATTACHMENT 6 Main Office: 1.ALEA & BRAZE ENGINEERING, INC. 2495IndusCAl9Pkwy 4545West Hay ,CIVIL ENGINEERS I LAND SURVEYORS Ph:510.887.4086 Fx:510.887 3019 Sacramento Region: 3017 Douglas Blvd.,Ste.300 Roseville, CA 95661 Job:2130851 CI Ph:916 966 1338 Dated: November 18,2015 Fx:916.797.7363 Revised: January 07,2016 Revised: February 11,2016 HYDROLOGY STUDY 25700 Bassett Lane Los Altos Hills, California . ,..-_ Pr . , . ,... .. . .. 1 . \,...?.......,..,„ .. . ..:.... .„try_.: 4 .7.....-. ._. ...: t:„...,.... .,. . , t .,.. . _....;.... . . ,..4...r.. ..._ -.„.4 4... ,„ *.e, , '''' , ->, •--”. - ' - r . . . ' .f r j,• r . - -, ''..4.-,Ve 'ars, Wm. .ifit ,,, ti nisII t (? K' ' r,.. .-.'" •M„'_ ter_= '.tilt l.e ,� x + '25700 Basse - cn., Bch 1 :14. v - le' 7.7-, •1' .\ fi. _y -'1,;°. fin. r. :+ �,�7�(� :".i...:;:-`,.'4 �h•'.••ki..., yk•s t. 'yam y '}, '�44 • T t+. 1 k- , A /1' !"f ... f'} 41-' I _ , s' •r 1m� iA hyo y P r s . LLEA & BRAZE ENGINEERING, INC. Main 495Industrial Pkwy.West CIVIL ENGINEERS I LAND SURVEYORS PhPh::5510.887.47486545 10086 Fx:510.887.3019 This package includes: Information Sheet Sacramento Region: 30- Hydrology Calculations Roseville. Douglas 5 .,Ste 300 Rosee ville. CA 95661 100 Year Flood Calculations Ph:916.966.1338 Fx:916.797.7363 References: Topographic Survey by Lea&Braze Engineering, Inc. Grading&Drainage Plan by Lea&Braze Engineering,Inc. Los Altos Hills Rainfall Intensity-Duration-Frequency MAP - Town of Los Altos Hills Drainage Design Criteria Santa Clara Valley Water District's Guidelines and Standards for Land Use Near Streams Project Location: 25700 Bassett Lane P/ • P.-•!-. Los Altos Hills,CA. `� •� APN: 336-43-013 o ,Site and Drainage Basin Informations ` 717Gross Parcel Size: 67,140 sqft. (1.541 acre) �9,c, •�- CIVIL ., Drainage Basin Area: 445,278 sqft. (10.222 acre) �''+4%CP Ta es`�,e�° $ydrologv Information: Study Information: 10 and 100 Year Return, 23.2 minute time of concentration (From overland and channel flow analysis) MAP Zone: Zone 8 (From Los Altos Hills IDF Map) Intensity(I): 10 Year= 1.60 and 100 Year=2.48 In/hour (From Los Altos Hills Rainfall Intensity Curve) Runoff Coefficient(C): 0.4 Manning Number (n) 0.30 Assessment of Drainage Basin: This letter and supplemental hydrology calculations are documentation of the assessment of the overland release conveyance swale located along the eastern side of the subject property and its impacts on the proposed landuse and improvements currently under review with town staff and the Planning Commission. It is our opinion this swale is not a stream,channel,nor creek and should not be subjected to the 25ft. setback per LAH municipal code 10-2.702(E)under the following observations: 1. The swale is not a mapped blue lined creek. 2. The swale does not meet Santa Clara Valley Water District's definitions for a steam channel or creek. a. Flows are not conveyed through a bed or channel having banks. b. There is no evidence of riparian vegetation c. There is no evidence of aquatic fish and or aquatic life. 3. The swale does not satisfy all three features and criteria presented in SCVWD Guidelines and Standards for Land Use Near Streams since the swale lacks hydraulic connectivity to an identified watercourse immediately above or below the site. A 100 year flood assessment was performed on portions of the swale nearest to the proposed residence. We first looked at the town aerial maps to determine the net contributing drainage basin for the swale. From there we used the rational method to determine flows for both a 10 and 100 year return event with intensities at 1.60 in/hr and 2.48 in/hr respectfully, a 23.2 minute time of concentration, and a C value of 0.4 since the overall area can be described as light density single family residential. Lastly, flood elevations were determined using the Manning's equation with a Manning's number of 0.3. Sections were taken along the swale to sample the varying swale geometry and slopes. Supporting calculations and exhibits can be found attached. The purpose behind the 100 year study was to better understand the swale's influence on the location for the residence.As a result of our investigation,portions of the residence were redesigned and relocated a minimum 5ft. from the 100 year flood limit to avoid flooding damages. Attachments: - LAH IDF Map - Zone#8 M.A.P. 23" - Drainage Basin Exhibit - 100 Year Flood Study Exhibits J A B C D F 7 or,0+ "5. 9s) N RD et \ 7 cHARtis g tf.?. „.„,,,srp, v , 6, ,....;, t.‘•,` i ' 44 * „st5.4". ,,.,.0..a 1 , 430.; ,t "N, 46, 4'At/4 S.0. •RS) r ''''''' DR ,,,0 lclaArrA 11 socv-„, rtr,, qb 1 mor4IN Is).64,_ •=1, (.14- <P\' t. 1.„ 4,g' 1 S 't # 4'> BREA,De, li• 4, , 'PR tt,p ALM 280 , . ,, '1,b r''' 0, '—‘..* \l• •*. 280 cr EN Rptl\... ) ...,"- ,,,5:P4 '900 JOSEFA be 1°1*Dcrt 0,RIMETER •‘ ,E 26700 _ ‘<<‘• 2 , 732J.0c*s&0,o.P'4L6v,,, 0''ti,x 3•-ey08`36114110,9"j-A,'NRER<PA co'11 0)lto 2e.03A'ti114o\-Isk \',4;, •' fee'C',.1t,.k0gt3 RD4 2R5D30FC0OO•O•L •TL#HEIGiLEiLP*v.v•.\*7W•W.AVI#I,1 r-DiF'.S'7 S4,TREO0IDLNE_._,T-_ ,,W , e4• , 2 25600 1NT R00 2 5 3 0 0 44, ‘....07, CT \4"\\-‘).' ' ‘1 6 4 t •S'.'' 4:4'0 '1.2[5 84 1,3:14- \-* -1 ovr woo c. 5\ .., CI 6 914,4, C T RD e cfrt ,.0.-- ,„ N.,., PROSPECT u, 4*- t cf) .,, 4 s "114,7°E1 Ay 3 )4t, 14 c,, g,5 3 4 c'i lir tic,,,.." mmn- (4 § 1400 "-""` - 8N1 u, x --) ., r-•\ t WOOD RD ,„ ON '0,„ °000 07 toil 1 a'-' ° „ '<NOLA., , ,Q , `' v2A° 2 701.)113a '§ettr-;En : ,„.... * '' /to <4, '' .-- , 6 , , DR .ESER VOIR \ U .. . -., ,.3 a • , _Y/ .. .3 ‘1 4,6i /BROOK 1 OD Tr, .... . * d'').' / N. /1 j/ ,\./:.N(/‘ 4 'I, ..... ' .."--5:-......:7:.:.-- ...,cHAN . ., 4 4 ..<,' ,, / /1 -1 • ..• ., ,,,,„.,.. , , ........ . V... — // C...--, TR ,. .: A, , , ........-, .,.. - I , 4 I I 'Pee Cr? . ..._ 6'. ) irk....\:\ ....../1/d.,---...Y '-':". .) '-- ''/if A100 \ 1 ---- S<C, 5 \.ic, C \ , \,.......„_.„ A , ........... •:•_\ . ) 7:9 5 ' .... ------.,_--, . ., RESER VP-LR" I '.., ,. A-vcoe _ ) 17 ,,../ RANCHO SAN ANTONIO OPEN SPACE A...., NEAdo ..--. -_4, IR ..... -...... c> iy-,....,.,_,..e,_ •x.1 ti( ---. HI 6" C --• •...." ......,--, ..-- 6 6 \ k' ..,, ( J 0 ft 1200 2400 ©2006 Rand McNally&Company -- ,, „ ,, (7 L..........1..6.1.....i — J A B C D 25700 Bassett Ln:Los Altos Hills,CA 94022, 831 -B3 LOS ALTOS HILLS SANTA CLARA COUNTY .r .., s • •,,,,,, : VP •..4. k 0. wr -A*4 ,, • , , v) ,,` O N .,♦.,. I 0 co , • •.e \ • v. ( '•, if ,, by 47 7 `( j I .A I. S ♦ •I,•'%ON tit,6 LK ',, Q W. R M.NT . F •,,'4, Si' , \ , ♦,• • ♦,,•, l� , ,,,,, • r .... . cr.._ , r s ,,,,, , \.0 # / t .,..„ # . 1,,,,,... i .., 4..; -. 4, \sc, s., tii ; ,, 4.,- „,,,,,, ,,,,,, , --, ..0......_ • ,.. , r, ' �1, s , , y••tri,, ''• Q • ��i •,,.• �• �� , Q 'y 4 • f jr•` Dr .�� v . � • ..(„ ' , .s'`, ,,, 1414r4A 4.rrel P. VP 11”. : 0-5\ --- :A1 _... .•fr A ,,,, YOMp-Hp —"1,01 -41,,.. j p0- SIIIPIRP –F1'r••ApfE po N S E R A A ` �•.� .4' -, Os, 1• ,• o ,,,,, • 0., • k,ri,....-- ',..„ -.D.'.,,r, 1 -'. ,iii*,"' 4 `, , fz.!!".74"" - ) ,,,,,,c CI-c---4-\ '4„, - , d 6 . ,,,, _ . 4 A, .4. A' l • .1- ,,,,, ^l ,• ' I,,''• '7/,,' , ,••i p� ADOBE CR. ,�, 5 O (`'� ••♦,• ;r,• A • r • , / •, �r� Y r9 ,' #5,4�,,,, 2 0 '•),,••,,,• C ,,� 8 C s,,,,/ ,• •,`•�,,♦' •N,,, I �P�.•/ , 0. II C- Iv •, • et ,� ,,,r 4, hq 97 '•. , f r 54 0 .,�,L7, iii.:,,,,, ,,,,, ,,,,,•,•, ',♦,,,,•r, ,♦,,,'•,•}4h�h� •♦I♦',•♦ ','•,• ^'��'' , �'••►I INTENSITY - DURATION - FREQUENCY ZONES PROJECT DATE 25700 Bassett Lane February 11,2016 LEA & BRAZE ENGINEERING, INC. JOB NO. BY 2130851 R.West CIVIL ENGINEERS I LAND SURVEYORS DRAINAGE BASIN TIME OF CONCENTRATION CALCULATIONS for 25700 BASSETT LANE LOS ALTOS HILLS Time of Concentration(Tc)by Kerby-Kirpich Method Tc=Toverland+Tchanel Toverland= Tol=0.828((L x N)^0.467)(SA-0.235) Length(L)= 677 ft (From Drainage Basin Exhibit) Retardance(N)= 0.50 (Retardance Coefficient for Lightly Wooded Area) Slope(S)= 0.1699 (From Drainage Basin Exhibit) Toverland= 19.07 min. Tchanel= Tch=0.0078(LA0.770)(S^-0.385) Length(L)= 1,320 ft (From Drainage Basin Exhibit) Slope(S)= 0.1477 (From Drainage Basin Exhibit) Tchanel= 4.12 min Tc(Total)= 23.18 min LOS ALTOS HILLS SANTA CLARA COUNTY INTENSITY - DURATION - FREQUENCY 4?s, { _ i - 3.5 +< _ , 3 �' M.A.P.= 23" .�` �.i ��` i ; � Tc = 23.2 min. 2 5 - _ __ �'�- 1100 Year = 2.48 in/hr ___ } W a. - , i 1 4 1 ! 4 "- 1,. - ‹ N-- Z N 1 .5 I I IIANb..khk. ' 'ir U 1 _ _ � „ ,:ss 1pp , 1 M.A.P.= 23” I 1 I '�_, �, I Cr z QTc = 23.2 min. -� I. � _ T - ? = W 8 1 10 Year - 1 .60 in/hr - i a . - I- i - !' i rp- Z .7t T T 1 Z 6 � I � Z W .5 �— F— I— 1 ' I W Z .4 = t t .35 i _ .3 5 10 20 30 40 50 60 2 H MINUTES HOURS--i D U R ATION ZONE # 8 MEAN ANNUAL PRECIPITATION 23" 1s333ws w>u 10 run LSC O-1 910410101101100 JO NIL 19103 L84 1001 1. 3111 111010 c1-.i 3nas 3.103 m 0191 Ko)1.10.400 Wad LALA O.900 9uuvrn�39.. 90 13015 499 31103 and no MN Vl m u) a//N M2 (u uoalw 9rMm1 l 1t WU 001 OW acrid 13111N13111N1.0110 10 14101241 9101003.1(3- 'a V sold'ammo Sac Oil OL 0 pm 00 w'� CG W9 (0)0090,11 Wad 01191 31•l 000.a :AI MOS (W 31102 101 4101 Ci111 Vl IOW) 3Wm W'l (U AIOo. 910V MIL Wu 01 V OW YV9 13 0101 a-.1 :ZN9s 0310141 lZ 0• /1 09 31102 3102 30904010 11 as:11011 3Wmv3 JO Waot 9.00YOd On)nnu ammo111 -.1-00 91x3 WAY md09�.30 A930I1)>�r CR91 (Y42)13a3)l.1 .114=4VIVI 1,019 119-013 19100.0•4110 910 1J L•11.1 :W3Ni11LLv.1 arIMOIN mol s1100UCa 991 as " _ • ' . ,00H1314 r.L.11 owsn ww iv]1.10.1111 I. DOM. -. '''''',744' ( +d ::VP ;ww 9 ..1 ' - t ,r 37,0, M" ri , L„.„,....,..;,/ - `, , I� .-'e" - '*" , M'. .4 r'' !.14 1"g' "' .,--4.- .✓ IJ• - - a 'd,a• ( ( ! ; f i { � f - .Jy. yI - . i.- - .in. . ) y , _ - - a: w. ,, ^ t 1Iily s wpt r f AS ,F*a1.9t �.' Y ,Gr •Y7 a. "pe fr \ -+ 9 )97,7,9 � Y-.F +w -,.' . • • . y . 4 1 m : _ 's r . wo• ad .# a •r ..>� s Z I � '�•`y . F pIf � e> r E 1 S.� .t.i.• - • ,r y - �4 • ,µ ti u d S '-r Cil -. :° nia I r1 '' f 1 1 �'' '' . ,,3 Lr - i 3 / 4. .ter'• c _ 1! # SHf�y V� I a .tt!/' 4; �y rtyp 'F , - /,� T .. ,�,�a'av,.• ti, *y�•`�l M 3 •... 1 x7,3 /3 iii r J �� + f ' C'•J ( - t rk r 117,11'... ,,.. �'.,��'t " l .3 ,� , , 1 '7.M 1, fir, ri✓ r -� $y113 l € \ sv"1 � ` .I. .r i �' ,.., ' �' +�— #C ' •� ..d, ,-.00 '.�' ?s\........s..::..<....} / i j err =�".� # f 'tie� ►e A ' °www !'s,''''' Ll.._,......,-v ., .mss�• 4 M..,, / i:: �,•. 11 w'' 11� .+I rte.\� -i� a} r��� ....'�1 1 '3� Arir �j.,.yam .r '''.4„•t` \•� fr.:4; .1 /,,rte`'~. f,Yf"f' e 1 1 ,,.-9-........... --„.......--_,..........., „,,,Ott?' 0 0 1 all a• 4y i.` IN��y u'F�j' y= //`• ; d�= v• :-'- s� fw 1 ' }� e NOTES EASEMENT NOTE Drainage Basin Calculations iilii NL on,we nos oe on r OT. o`w'en nus.s�ea anz REPORT .4 eO° .r¢r AHD oMN O a 6 ram. "Veer Trnz Given Input Data: (From Drainage Basin Exhibit) L WAHT rwcT no.4316-4415x:wwo -�- 60weoweeure MUT LOCATION MT J1•PO's sem , Time of Concentration(Tc) 23.18 min li r Is ONSIED OR z evoai 1 MOM FAT OOTPRINTS L ucc M- h 10 Year storm event '•e it r>j'•,- "�"�' SITE BENCHMARK ''-4 Intensity(I) _ 1.60 in/hr '444....'. , MASH FLOOR FLIVAIIMS ARE TN. , s "T pO0"MRp10s meoi g MGs v COwM.PONT T 10 year flow rote(0) 6.54 du arx"nw-suer 100 Year storm event k BENCHMARK (IMO ear -lzser Y iiA3 6_22.x. Intensity(I) 2.48 In/hr ��r Tow,o vas zeros vas worn on o-'zss•°5 100 year flow rate(0) 10.14 efe 3iR LOWED OI TI GTCR AT S.1T TE FD ROM VICINITYMMAP axe or,K me MY 6r su66r WOOD Row $ i.n.w �S i 2: °E"n "weoniouoo el O SCAM 1N6z .p�', Section A Flood Elevation Calculations Section D Flood Elevation Calculations R Egg Given Input Data: (From site survey) Given Input Data: (From site survey) 4 x.00 BP w.6• Shape Trapezoidal Shape Trapezoidal w 3 O-.e,n•43• Solving for Depth of Flow Solving for Depth of Flow 4 33pa 10 Year flow rote 6.54 cfs 10 Year flow rate 6.54 cfs * # YS 100 Year flow rate 10.14 cfs 100 Year flow rate 10.14 cfs a Ili9 Swale slope slope site.. 0.2530 ft/ft Swale slope slope site.. 0.2489 ft/ft -�6'.6: -� -_ - i°viu- Mannings n 0.0300 Manning's n 0.0300 ille / �' Sal:, Grade at flow line 537.20 ft Grade at flow line 523.33 ft i ' er";r Bottom width 0.00 ft Bottom width 0.00 ft -----7425 --1 Left elope 0.1054 ft/ft(V/H) Left slope 0.1414 ft/ft(V/H) § cs v Right slope 0.3418 ft/ft(V/H) Right slope 0.2586 ft/ft(V/H) // I Calculated Results: Calculated Results: W ____�- S ►dz7 M,_ 10 Year storm: 10 Year storm: // ., ' r r-� t , flow depth 0.36 ft(4.3771 in) Flow depth 0.38 ft(4.6042 in) /' i r 10 year flood elevation .... 537.56 k 10 year flood elevation.... 523.71 k M ii / ' J 1 �P 100 Year storm: 100 Year storm: Rr+z / !PARCEL �Cr f"r2w s•Ror.omundvr `1 Flow depth 0.43 ft(5.1595 in Flow depth 0.45 ft(5.4272 in) W g r 1p' 1 emu sv,. 1 DRAINAGE SWALE 100 year flood elevation .. 537.83 k 100 year flood elevation.. 523.78 k O O ' PARCEL 1 ,g/ "°°"°a t 0 10: 6.54 CFS E g�o r i / , , 0 100: 10.14 CFS 1.� /s: F 1; Section 6 Flood Elevation Calculations Section E Flood Elevation Calculations C '"�P ' 1 r Given Input Data: (Pram site survey) Given Input Data: (From site survey) p 0 r , i y, E yr 1 I Shape Trapezoidal Shape Trapezoidal O O i %' ;g1' I 5i Ei Solving for Depth of Flow Solving for Depth of Flow e-a i D1� 10 Year flow rate 6.54 cfs 10 Year flow rate 6.54 cfscm 1 1 , / `:;1 �D 100 Year flow rate 10.14 cfs 100 Year flow rate 10.14 cfs 1 "T --rte Swale slope slope site.. 0.2098 ft/ft Swale slope slope site.. 0.1750 ft/ft i : C i ' C Mannings n 0.0300 Mannings n 0.0300 1 1 LIMIT OF 100 YEAR STORM 1 1 r r ,�. Grade at flow line 532.81 ft Grade at flow line 519.70 ft 1 2 2 B , ' Bottom width 0.00 ft Bottom width 0.00 ft 11`6 i' H' \1 11 Left slope 0.0626 ft/ft(V/H) Left slope 0.0912 ft/ft(V/H , A ,4 1- Right slope 0.3420 ft/ft(V/H) Right slope 0.1743 ft/ft(V/F1; q IR `@4 11 i Calculated Results: Calculated Results: E 1 / / 1 1 l 10 Year storm: 10 Year storm: 1..1 11 T 11 Flow depth 0.32 ft(3.8655 in) Flow depth 0.35 ft(4.1863 in) Da \, \ ` / j 'l \ 10 year flood elevation ... 533.13 ft 10 year flood elevation.... 520.49 ft m°.'� 1e 111 ne¢ j �t 100 Year storm: 100 Year storm: P°fig w��"« 1 gig Flow depth 0.38 ft(4.3408 in) Flow depth 0.41 ft(4.7010 in) .��-» ` \ ; 11 I 100 year flood elevation .. 533.19 ft 100 year flood elevation..520.55 ft (rr.�� S, Section C Flood Elevation Calculations Section F Flood Elevation Calculations Given Input Data: (From site survey) Given Input Data: (Fran site survey) � Is \ Shape Trapezoidal Shape Trapezoidal 6b.. � wi�e. P Solving for Depth of Flow Solving for Depth of Flow ` t i ' OHO--mac ` ° 10 Year flow rats B.S4 cfs 10 Year flow rate 6.54 cfs ' --�- 100 Year flow rate 10.14 cfs 100 Year flow rota 10.14 cfs \� \ Swale slope slope site.. 0.2190 ft/ft Swale slope slope site.. 0.1481 ft/ft 6 n"u en K �•a2.°e E, �� Manning's n 0.0300 Manning's n 0.0300 /�.__ i `�'llrvlt� �'::4 Grade at flow line 528.52 ft Grade at flow line 515.80 ft 117.40.;19,P g.4,. \ Bottom width Q00 ft Bottom width 0.00 ft 5 0" 6// \h\11 Left slope 0.1016 ft/ft(V/H) Left slope 0.0813 ft/ft(V/H) - e a \a;.+d'r id'uA4 OF BtCN1AFrd: :. \ \1 Right slope 0.0920 ft/ft(V/H) Right slope 0.1035 ft/ft(V/H) nO1'Ot n, Or;o•.r,./:///: Aft:&9e--31-01, \\\ N11 1049 AL`. Calculated Results: Calculated Results•. ,a M 2130•61 i� ' 1s so ss wo 10 Year storm: 10 Year storm: e 03/10/15Flow depth 0.31 ft(3.6997 in) Flow depth 0.33 ft(3.9042 in) s^"•• 1•_sr SCALE: t"m91 10 year flood elevation .... 528.83 ft 10 year flood elevation 516.16 k aver WO PC Year storm: 100 Year storm: MT Ma I., Flow depth 0.36 ft(4.3610 in) Flow depth 0.38 ft(4.6021 In) E- 100 year flood elevation .. 528.88 ft 100 year flood elevation ..516.21 ft I of 2 SHEETS, ) /, I lII : | _ „ ; ; ! ! , lig ; \ „ i ! ; ƒ , ! , : „ „ | | ; | ; \ ai / ;; , ) t/ sl 9 il ,4\ `• )§ f� } f) - ) f§ " \§ _ 1.1 ` ® . L. d® \§ % _ 7- ' �� . i k1\\ -i /§ ; © j . _ . ; N )! : ; < „ : ; I ; ; N : „ E „ ! I , ■ � : , , . ; ; ; - \ ii 1.` --g , % \ § q § : .m ii 1 \ : A § / f2 h ) `] / ) § :; y $ :; , ) :; ) 1_ §�_ \& �\ : \\ -- a z. ; gi ill / §/ \ \ ® \ z ; . ] !. g :. ` / 5141 ;| i. ;� P - mU § ; | • z700sq�TLA4 a._ C. Gi � X © |4444, s�E EXHIBIT LOS ALTOS HILLS . r . , ,1 . SECTIONS CALIFORNIA Q \" ) ;! | , ; , . . , ®� - ( . ® ,