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3.1 Attachment 7
ATTACHMENT 7 SHUTE M I I--I A LY WELNBERGERLLP 3,96 HAYES STREET, SAN FRANCISCO, CA 94102 SARAH H. SIGMAN T: (415) 552-7272 F: (415) 552-5816 Attorney www.smwlaw.com sigman@smwlaw.com • January 20, 2016 Via E-Mail and U.S. Mail Suzanne Avila 'Planning Director , Planning and Building Department 26379 Fremont Road,. • Los Altos Hills, California 94022 E-Mail: savila@losaltoshills:ca:gov Re: Stirling'SubdivisionMitigated Negative Declaration Dear Ms. Avila: On behalf of the Friends of Upper Matadero Creek, we submit the following comments on the initial study and mitigated negative declaration ("Initial Study"'Or"IS") for the 18-acre Stirling Subdivision (the "Project") initially proposed by :the Stirling Family ("applicant").1 As explained in more detail below, the Initial Study is legally deficient. We have substantial concerns that the Project, as proposed, would result in significant impacts to the environment and nearby communities. In particular, the.Initial Study fails to describe the Project and the environmental setting in sufficient detail. The Initial Study also fails to identify and analyze significant impacts of the Project, including the Project's effects on heritage oaks, hydrology and water quality, local aesthetics, and wildlife. Moreover, the mitigation proposed for several of these impacts patently violates the California Environmental Quality Act ("CEQA"), Public Resources Code section 21000 et seq. and 1 The Town of Los Altos Hills has circulated a single document entitled "Initial Study/Mitigated Negative Declaration, Stirling Subdivision," which includes separately paginated documents entitled "Stirling Subdivision‘Mitigated Negative Declaration" and "Stirling Subdivision Initial Study" under a single cover. Citations to the "MND" are to the former section and citations:to the-"IS" are to the latter Initial Study and appendices. This letter generally refers to the Initial Study, which provides the bulk Of the relevant analysis. Suzanne Avila January 20, 2016 Page 2 the Initial Study completely fails to discuss the ProJect's cumulative effects. Because of the legal shortcomings of the Initial Study, and the impracticability of mitigating impacts that will clearly result from the Project, the Town of Los Altos Hills ("Town").must reject the Initial Study and require an environmental impact report ("EIR") in its place to fully analyze the Project's impacts and propose a full range of alternatives. As Town residentsand neighbors of the Project, my clients are deeply concerned that the Project will have significant impacts on the environment and the Town's failure to require an adequate review will leave the.Town vulnerable to legal challenge. Please do not hesitate to contact me to discuss ways to resolve the concerns identified below. • I. These Comments Are Timely, as They Are Submitted Before Either Hearing on the Project. PublicResources Code section 21177(a)requires that a person or group submit comments on an environmental documentsuch as this Initial Study "during the public comment period . . . or prior to the close of the public hearing on the project before the issuance of the notice of determination." The Town closed its designated comment period on the Initial Study on October 23, 2015, although its notice recognized that "[c]omments may also be made during related public hearings."Los Altos Hills, Planning and Building Department, Notice Of Intent To Adopt A Mitigated Negative Declaration.2 Section 9-1.514 of the Town Code requires a public hearing on tentative maps such as the Project at issue here, and the Planning Department has indicated that the Planning Commission and City Council both plan to hold the required hearings. Id. Accordingly, these comments—and any others submitted prior to or during the hearing—are timely and part of the record for the Town's decision on whether or not to certify the Initial Study and approve the Project as currently proposed. II. The Initial Study's Description of the Project Is Inadequate and Incomplete. "An accurate, stable and finite project description" is fundamental to "an informative and legally sufficient"review:of a project's environmental impacts. San Joaquin Raptor/Wildlife Rescue Center v. County of Stanislaus (1994) 27 Cal.App.4th 713, 730 (quoting County oflnyo v. City of Los Angeles (1977) 71 Cal.App.3d 185, 193). "The negative declaration is inappropriate where the agency has failed either to provide an accurate project description or to gather information and undertake an adequate 2 Available at: http://www.losaltoshills.ca.gov/documents/departments/planning/ stirling subdiv/stirlingsubdiv notice of intent.pdf. SHUTE MIHALY SHUTE, Suzanne Avila January 20, 2016 Page 3 • environmental analysis." City of Redlands v. County of San Bernardino (2002) 96 Cal.App.4th 398, 406, 410. As a result, courts havefound that use of a"truncated project concept"violates CEQA, whereas "[a]n accurate project description is necessary for an intelligent evaluation of the potential environmental effects of a proposed activity." San Joaquin Raptor, 27 Cal.App.4th at 730 (quotation and citation omitted). A. The Initial Study Provides No Information Regarding the Construction or Design of the Footbridge Crossing the Tributary to Matadero Creek. The Initial Study's description of the Project is incomplete. For example, the Project includes construction of.a footbridge across Matadero Creek for a publicly accessible pathway near the northwest corner of the Project site. IS, p. 14. The footbridge will accommodate pedestrians, equestrians, and cyclists and connect users to existing pathways in the area, including the Scenic Stegner Path. The proposed general location is a 75-foot wide pathway easement within the open space easement and in a dense thicket of arroyo willow and other riparian vegetation. IS,pp. 32, 37; see also id., Appx B. Habitat Assessment Report, Appx B. USF:WS CLRF Site Assessment Data Sheet. However, the precise location and design of the footbridge (e.g., length, width, and materials for span and abutments) are not yet planned and therefore not described or evaluated in the Initial Study. IS, p. 51 ("It is likely that this small foot-bridge will not impact the bed or banks of the creek or require the removal of riparian trees/habitats. However, because the bridge design is not yet available for review, there is potential that this project element could [cause] impact[s] . . . ."). CEQA prohibits such segmentation of a project. See Tuolumne County Citizens for Responsible Growth, Inc. v. City of Sonora (2007) 155 Cal.App.4th 1214, 1229 ("when one activity is an integral part of anotheractivity, the combined activities are within the scope of the same CEQA project" and must be analyzed together); Guidelines3 § 15378(a) ("Project' means the whole of an action, which has a potential for resulting in either a direct physical change in the environment, or a reasonably foreseeableindirect physical change in the environment."). Moreover, it is not possible,to assess potential impacts of this part of the Project on the creek, adjacent riparian habitat, or wildlife without the missing information. San Joaquin Raptor, 27 Cal.App.4th at 730. Rather,the Initial Study must provide a sufficient description of the bridge to allow the public and the Town to evaluate potential environmental impacts. 3 The CEQA Guidelines, 14 Cal. Code Regs. § 15000 et seq., are referred to herein as "Guidelines." SHUTE MIHALY -W'EINBERGERup • Suzanne Avila January 20, 2016 Page 4 A sufficient project description would include, at a minimum, location, bridge design, and information about construction materials and methods. Regardless of its precise location, construction of thefootbridge will impact the steeply sloped and wooded portion of the Project site that the Initial Study repeatedly identifies as environmentally sensitive and significant. See, e.g., IS, pp. 50 ("The project would protect the Matadero Creek riparian corridor for wildlife use by including an open space easement along the creek/riparian corridor."), 9, 14, 31, 39. Construction of the footbridge will bring equipment, materials, and workers into the deeply incised creek bed, with the associated risk of introducing debris and sediment into waterways. The Town's mitigated negative declaration for the footbridges constructed over Deer Creek for the Taaffe pathway illustrates these deficiencies. That document includes descriptions of the bridge locations arid design (e.g., length, width, and materials for span and abutments). Ex. 1 (Los Altos Hills Taaffe Road Pathway Draft Initial Study/Mitigated Negative Declaration), pp. 1 ("The streams would be crossed by constructing wooden footbridges approximately 20 to 24 feet long and 6 feet wide. The bridges would be founded on concrete abutments."), 22-23 (identifying impacts and mitigation measures for same). This analysis also requires evaluation of the Project's impacts on water quality during bridge construction. Any significant water quality impacts must be mitigated to reduce impacts on water quality during bridge construction through such measures as scheduling construction when water levels are low, using a protective impermeable barrier between the bridge work and surface water, filtering dirty construction water, and containing sawdust and chips from treated wood. Id., pp. 22-23. An adequate project description will also allow necessary analysis of additional impacts to and mitigation for, e.g., slope stability and biological resources. Because the Initial Study for the Stirling project never even describes the footbridge or its construction, it also fails to analyze any of these impacts or to consider mitigation measures. CEQA prohibits such omissions. Guidelines § 15378(a). B. The Initial Study Does Not Describe Numerous Additional Project Activities, Many of Which Will Occur in the Steeply Sloped and Wooded Riparian Area Covered by the Proposed Open Space Easement. The Initial Study also omits any information about construction of other Project-related activities in the riparian area that will be subject to a new open space easement. In addition to the footbridge and path discussed above, these activities include, at a minimum, construction of a drain running down from the stormwater detention tank, through the full width of the open space easement, to an energy dissipater and storm drain SHUTE MIHALY & -WEINBERGEREEF Suzanne Avila January 20, 2016 Page 5 outfall at Matadero Creek; construction of subdrains on Lots 5 and 6; anddemolition of an existing structure on Lot 9. MND, p. 1; IS, Appx. A, Maps 3, 7; Ex. 2 (Lands of Ko, Proposed Subdivision, Map 3 (Oct. 16, 2015)) (showing significantly longer subdrains than Initial Study originally indicated, extending hundreds of feet into the open space easement).The Project includes additional site improvements and activities planned for locations immediately adjacent to the open space easement, including remedial grading on Lot 7; construction of homes on all lots adjacent to the creek; demolition of a structure on Lot 8; and additional grading throughout the site, which the Initial Study never describes in sufficient detail to identify the location, area, or volume of soil affected. See IS, Appx. A, Map 3. More recent maps submitted to the Town after publication of the Initial Study also show a new retaining wall above the bioretention pond on Lot 7. Ex. 2 (Lands of Ko, Proposed Subdivision, Map 3 (Oct. 16, 2015)). The Initial Study never describes how any of these project components will be constructed, much less how their construction will impact this particularly sensitive portion of the environment. See, e.g., IS, p. 61 ("Site preparation and construction activities such as grading and trenching will result in exposure of site soils to the erosive effects of rainfall/storm water runoff and wind."). In particular, several of these components are depicted within the steep, densely wooded open space easement and the drain appears to be placed in or adjacent to a natural swale that the consulting geologist described as "an ephemeral creek." Ex. 3 p. 5 (Engineering Geologic Hazard and Preliminary Geotechnical Investigation Lands of Stirling Subdivision); compare IS, Appx. A, Map 7 (stormwater control infrastructure) with id., Map 3 (showing easement). Any construction or other activity in this location would conflict with.the Initial Study's depiction of this area as undisturbed and its resulting conclusion that the Project will have no significant impacts on the environment. See, e.g., IS, pp.3.1 ("The easement is intended to protect areas of steep slopes and vegetation located along Matadero Creek. This area contains high quality oak woodland habitat and riparian areas."), 9, 14, 39, 52. Theseomissions undermine much of the Initial Study. Construction in and immediately around the steeply sloped riparian corridor will cause impacts to, at a minimum, aesthetics, biological and cultural resources, geology and soils, and hydrology and water quality. The extent of grading on the site has further implications for impacts to air and water quality. None of these impacts have been disclosed, analyzed, or mitigated. "Where an agency fails to provide an accurate project description, or fails to gather information and undertake an adequate environmental analysis in its initial study, a negative declaration is inappropriate. An accurate and complete project description is necessary to fully evaluate the project's potential environmental effects."Nelson v. County of Kern (2010) 190 Cal.App.4th 252, 267 (quotation and citation omitted). SHUTE MIHALY & -WEINBERGERup Suzanne Avila January 20, 2016 Page 6 Accordingly, the Town must reject the Initial Study and require preparation of an EIR to consider all aspects of the project and all necessary and feasible mitigation. III. The Initial.Study's Description of the Environmental Setting Is Inadequate. CEQA requires that an initial study contain "[amn identification of the environmental setting." Guidelines § 15063(d)(2). Such "accurate and complete information pertaining to the setting of the project and surrounding uses" is essential to provide a.baseline for evaluating Project impacts.San Joaquin Raptor, 27 Cal.App.4th at 729. As such, an adequate description of the environmental setting is prerequisite to '.environmental review and cannot be added after the fact. The Initial Study completely omits information on several current conditions, however, including the presence of sensitive plant species or hazardous materials in the existing structures onsite. Each omission makes it impossible for decision makers or the public.to assess whether the Project is likely to cause impacts that require mitigation. A. The Initial Study Lacks Data on the:Presence of Special Status Species on the Project Site. The Initial Study acknowledges that state databases identify five special status plant species that may be present on the site, based on geography and site characteristics. IS,p. 39. But the record_contains no plant surveys beyond the brief description of the grassland and oak woodlands, instead stating that"there is low potential for five special-status plant species to occur in the `impact area'of the site (area proposed for development)."Id. at 32-33, 39. This statement is completely unsupported. Id. The same discussion illustrates precisely what is missing from the description of the environmental setting. Mitigation Measure BIO-1 requires that the presence/absence of Congdon's tarplant, Franciscan onion, western leatherwood, whiteflowered rein orchid, and woodland woollythreads shall be determined prior to initiation of construction activities. The applicant shall retain • . a qualified biologist to conduct focused botanical surveys,in accordance with current CDFW and CNPS rare plant survey protocols during the peak blooming periods forthese species. The surveys should cover all proposed impact areas, including the pedestrian bridge/trail in the open space easement area. SHUTE MIHALY -WEINBERGERLP Suzanne Avila January 20, 2016 Pagel Id. at 40. It then directs the applicant to mitigate for impacts if the protected species are found, including possible additional open space easement areas. IS, pp. 40-41. This approach is the opposite of what CEQA requires. See San Joaquin Raptor Rescue Center v. County of Merced(2007) .149 Cal.App.4th 645, 659 ("County of Merced") ("This failure to clearly and conspicuously identify the baseline assumptions for purposes of describing the existing environmental setting further degraded the usefulness of the EIR and contributed to its inadequacy as an informational document."); Lotus v. Department of Transportation (2014) 223 Cal.App.4th 645, 656 (agency must determine the significance of an impact before adopting mitigation, rather than "compressing the analysis of impacts and mitigation measures into a single issue"). Instead, the description of the environmental setting must disclose existing conditions, based on actual surveys during the appropriate bloom period, to determine whether protected species are present on the site. Without such information, there is a fair argument based on substantial evidence that impacted species may inhabit the Project site and thus could be affected by the Project. See No Oil, Inc. v. City of Los Angeles (1974) 13 Ca1.3d 68, 75; Friends of"B" St. v. City of Hayward(1980) 106 Cal.App.3d 988, 1002; Guidelines § 15064(f)(1). B. The Initial Study Improperly Defers Investigation of Whether Asbestos and Lead-based Paint Are Present. The Initial Study takes the same approach to hazardous materials, specifically asbestos and lead-based paint, as it does to the protected plant species discussed above. The analysis of Hazards and Hazardous Materials notes that both materials may be present in buildings constructed prior to 1980, including the buildings on the Project site that will be demolished. MND, p..1; IS, p. 65. Rather than ' documenting whether these potential hazards actually are present, however, the Initial Study again defers the required inquiry and directs the applicant to retain a qualified contractor to conduct the necessary "visual inspection/predemolition survey, and possible sampling,prior to the demolition of the on-site residences to determine the presence of asbestos-containing materials and/or lead-based paint."Id. Once again, this deferral of an adequate investigation violates CEQA and deprives both decision makers and local residents—including those living in homes adjacent to the Project site—of the required information regarding the environmental setting. This omission further supports a fair argument that there may be hazardous materials on the site, with associated impacts. See County of Merced, 149 Cal.App.4th at 659. SHUTE MIHALY -WEINBERGERLLP Suzanne Avila January 20, 2016 Page 8 IV. The Potentially Significant Impacts of the Project Require Preparation of an EIR. A negative declaration is inappropriate where an agency has failed to "gather information and undertake . . . environmental analysis." City of Redlands, 96 Cal.App.4th at 406. The Initial Study contains an incomplete project description and inadequate description of the existing environmental setting;thus, its analysis of potential impacts cannot be relied upon. Id. at 406, 410. Moreover, the Initial Study's findings of no significant impacts are not supported by substantial evidence in the record. See Sundstrom v. County of Mendocino (1988) 202 Cal.App.3d 296, 311. A. CEQA Establishes a Low.Threshold for Requiring Preparation of an EIR. It is well settled that CEQA establishes a"low threshold" for initial preparation of an EIR, especially in the face of conflicting assertions concerning the , possible effects of a proposed project. See Pocket Protectors v. City of Sacramento (2005) 124 Cal.App.4th 903, 928; see also Pub. Res. Code § 21080(c)(1) (negative declaration, rather.than EIR, appropriate only if"[t]here is no substantial evidence, in light of the whole record before the lead agency, that the project may have a significant effect on the environment"). A.lead agency may adopt a mitigated negative declaration only when all potentially significant impacts of a project will be avoided or reduced to insignificance. Pub. Res.,Code § 21080(c)(2); Guidelines § 15070(b). An initial study must provide the factual basis, with analysis included, for making the determination that no significant impact will result from the project. Guidelines § 15063(d)(3). In making this determination, the agency must consider the direct and indirect impacts of the project as a whole,Guidelines § 15064(d), as well as the project's cumulative impacts. See City of Antioch v. City,Council of Pittsburg(1986) 187 Cal.App.3d 1325, 1332-33. An agency must prepare an EIR whenever it is presented with a"fair argument" that a project may have a significant effect on the environment, even if there is also substantial evidence to indicate that the impact is not significant. See No Oil, Inc., 13 Ca1.3d at 75; see also Friends.of"B" St., 106 Cal.App.3d at 1002; Guidelines § 15064(f)(1). Where there are conflicting opinions regarding the significance of an impact, the agency must treat the impact as significant and prepare an EIR. Stanislaus Audubon Society v. County of Stanislaus (1995) 33 Cal.App.4th 144, 150-51; Guidelines § 15064.(f)(1). SHUTE MIHALY --WEINBERGERLLP Suzanne Avila January 20, 2016 Page 9 Here, the Town must prepare an EIR because there is a fair argument that the Project will cause significant impacts on heritage oaks, hydrology and water quality, aesthetics, and wildlife, in addition to those discussed above related to the inadequately described Project and existing conditions. B. The Initial Study Understates Impacts on Heritage Oaks and Lacks Adequate Mitigation. The Initial Study's description of the Project does not accurately or consistently describe its effect:on protected trees on the site. Notably, the Initial Study itself states that the Project will require removal of 22, 23, or 30 heritage oaks, which measure 12 inches or more in diameter and are expressly protected by the Town Code. IS, pp. 53, 17; IS, Appx. A, Maps 3 and 4; Los Altos Hills Municipal Code § 12-2.101. Further, the Initial Study maps conflict with the applicant's own Arborist Report as to the number and the specific heritage oaks to be removed. Compare IS, Appx. A, Maps 3 and 4 with Ex. 4 (HortScience, Inc., Arborist Report, Table 4 (November 2014) ("Arborist Report")).This continually changing description of the site and the Project's impacts on it creates enough uncertainty to require an EIR. See Banker's Hill, Hillcrest, Park West Community Preservation Group v. City of San Diego (2006) 139 Cal.App.4th 249,.263; Stanislaus Audubon Society, 33 Cal.App.4th at 150-51; Pub. Res. Code § 21080(c)(1). 1. The Initial Study Does Not Provide Adequate Mitigation for the Heritage Oaks that It Admits the Project Will Remove. The Initial Study finds the impact from removing the identified heritage oaks to be less than significant after mitigation. IS, p. 53. Butthe only mitigation applicable to the removed trees provides that the "applicant shall prepare and implement a tree replacement plan pursuant to municipal code Title 12, Article 3 for all Heritage Oaks to be removed as a result of project implementation." IS, p. 53. Article 3 makes no reference to tree replacement plans, however; in fact, the only "mitigation" for removal of heritage oaks that it mentions is entirely discretionary and places only an upper bound on the amount of mitigation that can be required: "The City Manager (or designee) or the Site Development Committee, whichever is applicable, may attach reasonable conditions to the approval of a removal permit, including, but not limited to, the requirement that up to five (5) trees be planted for each one removed:" Los Altos Hills Municipal Code § 12- SHUTE MIHALY '& WEINBERGER►L Suzanne Avila January 20, 2016 Page 10 2.306 (emphasis added).4 Under well-established case law, the Initial Study must engage in a.project- specific analysis of potential impacts and the effects of regulatory compliance in order to support a determination that compliance is sufficient to prevent significant impacts. See Californians for Alternatives to Toxics v. Dept. of Food and Agriculture.(2005) 136 Cal. App. 4th 1, 17 ("Compliance with the law is not enough to support a finding of no significant impact under the CEQA."); California Clean Energy Corn. v. City of Woodland(2014) 225 Cal.App.4th 173, 211 ("requirement that [a project] comply with the [applicable] Code does not,by itself, constitute an adequate assessment of mitigation measures"). Moreover, uncertain, vague, and speculative mitigation measures are inadequate to reduce the significance of an impact because they lack a commitment to enforcement. See, e.g.,Anderson First Coalition v. City of Anderson (2005) 130 Cal. App. 4th 1173, 1188-89 (holding traffic mitigation fee measure inadequate under CEQA due to vagueness in program for implementing required improvements). Here, the Initial Study must require a detailed and binding tree replacement program that specifies a minimum tree replacement ratio, the location of the replacement plantings, and a minimum monitoring, maintenance, and replacement period before it concludes that removal of the identified heritage oaks is a less than significant impact. The existing mitigation for the acknowledged removal of 22, 23 to 30 heritage oaks meets none of these criteria. 2. The Initial Study Neither Describes Nor Provides Mitigation for Additional Impacts to Heritage Oaks. The Initial Study reports only the impacts on heritage oaks that will be removed for the road and, in some instances, for slope stabilization. IS, pp 14, 17, 53. It fails to consider, much less mitigate for, additional oaks that may be lost or harmed as a result of subdivision improvements constructed within oak woodlands or close to heritage trees. For example, the applicant's Arborist Report identifies 13 additional heritage oaks on the new road extension and 10 additional heritage oaks along the access road that are at risk for:decline or loss because of proximity to the road. See Ex. 4, pp. 6-7. As the Arborist Report explains, oaks close to the road are at especially high risk of damage both because of methods used to grade and construct the road itself and to install utilities in the right of way and because many of these trees will require pruning to provide clearance 4 The Initial Study does not even mention additional provisions of the Town Code that regulate removal of trees, some of which include mandatory minimum replacement ratios. See Los Altos Hills Municipal Code § 9-1.607. SHUTE MIHALY 0--WEINBERGERLU' Suzanne Avila January 20, 2016 Page 11 . for construction vehicles travelling on the road. Id., pp. 6, 7, 13, 15. The Initial Study • discloses none of this information. The Initial Study similarly fails to address how oaks will be affected by construction of new homes and driveways. IS, pp. 52-54. The Arborist Report lists 50 oaks, 42 of them heritage trees, that stand within portions of the Project site identified for future site development (i.e., within or adjacent to building envelopes). Ex. 4, pp. 6, 11. Yet the Initial Study:provides no description of the effects of construction on these trees, nor does it specify clear and mandatory mitigation measures. Although.the Arborist Report recommends establishing protection zones for these 50 oak trees to minimize harm from Project activities, these protections are suggestions only and are not binding. Instead, Mitigation Measure BIO-8 directs that "the project applicant shall fully implement the protection methodology for tree preservation contained in the HortScience 2014 revised project arborist report. The applicant shall be responsible for the implementation of this mitigation measure, subject to monitoring by the Town of Los Altos Hills." IS, pp. 53-54. This general reference to an external document that is not even appended to the Initial Study is itself insufficient. See Santa Clarita Organization for Planning the Environment v. County of Los Angeles (2003) 106 Cal.App.4th 715, 722'(agency's analysis must be contained in the EIR, not "scattered here and there in EIR appendices"); Vineyard Area Citizens for Responsible Growth, Inc. v. City of Rancho Cordova(2007) 40 Ca1.4th 412, 442 ("The data in an EIR must not only be sufficient in quantity, it must be presented in a manner calculated to adequately inform the public and decision makers, who may not be previously familiar with the details of the project."). And even if this reference was sufficient, the Arborist Report does not identify clear and"fully enforceable" measures as required by CEQA. Pub. Res. Code §§ 21081.6(b), 21002; Guidelines §§ 15002(a)(3), 15126.4(a)(2). Rather, the Arborist Report includes six pages of"Evaluation of Impacts and Recommendations" (Ex. 4, pp. 6-11) and an additional three pages of"Tree Preservation Guidelines" (id., pp. 13-15), plus further discussion of additional concerns such as the risk posed by Sudden Oak Death (id., pp. 12-13) and the importance of annual inspection and maintenance of trees after completion of the Project (id. at 16). None of these measures are stated in mandatory, much less enforceable terms. See, e.g., id. p. 11 (table identifying "Recommended Tree Protection Zones for future lot development"), pp. 13-15 (Tree Preservation Guidelines include "Design recommendations," "Pre-construction treatments and recommendation," and "Recommendations for tree protection during construction"). In fact, the Arborist Report provides conflicting recommendations regarding several key protections. To provide just two examples, Table 5 (id. at 11) SHUTE MIHALY --WEINBERGERLLP Suzanne Avila January 20, 2016 � Page 12 specifies.Tree Protection Zones of 20 feet in all directions for tree numbers 62 and 63, while the table on page 14 specifies Tree Protection Zones of 35 feet to the northwest and to the dripline elsewhere for the same trees. Inconsistent protection zones are also given for heritage oak trees number 46, 64, and 66.Id., pp. 11, 14. Further, Table 5 recommends tree protection zones for heritage oaks number 82, 83, 84, 85, 86, and 92, whereas Initial Study maps show all of these trees are designated for removal for the slope stabilization repair. Id. at 11; IS, Appx. A, Map 3. These differences are significant as they define the extent of protections required on this congested site. There is no discussion of the overlap between these purportedly mandatory mitigation measures and other design features on the site such as,building envelopes, drainage areas, setbacks, and other constraints. Accordingly, there is a "reasonable possibility of a significant effect" on additional heritage oaks and oak woodlands, which requires preparation of an EIR. Banker's Hill, 139 Cal.App.4th at 263 (emphasis in original). The Tree Protection Guidelines in the Arborist Report also address only heritage trees along the road, and not trees located away from the road within or adjacent to building envelopes (i.e., those listed in Table 5). Ex. 4, p. 13. The Tree Protection Guidelines are flawed for the additional reason that they provide conflicting statements regarding prohibition of construction activities within the Specific Tree Protection Zones. Page 13 states "A TREE PROTECTION ZONE must be established for trees to be preserved in which no disturbance is permitted . . . .No grading, excavation, construction, or storage or materials shall occur within that zone." Likewise, "[n]o underground services including utilities, subdrains, water, or sewer shall be placed in the TREE PROTECTION ZONE."Id. at 14.Yet another provision in the same section totally negates this tree protection by stating that trenching and other activity will be allowed within tree protection zones: "Where encroachment cannot be avoided, special construction techniques such as hand digging or tunneling under roots shall be employed where necessary to minimize root injury."Id. at 13. These contradictions fall far short of CEQA's requirement that mitigation must be clear and fully enforceable. See Pub. Res. Code §§ 21081.6(b). Finally, the Initial Study states in conclusory terms that the more than 500 trees, including 285 heritage oaks, located in portions of the Project site not slated for development "would all be preserved on the property in the open space easement area." IS, p. 53. As discussed in Section II above, this statement fails to consider the impact that construction of site improvements clearly planned for this area, including the footbridge, new pathway, subdrains, and stormdrain.outfall, will have on this steeply sloped and heavily wooded riparian area. See IS, Appx. A, Map 7. Given the steepness and the high density of mature oaks in this area, these improvements will certainly cause loss of SHUTE MIHALY -WE1NBERGERLLP Suzanne Avila January 20, 2016 Page 13 additional oaks. See id., Map 5 (slopes on Lot 7 in area of stormdrain ranging from 30-55 percent); Ex. 2 (Lands of Ko, Proposed Subdivision, Map 3 (Oct. 16, 2015)); Ex. 4, p. 4 (Arborist Report, describing "dense cover of oak-bay woodland" on sloped portion of site). The Initial Study must evaluate impacts of all foreseeable development. It not only underestimates planned and likely heritage oak losses from subdivision improvements, but also makes the extremely unlikely assumption that no additional heritage trees will be removed for site development for nine new houses, driveways, drains, and other associated improvements. Without such analysis, it is impossible to understand the impacts of the construction required to build the Project, much less to mitigate those impacts to a less than significant level. A more thorough analysis is required in an EIR. C. The Initial Study Fails to Adequately Analyze and Mitigate the Project's Impacts on Hydrology and Water Quantity. The Initial Study includes virtually no discussion of the potential impacts to hydrology and water quality, yet it concludes that the Project's impacts in these areas would be less than significant. This conclusion isnot supported by substantial evidence and, in fact, the Project has the potential to significantly alter site drainage and the stream channel that runs through the property. While the Initial Study provides a general discussion of these potential impacts, it contains no supporting studies and only cursory data and it relies entirely on future preparation of a Storm Water Pollution Prevention Plan ("SWPPP") and compliance with existing regulations to reduce the Projects impacts to a level of insignificance. As discussed below, this approach does not comport with CEQA. In steep terrain like this, it is very difficult for projects to comply.with National Pollutant Discharge Elimination System ("NPDES") requirements, which is evidenced by the Project's proposed detention basins. Thus, relying on compliance with existing requirements is particularly unacceptable in this situation. In addition, steep terrain such as this makes remediation of unstable soils (which the geologist report:shows cover approximately 70 percent of Lot 7) very challenging. 1. ' The Initial Study Fails to Adequately Describe the Existing Hydrological Setting. The Initial Study provides no information on the hydrology and water quality setting. Without describing the hydrology of the on-site drainage and that of Matadero Creek downstream, the reader of the Initial Study has no context within which to evaluate potential project impacts. Perhaps most importantly, the Initial Study does not SHUTE MIHALY &-WEINBERGERLLP Suzanne Avila January 20, 2016 Page 14 provide any discussion of thewater quality of Matadero Creek and its impairment from diazinon and trash. Exs. 5 (Final California 2010 Integrated Report 303(d) List/305(b) Report), 6 (Santa Clara Valley Urban Runoff Pollution Prevention Program). The analysis must be revised to include a Hydrology and Water Quality section that adequately describes the hydrologic setting. 2. . The Initial Study Fails to Adequately Identify the Project's Impact on Water Quality. The Initial Studydiscloses that stormwater run-off from the Project area discharges into Matadero Creek and eventually drains to Mayfield Slough and the San Francisco Bay. MND, p. 2. Unfortunately, while the Initial Study provides details regarding regulatory requirements for water quality protection, its discussion of the Project's compliance with these requirements is scant. Instead of providing facts or analysis to show that the Project's water quality impacts will not be significant, the Initial Study provides only unsupported conclusions. For example, the applicant's plan to extend a drain from the proposed detention basin to the outfall into the creek will require construction within the steep slopes of the:open space easement area and in the creek channel, as discussed in Section II above. These construction activities have the potential to increase stream channel erosion and transport sediment into the creek. The Initial Study fails entirely to describethese construction activities, let alone analyze how this construction will impact the creek's water quality. Moreover, while the Initial Study states that the project complies with C.3 provisions of the Santa Clara County municipal stormwater NPDES permit, this statement is unsupported. IS, p. 69. The County's guidance on complying with C.3 provisions requires, among other things,"evaluation.of a project's effect on drainage patterns . . . to assess the significance of altering existing drainage patterns and to develop any mitigation measures." Ex. 7 (County C.3 Stormwater Handbook, Attachment II-7). This evaluation is to take place during the CEQA process, not after project approval. Id. In addition, the County directs applicants to evaluate stream crossing impacts, turbidity limitation:for discharged water, impacts of runoff on water ecology, and off-site impacts to channels. Id. at 2. This Initial Study fails to provide any of the required assessments. Having failed to analyze the Project's impacts on water quality, the Initial Study also fails to identify feasible mitigation measures. Here, the Project would result in substantial grading, moving thousands of cubic yards of soil. IS, Appx. C, Cotton Shires Geology and Geotechnical Peer Review, Stirling Tentative Map, August 20, 2014. Such grading activities on a site that has steep slopes and unstable soils is likely to result in erosion and siltation,.which would lead to:water quality and aquatic habitat impacts in SHUTE MIHALY Q�-WEINBERGERLLP Suzanne Avila' January 20, 2016 Page 15 Matadero Creek. See IS, Appx. A, Map 5 (development sites include slopes up to 30 percent,.and even greater in localized areas). The Initial Study never identifies or describes specific protective measures that will be employed;during construction; therefore, there is no evidence that the Project will protect water quality, much less reduce water quality impacts to a level of insignificance. Postponing the identification of specific mitigation measures is unlawful. Sundstrom, 202 Cal. App.3d'at 306-07. An EIR must evaluate these significant impacts and identify feasible mitigation to address them. 3. The Initial Study's Analysis of Flooding and Erosion Impacts Downstream Is Inadequate. According to the Initial Study and area residents, Matadero Creek is highly incised with oversteepened creek banks. IS, Appx. B (Habitat Assessment Report). This indicates that portions of the creek may be unstable. There are areas in the Town where homes are located close to the top of the bank of Matadero Creek (e.g., 2344 Old Page Mill Road,where the house is located only 10 feet from the top of the bank). See Ex. 8, p. 1 (Town of Los Altos Hills Planning Commission Agenda, Feb 16, 2006). Bank failure has already occurred in several locations in Town along Matadero Creek downstream from the Project site, notably where the creek crosses under Page Mill Road just north of Berry Hill Court. The Town is planning a major bank stabilization project there "to address erosion and bank slumping in the stream." Ex. 9, p. 35 (Initial Study and Negative Declaration for the Matadero Creek Restoration and Bank Stabilization Project). Flows to the creek in the vicinity of the project have already been increased as a result of development in recent years and stripping of understory vegetation along the riparian corridor (e.g., on parcels on Melody Lane and Natoma Road). Loss of numerous mature oak trees within the creek corridor from Sudden Oak Death, which is endemic in the Project vicinity, has also contributed to increased flows and undercut and eroded banks. Ex. 4, p. 12 (Arborist Report). In addition, property owners, including several just downstream from the Project site, have hardened their creek banks to try to limit bank failure—a strategy that worsens erosion in other locations. Further change to the hydrology of flows in Matadero Creek from the Project could result in hydromodification and cause increased erosion and creek bank failure, which may jeopardize existing structures. The Initial Study fails to provide any meaningful explanation as to how the detention basin would be operated to prevent erosion of existing stream banks and flooding downstream along Matadero Creek, and it is not clear that they can be so operated. Simply delaying flows in detention basins is not an effectiveapproach to - preventing downstream hydromodification of Matadero Creek. The Project would result in a substantial amount of new impervious surfaces conveying increased flows to a SHUTE MIHALY ?`-WEINBERGERay Suzanne Avila January 20, 2016 Page 16 centralized basin. IS, pp. 69-70. This would in turn increase total discharge volume to Matadero Creek. Even moderate flows to the creek, if sustained for longer periods of time than would occur without the project, could cause significant downstream erosion. This is a potentially significant impact that must be fully analyzed under CEQA. In sum, the Initial Study lacks sufficient evidentiary support for its conclusion that the Project's impacts on hydrology and waterquality would be less than significant. An EIR that comprehensively evaluates and mitigates the proposed Project's hydrology and water quality impacts must be prepared and circulated. D. The Initial Study Does Not Attempt to Demonstrate or Analyze Aesthetic Impacts of the Project. CEQA requires analysis of a project's impacts on "view and other features of beauty." Ocean View Estates Homeowners Assn., Inc. v. Montecito Water.Dist. (2004) 116 Cal.App.4th 396, 401. Relevant impacts include a project's visibility from both private property and public trails, parks, or open space. Id. at 402 ("the record contains photographic evidence from which a fair argument can be made that the cover will be visible from public trails"); Quail Botanical Gardens Foundation, Inc. v. City of Encinitas (1994) 29 Cal.App.4th 1597, 1605, 1607 (housing project could have significant aesthetic impacts if it would block views from a public park). On this topic, "the opinions of area residents, if based on direct observation, may be relevant as to aesthetic impact and may constitute substantial evidence in support of a fair argument; no special.expertise is required on this topic."Pocket Protectors, 124 Cal.App.4th at 908, 937 (requiring EIR, rather than Initial Study, in part to address neighbors' concerns regarding aesthetic impacts of project). Here, the Initial Study does not provide the comprehensive analysis necessary to accurately evaluate the severity and extent of the project-specific impacts. The accepted approach to analyzing visual and aesthetic impacts is as follows: a. Describe the criteria for significance thresholds. b. Characterize the existing conditions of the project site and the surrounding area by photograph and description, and select key viewpoints within the area, including scenic corridors and landscapes. c. Use photomontages or visual simulations, to illustrate the change in character of the project site before and after project implementation. SHUTE MIHALY WE INBERGERLIP Suzanne Avila January 20, 2016 Page 17 d. Identify feasible mitigation measures and alternatives to reduce or eliminate significant impacts. e. Where mitigation measures are proposed, use the simulations to illustrate the change in character before and after project mitigation measures are imposed (e.g., landscaping at various stages of growth, setbacks, clustering, reduced scale and height, building color modification). The Initial Study fails to use this approach. Tellingly, it does not provide a single photograph showing the existing scenic corridors (e.g., to Skyline Ridge) or a single simulation of the project at full buildout, despite comments submitted on an earlier version of the Project by the Town Open Space Committee that emphasized the importance of maintaining the open space characteristics of the Town and avoiding "gridding" and continuous fencing. See Open Space Committee Comments on Stirling subdivision proposal, p. 2 (Jan. 20, 2014). The Town Environmental Design Committee also recommended view easements for properties adjacent to Lots 1 to 4. See EDPC Comments on the Initial Study of the Stirling Subdivision, October 23, 2015. The applicant has provided no evidence regarding the appearance and visual impacts of the Project to surrounding residents or pathways.'IS, pp. 7, 9 (existing conditions), 23-24 (impact analysis, with no images). Instead, the Initial Study simply concludes that the Project"will result in development that is consistent with residential uses throughout the Town, including on properties adjacent to the project site" and review of individual home designs "for consistency with zoning and design standards intended to assure visual compatibility of new development with its environment . . . will assure that visual effects will be less than significant." IS, p. 23. But the fact that the Town will review for consistency with zoning standards is not enough to satisfy CEQA: "a requirement that [a project] comply with the [applicable] Code does not, by itself, constitute an adequate assessment of mitigation measures that can be taken to address the . . . impacts during construction and operation of the project." California Clean Energy Corn., 225 Cal.App.4th at 211. In contrast, an analysis consistent with the approach detailed above would allow decision makers and the public to evaluate the aestheticimpacts of the project more fully and easily than does the sparse narrative currently provided in the Initial Study. For example, photomontages or visual simulations could provide a direct experience of the visual impact of a new street and residential development on a parcel currently dominated by oak woodlands, open grassy areas, and a steeply sloped stream corridor. See Ex. 10 (photographs). Such an analysis could assist decision makers in determining whether a smaller, less intrusive development should be permitted on that site or whether design SHUTE MIHALY SHUTE, Suzanne Avila January 20, 2016 Page 18 features such as enhanced setbacks or additional fencing limitations would mitigate the proposed changes. Such an analysis would also demonstrate the project's aesthetic effects on the multiple segments of the.Town pathway system, including the Scenic Stegner Path, that runs through a 50-foot "Scenic and Pathway Easement" along much of the western boundary of the site. IS, Appx. A, Map 6. This is precisely the type of public and communal resources that courts have identified as exceptionally important when evaluating visual resources. See Ocean View Estates, 116 Cal.App.4th at 402 ("But here there is more involved than private views . . . the [project] will be visible from public trails."), Quail Botanical Gardens, 29 Cal.App.4th at 1605. An adequate analysis must include detailed and thorough discussion of the project's likely aesthetic impacts, as outlined above. It must provide an adequate analysis that would permit informed decisions about the project, effective mitigation measures, and alternatives that could have less intensive impacts. It must also analyze all project components that could impact views. E. The Initial Study Neither:Analyzes the Project's True Impacts on Wildlife Nor Adopts Feasible Mitigation Measures Recommended by the Town's Own General Plan. There is broad consensus that loss or significant disruption of wildlife corridors can adversely affect species' population dynamics, inhibit evolutionary changes and the ability for species' ranges to shift in response to environmental stressors, prevent re-population of areas following catastrophic events such as fire, and effectively reduce habitat size for area-dependent species. See, e.g., IS, p. 52; Live Oak Associates, Inc., The Town of Los Altos Hills.Wildlife Corridor Study ("LOA 2006"), p. 6 (Dec. 18, 2006); CEQA Guidelines, Appx. G § IV(D). The Town's own General Plan repeatedly emphasizes the importance of"[p]lanning for natural movement of wildlife;"planning development to "link wildlife habitat" rather than fragmenting it with the construction of "roads, fences, homes, and other development;" and allowing "[w]ildlife [to] move through the planning area along natural passageways," especially those designated by the Town as Open Space Conservation Areas. Los Altos Hills General Plan ("General Plan"), Conservation Element, p. 6; see also LOA 2006, p. 4 ("[A]n accumulation of smaller projects can alter wildlife movement through [Los Altos Hills] if movement corridors are not planned for and protected in advance of future development or modifications of existing parcels."). Despite the importance of wildlife corridors—and particularly of this specific site, part of which is designated as Open Space Conservation Area, and which is one of the only remaining large parcels of undeveloped land between important resources SHUTE MIHALY ?T-WEINBERGER LU' Suzanne Avila January 20, 2016 Page 19 including Poor Clares, Foothills.Park, Arastradero Preserve, and Byrne Preserve—the Initial Study fails to analyze the Project's actual impact or to even consider mitigation measures. See General Plan, Open Space and Recreation Element, pp. 5-6. The Initial Study acknowledges that the Project site has been identified as lying within an important corridor for movement of wildlife. IS, p. 52. This statement is consistent with numerous other investigations and actions taken over the past decade to preserve wildlife corridors across this specific property. For example, the "Wildlife Movement Exhibit" included with maps for the Stirling subdivision submitted to the Town in October 2013 clearly identifies both the riparian area and the eastern border of the property as established routes that wildlife use to navigate through residential areas and between key blocks of open space. See Ex. 11 (Lands of Stirling, Map 7, October 9, 2013). Likewise, when the Stirling property was fenced in 2005, then-City Council Member Jean Mordo negotiated an agreement to prevent complete blockage of the long- standing corridor that allows wildlife to travel between Poor Clares, the Stirling property, lower Matadero Creek and beyond, via the established Simon Lane corridor. The Initial Study recognizes that the site is or is likely to be used by numerous species, including a variety of birds, amphibians, small mammals, and larger, wider-ranging species. Id. Yet the Initial Study never actually describes the impacts that either construction or occupancy of the new homes or associated fencing on the parcels will have on these animals. Instead, it provides a single, conclusory page of discussion. It finds that, "even though this project will lead to changes in spatial use patterns of local common species of wildlife," its effects will be less than significant and does not consider, much less impose, mitigation measures: The proposed project would retain a maximum number of native mature oak trees/woodlands, includes large lots on the most buildable portions of the property and preserves the highest quality wildlife movement corridor and overall most valuable wildlife habitat along the Matadero Creek tributary corridor in a permanent open space easement (within which no development and no impediments to wildlife movement would be placed). Therefore, project impacts to wildlife movement would be less than significant and no mitigation is required. Id. SHUTE MIHALY -WEINBERGERu.P Suzanne Avila January 20, 2016 Page 20 This analysis is not only inadequate but factually incorrect and reliant on unsupported assumptions. First, as discussed in Section II above, the Initial Study and supporting maps clearly indicate that the Project will require:significant construction activity in the steep riparian corridor. Construction of a new footbridge and path, as well as subterranean drains, outfalls, and other infrastructure shown on the applicant's maps directly contradicts the Initial Study's statement that "no development and no impediments to wildlife movement would be placed"within the "most valuable wildlife . habitat along the Matadero Creek tributary corridor." IS, p. 52. The Initial Study never acknowledges, much less analyzes, the impact of construction and operation of these features on this essential and fragile ecosystem. Accordingly, it has no basis on which to conclude that the Project will have less than significant impacts on the wildlife that inhabits and passes through it. The Initial Study's conclusion is flawed for the additional reason that it relies almost exclusively on the "Analysis and recommendations regarding the comments from the Town of Los Altos Hills regarding proposed development on the Stirling Property"prepared by Live Oak Associates and dated November 11, 2014 ("LOA 2014"). See IS, p. 52. This report makes the same mistake described above, crediting the Project with preserving the entire riparian corridor in a pristine state. LOA 2014, p. 3. It then acknowledges that "a number of wildlife species move from the.gaps in the fence along the eastern and northern boundary across the property."Id. As a result, the Project "will . . . alter the use of the site for some wildlife species, particularly deer."Id. But the report concludes that "this change is not significant under CEQA[,] as based on my experience and evidenced by the regional distribution and abundance of deer, deer will continue to access this site with regularityassuming that the individual lots are not surrounded by impermeable fencing."Id..(emphasis added). There is no basis for this assumption in the Initial Study, nor in the maps depicting the Project. Map 3 in Appendix A to the Initial Study notes that the boundary fenceon at least parts of the north and east sides of the Project will be replaced with a wildlife permeable fence but provides no such requirement for the individual lots that will carve up the currently open and undeveloped area. The Town code allows fencing to be installed'around entire parcels, including on the property lines on the sides and back. See Los Altos Hills.Municipal Code § 10-1.507. This lack of any setback requirement for side and rear'fences will allow new residents to erect an impenetrable barrier of fencing across Lots 1 to 4, completely blocking access to the wildlife permeable fence proposed along the eastern border. The analysis on which the Initial Study bases its conclusion thus incorrectly assumes away exactly the barriers that it acknowledges can impede movement of wildlife and cause substantial impacts. SHUTE MIHALY �T-WEINBERGERLL Suzanne Avila • January 20, 2016 Page 21 An adequate analysis would consider the effects of the actual Project—with all of its features as proposed—on both species within the riparian corridor and those that cross and graze on the property. The Town must require an EIR that not only provides the missing analysis, but also mitigates the impacts that the current Initial Study dismisses. Such mitigation should include, at a minimum, the measures endorsed in the General Plan: dedication of permanent conservation or open space easements to protect not just the steeply sloped riparian corridor, but rather the full extent of the designated Open Space Conservation Area on the property and the full eastern boundary to preserve that key corridor from being blocked and fragmented by new homeowners' personal fences, outbuildings, and other structures.5 V. The.Initial Study Fails to Provide Any Analysis of the Project's Cumulative Impacts. CEQA requires that an agency prepare an EIRrather than a negative declaration if a "project has possible environmental effects that are individually limited but cumulatively considerable." Guidelines § 15065(a)(3). Here, the Initial Study provided no information about cumulative impacts. Its "Notes" regarding evaluation of environmental impacts state that"[a]11 answers take account of the whole action involved, including off-site as well as onsite, cumulative as well a project-level., indirect as well as direct, and construction as well as operational impacts." IS, p. 21. But, as discussed above, the actual analyses provide minimal information about many of the impacts, and no consideration at all of their additive effects, and none whatsoever about nearby or otherwise cumulative projects and impacts. The Town must reject such an incomplete analysis and require an EIR. See Guidelines § 15065(a)(3), Citizens Assn.for Sensible Development of Bishop Area v. County ofInyo (1985) 172 Cal.App.3d 151, 164 (rejecting MND for failure to consider cumulative impacts). CEQA defines "cumulatively considerable" impacts as occurring when "the incremental effects of an individual project are significant when viewed in connection 5 Map 3 in Appendix A to the Initial Study appears to show minimum setbacks from each individual property boundary within the Project. However, neither this map nor any other part of the Initial Study explains what features would be governed by any setback (e.g., fences, structures), nor is there information regarding its measurements or other requirements. Even if the applicant intended to establish a minimum setback, the Initial Study lacks sufficient information to assess the effects of any such requirement. Moreover, recorded easements as recommended by the General Plan would provide far more robust and enforceable protection of the space required for movement of wildlife. SHUTE MIHALY SHUTE, Suzanne Avila January 20, 2016 Page 22 with the effects of past projects, the effects of other current projects, and the effects of probable future projects." Guidelines § 15065(a)(3). Thus, a project can have cumulatively significant impacts even if its individual impacts are not significant. The Initial Study does not consider the impacts of any other project in conjunction with the Stirling Subdivision and provides no information whatsoever about conditions and activities near the project site. This alone raises the possibility of cumulatively significant impacts. See Guidelines § 15065(a). Following the mandatory findings of significance, the Initial Study includes a single paragraph regarding cumulative impacts that characterizes the Project as small in a generally urban area and thus not cumulatively significant. IS., p. 88. This discussion does not provide any information about local conditions or projects, however, and is no substitute for the substantial evidence required by CEQA. In fact, a brief review of projects currently planned for Matadero Creek alone demonstrates the importance of this omission and provides substantial evidence that the Project will "ha[ve] possible environmental effects"that are cumulatively considerable.Id. For example, and as discussed in Section IV:C above, the Town is currently reviewing a proposal to restore and stabilize banks of the creek downstream. See Ex. 9(Initial Study and Negative Declaration for the Matadero Creek Restoration and Bank Stabilization Project). Construction of two major projects in the same vicinity along the same riparian corridor could implicate impacts to water quality and hydrology, as well as to local wildlife. Likewise, both projects and their associated infrastructure have the potential to alter the hydrology of Matadero Creek. Yet the Initial Study never mentions the bank stabilization project. Similarly, the Initial Study provides no information about other development projects or the additional property-line fencing that has been installed in the area that might interfere with wildlife mobility or impede movement of the same species affected by the Stirling project. See IS, p. 52. This silence does not meet the Town's obligations under CEQA and deprives the Initial Study of substantial evidence:to support its mandatory finding that "the project [will not] have impacts that are individually limited, but cumulatively considerable." IS, p. 87. VI. Conclusion For the reasonsstated above, the Town may not adopt the Initial Study because it does not meet the requirements of CEQA. First, the Initial Study's description of the Project and the environmental setting fail to provide-crucial information to determine the scope of the Project and its impacts. Second, a fair argument exists, based on substantial evidence, that significant impacts would result from the Project as proposed. Third, the Initial Study's analyses of biological resources, hydrology and water SHUTE MIHALY ?`--WEINBERGERup Suzanne Avila January 20, 2016 Page 23 . • quality, and aesthetics are not supported by substantial evidence. And the Initial Study provides no information whatsoever about cumulative impacts. The Town must reject the Initial Study for the.Project for each of these reasons. Instead, the Town must require an EIR that fully analyzes the Project's potentially significant impacts and feasible mitigation, and that evaluates:a full range of alternatives. Very truly yours; SHUTE,MIHALY & WEINBERGER LLP Sarah H. Sigman 729954.11 SHUTE MIHALY - WE IN B E RG ER LLP Suzanne Avila January 20, 2016 Page 24 Exhibits 1. Los Altos Hills, Taaffe Road Pathway Draft Initial Study/Mitigated Negative Declaration (Sept. 2008) 2. Lands of Ko, Proposed Subdivision, Map 3 (Oct. 16, 2015) - 3. Romig Engineers, Inc., Engineering Geologic Hazard and Preliminary Geotechnical Investigation Lands of Stirling Subdivision (May 2014) [Attachments and Exhibits Omitted] 4. HortScience, Inc., Revised Arborist Report (Nov. 2014) 5. Final,California 2010 Integrated Report 303(d) List/305(b) Report (available at http://www.waterboards.ca.gov/water_issues/programs/tmdl/2010state irreports/ca tegory5_report.shtml) [Excerpt] 6. Santa Clara Valley Urban Runoff Pollution Prevention Program (available at http://www.scvurppp-w2k.com/ws -matadero.shtml?zoom_highlight=matadero +creek) 7. Santa Clara County C.3 Stormwater Handbook, Attachment II-7 (May 20, 2004) 8. Town of Los Altos Hills Planning Commission Agenda, Feb. 16, 2006 9. Draft Initial Study for the Matadero Creek Restoration and Bank Stabilization Project (October 2015) [Excerpt] 10. Photographs of Project Site 11. Lands of Stifling, Wildlife Movement Exhibit, Map 7 (October 9, 2013) SHUTE MIHALY -WE IN B E RG ER LLP EXHIBIT 1 Los Altos Hills Taaffe Road Pathway TOWN OF LOS ALTOS HILLS Draft Initial Study/Mitigated Negative Declaration • • • September 2008 • Prepared for: �5 ���� Richard Chiu, Public Works Director Town of Los Altos Hills 26379 Fremont Road Los Altos Hills, California 94022 Prepared by: CALIFORNIA - MHA Environmental.Consulting, An RMT Business 4 West Fourth Avenue, Suite 303 pt IT MHA San Mateo, California 94402 Environmental Consulting www.rmtinc.com www.mha-inc.com LOS OSHILLS - _ LOS ALTOS FULLS • .. , DRAFT INITIAL STUDY/MITIGATED NEGATIVE DECLARATION CALIFORNIA PURPOSE OF DOCUMENT:•This Initial Study/Mitigated Negative Declaration (IS/MND) is a public document that provides an assessment of the potential . environmental effects of the'Los Altos Hills Taaffe Road:Pathway Project;as required by the California Environmental Quality Act (CEQA) and in compliance with the State CEQA Guidelines (14 California Code of Regulations 15000 et seq.). It serves as an information document to be used in the local planning and decision-making process; it does not.recoinmend:approval or denial of the project.The Town of Los Altos Hills (Town), the state Lead Agency for the project under CEQA, must evaluate the environmental effects of the project when considering whether to approve it.The Townhas prepared a MND for the project because potential impacts related to the project are considered less thansignificant with the incorporation of mitigation measures. PROJECT DESCRIPTION: The proposed project involves the construction of an unpaved recreational pathway to accommodate hikers and equestrians. The pathwayy would connect an existing pathway to Taaffe Road and would be approximately 1,300 feet long (see Figure 1).The constructed trail would be.a 4-feet wide, base rock surfaced path on balanced cut and fill. A central segment of the pathway would include switchbacks as narrow as 3 feet.The northern segment of the pathway would traverse a moderate'(20 to 25 percent) slope and include two crossings of local streams(Deer Creek and a tributary of Deer Creek)..The streams would be crossed by • constructing wooden footbridges approximately 20 to 24 feet long . and 6-feet wide. The'bridges would be founded on concrete abutments. The central segment of the pathway would traverse an area with an average slope of approximately 50 percent, with some areas as steepas 65 percent. Due to the steep terrain and switchbacks,timber crib or tie-back retaining thralls would be required on certain portions of the pathway. Portions of the central segment would include steps designed to accommodate the safe passage of horses. The southern segment of the pathway would:traverse slopes of approximately 7 to 8 percent, and would terminate at the trail's intersection with Taaffe Road. Signage would be posted at either end'of the pathway warning trail users to use caution and to be aware that both hikers and equestrians may use the trail. The signagewould also warn equestrians that the trail is suitable for conditioned horses only. Only one tree, a fallen eucalyptus tree located near the southern end of the pathway by Taaffe Road,would be removed. Los Altos Hills Taaffe:Road Pathway Draft IS/MND MHAIRMT'1 September 2008 TOWN OF LOS ALTOS HILLS Figure 1:Proposed Project Location _ - • }� :=r.,,..,T -�s�y.‘,,.. 4.,...„..21,. 3 :: � ' `;f S.F. Bay Area -1 ,. • ,,ri r. rrC ,. f` parr _. rIIL'T▪ !..,,,,,,i' rr �"r • ",•4 ''• / ,d. true + ,-', S �' �k'' ►' • ->yy -1 ,•••'4,r#,.. , ' !`,r 4o r \ � " r 44. ,,s Yr r ' •r'1•-At. 4Rf3 . y r -1 ri r 'a= ) e F� i^,,4...: �. •�� •a1 r •bra'. N. r • p, F.� .: n▪ .1 x:290 4 q '' J,c iti, A 'Pit �fl _'.,*IL j f 1."` �* '-1 '` n,i tC^` 'j�3Y` ••�` ,:„X.....:• t....... .:c.� 4. 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E. -• '' •`L-'x. fir' .7 is „., r,kt:Iiin�':• Li - • ( r `�,,,.{ i- _.:;),.,C__rv,-r7•r`y- SOURCE:U.S.Geological Survey,EROS Data Center,Sioux Falls,SD and MHA Environmental Consulting 2008 LEGEND mama Proposed Project Extent ;To Interstate Highway N /C� 5Y�' L r t ��n MHA S 0.25 0.5.__ _0.75 1 Miles 4 si' 2 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft1S/MND • September 201)8 TOWN OF LOS ALTOS HILLS 1.Applicant: Town of Los Altos Hills Public Works Department 26379 Fremont Road Los Altos Hills, CA 94022 2. Proposed Location: Northward from Taaffe Road at a Iodation west of Elmberg Ridge to an existing pathway that extends.north:to Black Mountain Road and east to Elena Road (see Figure .1). 3. Proposed Action: Construction of a pedestrian'and equestrian pathway within established Town pathway right-of--way, and the construction of two wooden-footbridges over locai,streams. NEGATIVE DECLARATION MITIGATION MEASURES: Air Quality: Mitigation Measure 3-1: Dust control measures shall be implemented during site preparation and construction activities as per Los Altos Hills Municipal Code requirements. Dust control measures shall be listed on the project plans, to the satisfaction Of the Director of Public Works. Mitigation Measure 3-2:Construction vehicles shall not idle unnecessarily. Paint and finishing spray applications shall not be conducted during windy periods(winds exceeding 20 miles per hour). Biological Resources: Mitigation Measure 4-1: Prior to project construction, a certified biologist shall survey the project area for Franciscan onion and Western leatherwood.Any.occurrences of these plants shall be flagged and avoided. If avoidance isnot possible,the plant shall be relocated to an adjacent area by the certified biologist. Mitigation Measure 4-2: Grading,clearing and other land disturbance shall be scheduled to avoid the rainy season when California red-legged frogs are most likely to be moving between different bodies of water. Grading, clearing and other land disturbance shall generally be performed between April 15th and October 15th, but shall occur no earlier than two weeks before the last spring rainfall and shall Cease at the onset of fall rains. Construction timing shall also be consistent with anylimitations imposed by the CDFG, RWQCB and/or the USFWS. Prior to construction,a certified biologist shall: 1. Conduct an education training session for all construction personnel.The biologist shall either be bilingual(English and Spanish)or an interpreter shall participate to instruct personnel in Spanish as needed.The program shall consist of a brief presentation explaining endangered species concerns,,te include: a) A description of each of the special status species and their habitat needs. b) An explanation of the status of the species during project construction and implementation. • c) Measures to protect and avoid effects to the species. A fact sheet conveying this information shall be prepared for distribution to the above- mentioned personnel and anyone else who may enter the construction area. Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 3 September 2008 TOWN OF LOS ALTOS HILLS . 2. Survey the project area for.California red-legged frog.Any frogs located in the project area shall be relocated to avoid impacts.A biologist shall remain onsite during construction within 250 feet of streams to monitor for California red-legged frog and relocate any individuals found. Cultural Resources: . Mitigation Measure 5-1: Prior to excavation or construction,the Town shall incorporate a note on the first page of the construction plans stating that should cultural resources be encountered during site grading or other site work, such work shall immediately be halted in the area of discovery and the project sponsor shall immediately notify the Community Development Directorofthe discovery.The applicant shall be required to retain the services of a qualified archeologist for the purpose of recording, protecting,or curating the discovery as appropriate.The cost of the;qualified archaeologist and of any recording, protecting, or curating shall be borne solely by the project sponsor. The archaeologist:shall be required to submit a Cultural Resources Management Plan, per City Requirements, to the Community Development Director for review and approval that outlines the findings and mitigation methods of curation and/or protection of the resources. No further grading or site work within the area of discovery shall be allowed until the preceding has occurred.Disposition of Native American remains shall comply with CEQA Guidelines Section 15064.5(e).The note on the plans shall be subject to review and approval of the Planning Division. Hazards and Hazardous Materials: Mitigation Measure 7-1: The contractor shall submit a spill response plan prior to the onset of construction to ensure a prompt and effective response to any accidental spills or leaks of diesel, gasoline, oil or other contaminating materials that might flow or migrate to the creek. Mitigation Measure 7-2: Construction personnel shall dispose of cigarette butts in the appropriate trash containers and shall not dispose of cigarette butts on the ground. Construction personnel shall be briefed regarding this measure prior to construction. Hydrology and Water Quality: _ Mitigation Measure 8-1:An erosion control plan shall be.prepared for review and approval by the Director of Public Works prior to commencement of any project activities. The plan • shall specifically address measures to control erosion during construction and to minimize erosion fromtrail use and maintenance after construction. Mitigation Measure 8-2: Footbridge construction and installation shall be scheduled when water levels are predicted to be low in order to reduce the likelihood of construction related debris or sediment entering the river.Additional efforts to reduce water quality degradation include; a) The contractor will be required to install a protective impermeable barrier, such as a tarp, between the bridge work area and any surface water. b) Dirty,construction water will be filtered through burlap and poured into a sump at least 100 feet from surface water., c) Sawdust and chips from treated wood will be packed out as trash and most of the cutting and drilling of treated wood will be done in the staging area before the lumber is brought in. MITIGATION MONITORING AND REPORTING PLAN The California Environmental Quality Act(CEQA) requires that a plan for implementing defined mitigation and monitoring and/or reporting on defined mitigation must be adopted to ensure that 4 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 TOWN OF LOS ALTOS HILLS mitigation is implemented accordingly. The Town of Los Altos Hills has prepared a Mitigation Monitoring and Reporting Plan (MMRP) in tabular format that contains the mitigation measures defined in the Initial Study, the implementation/monitoring method(s), the responsible party, and the implementation schedule. The MMRP will be attached to the.Draft Initial Study (IS)IMND as Attachment 1. • REVIEW PERIOD: Allcomments regarding the correctness, completeness, or adequacy of this Mitigated Negative Declaration must be received by the Town of Los Altos Hills Public Works Department, 26379 Fremont Road, Los Altos Hills, .CA 94022 no later than 5:00 p.m. on November 21, 2008. CONTACT PERSON(S): Richard Chiu Tel: (650) 947-2516 Public Works Director Fax: (650)941-3160 • . Town of Los Altos Hills 26379 Fremont Road rchiu losaltoshills.ca.gov Los Altos Hills, CA 94022 • • • • Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 5 September:2008 TOWN OF LOS ALTOS HILLS ENVIRONMENTAL CHECKLIST FORM 1. Project Title: Los Altos Hills Taaffe Road Pathway 2. Lead Agency Name and Address: Town of Los Altos Hills, 26379 Fremont Road, Los • Altos Hills, CA 94022 . 3. Contact Person and Phone Number: Richard Chiu, Public Works Director, (650) 947-2516 . 4. Project Location::Northward from Taaffe Road at a location west of Elmberg Ridge to an • existing pathway that extends north to Black Mountain Road and east to Elena Road, in the Town of Los Altos Hills (Figure.1) . 5. Project Sponsor's Name and Address:Town of Los Altos Hills, Public Works Department, 26379 Fremont Road, Los Altos Hills, CA 94022 • 6. General Plan Designation: Open Space Conservation Area adjacent to Residential 7. Zoning: Residential 8. Description of Project:The proposed project would involve construction of an unpaved recreational pathway to accommodate hikers and equestrians.The path would extend south from an existing path (that extends north to Black Mountain.Road and east to Elena Road) to Taaffe Road at a location west of Elmburg Ridge to(see Figure 1). The path would be located along the boundary of several private residential parcels and within existing pathway easements.These easements are generally 10 feet wide on the east side of the trail project area and 20 feet wide on the west side of the project area. There is also a triangular area of the easement located near the east side of the proposed switchbacks (see Figure 2).The northern segment would traverse rolling moderate terrain of approximately 20 to 25 percent slope, and would include two crossingsoflocal streams: Deer Creek and one of its tributaries. The central segment of the proposed trail would traverse steep terrain with an average slope of approximately 50 percent,with some ,portions as steep as 65 percent. The southern segment of the proposed trail would traverse relatively gentle terrain that has an approximately 7 to 8 percent slope. The constructedtrail would be a 4-foot wide, base rock surfaced path for the majority of the pathway. The steep terrain combined with the relatively narrow 30-foot easement corridor would require a number of switchbacks, and the trail would be as narrow as 3 feet in portions of the central section of the pathway. The design objective for the gradient of the trail in the central segment would be a maximum slope of 20 percent, similar to the existing trail to the north; however, the easement constraints could require a trail gradient as steep as 25 percent. Timber crib or tie-back retaining walls would be required on some portions of the.central segment. The retaining walls would have railings similar to existing walls along some portions of the Town trail system (e.g., Elena Road). Steps would also be constructed in the steepest portions to assure shallower slopes and the safe passage of horses. No hand railings would be installed to accompany the steps. Signage would be posted at either end of the pathway warning equestrians that the pathway is for conditioned horses only and not for novice riders.This signage would also warn pedestrians of possible conflicts with equestrians on the trail. 6 MHAJRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 • : r-- . -I i r = COM aldind Purl a 311i1OS : fe I/. .. ........_ ...__._.... �•.r•r••n,-,.,n.•.....:_.._,... n_.-,..1 :r_::-u:^:n. .r..:n....n•. ..._......u:a..n..n•vr .......:a.u... n..c. .,u.. y. .�::.: .:-:.. . ::_.,t-. ...._. e.n.:.-. i F— 1... • . „cei4 _ • Q 8l�i9 3d9tla= lit :VOA, • i u) . .=. .... •. ...„3"sy0.0404......, . itiii-% • 0 i , t is IL'Lk k2 4 i.itI 44- 0 A. } ' AYAUNLYd e • ..o. ti+ti 1 .7• �i •' •,..•• -_ b : 1 !• � . / O a� I! i�� t V% t . i, - •I. . r 9;t ItMJC� W ! 55 sr xi�d Q�Pia .:y. 4 , .. ' .. - '71':. 11 _1 „6 ii,4 7., ......,..1, .. it 4er ,,,,,,,:, _ , • • • • ' , 4ti a3fSIJJl4ltl+11 • 1, r.t Z : ' •. ., \ . , ^• .� • 1 ,r 2t1.91 �F�b,,.G,yB� t .a i .damco .. . � ,r ii. •, �� I CO O • cydau3CI) tt iodol put s uaat@G 1031o.id :z 3in6r. • TOWN OF LOS ALTOS HILLS Thetwo stream crossings would be bridgedby wooden footbridges approximately 20 to.24'feet long and 6 feet-wide.The bridges would have poured-in-place'concrete abutment foundations and guard railings that would be 4 feet, 6..inches.high. The proposed pathway routepasses through oak woodland, non-native eucalyptus- dominated areas, non-native grassland, and riparian woodland habitat. One fallen eucalyptus tree that currently blocks the trail route would be removed. No other trees would be removed. 9. Surrounding Land Uses and Setting:The-project area is surrounded by single family residences. The Los Altos Hills General Plan land use designation for the project area is Open Space- Conservation Area(OSCA),which is anoverlay designation that is superimposed upon the residential land use areas on the Town's Land Use Diagram. Theoverlayis generally applied to areas of steep slopes, canyons, and ravines:associated with major creeks or their tributaries, as well as creek corridors and other areas of heavy vegetation that the • Town has determined should be protected.Within these areas, the Town requires that special.measures be taken to conserve the natural quality of the area and to avoid environmental degradation. The Town encourages that residences be placed on the most buildable portions of lands designated OSCA, and carefully sitedso as to preserve existing trees, vegetation, and wildlife habitat. The surrounding land use is zoned Residential, which allows for one single family dwelling per parcel. Accessory uses, including one secondary dwelling unit, may be permitted. Agricultural activities and conditional uses such as religious facilities and schools may also be allowed. 10. Other public agencies whose approval is required(Responsible Agencies):The trail and bridges would require review, and potentially a perrnit, from the California Department of Fish and Game. The projectwill not include dredge:or fill of waters of the U.S. and thus will not require a permit from the U.S.Army Corps of Engineers:: • 8 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 TOWN OF LOS ALTOS HILLS • • ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED The environmental factors checked below would be potentially affected by thisproject, involving several impacts that are"Less than Significant with Mitigation Incorporated" as indicated by the checklist on the following pages. Aesthetics and Visual Agricultural Resources J Air Quality /• Biological.Resources. ,J Cultural Resources Geology/Soils 4 Hazards & Hydrology/ Land.Use/ Hazardous Materials Water Quality . Planning Mineral Resources ,J Noise Population/Housing Public Services Recreation Traffic/Transportation Utilities/Service , Mandatory Findings of Systems Significance DETERMINATION On the basisof this initial evaluation: I find that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION willbe prepared. I find that although the proposed:project could have a significant effect on the environment, there will not be a significant effect in this case because revisions in the project have been made by or X agreed to by the project proponent.A MITIGATED NEGATIVE DECLARATION will be prepared. I find that the proposed project MAY have a significant effect on the environment and an ENVIRONMENTAL IMPACT REPORT is required. I find that the proposed project MAY have a "potentially significant impact" or "potentially significant unless mitigated" impact on the environment, but at least-one effect (1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and (2) has been addressed by mitigation measures based on the earlier analysis as described on attached sheets. An ENVIRONMENTAL IMPACT.REPORT is required, but it must analyze only the effects. that remain to be addressed. I find that although the proposed project could have a significant effect on the environment, • because all potentially significant effects (a) have been analyzed adequately in an earlier EIR or NEGATIVE DECLARATION pursuant to applicable standards, and (b) have been avoided or mitigated pursuant to that earlier EIR or NEGATIVE DECLARATION, including revisions or mitigation measures that are imposed upon the proposed project, nothing further is required. 7ac,e,a-j C4,1 ?7(08 Signature Date Richard Chiu Printed name Public Works Director • Title Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 9 September 2008 TOWN OF LOS ALTOS HILLS ,,,,..zitrArn,7,- --IRA-4w;r..41 ---7.,-.;:a1.3.-:.•?:---..;'.9i.17: 17-47117-. 1f-.7,-;FP-44_,VF.7",.-1-1MI:Ply-W4-173,. 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"?..,..'---4 iP,'41; ,,,,,,-;:e-..,.. -f*,i-v-t-..,.4 tAt`.7:7 It.:'...r.,",.'"-1,.."-W,.,0.e....4"-_;'74.r.li:1,?"'f,.,,`-'1,-„,:Stv--r„••••"71.;t,".-3,'ztk-4,),J..._.4:4,g.I.,;;':-.M1.,,Tke,Atql---47-..,-,.!.efg-) 44-'1..?..f:I•q"..641.7.:17!-;-,-,:.1.-:ltt'.;,'.;•'e'il-•. 0,0J....7..4.4....-._1•,--:,:_rov•;.i.z4,,f:,...,:-:-:%.31.'1+,,,,E,..,....,...4',747..,-..tr..11eDrity,4...,:.:- ...",Ailr.4..S.g.£;',..:±±..-Z-..e.:::?..%.-1 -4.:tkg.r.c..-,-,,.T.,..-acj:i 4,:2-—.E.'.1..In.z.a..-C..5..!-.ati.:ren:,!:0- l'..Atvoifetimmotoii:iblr.project. . • ••••••• ...-- .., ,: ...- .-i.•,-.; ,-_-., , •,..•..:. • -;.,:, -:...-- •••; •:.:•.•-.-...: .:.,-;:, ...• -,-, -..• a) Have a substantial adverse effect on a scenic vista? . q A,B - . • b) Substantially damage scenic resources, including but . • riot limited to trees, rock outcroppings, and histOric -,/ A,B. :buildings within a state scenic highway? : • . c) Substantially degrade the existing visual character or q A,B quality of the site and its surroundings? • • d) Create a new source of substantial light or glare which would adversely affect day or nighttime views I/ A in the area? ' 2 • . . . . ._ . :,• :,"•,--idikiiiiikilig-g•bijkoke.:i.64-riigi--iiiiie:6iiii4.6:;..-..iiiii..iiiiiI4ii,.ralia.,..,.-1.36,44:iiei.iiimp..51.a:s.: :odonatiiiiiisilo-otioliNtiOrif:4:it:0046.01.:*fli1007:00140,,,310#04.0,14N134011.,44t0„04(4.V2P.P . .t.t, o-- ,Conservationo---i-tronOj•Wg-a.1jii:.A-0-,i•:-0O:•i14go.iiiiStaV,k.i.O,kt:g9-.,i,l.4ifi-•ti4.y.*.400.:0'".•:0.:,00410o•tti0',ll*01V1Ael.w:lf40.-g11ib.k:oVtkito•PfAlili 6f:00'i4e13•t':.i..#f•...*...M0•..*.r..q..I...“ itMOVi_aII;W riag , 0 )- ff21rfi , ', . =- & the •••• .• :.: a) Convert Prime Farmland, Unique Farmland, or • Farmland of Statewide Importance(Farmland), as shown on the maps prepared pursuant to the i A,B,E Farmland Mapping and Monitoring'Program,of the , California Resources Agency, to non-agricultural • use? • b)Conflict with existing zoning for agricultural use, or a .si A,B,D • . , Williamson Act contract? i • . c)Involve other changes in the existing environment • • 'which, due to their location or nature, could result in .4 A,B,C • conversion of Farmland to non-agricultural use? • ....„..,...v.a..4.42,,ti?;:,-,-..i:-..,..:.:4.,,'':6.:-•,,,;., ,..-...-4..p:,-.... • •• ,•••••,-,.:•••:,-,,,,,,--:•:-..:?::;,.!.•,.',.i,e;r1A-.6-fr-c!--;-.',;.::.:1::::i!:.::;'.a.l.s.:a.z:,.7-',..",'-'..;,--s-•:^1:4.iiii.ii:i•fir'Ai, ". .,...,..... ...,aii ..!... ,....„.„,. .....,,,,. !**..AIR9PAPITil.;*11:0.00Y.airkblekthlk:OlinjOgi.1.4. OflOtr AS .... 4 ,40.,,...YA4M00. .10:,a1r,cigalitik . 41:artage. it1:4it',4eviliseiiihsw.6toti:Tcootto:t o•i,...l.1'.5ii lo...7..:....•.Ol' c`...jtoi-ai.1 vii,-•i,f,;-f4ii,...1:!0g;ili:73:$;142,,;1..p.l6fa.,Ti0lya.p,.Wris:..;R * iiferifi1lat1ei*7Wii11ti3OkikOj ,t ' ;.--7..ii:;l..::: • a) Conflict with or obstruct implementation of the 4 A : applicable air quality plan? b)Violate any air quality standard or contribute to an q • - A,F .. existing or projected air'quality violation? . . • • 10 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND , September 2008 • TOWN OF LOS-ALTOS•HILLS < '"> , t Sj(^.^�^s�' �. . •-tri....Y-v' .. .. r L-. ,. , `s, +. •^",� it/ - .x...w, L'..,.,.i�ra...•:'..�..�...i.:_•C�= _.:r,.c-,s.....��.::i 1/-i?.:..:.. ....f._.- 4-...nct.,_:.•__v- ...,5 c) Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state A,D,F ambient air quality standard(including.releasing emissions which exceed quantitative thresholds for ozone precursors)? d) Expose sensitive receptors to substantial pollutant ■ A concentrations? e) Create objectionable odors affecting a substantial A number of people? - , i`v �1`Bli0l;0.G1 A '� O R ,W+a ••.!,:;.-•:-,• a) Have a substantial adverse effect, either directly or ' through habitat modifications, on any species identified as a candidate, sensitive, or special-status A,B,G, species in local or regional plans, policies, or H,L regulations, or,by the California Department of Fish and Game, U.S. Fish and Wildlife Service, or NOAA- Fisheries? b) Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by - A,B,P the Califomia Department of Fish and Game or U.S. ' • Fish and Wildlife Service? • c) Have a substantial adverse effect on federally • protected wetlands as defined by Section 404 of the Clean Water Act(including, but not limited to, marsh, .4 A,B vernal pool, coastal)through direct removal, filling, hydrological interruption, or other means? d) Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife A,B corridors, or impede the use of native wildlife nursery sites? e) Conflict with any local policies or ordinances A,B,C, protecting biological resources, such as a tree D,p preservation policy or ordinance? Los Altos Hills Taafe:Road Pathway Draft IS/MND V MHAIRMT 11 September 2008 TOWN OF LOS ALTOS HILLS •."'S"r V ._�.. a w� "'"^".ti .+^s.-R :z r,,M r r 9 A.•+•n ,.4a .,.,r r Yiiial x�R �;i r.at�'^'S' -c:t'�En.>w �7.kfi r _�r ..#+^ _ -€ - ..� r t >;.f -J rr- `iE` -2 e • j,ky r ti 0147.: t - r -2-t E f -''E •Lk~ ` 3 L ! •015T !4 a.J ="• .r `" r r ,1 E»h all! S y:arl � �•' k j "Ysr a" r { r r I- t ...QEF - r Lex f) Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation A,B,D Plan, or other approved local, regional, or state habitat conservation plan? g)Adversely affect previously established mitigation site(s)for other project(s)? A 5i'CULTU0AL RESOURCES.Would,the project: a) Cause a substantial adverse change in the significance of a historical resource as defined in . A,B,C §15064.5? b) Cause a substantial adverse change in the significance of an archaeological resource pursuant to ,j A,B,C §15064.5? c) Directly or indirectly destroy a unique paleontological ■ ■. A,B,C resource or site or unique geologic feature? d) Disturb any human remains, including those interred outside of formal cemeteries? A,B,C GEOLGY:AND.._:" ISu.,�ridsk het'tr�o a" aves _effeCtsliIdi . . . -e.":nX:.•c'Peo.-i�:'iFsy�rlr:i_ uibai A}'=i•yr�l,:h:o.a}r6�>:F.�`�r.�yl�e!Y a='ti.f:-.1:-t.•o•-:E.iiwlzr^^e_n_:;:::{µt::u,�!+f.}��!:[�sv.:.u..},b1.:.s-.=..t.._-a�•-: ttie"•ia:.`�7E • • ��ii`r•_i`:�,j:'- ... u- ...........s......: -.- _.............. ..;?%p;�f•:-t3B5'iPii:a.'cri,_._...... .._'l j..�4,'}'L •-a�;:o-!8ff: - ......i.. �. a) Rupture of a known earthquake fault, as delineated on the most.recent Alquist-PrioloEarthquake Fault Zoning Map issued by the State Geologist for.the A,O area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. b).Strong seismic ground shaking? A,M c) Seismic-related ground failure, including liquefaction? ® ./ A,M d) Landslides? ® ■ A e)Would the project result in substantial soil erosion or ■ . A,I the loss of topsoil? f)Would the project be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project,.and potentially result in on- or off- A,C,N site landslide, lateral spreading, subsidence, liquefaction or collapse? 12 MHAJRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 TOWN OF LOS ALTOS HILLS hr-a: _ "_ a- ;y- :y_'vF` "' -7? •-s+ �� �. r---tom r Z..:.,... Y.r q:._ J. Y t , g)Would the project be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code A,C (1994), creating substantial risks to life or property? h)Would the project have soils incapable of adequately supporting the use of septic tanks or alternative waste water disposalsystems where sewers are not A,B available for the disposal of waste water? -NAD 'p A Ai OUS Mn7ERFRLS.1Youldfie7'i$pt.. R: ^ • ,7 is•::'' • a) Create a significant hazard to the public or the environment through the routine transport, use, or �( A disposal of hazardous materials? b) Create a significant hazard to the public or the environment through reasonably foreseeable upset A and accident conditions involving the release of hazardous materials into the environment? c) Emit hazardous emissions-or handle hazardous or acutely hazardous materials, substances, or waste : ,f A within %mile of an existing or proposed school? d) Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section.65962.5 and,as a result, . A,B would it create a significant hazard to the public or the environment? e) For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, A would the project result in a safety hazard for people • residing or working in the project area? f) For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people ,j A residing or working in the project area? g) Impair implementation of or physically interfere with an adopted emergency response plan or emergency A,C evacuation plan? h) Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including A,B where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands? Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 13 September 2008 . TOWN OF LOS ALTOS HILLS Prr.s, .- � _tea x+- -r>.- _ i _t+-•-r{ ��.,r^ti„ t c v� R-. a-9..cmu-a^�� . l A- ' • r•' i • T_ S • f .., �, Ta t 1 f w•:I if.,._ � I S N.: ��: z � i!' A , _-%r .-.Y '•'• y ; HYDROLOGY-AND: {IATEf QUALITY.Would the pr ect: y ° ft," • a 1 , 4• a) Violate any water quality standards or waste . A,B,I discharge requirements? b) Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local ground water table A level (for example,the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)? . c) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the A,B course of a stream or river, in a manner which would result in substantial erosion or siltation on- or off-site? d)Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase A,B, the rate or amount of surface runoff in a manner which would result in flooding on-or off-site. e) Create or contribute runoff water which would exceed the capacity of existing or planned storm water A,B drainage systems or provide substantial additional - sources of polluted runoff? f)Otherwise substantially degrade water quality? ,J A,B g) Place housing within a 100-year flood-hazard area as mapped on a federal Flood Hazard Boundary or A C J Flood Insurance Rate Map or other flood hazard delineation map? h) Place within a 100-year flood-hazard area structures A,C,J which would impede or redirect flood flows? i) Expose people or structures to a significant risk of loss, injury or death involving flooding, including A,C;J flooding as a result of the failureof a levee or dam? j) Inundation by seiche,tsunami, or mudflow? A 14 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 TOWN OF LOS ALTOS HILLS «T - -i -.'L :c.ss-.x:= r •t'- - t.'•..s, ,!.t_ INv. .t r _ � •i, a< _ r,, r ?t" vs i c r r1 •9 LAND.USEAND-PLANNING.Would.the.projectc a) Physically divide an established community? A,B,C, D b) Conflict with anyapplicable land use plan, policy, or regulation of an agency with jurisdiction:over the project(including, but not limited to the general plan, A,C specific plan, local coastal program, or zoning ordinance)adopted for the purpose of avoiding or mitigating an environmental effect? c) Conflict with any applicable Habitat Conservation Plan or Natural Community Conservation Plan? A • p1t~:�E. OU CES-*Wo>uldt e a) Result in the loss of availability of a known mineral resource that would be of value to the region and the A,B,C residents of the state? b) Result in the loss of availability of a locally-important mineral resource recovery site delineated on a local .4 A,B,C general plan, specific plan, or other land use plan? -1_ti:NOJSE Wold•uthe'pwjet+t res• ult in: a) Exposure of persons to or generation of noise levels in excess of standards established in the local A,P general plan or noise ordinance or applicable standards of other agencies? b) Exposure of persons to or generation of excessive A ground borne vibration or ground borne noise levels? c) Substantial permanent increase in ambient noise levels in the project vicinity above levels existing A,B without the project? d)A substantial temporary or periodic increase in ambient noise levels in the project vicinity above A,B levels existing without the project? e) Fora project located within an airport land use plan or,where such a plan has not been adopted, within two miles of a public airport or public use airport, A,B,C would the project expose people residing or working in the project area to excessive noise levels? Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 15 September 2008 TOWN OF LOS ALTOS HILLS • f... _c•Y. �^M1, =Y �.-r•--.•.� r+•r+ �`/f3F �... r-' -� j ..r e _ten c -J' "" i L s ..:X; • f9 iti t; a€1_ �I " :•;";•';• s • piu.,..,r_ .........:-•,-...... ..� ......_r�. ..t-.__s,.,.�... ._. '`.-.. 3..G1i........!- ala•,. ;:,•••4`•--,-r•••• i.._._._ .�..:=�1�.. f) For a project within the vicinity of a private airstrip, would the project expose people residing or working , A,B,C in the project area to excessive-noise levels? • '12 POPULATION.AND •HOUSING:Would'the •�project - `'' -; a) Induce substantial population growth in an area, either directly (for example, by proposing new homes A • and businesses)or indirectly (for example, through • extension of roads or other infrastructure)? b) Displace substantial numbers of existing housing, A necessitating the construction of replacement housing. elsewhere? c) Displace substantial numbers of people, necessitating the construction of replacement housing elsewhere? A _ - - :.m_ moi:;:' •,•a•- :3+C�r'N["� .iL a.. :y F?:�::ir':�`�.i��^,;-i a( _`'13 PUBLIC SERI ICES<Wauld�t a pioiect es ilt in: res 'ntiat adverses h: ica ss dated - � .:.t 'di .ti='rc_';:xz. _ - C�.:..•lcy: _ :.trtv. ,l.Ta;:::i�::^ Y�..��:�_:[:S.;f=i�`��'i�l��.i�-..--�`-^ .OW!!t.�µ:= .with tl e; �rovis on `fne--:or physically al ei a�.. r �{ - s P--- .): ,, , !t,. .Q.:Y. ..X.. ,t. i gairtitrii040f'facai S`�*4:4 , ,t'crr�0.t h 0:!1 'i.::i�.4r '::i - _ .rpv n:'r .Y:T_.e• a. .•.nirJ li!` "rrir4T" .F _d.y. .a. _.'g.-: altered ovei'nmental facilties-. e coi str ctori o h r-5oa d. Aro -� � ........... .,�.,•_.,-... �_:,..:.:;•-:w•r �"�i�. _ t�� �aos��ignrffcan�erii�r��ar�mec ::�:_,. -gym ac -: -r -,. e . ..,� �:'_�^.::.:'. _ ;:.:. j �;,.,� ;...f .i ord r-to' iintai �acce- tabfe:servi aflos;ep*fi. s1 r oth eri tic 1;r C 1. s.ori—.:.•i iY �•[�:°. r:a::• - :iai -':yti•. •.o ctiv¢a�or�a .oP�tre ilb •5elrvlCB's. '_i:,��,.-: _ _I.r .h _ _ r. a)Fire protection? ,J A,B b) Police protection? A,B c) Schools? A,B • d) Parks? A,B. e) Other public facilities? - A,B 14.0E•CRE...7l0 N::1Noiilii.the• tso ectc • ./ 4. • • • .4 2 a) Increase the use of existing neighborhood and regional parks or other recreational facilities such that A substantial physical deterioration of the facility would occur or be accelerated? b) Include recreational facilities or require the A construction or expansion of recreational facilities which might have an adverse physical effect on the environment? • 16 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 • TOWN OF LOS ALTOS HILLS Tom.-r • t:ta.S_ �wr• rr r�i ;.,:_ r r ii•r,^ -k- �• t.. ^c.•• S.r r'S,rt a . •:• p - . •. _ - .7: t • • • ! fix j "'IRiANSPORT;f1 IOWTRAf FIC llllotitd the rod st it r�F a) Cause an increase in trafficwhichis substantial in' relation to the existing traffic load and capacity of the street system (for example, result in a substantial • A,P increase in either the number of vehicle trips, the . volume to capacity ratio on roads, or congestion at . intersections)? b) Exceed, either individually or cumulatively, a level of service standard established by the county 4 A C congestion management agency for designated roads or highways? c) Result in a change in air traffic patterns, including either an increase in traffic levels or achange'in V A,B location, which results in substantial safety risks? d)Substantially increase hazards due to a design V , feature(for example, sharp curves or dangerous A,B,P intersections)or incompatible uses (for example,farm equipment)?. e) Result in inadequate emergency access? ' -3 • A,B f) Result in inadequate•parking capacity? - � A,B,P g) Conflict with adopted policies,plans, or programs supporting alternative transportation (for example, ,j A,B bus turnouts, bicycle racks?' • a) Exceed wastewater treatment requirements of the ._ A B applicable Regional Water Quality Control Board? V b) Require or result:in the construction of new water or wastewater treatment facilities or expansion of A,B existing facilities, the construction or which could causesignificant environmental effects? - c) Require or resultin the construction of new storm water drainage facilities or expansion of existing A,B facilities, the construction of which could cause significant environmental effects? d) Have sufficient water supplies available to serve the project from existing entitlements and resources, or ,j A,B arenew or expanded entitlements needed? ' Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 17 September 2008 • TOWN OF LOS ALTOS HILLS. '�C p.,. 't•'f^^.kT- (. 1`�,'-^'t-..-.A:'C' x. 4+y..a.3 '.�zuy. -SP i .f..;—r'wC ,o t ._{ rr•_v SCti. � >y ---7 f y FY ;-1 • r rr- it F_i.�'4 t_t J�� \{ i • i _• z '..r > i! �c '.._a �-r .t is cy,ar r Y ._,1 ._«...�.,.s ,. :r;-� _tr:� _ ..+.»tic;._ .� ..>>:. .._.......;.:itt r.a.. �..::ifa• .. ... _ ..: _ ..:..Fa.._->.._ e)Result in a determination by the wastewater treatment provider which serves or mayserve the project that it has adequate capacity to serve the project's A,B projected demand in addition to the provider's existing commitments? f) Be served by a landfill with sufficient:permitted capacity to accommodate the project's solid waste A,B • disposal needs? g)Comply with federal,'state, and local statutesand regulations related to solid waste? A,B 17 ADA ORY FIND NGS..OF•SJGNIFJCANN41E:-Doestl a ro ect: : :;. .: ":=`:`.••' <:r: a) Have the potential to degrade the quality of the environment,substantially reduce the habitat of a fish • or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to A,B,G, eliminate a plant or animal community, reduce the . HL number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history or prehistory? b) Have impacts that are individually limited;but cumulatively considerable? ("Cumulatively considerable"means that the incremental effects of a project are considerable when viewed in connection A,B with the effects of the past projects, the effects of other current projects, and the effects of probable future projects.) - . c) Haveenvironmentaleffects which will cause substantial adverse effects on human beings, either , A,B directly or indirectly? ' ENVIRONMENTAL ANALYSIS • The following analysis is intended to explain responses,outlined in the Environmental Checklist (above), pursuant to the requirements of the California Environmental Quality Act(CEQA). Responses are provided to all checklist questions marked.as"Less than Significant" or"Less than Significant with Mitigation Incorporated."Questions marked as"No Impact" are not discussed in detail below, but the checklist indicates sources used to make that determination. 18 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft.IS/MND September 2008 • TOWN OF LOS ALTOS HILLS 1. Aesthetics Nolivetrees or any other scenic resources would be removed or altered'as part of this project. The project would not include new lighting and would not cause light or glare. The project would have.a temporary impact on the scenic vista and quality of the project site during construction due to the presence of equipment and crews.There are no designated scenic views that would be affected by the construction. This impact would be temporary and minor,and would be considered less than significant. 2. Agricultural Resources • There are no agricultural resources in the project vicinity; the proposed project would have no impact on agricultural resources. No mitigation is required. - 3. Air Quality Construction activities may temporarily affect local air quality._Particulate matter less than 10 microns in size (PM10) and less than 2.5 microns in size (PM2.5) are the pollutants of greatest concern with respect to construction activities. Project construction could generate dust(including PM10) from a variety of activities, including grading, soil disturbance, and vehicle and equipment exhaust. The sources of PM2,5 include fuel combustion from automobiles,and diesel powered vehicles. These fine particles are also formed in the atmosphere when gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds (all of which are also products of fuel combustion) are transformed in the air by chemical reactions. Emissions would vary from day today depending on equipment and vehicles usedand the wind speed during construction. Construction-related dust emissions would've y from day to day, depending on the level and type of activity, silt content of the soil, and weather. The Bay Area Air Quality Management District's (BAAQMD) approach to the CEQA analysis of construction impacts is to emphasize implementation of effective and comprehensive control measures, rather than detailed quantification of emissions.The BAAQMD has identified a set of feasible PM10 and PM2.5 control measures for construction activities. The Town's dust control measures effectively implement the BAAQMD requirements (BAAQMD.1999). Implementation Of these controls as outlined in the following mitigation measure would reduce air quality impacts from construction activities to a less than significant level. Mitigation Measure 3-1: Dust control measures shall be implemented during site preparation and construction activities as per Los Altos Hills Municipal Code requirements. Dust control measures shall be listed on the project plans,to the satisfaction of the Director of Public Works. Mitigation Measure 3-2: Construction vehicles shall not idle unnecessarily. Paint and finishing spray applications shall not be conducted during windy periods(winds:exceeding 20 miles per hour). 4. Biological Resources A California Natural Diversity Database (CNDDB) search was conducted for the project area. No special-status species have been identified at the project site. Nearby occurrences of special status species include: Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 19 September 2008 • Franciscan onion(Allium peninsulare var. franciscanum) • Western leatherwood (Dirca occidentalis) • California red-legged frog(Rana draytonii) Franciscan onion—The Franciscan onion is listed:as 16.2 on the California Native Plant Society (CNPS) list,which means that the plant is rare throughout its range and fairly threatened in California.The CNPS notes that the species occurs within the Mindego Hill quadrangle,within which the project is located. The habitat for the onion is listed by the CNPS to be cismontane woodlands or valley and foothill grasslands. There is a high potential for the onion to occur in the project area.The plant's survival is noted to be threatened by foot-traffic. Potential impacts to the Franciscan onion would be reduced to less than significant levels with the implementation of the following mitigation measure. Mitigation Measure 4-1: Prior to project construction, a certified biologist shall survey the project area for Franciscan onion and Western leatherwood.Any occurrences of these plants shall be flagged and avoided. If avoidance is not possible,the plant shall be relocated to an adjacent area by the certified biologist. • Western leatherwood-Western leatherwood is also listed as 16.2 on the CNPS list. It occurs in the Mindego Hill quadrangle and is known to bloom on hillsides and slopes near or in riparian habitats or mountainside.woodlands. The potential for the plant to occur at the project site is high and impacts may occur. Mitigation Measure Biology-1 would reduce any potential impacts to less than significant levels. California red-legged frog—The California red-legged frog is Listed Threatened (LT) by the US Fish and Wildlife Service (USFWS)and is found in shallow water and creek habitats in Santa Clara County.The frog prefers shaded riparian areas and dense vegetation. The project includes two crossings of streams with similar habitat to that preferred by the California red-legged frog.The potential for the California red-legged frog to occur in the project area is considered high. Mitigation Measure Biology-2 would reduce any potential impacts to the red-legged frog to less than significant levels. Mitigation Measure 4-2:Grading,clearing and other land disturbance shall be scheduled to avoid the rainy season when California red-legged frogs are most likely to be moving between different bodies of water.Grading,clearing and other land disturbance shall generally be performed between April 15th and October 15th, but shall occur no earlier than two weeks before the last spring rainfall and shall cease at the onset of fall rains. Construction timing shall also be consistent with any limitations imposed by the CDFG, RWQCB and/or the USFWS. Prior to construction, a certified biologist shall: 1. Conduct an education training session for all construction personnel.The biologist shall either be bilingual(English and Spanish)or an interpreter shall participate to instruct personnel in Spanish as needed.The program shall consist of a brief presentation explaining endangered species concerns, to include: a) A description of each of the special status species and their habitat needs. b) An explanation ofthe status of the species during project construction and implementation. . c) Measures to protect and avoid effects to the species.A fact sheet conveying this information shall be prepared for distribution to the above- mentioned personnel and anyone else who may enter theconstructionarea. 2. Survey the project area for California.red-legged frog.Any frogs located in the project area shall be relocated to avoid impacts.A biologist shall remain onsite during construction within 250 feet of streams to monitor for California red-legged frog and relocate any individuals found. . Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 20 September 2008 - TOWN OF LOS ALTOS HILLS Local wildlife species, including deer, use the project site as a minor corridor within the Los Altos Hills area. Deer were seen using both the project site and existing pathways during the site visit on July 23, 2008. Construction would have a temporary impact on deer and other animals that:use the project area as a corridor through the Los Altos Hills; animals would tend to avoid the area during times of human presence.The impacts would be temporary and less than significant. No trees would be removed as part of the proposed project. Temporary ground disturbance, including vegetation removal and blading and grading of the soil, is expected for 200% of the trail area.The construction disturbance areasbeyondthat needed for the trail would not be cleared but vegetation may be crushed;these areas would be revegetated with appropriate;native grass and plant seeds, which would be hand spread and mulched with punched straw. 5. Cultural Resources • There are no known archaeological or historical resources on or near the site.The project site is part of a hillside in a residential area.The proposedproject would require minimal site excavation with the potential to unearth undiscovered cultural resources. Discovery of and construction,effects to buried or previously unidentified resources would represent a significant effect. The following . mitigation measure would reduce impacts to any previously unidentified historical or archaeological resources to less than significant levels. Mitigation Measure'5-1: Prior to excavation or construction,the Town shall incorporate a note on the first page of the construction plans stating that should cultural resources be encountered during site grading or other site work, such work shall immediately be halted in the area of discovery and the project sponsor shall immediately notify the Community • Development Director of the discovery.The applicant shall be required to retain the services of a qualified archeologist for the purpose of recording,protecting,or curating the discovery as appropriate.The cost of the qualified archaeologist and of any recording, protecting, or curating shall be borne solely by the project sponsor.The archaeologist shall be required to submit a Cultural Resources Management Plan, per City Requirements, to the Community . Development Director for review and approval that outlines the findings and mitigation methods of curation and/or protection of the resources. No further grading or site work within the area of discovery shall be allowed until the preceding has occurred. Disposition of Native American remains shall comply with CEQA Guidelines Section 15064.5(e). The note on the plans shall be subject to review and approval of the Planning Division. 6. Geology and Soils The project site islocated approximately 3.4 miles east of the San Andreas Fauit Zone but is not located within an Alquist-Priolo fault zone.The project is located near the Monte Vista Fault,which is a Quaternary Fault and not listed as an Aiquist-Priolo.Fault Zone. Impacts associated with fault rupture would therefore be less than significant. The project area has the potential for moderately high shaking intensity in the event of an earthquake. Impacts would be less than significant as no structures exist that could collapse and cause injury or loss.There is no to low potential for liquefaction on the project site. The proposed project would be located on a hillside with moderate to steep slopes. This hillside has few landslide deposits but has the potential for landslides. The proposed project would involve the construction of retaining walls along the central segment of the pathway where the hillside slopes are steepest. These retaining walls would not eliminate the potential for landslides, but would help the stability of the hillside. Landslide impacts would be less than significant. Soil erosion and loss'of topsoil would increase as a result of hikers and equestrians using the pathway. The Town would conduct regular erosion maintenance. Impacts related to erosion would. be considered less than significant due to the Town's proposed erosion maintenance. Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 21 September 2008 ' • TOWN OF LOS ALTOS HILLS The project is located on a geologic unit of Cretaceous greenstone of the Franciscan Complex, which would not be prone to lateral spreading, subsidence, liquefaction, or collapse.The Town of Los Altos Hills General Plan describes the soils groups that the Town is located on as having moderate to high shrink-swell characteristics (i.e., expansive soils). Impacts-related to expansive soils, however, would be less than significant as no buildings or structures would be constructed: on these soils as a part of the project. 7. Hazards and Hazardous Materials . The proposed project would not involve hazardous materials use beyond those routinely used in construction. The following mitigation measure would reduce the potential impactsof the use of standard construction hazardous materials to a less than significant level. Mitigation Measure 7-1:The contractor shall submit a spill response plan prior to the onset of construction to ensure a prompt and effective response to any accidental spills or leaks of diesel,_gasoline, oil or other contaminating materials that might flow or migrate to the creek. Construction of the pathway could pose a threat of wildfire due to construction workers disposing of cigarettes into the dry grasses on the hillside. The following mitigation measure would reddce' impacts to less than significant levels. Mitigation Measure 7-2: Construction personnel shall dispose of cigarette butts in the appropriate trash containers and shall not dispose of cigarette butts on the ground. Construction personnel shall be briefed regarding this measure prior to construction. The proposed pathway would include stepped switchbacks due to the steep nature of the hillside. The proposed pathway would still be steep for hiking and horse-riding. The pathway may be dangerous for novice riders and unconditioned horses;the steep terrain could also cause conflicts between horses and hikers. The Town would post signage at both ends of the pathway warning equestrians that the trail is not suited for novice riders and unconditioned horses, and also warning pedestrians.of possible conflicts on the trail with equestrians. With the signage proposed by the Town, the potential hazards caused by the steep nature of the hillside and the use of the trail by' both pedestrians and equestrians would be less.than significant. 8. Hydrology and Water Quality: . Cutting into the hillside for the construction of the new pathway and construction of the bridges would have potential for soil erosion. Trail use would also lead to increased erosion and siltation• . impacts to Deer Creek andits tributary.To avoid potential soil erosion and siltation impacts,the following mitigation measure is provided. Implementation of this measure would reduce potential hydrology and water quality impacts to a less than significant.level. Mitigation Measure 8-1:An erosion controlplan shall be prepared for review and approval by the Director of Public Works prior to commencement of any project activities. The plan shall specifically address measures to control erosion during construction and to minimize erosion from trail use and maintenance after construction. Footbridge construction and installation could potentially introduce a significant amount of debris andsedimentation into waterways:To minimize impacts to a less than significant level, the following mitigation measure will be implanted. Mitigation Measure 8-2: Footbridge construction and installation shall be:scheduled when water levels are predicted to be low in order to reduce the likelihood of construction related debris or sediment entering the river.Additional efforts to reduce water quality degradation include; 22 MHAIRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 • TOWN OF LOS ALTOS HILLS a) The contractor will be required to install a protective Impermeable barrier, such as a tarp, between the bridge work area and any surface water. b) Dirty construction water will be filtered through burlap and poured into a sump at. least 100 feet from surface water. c) Sawdust and chips from treated wood will be packed out as trash and most of the cutting and drilling of treated wood will be done in the staging area before the lumber is brought in. 9. Land Use and Planning The Town of Los Altos Hills General Plan characterizes the majority of the community, including the project area, as single-family residential. The Land Use Element of the Town of Los Altos Hills General Plan lists goals and policies for development in the Town. The Land Use Element outlines an overall objective of maintaining the rural character of the Town and minimizing disturbance to the natural terrain.The project involves minor physical changes to the natural environment, and would not induce growth.The proposed project would not have an impact on any applicable conservation plans. The proposed project would not divide an established community, as it would create a connection to an existing path. No mitigation is required. 10. Mineral Resources There are no known mineral resources on the project site. No mitigation is required. • 11. Noise Anticipated construction noise would be temporary in nature and would mitigated by standard project best management practices. Construction activities, including demolition, would be required to comply with Section 10-2.403 of the Town Municipal Code, which regulatesthe hours of construction to between 8:00 a.m. and 5:00 p.m., Monday through Friday, and not on public holidays. The use of the new trail segment would not exceed the noise level limits established in the General Plan. 12. Population and Housing The proposed development of an extension of an existing pathway system would not induce substantial population growth. No people or residences would be displaced bythe project. No mitigation is required. 13. Public Services Existing fire, police, and other governmental services are sufficient to accommodate the service needs of this project.The project would not necessitate the expansion of the equipment,facilities, or manpower of responsible fire, police, health, and school services in order to maintain current service ratios and response times. The project also would not result in substantial adverse physical impacts associated with the provision of new or altered fire, police, health, or school facilities. There would be no need for new or physically altered governmental facilities. No mitigation is required. • Los Altos Hills Taaffe Road Pathway Draft IS/MND •MHAIRMT 23 September 2008 TOWN OF Los ALTOS HILLS • 14Recreation The proposed project is intended to increase the use of the area for recreational purposes for hikers and equestrians:Novice.equesfrians would be warned by signage of the steep slope on-the pathway. Mitigation measure 7.2 would warn hikers of the potential for horses to be on the trail: • The project would provide hikers and equestrians with a connecting pathway from the existing path shown.on.Figure 2 to Taaffe Road..The linkage Of pathways could slightly increase the use of the existing pathways and other recreational facilities, but would not be substantial enough to cause significant deterioration. No additional recreational facilities would be required and the potential impacts to recreation would be less than significant. 15. Traffic and Transportation Temporary minor impacts to traffic may occur along Taaffe Road and Elena Road during project. construction. No more than six construction workers at one time Would be working at the site. Workers would be directed to park transportation vehicles and store construction equipment(which may include:srmall tractors, backhoe, bobcat, and small dump truck) along Elena Road and/or La Vida:Real. Construction equipment maybe stored along Elena Road for approximately One month. The presence of the construction vehicles, equipment, and personnel may cause a temporary. decrease in traffic speeds due to curious local residents and passersby. The constructioncrew and equipment may temporarily reduce available parking for recreational trail users and local residents. The presence of construction equipment would not result in inadequate emergency access or incompatible uses. The temporary construction impacts on traffic and parking would be minor,and therefore less than significant. The project does not have the potential to cause an increase in traffic that is substantial in relation to the existing traffic load and capacity of the street system, and therefore no mitigation is required. 16. Utilities and Service Systems The project site is located on a hillside within a residential area that is furnished with established wastewater treatment and storm water drainage facilities, as well as existing water supply and distribution systems. The proposedproject would not generate any impact on existing water supplies. The project would comply with all applicable state and local codes that mandate the use of water conserving equipment: Impacts under this category are considered less than;significant; therefore, no mitigation is required. 17. Mandatory Findings of Significance a) The proposed project does have-the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or' wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal • or eliminate important examples of the major periods of California history or prehistory • unless mitigated..With the proposed mitigation, no significant impacts are expected. b) No new impacts are expected from approval of the proposed project, other than temporary dust, noise, and traffic impacts.AU potential impacts would be reduced to a less than significant level after implementation of proposed mitigation measures.The project, : therefore, will not have any impacts that would be cumulatively considerable. c) The proposed project would have temporary construction impacts related to air quality and noise.These impacts would, however, be mitigated to less than significant levels with the 24 MHAJRMT Los Altos Hills Taaffe Road Pathway Draft IS/MND September 2008 TOWN OF LOS ALTOS HILLS requirement of dust control measures and limited hours for construction.The proposed • ' project is not expected to result in any permanentimpacts that have,substantial adverse effects on human beings, either directly or indirectly. • INFORMATION SOURCES The following information sources were used in the preparation of this document and referenced throughout the Initial Study Checklist: A. Project Plans,Land People, June 30,2008 B. Field Inspection, MHAIRMT, July 23, 2008 • C. Los Altos Hills General Plan, updated through 2007 D. Zoning Ordinance of the Town of Los Altos Hills, 2003 E. Farmland Mapping and Monitoring Program,ftp://ftp.consrv.ca.gov/pub/dlrp/FMMP/, accessed July 25, 2008 F. Bay Area Air Quality Management District CEQA Guidelines: 1999.Assessing the Air Quality Impacts of Projects Plans G. California Department of Fish and Game Natural Diversity Database, Special Vascular Plants, Bryophytes, and Lichens List, July 2008 H. CNDDB Search, conducted by MHAIRMT on August 4, 2008 I. Review of Proposed Taaffe Trail, Town of Los Altos Hills, California,Timothy C. Best, CEG, July 17, 2008 J. Flood Hazard Map, Hazard Information and Awareness Site,www.esri.com/hazards K. Seismic Hazard Zoning Map, http://www.conservation.ca.gov/cgs/ship/, accessed July 28, 2008 L. California Native Plant Society Inventory of Rare and Endangered Plants, http://cnps.web.aplus.net/cgi-bin/inv/inventory..cgi, accessed August 6, 2008 M. Association of Bay Area Governments (ABAG)Earthquake Maps and Information, http://www.abag.ca.gov/bayarea/egmaps/, accessed August 7, 2008 N. Geologic map-of the project area, MHAIRMT,August 7, 2008 O. Fault map of the project area; MHAIRMT, August 7, 2008 P. Data Needs Responses, LandPeople,August 28, 2008 Los Altos Hills Taaffe Road Pathway Draft IS/MND MHAIRMT 25 September 2008 LIST OF PREPARERS Preparers Laurie Hietter, Quality Assurance/Quality Control (QA/QC) Jeffrey Smith, Senior Planner, Project Manager Chrissy Spanoghe, Environmental Scientist Bonny Engler, Environmental Analyst • Corey Fong, GIS Specialist MHA Environmental Consulting,An RMT Business 4 W. Fourth Avenue, Suite 303 San Mateo, CA 94402 Los Altos Hills Staff Richard Chiu, Public Works Director Michelle Chen, Associate Engineer Town of Los Altos Hills Public Works Department 26379 Fremont Road Los Altos Hills, CA 94022 . ATTACHMENTS 1. Mitigation Monitoring Plan r • Los Altos Hills Taaffe Road.Pathway Draft IS/MND MHAIRMT 26 September 2008 EXHIBIT 2 • • • EW-TsO➢ArnwOti:•• I 't/ % .: ... 1/ 1 , .,1, 1 /nc^,':17 LEGEND • / ,11 i;-b /' SWiT:.itOA 6,TJ1,'I,AFY E200070 trM WM r;m' 1 I� _ 1 -- 1 ' `,l t'iv;: Ea um WI rs.- ro0 swum ttfV rD�r los I'l , '• 1rf�1:it O ILIO 113 R9 Cir'- '6r, I J �I I .___....____.___ Glt[12N7 IOZ 017 Sf1EACY ,1 FOAMED JCOIi TP➢xN • I +• Ir • _-- _ - �I!Ac_- _, 9 < J 1 =T - FAULT um' SO WINED ada%Ei7: '�Il' 1-> -- -- I I aCVc:T Or,f[1rlJrv) II 5 1 u��'LrtCvaDax rErrre eLSj•,l / •/ j ;{{{,r rear,or v.mENt ,) --3 L cc tux(10 PC CPVOJW°a FIR tccula701 1(ILport➢1FAUAI�rF f— i I +',Tl 17 12 i0.��/ / / / j 11 (Sa Roo a rtrloS e.lit MS=IAfq$IFJt L PA i j:i' \ (; I o I sipl I ns;�ul� s u1� .¢• /1 / i ! DEM;GLAVN0 1 i/ RCE TJ EE 70710 II 14,I 3i v8 LOT 2- cart p •' IY -_Ti ; l I 'I',: Cs - .• fE6f070 rSTA o I _ LOT 3 _r ,5 {fI FIR 7011-WCAL EM T TO 2 F�'-St0 TGC.17017 . . I '1 r,8 © 1 1 , ae n i ?) 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GEOTECHNICAL&ENVIRONMENTAL SERVICES ROMIG ENGINEERS, INC. GEOTECHNICAL&ENVIRONMENTAL SERVICES May 15, 2014 2559-1 Ms.Avigale McLoughlin RE: ENGINEERING GEOLOGIC HAZARD AND do Los Altos Property LP. PRELIMINARY GEOTECHNICAL 4252C Omoa Road INVESTIGATION Koloa,Hawaii 96756 LANDS OF STIRLING SUBDIVISION 28030 NATOMA ROAD LOS ALTOS HILLS,CALIFORNIA Dear Ms. McLoughlin: In accordance with your request,we have performed an engineering geologic and preliminary geotechnical investigation for the proposed residential subdivision to be constructed on the 18-acre Lands of Stirling property located at 28030 Natoma Road in Los Altos Hills, California. In particular,we have evaluated the potential for landsliding and for ground surface rupture by the Monta Vista Fault,which is considered to be potentially active by the Town of Los Altos Hills. The accompanying report presents our evaluation of the potential for geologic hazards including fault rupture and landsliding to affect the subdivision, and provides preliminary geotechnical recommendations for the proposed subdivision. This investigation included evaluating the potential for ground surface rupture on the Monta Vista fault. We concluded that the fault at this location is not capable of surface rupture. We have nevertheless conservatively recommended that the foundations of the proposed residences be designed to avoid extending below the fault plane,to reduce the potential for damage to the residences from secondary sympathetic movement on the fault. We refer you to the text of our draft report for specific findings and recommendations. Thank you for the opportunity to work with you on this project. If you have any questions or comments concerning the findings or recommendations of our investigation, please call. Very truly yours, `ya`�,oF HOLLoo<sW ce i. Na.115B to urnmED ,,, ROMIG ENGINEERS,INC.: + oENGERINti oil LO AR- OF CALY Christina M. Tipp David F. Hoexter,P.G, Expires 11/30/15 co��NFEa ca1� � 002157 r:Iayti)1, 77883 • * 9 '�e+CFO - \G'r� Tom W. Porter, P `nl7r CMI �1 Gfen A. omi_, '•;-1r;'cAi►e0�� �.�F CflL1F0 1390 El Camino Real,Second Floor • San Carlos,California 94070 o (650)591-5224 o Fax(650)591-5251 • Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 2 of 2 Copies: Addressee (1) Wilsey Ham (4) Attn: Mr. Jeff Peterson GAR:DFH:TWP:CMT • • • • • ROMIG ENGINEERS,INC. ENGINEERING GEOLOGIC HAZARD AND PRELIMINARY GEOTECHNICAL INVESTIGATION LANDS OF STIRLING SUBDIVISION 28030 NATOMA ROAD LOS ALTOS HILLS, CALIFORNIA 94022 PREPARED FOR: MS.AVIGALE MCLOUGHLIN 4252C OMAO ROAD KOLOA,HAWAII 96756 PREPARED BY: ROMIG ENGINEERS,INC. 1390 EL CAMINO REAL, SECOND FLOOR SAN CARLOS, CALIFORNIA 94070 MAY 2014 ROMIG ENGINEERS,INC. TABLE OF CONTENTS Page No. Letter of transmittal Cover Page • TABLE OF CONTENTS INTRODUCTION 1 Project Description 1 • Scope of Work 1 Limitations 2 SEISMIC HAZARD SETTING 3 • REVIEW OF TOWN INFORMATION 3 • PREVIOUS ON-SITE INVESTIGATION 4 • SITE EXPLORATION AND RECONNAISSANCE 4 Surface Conditions 4 • Subsurface Conditions 5 Exploratory Borings S5 • Test Pits 9 Laboratory Results 13 Ground Water 13 GEOLOGIC SETTING 14 Regional Geology 14 Site Geology 15 • Engineering Geologic Reconnaissance 16 Aerial Photographs 18 • Landslide Evaluation 19 Fault Evaluation20 • Faulting and Seismicity 23 Table 1. Earthquake Magnitudes and Historical Earthquakes 23 • Earthquake Design Parameters 24 • Additional Geologic Hazards Summary 24 • CONCLUSIONS AND DISCUSSION OF FINDINGS 25 FEASIBILITY OF PROPOSED RESIDENCE SITES 26 Subdivision Lots 1 Through 4 26. • Subdivision Lots 5 Through 8 26 Subdivision Lot 9 28 UPPER DORMANT LANDSLIDE& COLLUVIAL SWALE MITIGATION 28 Slope Grading 29 Subdrains 29 SUBDIVISION ROAD PAVEMENTS • 30 • Table 2. Minimum Pavement Section Thicknesses 30 • SLABS-ON-GRADE 31 General Slab Considerations • 31 • Exterior Flatwork 32 EARTHWORK RECOMMENDATIONS 32 Clearing and Subgrade Preparation 32 • Compaction 33 Table 3. Compaction Recommendations 33 Material For Fill 33' ROMIG ENGINEERS,INC. • TABLE OF CONTENTS (Continued) General Hillside Grading 34 Temporary Slopes and Excavations 34 Finished Slopes 34 Surface Drainage 0 35 FUTURE SERVICES 35 Plan Review 35 Construction Observation and Testing 36. REFERENCES FIGURE 1 - VICINITY MAP FIGURE 2- TOWN GEOLOGIC MAP FIGURE 3 - TOWN SEISMIC HAZARD MAP FIGURE 4- ENGINEERING GEOLOGIC RECONNAISSANCE MAP FIGURE 5 - LOCATIONOF MONTA VISTA FAULT MAP FIGURE 6- LOCATION OF GEOLOGIC CROSS-SECTIONS FIGURE 7- GEOLOGIC SECTION A-A' FIGURE 8 - GEOLOGIC SECTION B-B' FIGURE 9- GEOLOGIC SECTION C -C FIGURE 10- GEOLOGIC SECTION D-D' FIGURE 11 - GEOLOGIC SECTION E-E' FIGURE 12- GEOLOGIC SECTION F -F' FIGURE 13 - GEOLOGIC SECTION G-G' &H-H' FIGURE 14- GEOLOGIC SECTION I-I' FIGURE 15 -LOT 7 CONCEPTUAL GRADING PLAN FIGURE 16-LOT 7- SLOPE GRADING CROSS-SECTION FIGURE 17- CONCEPTUAL BENCHING DETAIL APPENDIX A-LOGS OF EXPLORATORY BORINGS Figure A-1 -Key to Exploratory Boring Logs Figure A-2-Key to Bedrock Descriptions Exploratory Boring Logs EB-1 through EB-32 APPENDIX B - SUMMARY OF LABORATORY TESTS • Figure B-1 -Plasticity Chart APPENDIX C -LOGS OF TRENCHES AND TEST PITS Figure C-1 -Test Pits TP-1 and TP-2 Figure C-2-Test Pits TP-3 through TP-5 Figure C-3 -Test Pits TP-6 through TP-8 Figure C-4-Test Pits TP-9 through TP-11 Figure C-5 -Test Pits TP-12 through TP-14 ROMIG ENGINEERS, INC. ENGINEERING GEOLOGIC HAZARD AND PRELIMINARY GEOTECHNICAL INVESTIGATION FOR • LANDS OF STIRLING SUBDIVISION 28030 NATOMA'ROAD LOS ALTOSHILLS, CALIFORNIA INTRODUCTION This report presents the results of our engineering geologic hazard and preliminary geotechnical investigation for the proposed residential subdivision to be constructed on the Lands of Stirling property located at 28030 Natoma Road in Los Altos Hills, California. The location of the site is shown on the Vicinity Map, Figure 1. The purpose of this investigation was to evaluate the potential for geologic hazards including fault ruptureand landsliding to affect the subdivision and to provide a feasibility level geotechnical evaluation of the property. Project Description The project consists of subdividing the 18-acre Lands of Stirling property in Los Altos Hills. The property will be subdivided into 9 lots; one of the lots includes an existing residence, which is expected to remain on the site. Four lots o_f the subdivision will be developed on the gently to moderately sloping areas of the site and four lots are planned adjacent to or extend onto the steeper western slopes. Charles Avenue will be extended through the middle of the property to provide access to the subdivision. Scope of Work The scope of work for this investigation was presented in detail in our agreements with you dated February 4, 2011, July 15, 2011, and October 3, 2012. In order to accomplish this investigation,we performed the following: • Review of geologic, geotechnical, and seismic conditions in the vicinity of the site. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 2 of 36 • Subsurface exploration consisting of drilling, sampling, and logging-32 exploratory borings and excavating and logging 14 test pits to collect data regarding subsurface conditions. • Geologic reconnaissance by our certified engineering geologist and geotechnical engineering staff. • Interpretation of stereo-pair aerial.photographs. • Laboratory testing of selected samples to aid in soil classification and to help evaluate the engineering properties of the surface and near-surface soil. • Preparation of this report presenting our findings and geologic and geotechnical recommendations for, the proposed subdivision. The report also provides recommendations for the expected subdivision improvements. Limitations This report has been prepared for the exclusive use of Ms. Avigale.McLoughlin for specific application to evaluating geologic hazards and developing feasibility level geologic and geotechnical design criteria for the currently proposed residential subdivision to be constructed at 28030 Natoma Road in Los Altos Hills, California. We make no warranty, expressed or implied, except that our services were performed in accordance with geotechnical engineering principles generally accepted at this time and location. This report was prepared to provide engineering opinions and recommendations only. In the event there are any changes in the nature, design or location of the project, or if any future improvements are planned,the conclusions and recommendations contained in this report should not be considered valid unless 1)the project changes are reviewed by us, and 2) the conclusions and recommendations presented in this report are modified or verified in writing. The analysis, conclusions, and recommendations presented in this report are based on site conditions as they existed at the time of our investigation;. the currently planned residences; review of readily available reports relevant to the site conditions;. and laboratory test results. In addition, it should be-recognized that certain limitations are inherent in the evaluation of subsurface conditions, and that certain conditions may not be detected during an investigation of this type. Changes in the information or data gained from any of these:sources could result in:changes in our conclusions or recommendations. If such changes occur, we should be advised so that we can review our report in light of those changes. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 3 of 36 SEISMIC HAZARD SETTING A trace of the potentially active Monta Vista Fault is shown on the Los Altos Hills Geologic Map as trending roughly north to south through the middle of the property and then bending eastward across the southern portion of the site (Cotton, Shires & Associates, 2005, see Figure 2). The presence of the mapped fault across the property results in designations of Zone "F" and Zone "D" on the Los Altos Hills Geotechnical and Seismic Hazard Zones Map (Cotton, Shires & Associates, 2004, see Figure 3). Zone "F" is designated as a potential fault rupture zone which "encompasses all land located within 200 feet of a recognized trace of a potentially active fault (includes State designated active 'Type B' faults)"; Zone "D" is designated as a potential ground . deformation/fault rupture zone which "encompasses all land located within 660 feet of a recognized trace of a potentially active fault (includes State designated active 'Type B' faults)". REVIEW OF TOWN INFORMATION We visited the Town of Los Altos Hills Building Department on February 9, 2011 to review available documents concerning the site and geotechnical and geologic investigations completed in the near vicinity of the site. No applicable: reports were available for adjacent or nearby properties. • The Town Geologist provided a report that was performed on the adjacent property north of the site. The report was prepared by Murray Engineers Inc. (MEI) dated September 30, 2010 for 13456 South Fork Lane. MEI performed an engineering geologic and geotechnical investigation which included advancing six exploratoryborings and excavation of two leach field exploration pits. One purpose of the MEI investigation was • to identify the location of the Monta Vista Fault. The fault plane was delineated based on exploratory borings; neither trenching nor test pits for the purpose of locating the fault were included in the investigation. All of the MEI borings were advanced on the up- thrown block of the fault and the borings generally encountered limestone, greenstone, and mélange bedrock of the Franciscan Complex. The borings advanced near the',fault trace encountered the fault plane at depth with claystone, siltstone, and sandstone conglomerate bedrock of the Santa Clara Formation underlying the Franciscan Complex. MEI derived cross-sections from its boring logs to illustrate the topography of the site and locations of the borings and then extended the fault plane based on the boring data to delineate the ground surface trace of the fault. MEI concluded that the fault trace was located farther west than shown on the Town Geologic Map, and downslope(west) of the proposed residence. The cross-sections portray the fault trace dipping approximately 10 degrees into the hillside (to the south and the east) across the property. A 20 foot setback was recommended by MEI for residential development. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 4 of 36 PREVIOUS ON-SITE INVESTIGATION We previously conducted a geotechnical investigation at the site for the garage that was recently constructed at theexisting residence on the property; the results were presented in our report to you dated July 18, 2011. The investigation included advancing three exploratory borings to depths between 8.2 and 16 feet (Borings EB-15 through EB-17). A description of the subsurface conditions encountered in the borings is presented later in this report and the boring logs are attached in Appendix A. SITE EXPLORATION AND.RECONNAISSANCE Site reconnaissance and subsurface exploration were performed from February 15, 2011 through November 12, 2012. The exploratory borings were advanced using a track mounted drilling rig equipped with 4-inch solid flight augers and an automatic hammer and with portable Minuteman sampling equipment. Exploratory borings were advanced to depths ranging from 8.2 to 44.5 feet. The approximate locations of the borings are presented on the Site Plan, Figure 4. The boring logs and the results of our laboratory tests are attached in Appendices A and B, respectively. Fourteen exploration trenches and test pits, totaling approximately 260 feet in length, were excavated and logged April 22, 2011 through February 17, 2012. Most of the trenches and test pits were shored in order to provide safe access for logging the exposed side walls. The Town's consulting geologist, Mr. Ted Sayre, observed some of the subsurface exposures. Surface Conditions The approximately 18-acre site is located along an unmarked road, Charles Avenue, west of Natoma Road. The property is surrounded by residential properties.. The site has a long, gravel driveway extending from the Charles Avenue to the main residence. At the time of our investigation, the site was occupied by two primary structures. The primary structure was a single-story residence with brick siding. A new garage was in the process of being constructed and completed adjacent to the residence during the most recent phase of our study. A single-story cottage was located south ofthe residence. Brick and concrete flatwork were observed around the main residence. Two additional small residential or storage structures were located in the.center of the property. An active well was also located in the central part of the property which we understand' is the primary water source. A small well house and two water tanks were located near the well. A • possible additional (inactive) well was present near the active well. The site was landscaped with native grasses, small to large shrubs, and small to medium trees. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Landsof.Stirling Subdivision Page 5 of 36 The property generally slopes down toward the west at varying slope inclinations. The eastern section of the property slopes down toward the west at inclinations ranging from approximately 16:1 to 8:1 (horizontal:vertical). In the mid-section, the slope inclinations increase to between about 5.5:1 and 4:1. A drainage with a flowing creek is located along the western property line and wraps around the southern portion of the site toward Natoma Road. The sides of the drainage were generally steep with average inclinations of about 2:1 (horizontal:vertical), with increasingly steep slope inclinations near the base of the drainage in certain areas. A relatively broad shallow swale was present in the central area of the site,. An ephemeral creek descends from the swale down to the west to the flowing creek. Two dormant landslides, one essentially upslope of the second, were identified further north on the property. The main residence and driveway are located on a relatively flat area in the southern portion of the property with a steep 2:1 (horizontal:vertical) slope along the.southwest and south sides of the residence. The cottage is located near the driveway and extends slightly over the steep slope.. Subsurface Conditions Exploratory borings were initially used to identify the approximate fault location at the ground surface and at depth. Subsequent test pits and trenches were used to define the ground surface trace of the fault. Additional borings were then used to further define the fault. Subsequent sections of this report discuss the geologic setting and our conclusions and recommendations related to the fault. • Exploratory Borings Eastern& Southern Portions of Site Borings EB-14, -15, -16, and -17, were advanced at locations surrounding the existing residence. The borings were primarily utilized for a geotechnical investigation of the proposed garage at this location, but were also utilized for identification of the Monta Vista Fault location. Boring EB-14 encountered 5 feet of surface soils, underlain by severely weathered Franciscan Complex limestone to the total depth explored of 35.4 • feet. Borings EB -15, -16, and -17 variably encountered from 1 to 4 feet of lean to fat sandy clay, overlying weathered Franciscan Complex limestone and greenstone. Borings EB-30, -31, and -32, were advanced along the eastern portion of the site to delineate the orientation of the fault plane below the upslope lots (Lots 1, 2, 3, and 4). Boring EB-31, located furthest north on Lot 1, encountered 6 feet of surface soils, underlain by very severely weathered greenstone bedrock of the Franciscan Complex to a depth of 25.5 feet. Beneath the greenstone bedrock, sheared bedrock appearing as extensively sheared greenstone extended to the maximum depth explored of approximately 44.5 feet. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 6 of 36 • Boring EB-30, located near the property line of Lots 2 and 3, encountered approximately 5 feet of surface soils underlain by very severely weathered greenstone bedrock of the Franciscan Complex to a depth of approximately 11 feet. Sheared bedrock appearing as a very severely weathered sandy claystone with minor caliche was observed extending from a depth of 11 to 27.5 feet. Beneath the sheared bedrock, moderately weathered claystone of the Santa Clara Formationwas encountered extending to the full depth:explored of approximately 41.5 feet. Boring EB-31, located furthest south on Lot 1, encountered about 5 feet of surface soils underlain by Franciscan Complex greenstone bedrock. Sheared bedrock was encountered at a depth of approximately 15 feet, underlain by claystone of the Santa Clara Formation at a depth of approximately 16 feet. The severely weathered claystone extended to a depth of approximately 41.5 feet beneath the ground surface. Northern Property Line Exploratory Borings EB-2, -3, -24, and -25 were advanced near the northern property line. The primary purpose of these borings was to identify the location of and depth to the Monta Vista Fault. Boring EB-25 encountered approximately 5 feet of surface soil underlain by severely weathered, sheared greenstone bedrock of the Franciscan Complex to a depth of about 30 feet. Beneath the greenstone at approximately 30 feet, conglomerate of the Santa Clara Formation was encountered extending to the boring depth of 31.5 feet. Boring EB-3 'encountered 4.5 feet of sandy fat clay of moderate to high plasticity underlain by very severely weathered and sheared greenstone bedrock of the Franciscan Complex that extended to 9 feet beneath the ground surface. Further upslope at the location of Boring EB-2, 4.5 feet of sandy fat clay of moderate to high plasticity was encountered. The clay was underlain by very severely weathered; firm greenstone bedrock of the Franciscan Complex. Between 9 and 12.5 feet, a mixture of bedrock types was observed with caliche throughout that appeared pervasively sheared and friable. At 12.5 feet, very severely weathered and friable conglomerate bedrock of the Santa Clara Formation was encountered and extended to the maximum depth explored of 18 feet. Boring EB-24 encountered approximately 5 feet of surface soil underlain by very severely weathered, sheared greenstone bedrock of the Franciscan Complex. At approximately 20 feet, very severely weathered interbedded sandstone and claystone bedrock of the Santa ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 7 of 36 - Clara_ Formation was encountered. The bedrock transitioned to a conglomerate at approximately 30 feet that extended to the maximum depth explored of 36.5 feet. Northwest Portion of Site Exploratory Borings EB-26, -27, -28, and -29 were advanced within the limits of.a landslide identified during our field reconnaissance. These borings were used for both fault location and depth, and landslide characterization. Boring EB-26, advanced in the upper portion of the landslide, encountered 5 feet of,sandy fat clay of high.plasticity. Beneath the clay, very severely weathered and sheared greenstone bedrock of the Franciscan Complex was encountered extending to 12.5 feet. At 12.5 feet, interbedded claystone and sandstone bedrock of the Santa Clara Formation was encountered. The bedrock transitioned to claystone from 15 to 25 feet and to sandstone at approximately 30 feet. The sandstone extended to the full depth explored of 34.5 feet. - Borings EB-27, -28, and -29 encountered about 7.5 feet of sandy fat clay and sandy lean clay ranging from low to high plasticity. Santa Clara Formation bedrock encountered beneath the surface soils generally consisted of interbedded claystone and sandstone bedrock at relatively shallow depths transitioning to sandstone at greater depth. The transition to sandstone occurred at 25 feet in Boring EB-27 and 13 feet in.Boring EB-28. Boring EB-29 encountered sandstone near the surface and it became interbedded with claystone at approximately 13 feet, returning to sandstone at 15 feet. The sandstone bedrock extended to the full depth explored in these borings which ranged from 26 to 35 feet beneath the surface. Ground water was not encountered in the exploratory borings during drilling and sampling. Borings EB-27 and EB-28 remained open for several hours to monitor for potential ground water seepage and the borings remained dry. Ridge Along Mid-Section of Site Borings EB-4, -5, 6, -7, -9, -21, and -23, were advanced along the northeast to southwest trending ridge across the mid-section of the site. The primary purpose of these borings was to identify the location and depth of the Monta Vista Fault. • Boring EB-7, encountered surface soils underlain by claystone bedrock of the Santa Clara Formation that transitioned to sandstone at approximately 13 feet. At the locations of Borings EB-4 and EB-6, surface soils were underlain by very severely weathered, undistinguishable sheared bedrock with .caliche throughout that extended to the, full depths explored of 11.5 and 13.4 feet. The sheared rock.fragments most resembled Franciscan Complex greenstone. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 8 of 36 Boring EB-9, advanced near Boring EB-6, encountered surface soils underlain by undistinguishable sheared bedrock with an abundance of caliche to a depth of 15 feet..At approximately 15 feet, very severely weathered conglomerate and claystone bedrock of the Santa Clara Formation was encountered that extended to the full depth explored of 21.5 feet. Boring-EB-21, located slightly south of the ridgeaxis, encountered approximately 2 feet of surface soil. Beneath the surface soils, severely weathered and sheared Franciscan Complex greenstone was encountered: At 11.5 feet, sheared and very severely weathered interbedded sandstone and claystone bedrock of the Santa Clara Formation was encountered. The claystone at a depth of about 20 feet was laminated and exhibited a "wavy" undulating texture, which we attribute to soft sediment deformation. The Santa Clara Formation bedrock extended to the maximum depth explored of 26.5 feet. Boring EB-5, which was advanced further upslope than the previous exploratory borings, encountered surface soils underlain by very severely weathered and friable greenstone bedrock of the Franciscan Complex to a depth of about 11 feet. A mixture of sheared bedrock types, primarily greenstone, with abundant caliche throughout, was observed between 11 and 17 feet. 'At a depth of approximately 17 feet, very severely weathered and sheared sandstone conglomerateof the Santa Clara Formation was encountered that became claystone at 22.5 feet. The claystone extended to the maximum depth explored of 25 feet. At Boring EB-23, further upslope above the ridge, surface soils were underlain by very ' severely weathered and sheared greenstone of the Franciscan Complex with occasional • limestone, to a depth of approximately 35 feet. Claystone bedrock of the Santa Clara Formation was 'encountered at about 35 feet, and extended to the maximum depth explored of 41.5 feet. Central Portion of Site Borings EB-8; -18, -19, and -20 were advanced within the broad swale located centrally within the site. These borings were primarily used to identify the location and depth to the Monta Vista Fault, as well as the lateral extent and soil thickness within the swale. At the locations of'Borings EB-18 and EB-20, located upslope within the swale, approximately 6=feet of sheared greenstone bedrock of the Franciscan Complex was encountered. The greenstone appeared very severely weathered and sheared with caliche through-out. Beneath the greenstone at approximately 6 feet, severely weathered. and sheared claystone with interbeddedsandstone of the Santa Clara Formation.was encountered. The Santa Clara Formation transitioned to primarily claystone at depth in both borings, and was present to the full depth of exploration of 21.5 and 26.5 feet. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 9 of 36 At the location of Borings EB-8 and EB-19, located further downslope within the swale, approximately 8.5 to 10 feet of fat clay to sandy lean clay was encountered. The clays were underlain by bedrock of the Santa Clara Formation that extended todepths of 15 and 26.5 feet. The bedrock in Boring EB-8 was generally composed of claystone with claystone and sandstone constituting the bedrock within Boring EB-19. Borings EB-11, -12, and -13 were advanced in the area between the existing residence and the water tanks, to identify the location of the Monta Vista Fault. Borings EB-11 and EB-12, encountered 4.5 to 5 feet of surface soils generally consisting of sandy fat clay of high plasticity. Beneath the clay in both borings claystone and sandstone conglomerate bedrock of the Santa Clara Formation was encountered extending to the maximum depths explored of 14 and 16.5 feet. At Boring EB-13, surfacesoils were underlain by severely to very severely weathered limestone and greenstone bedrock of the Franciscan Complex. The greenstone bedrock appeared sheared and mylonized at depth and transitioned to a mixing of sheared bedrock types with an increase in caliche. Beneath the zone of mixed bedrock materials at approximately 21 feet, very severely weathered claystone bedrock of the Santa Clara Formation was encountered extending to the full depth explored of approximately. 28.5 feet. Test Pits In order to further address the potential for fault rupture hazard from the Monta Vista Fault and the potential for landsliding,we excavated several test pits with some extending into trenches. The test pits and trenches were excavated, cleaned, and closely examined by our Certified Engineering Geologist for evidence of fault-related features, landslide • deposits, and/or potential for future slope failure. Fourteen test pits, totaling approximately 260 feet in length, were excavated and logged on April 21 and 22, 2011 and on February 17, 2012. The excavation width was 36 inches and the maximum depth was about 14 feet below surrounding grade. The sidewalls were shored for entry for pits that extended greater than 5 feet beneath the surface. Logs ofthe trenches and test pits are presented in Appendix C. Upon completion of the logging,the test pits were backfilled using the materials from the excavation. The backfill was generally loosely compacted by the contractor. Thus, there is a potential for (relatively limited) ground surface settlement at the location of the test pits in.the future and the backfill will need:to be excavated and properly compacted in areas where improvements are planned. ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision . Page 10 of 36 Our test pits and trenches exposed native surficial soil cover underlain by varying types-of bedrock of the Franciscan Complex and:Santa Clara Formation.: The exposed Franciscan Complex generally consisted of very severely weathered greenstone with minor amounts of limestone, which lacked internal structure and became highly sheared near the fault trace. The Franciscan bedrock also exhibited an abundance of caliche near the fault trace. Thesheared and calcified.zone was also observed in many-of the exploratory borings. The Santa Clara Formation generally consistedof sandstone, conglomerate, and claystone. The Santa Clara Formation was also observed to be very severely weathered, with internal shearing and an abundance.of caliche near the fault trace. Further from the fault trace, the Santa Clara.Formation generally became a firm claystone with minor amounts of caliche and °distinct internal structure or a clastic sandstone/sandstone conglomerate. Segments of the fault zone between the two bedrock units were exposed in our.excavations. We also.observed 'a distinctive:"magenta" coloration of the rocks near the fault zone. Northern Property Line . Test. Pit TP-14, was excavated near the northern property line downslope of the exploratory borings. This test pit was intended to further define the Monta Vista Fault location. Approximately 2 to 2.5,feet of sandy fat clay covered the slope at this location, underlain by greenstone bedrock with minor limestone fragments. This pit indicated that the Monta Vista Fault is located further west/downslope. Northwest Portion of Site Test Pits TP-8, -11, -12, and.-13 were located within or along the margin of the landslide. The primary purpose of these_test pits was to characterize the landslide. The ground surface at the location of Test Pit TP-8 was moist, with a growth' of phreatophytic plants. The surface soil in Test Pit TP-8 consisted of sandy lean clay underlain by a lens of clayey gravel. Beneath the gravel lens,:Santa Clara Formation material consisting of sandy lean clay and weathered claystone and sandstone bedrock underlain by claystone bedrock was encountered. Free water was observed seeping - - quickly into the test pit at a depth of approximately 6 feet. The water rose under pressure • to near the ground surface, and the trench collapsed before we could enter the pit for detailed logging. Test Pits TP-11 and TP-12 encountered 5 to 8 feet of sandy lean clay,sandy fat clay, and clayey sand. Beneath the surface soils, claystone and sandstone bedrock of the Santa Clara Formation was encountered. A distinct depositional contact was observed between the claystone and sandstone, bedrock units of Test Pit TP-11. Near the top of the ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 11 of 36 sandstone bedrock unit of Test Pit TP-12, olive, yellow, magenta, and purple coloring indicative of faulting or proximity to a fault was observed within the sheared bedrock. Free groundwaterr was observed seeping into the test pit at approximately 10 feet below the ground surface. At the location of Test Pit TP-13, excavated along the toe of the landslide, approximately 5 feet of clayey sand and sandy lean clay surface soils were encountered underlain by the Santa Clara Formation conglomerate. Within the bedrock open fractures infilled with clay were observed. Ridge along Mid-section of Site Test Pits TP-3 and TP-4 were advanced relatively up-slope along the ridge axis. The soil cover within these two pits consisted of sandy lean clay underlain by greenstone and/or limestone bedrock of the Franciscan Complex. Faulting was not observed. In Test Pit TP-5, located mid-slope along the ridge axis, the soil covering the slope consisted of a varying thickness of sandy lean clay partially underlain by sandy lean clay with a gravel layer. From the upslope side of the pit to approximately 12 feet, greenstone bedrock was observed with a lens of tan to orange sandy clay with magenta sandy clay surrounding. Beneath the greenstone bedrock a distinct fault plane was observed dipping east into the hillside at inclinations ranging from 11 to 26 degrees. There were no indications of landsliding at this location, and thus the fault inclination into the slope at this location cannot be alternatively interpreted as the toe of a landslide. There were no indications of the faulting extending upwards into the overlying residual/colluvial soils. Internally sheared and altered claystone and sandstone bedrock of the Santa Clara Formation was encountered beneath the fault plane. This stratum was pervasively penetrated by caliche and appeared internally sheared with slickensides, with minor mixing of Franciscan Complex bedrock. Beneath the unit, less disturbed claystone and sandstone bedrock of the Santa Clara Formation was encountered. Within the Santa Clara Formation units, sandstone blocks prominently coated with caliche were observed. Free water was observed seeping into the test pit at approximately 10 feet beneath the surface. Test Pits TP-6 and TP-7 were located relatively down-slope along the ridge axis. The soil cover within these two pits consisted of sandy lean clay, underlain by sandy lean clay/weathered claystone and sandstone bedrock:of the Santa Clara Formation. The bedrock at greater depth consisted of decreasingly weathered claystone, with decreased shearing and decreased caliche. Free water was observed seeping into Test Pit TP-6 at approximately 8 feet. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 12 of 36 Central Portion.of Site Test Pits TP-1 and TP-2 were used to further define the approximate fault location identified by nearby borings. The colluvial soil cover in Test Pit TP-1 consisted of highly plastic fat clay. The surficial soil was underlain by greenstone bedrock of the Franciscan Complex. In Test Pit TP-2, the colluvium consisted of fat clay underlain by a thin layer of sandy lean clay. A lens of clay with gravel-which appeared to be.depositional, approximately 4 to 5 inches thick, was observed between the two clay soils. From the upslope side of the pit to approximately 5 feet, greenstone bedrock was observed with a lens of magenta colored sandy material and a sandy caliche zone. The greenstone bedrock and caliche zones generally dipped into the hillside. The greenstone was underlain by sandy lean clay and weathered claystone and sandstone bedrock of the Santa Clara Formation that was pervasively penetrated by caliche. The contact of the two bedrock units was a fault zone and it appeared that internal shearing had occurred within both units, above and below the fault plane, suggesting a shear zone approximately 3 feet thick. Within the sandy lean clay/weathered claystone and sandstone bedrock a thicker caliche zone dipping into the hillside was observed. At greater depth an increase of caliche was observed with a lens of magenta-colored sandy material. The unit was underlain by claystone and siltstone bedrock of the Santa Clara Formation, which appeared highly weathered with loss of internal structure. A clay seam and slickensides where observed within the claystone, suggesting internal shearing. The internal contacts of units within the Santa Clara Formation were generally horizontal. The fault plane and shear zone between the Franciscan Complex and: Santa Clara Formation generally dipped gently into the hillside (southeast), but- at varying inclinations, as shown on the test pit log. There were no indications of the faulting extending upwards into the overlying colluvium, which at this location,consists of two distinct units, identified as Unit B and Unit B2 on the log of Test Pit TP-2: This test pit was situated on-the upper slope of a broad colluvial swale. There are no indications of localized or larger-scale landsliding which would result in an interpretation that the observed features were caused by landsliding. Test pits TP-9 and-10 were utilized to evaluate the soil thickness in the large swale. They were also observed for indications of landsliding. Approximately 7 feet of variably low • to highly plastic. colluvial and residual clayey soil was observed in each of the test pits. There were no indications of landsliding. The soil was underlain by Santa Clara Formation sediments in each test pit. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin • Lands of Stirling Subdivision Page 13 of 36 Laboratory Results Liquid Limits ranging from 53 to 65 and Plasticity Indexes of 28 to 38 were measured on samples of soil obtained from Borings EB-1, EB-8, and EB-17. These test results indicate that nearsurface and residual soils on the site typically have high plasticity and high potential for expansion. Free swell tests performed on samples of claystone bedrock of the Santa Clara Formation in the borings indicated free swell values ranging from 90 to 210 percent.. These free swell test results suggest that the claystone bedrock of the Santa Clara Formation at the site has a moderate to high potential for expansion. Free swell, tests performed on samples of greenstone bedrock of the Franciscan Complex from our borings indicated free: swell values of 30 to 60 percent. The free swell test results suggest that the greenstone bedrock of the Franciscan Complex at the site has relatively low potential for expansion. Ground Water Free ground water was generally not encountered in our exploratory borings and test pits during the investigation. In general, the borings were backfilled immediately after sampling. Boring EB-22 encountered free ground water at a depth of approximately 25 feet below the surface. Boring EB-19 remained open from January 3, 2012 to March 8, 2012; free ground water was not present in March 2012. Free ground water was observed seeping into Test Pits TP-5 and TP-12 at approximately 10 feet and in Test Pit TP-6 at 8 feet beneath the ground surface. Free ground water was encountered in Test Pit TP-8 at approximately 6 feet below the surface and quickly filled the test pit. The occurrence of ground water in these test pits appears to relate to the observed faulting, most likely "perched" over fault gouge or less.permeable soil or rock; and probably is not representative of the site overall. • . There.was no information available regarding the well located on the property, although we understand that the well is currently in use. Based on our surface observations; a second, nearby, inactive well, may also be present. . Please be cautioned that fluctuations in the level of groundwater or ground water seepage can occur due to variations in rainfall, landscaping, underground drainage patterns,, and other factors. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 14 of 36 GEOLOGIC SETTING • Regional Geology The site is located within the central region of the Coast Ranges Geomorphic Province, which .extends from the Oregon border south to the Transverse Ranges. -The general topography is characterized by sub-parallel, northwest trending mountain ranges and intervening valleys. The region has undergone a complex geologic history of sedimentation, volcanic activity, folding, faulting, uplift and erosion. The relatively flat- lying, alleviated San Francisco Bay Plain is situated to the east of the site; the uplifted Santa Cruz Mountains are located to the west of the site. The site lies within the easterly foothills of the Santa Cruz Mountain Range. Based on Brabb et al (2000) and Cotton, Shires & Associates (2005), the property is underlain by two different bedrock units with a contact located through the middle of the property. The eastern portion of the site is mapped as being underlain by primarily sandstone bedrock of Franciscan Complex bedrock (KJfs), although our exploration generally encountered Franciscan Complex greenstone and limestone. Greenstone, the primary bedrock member encountered in this unit at the site, is generally described as highly- consolidated, red-brown to green, massive, fractured, altered basaltic volcanic rock associated with local lenses of dark chert and light tan to white limestone. Locally the unit may be highly sheared with closely spaced fractures, weathering to an expansive soil. The western portion of the site is underlain by the Santa Clara Formation (QTsc). The Santa Clara Formation is described as semi-consolidated to consolidated, comprised of yellow-brown to red-brown conglomerate interbedded with poorly-sorted sandstone, siltstone, and claystone. Locally the unit weathers to an expansive soil over fine-grained bedrock units. The geology of the site vicinity is shown on the Vicinity Geologic Map, Figure 2. The Berrocal, .Altamont and Monta Vista faults, low angle imbricate structure thrust faults that dip southwesterly towards the San Andreas Fault, have thrust older rocks of the Franciscan Complex over the younger rock of the Santa Clara Formation in the site vicinity. The contact between thebedrock units on the site is the Monta Vista fault zone. The fault is shown on the Town Geotechnical and Seismic Hazard Zones Map, Figure 3. The Berrocal, Altamont and Monta Vista faults are believed by some geologists and seismologists to have experienced sympathetic movement during the 1989 Loma Prieta Earthquake. Numerous homes southeast of the site in the Los Altos Hills vicinity were moderately to severely damaged during the October 17, 1989 Loma Prieta_Earthquake, which produced strong ground shaking in this area. Focusing of ground shaking was ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 15 of 36 particularly observed along ridgelines in the site vicinity. Recent geologic studies have indicated ground surface rupture within the recent (11,000 years) past (AEG, 2004). Although the Berrocal, Altamont and.Monta Vista faults are not part of the state mandated Alquist-Priolo Earthquake Fault Zones, they are considered to be potentially active by the County of Santa Clara and the Town of Los Altos Hills. Site Geology The Mindego Hill Quadrangle State Seismic Hazard Zone map for earthquake induced landslides, liquefaction, or other geologic hazards (2005) indicates the majority of the site is not located within a hazard zone. The steep western sloping hillside nearthe creek is within a potential seismically-induced landslide hazard zone. The Santa Clara County Geologic Hazard Zone Maps (2002, 2006) indicate the site is located within a fault rupture hazard zone with a landslide hazard zone mapped on the steep west sloping hillside near the creek. The site is not mapped within a County liquefaction hazard zone. The Town of Los Altos Hills Geologic Map (Cotton, Shires & Associates, 2005, see Figure 2) contains pertinent features of the site and immediate vicinity. The Geologic Map, generally confirmed by our site reconnaissance, exploratory borings, and test pits, indicates the presence of both Franciscan Complex and Santa Clara Formation bedrock underlying the site. The bedrock is generally overlain by various thicknesses of sandy fat clay and sandy lean clay, as observed in our borings and test pits. The map indicates the presence of Franciscan Complex greenstone and limestone on the east portion of the site and Santa Clara Formation on the west side of the site. The contact between the two units is a slightly inclined thrust fault,with the Franciscan Complex thrust over the Santa Clara Formation (see Regional Geology discussion). However, this investigation, as discussed below, has refined the fault location. The Monta Vista Fault is generally inclined downwards to the west and southwest (towards the San Andreas Fault) and trends from the northwest to the southeast. The subject property is located in an area where the fault departs from its northwest-southeast trend and exhibits a sinuous ground surface expression where it rises to a higher elevation from the southeast to the northwest, as mapped by Cotton, Shires & Associates (2005). To the east of the site near the I-280 freeway the fault returns to its general pattern, trending northwest to southeast and inclined toward the west. The fault on the property is variably inclined to the east (into the slope, Section E-E' and western end Section G-G'); west (along and out of the slope, Sections B-B' and D-D'); locally undulates (Section A- A'); and elsewhere is relatively flat-lying (the portion of Section I-I' within the site). We directly observed the fault contact in our Test Pits TP-2, -5 and -12, where older Franciscan Complex greenstone bedrock was observed thrust over Santa Clara Formation ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin, Lands of Stirling Subdivision Page 16 of 36 bedrock. Multiple borings and test pits advanced on the property confirm the presence of Franciscan Complex on the east portion of the Monta,Vista fault trace and Santa Clara Formation to the west of the fault trace. Many of the borings and test pits indicated the presence of zones of shearing and caliche formation, as well as magenta-colored soils adjacent to the fault within both the Franciscan Complex rocks and the underlying Santa Clara Formation strata. During our investigation we observed indications of landsliding on the property. At the northwest portion of the property two dormant slides were encountered on the west= dipping slope, which are not identified on the Town Geologic map. These two slides occur along the lot line dividing Lots 5 and 6. The uppermost (eastern), dormant slide was a hollowed, bowl-shaped feature with a slide mass toeing near the top of a smaller, apparently older slide observed further downslope. These two landslides have occurred within bedrock of the Santa Clara Formation where the slope inclinations increase as the hillside slopes down to the creek. We also observed a broad bowl-shaped feature in the center of the property, which is situated primarily within Lot 7. There were no current indications of landsliding, but the feature is the locus of an accumulation of colluvium, and may have experienced landsliding in the past. Engineering Geologic Reconnaissance Our initial engineering geologic reconnaissance was conducted on February 15, 2011 and consisted of walking the subject site to observe thetopography and surface conditions. During the reconnaissance, we traversed the areas surrounding the existing residence and cottage and the gently sloping eastern half of the property. The reconnaissance included traversing along the east and north property lines down to the creek, which we followed north of the property. We traversed the hillside and followed the path of the creek from below the northernmost landslide farther south where the creek bends to the east below the residence and cottage. The steep slopes extending down to the creek southwest of the residence and southeast of the cottage were also traversed. During the site reconnaissance we observed minor soil creep of the near-surface soils and colluvium in the downslope direction on the steep slopes of the drainage. Gravels and cobbles up to 2 feet in diameter were observed on the slopes. An outcrop of Santa Clara Formation conglomerate was observed in the creek at the northwest corner of the property. This was the only bedrock outcrop observed within the drainage channel. Franciscan Complex limestone and greenstone were observed on the slopes west, south, and southeast of the residence and cottage. Outcrops of resistant Franciscan Complex limestone were observed on the slope adjacent to and below the existing residence on the south. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 17 of 36 The primary topographic features within the subject site are the two landslides on the northwest portion of the site (Lots 5 and 6), which have experienced slope failure in the past, and the broad colluvial bowl in the center of the site (Lot 7). Figure 4 indicates the margins of the landslides and colluvial bowl. The landslide located upslope (on Lots 5 and 6) to the east appears to be a relatively stable and dormant feature. There are no indications of movement, except shallow slumping near the headscarp, since the oldest interpreted aerial photographs were flown in 1939. The headscarp of this landslide is approximately coincident with the ground surface location of the Monta Vista Fault. The lower landslide, located on the steepening hillside, also appears to be dormant. Subsurface exploration was performed within the limits of the upper landslide in an area feasible for future development. Exploration was not performed on the lower slide, where future development is not planned. A spring was observed on the eastern slide surface at the location of Test Pit TP-8 on April 22, 2011. The spring was not evident during the subsequent winter of 2011-2012 at the time of our subsequent field investigation. A wet ground surface is present at this location in the 1974 air photos. The spring is approximately coincident with the location of the.Monta Vista Fault. An additional significant site feature is the broad generally bowl-shaped drainage swale (Figure 4), which extends from above the water tanks a portion of the distance downslope to the creek in the central part of the site. The feature narrows where the slope inclination increases to the west. Active gully erosion is present in the narrowing portion of the swale incising the surface soils. The gully extends down the slope to the north-south flowing perennial creek on the west. There appeared to be evidence of soil creep within the surface soils of the broad swale and in Test Pit TP-10, although there was no indication of a slide plane. The soils encountered within the test pit consisted of sandy lean/fat clay from the ground surface to a depth of approximately 8 feet, where the soil was underlain by Santa Clara Formation claystone. There are no indications of soil movement within the feature since the 1939 aerial photographs were flown, although the ground surface was disturbed by discing, vegetation mowing and activities related to well, water tank and pipeline construction. Very subtle surficial features suggest possible landsliding pre-dating 1939, and although we were not able to confirm the presence of landsliding within the colluvial swale, we recommend considering this feature as a potential landslide for the purposes of development grading. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 18 of 36 Apparently wet soil was observed along the,axis of the bowl-shaped feature in the 1974 air photos. Free ground water was not,observed within the gully or the area of recent erosion. Exploratory Boring EB-22, located above the bowl feature, encountered ground water at a depth of 25 feet beneath the ground surface during the drilling. There were no indications of ground surface rupture or other surface indications of active faulting observed during our reconnaissance. Similarly, there were no indications of active or recent landslides or flows. Aerial Photographs We interpreted five sets of stereo pair aerial photographs to supplement our on-site engineering geologic observations (see References). The photographs, flown from 1939 to 2000, clearly showed the site and surrounding areas. The imagery indicates a general growth of vegetation over the years;thus the earlier imagery are more useful. The earliest imagery was flown in 1939. The existing primary residence, cottage, and an old orchard are present on the south part of the property. There are no indications of the existing well(s). Vague tonal variations within the northern half of the site, and extending offsite to the north and northeast, correspond approximately to the Monta Vista Fault as located during our investigation and on the Town of Los Altos Geologic Map. The northern slide and central swale areas are evident, with the heads of these two features approximately corresponding to the Monta Vista Fault as located by our subsurface investigation. • The well house is. visible in the 1955 imagery. There are no clear indications of the Monta Vista Fault. Both the northern landslide and central swale area are evident, although subtle. There are no indications of active landsliding. The central swale appears to be an accumulation of colluvium; there are no indications of landsliding. The feature narrows at the location where the slope increases. There is a shallow drainage channel along the swale center line. Wet/saturated soil is visible in the subsequent 1974 imagery, with the water seepage emanating from near the break in slope delineating the head of the northern landslide (near Test Pit TP-8), and draining the center of the central . swale. The upslope slope break of the northern slide area appears to be the landslide head scarp as well as correspond to the Monta Vista Fault as identified by soil borings and test 'pits at this location. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 19 of 36 The ground surface is extensively disturbed by discing and mowing of vegetation in the 1985 imagery. There are several apparent slope breaks which can be attributed to the discing and vegetation mowing. There is an apparently naturally occurring scarp at the head of the northern landslide, which is most evident in the 1985. imagery although also apparent on the older and more recent images, as well. The site is essentially the same in 2000, although with less ground surface discing and mowing. Continuation of vegetal growth is evident, particularly within the northern landslide, indicating that there has not been slope movement since the initial 1939 imagery, with the exception of minor slumps and flows from the scarp area. Landslide Evaluation Two areas of previous or potential landsliding were observed. We refer to these two areasas the northerly area and the central swale. Two slides are present in the northerly area, one directly upslope of the other. The lower slide was not investigated, as it is not within the area of proposed residential construction. In general, the lower slide appears to be a broad shallow bowl-shaped feature,which toes out at the north-south creek on the west and heads near the eastern margin of the wooded slope on the east. We observed Santa Clara Formation bedrock generally consisting of sandstone conglomerate with minor occurrences of claystone within the upper landslide. The bedrock consisted of fine to coarse grained sand with fine gravels. Bedding planes within the bedrock were generally dipping gently in the downslope direction. Approximately 5 to 8.5 feet of surface soil ranging from sandy lean clay to sandy fat clay and clayey sand were observed above the bedrock. Our interpretation of the subsurface conditions within the landslide is shown on Cross Section C - C' and D - D', Figures 9 and-10. Within surficial units of Test Pit TP-11, a distinct slide plane was observed at approximately 2.5 feet below_the surface. Heterogeneous sandy lean clay/clayey sand wasobserved to have internal (contraction/expansion) shears in the headwall from 5 to 9 feet. There was no indication of slide planes within the unit. Based on appearance and inclination, as well as the ground surface morphology in the immediate site vicinity, the landslide appears to be "old" and/or "dormant", although the precise_age cannot be determined. In general, the subsurface conditions indicate that varying clay and sandy soils cover the,slope and bedrock is relatively shallow (5 to.9 feet). Free ground water was encountered in two test pits in the area of the spring at depths of approximately 6 and 10 feet. ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 20 of 36 In our opinion, the upper landslide and surrounding slope may be repaired to mitigate potential slope failure prior to the proposed subdivision development or a reasonable setback from the slide margins may be used for development on Lots 5 and 6. If the slope is to be repaired, it can be stabilized by removal and replacement of the soils and weak bedrock to a depth on the order of 10 to 15 feet. The recommendations for slope mitigation would be similar to those presented in the following sections of this report for the broad central swale feature on Lot 7. In our opinion, the upper landslide may be left in place if structures are placed no closer than 20 feet to the slide margin, as shown on Figure 4. If the upper landslide will be left in place, we recommend that a series of subdrains be installed centering on the spring area, as discussed later in this report. Based on the scope of the current development, in our opinion, there is no need to address or mitigate the lower area of landslidingat this time. In our opinion, there is potential for slow, soil creep of the near surfacesoils within the broad central swale feature on Lot 7. While there are no indications of active or previous landsliding within the swale, the soils should be considered susceptible to shallow creep or slump type movement, with some potential for landsliding to occur in the future if the area is left as is. The slope can be stabilized by removal of the upper soil and weak bedrock to a depth on the order of 10 to 15 feet, and replacement with a properly benched and drained compacted fill. Recommendations for development within the swale are presented in the following sections of this report. Fault Evaluation Within the site, the Monta Vista Fault has thrust older Franciscan Complex rocks over younger Santa Clara Formation sediments. The fault is overlain by colluvium and residual soil, and can only be located approximately by field mapping. The fault is also not apparent on aerial photographs, and there are no clear geomorphic indicators of the fault. Many of the test pits and exploratory borings were located in the vicinity of the fault ground surface trace, or to identify the fault at depth. We observed Franciscan Complex bedrock situated over Santa Clara Formation along a fault plane and/or zone of shearing in four of the test pits (TP-2, -5, -9 and -12) and in 11 of our exploratory borings (EB-2, - 5, -13, -18, -20, -22, -23, -24, -26, -30, and -32). Abundant shearing, weathering, bedrock mixing, distinctive "magenta" coloration, and concentrated caliche were commonly observed in both bedrock units within or adjacent to the fault. Based on direct observation of the fault in test pits and the lithology observed in borings, we developed geologic cross sections (Figures 7 through 14) which show our interpretation of the trace of the Monta Vista Fault as projected to the ground surface and elsewhere at depth. We ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 21 of 36 have placed the fault on our cross sections and measurements of the thickness of the overlying (Franciscan Complex) as the upper limit of the sheared rock, i.e. at the base of competent (unsheared) Franciscan materials. We plotted the fault ground surface locations and projections on the engineering geologic reconnaissance map, Figure 4. In general, we found that the fault ground surface trace is located further west then presented on the Town Geologic Map and by MEI (2010) (refer to Figure 5), but further east in the vicinity of the broad colluvial swale. We carefully observed the soils for charcoal or datable material. None was observed. We did not observe clay rinds (coatings) on clasts or other indicators of relative soil age. We thus conclude that the overlying soils are likely to be less than 11,000 years (Holocene age). Thus, although the fault, where observed in test pits, does not extend into the overlying soils, we were not able to determine whether the fault has been • Holocene active where visually observed within the site. As discussed previously in this report, the Monta Vista Fault along its length is generally inclined down tothe west or southwest, towards the San Andreas Fault. However, the fault plane orientation at the subject site is highly variable, suggesting that the plane in the site vicinity has been warped by unrelated subsequent tectonic movements. The fault plane, inclination within Test Pits TP-2, -5 and -9 either dips down to the east into the slope or is relatively horizontal (the fault appears to be present but the plane orientation is not readily apparent in Test Pit TP-12). Extending the observed fault from Test Pit TP-2 to Boring EB-13 indicates an inclination down to the east (Section G-G'). Extending the fault further southeast to Boring EB-32 indicates the fault inclination transitions and ramps up toward the east (towards Boring EB-32). To the north along Section E-E', the fault is oriented down to the east in Test Pit TP-5. Further east, the fault plane undulates and is fairly planar through Borings EB-5 and -21, and then again dips down to the east at Boring EB-23. The MEI 2010 investigation indicates that the fault is generally inclined down to the east. Finally, at other locations, as shown on cross sections B —B', C — C', D — D', and F — F' (Figures 8, 9, 10, and 12), the fault dips to the west, althoughthe apparent dips are highly variable. The fault plane inclinationsaresimilarly variable on north-south orientations. Cross- section A — A' (Borings EB-24, 23, 22, 10) and I — I' (Borings EB-31, 30, 10, 32 including Borings EB-3, 4, 6 from MEI), Figures 7 and 14, indicate that the fault initially declines in elevation from north to south,then further south, rises in elevation. Further confirmation of the variably oriented fault plane was indicated in the deep borings advanced on the upslope lots :(Lots 1, 2, 3, and 4) (Section I-I'). In Boring EB-32, the fault zone was encountered at approximately 15 feet and is relatively thin, approximately ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 22 of 36 1 foot thick. The fault further north is a relatively thicker sheared zone;the base of the sheared fault interval is at greater depth in Boring EB-30, extending from 11 to 27.5'feet,' whereas the top of the sheared zone is relatively flat-lying. Further north at Boring EB-31, sheared bedrock was encountered at a depth of approximately 25.5 to 44.5 feet, and the contact between the Franciscan Complex/sheared bedrock and the Santa Clara Formation was not encountered (the boring was terminated at this depth due to permitting requirements for a boring deeper than 45 feet), further indicating the decline of the base of the fault zone from the south to the north. Finally, north of the site on the adjacent property, the fault appears to rise in elevation (Murray Engineers, 2010). The thickness of Franciscan Complex bedrock over the Santa Clara Formation on the subject was observed in several borings (Borings EB-2, 5, 13, 18, 20, 21, 22, 23, 24, 25, 26, 30, 31, and 32). The Franciscan Complex thickness (overlying soil not included) is highly variable, ranging from 4.5 to 30 feet overlying the Monta Vista Fault. In particular, the rock mass thickness overlying the fault in the upper elevations of the site are 6, 10 and 19.5 feet in'Borings EB-30, -32 and-31, respectively. In summary, the Monta Vista Fault across the site, in three-dimensional perspective, is highly irregular in configuration. The highly irregular fault surface reflects a similar configuration across the vicinity. For example, the fault occurs at an approximate elevation of 400 feet where it parallels Highway I-280 on the east. It is similarly at an elevation of 400 feet approximately 1 mile west, whereas one would anticipate the elevation to be significantly lower as the fault overall is inclined downward to the west. Thus, on a larger scale beyond the site, the Monta Vista fault plane is essentially horizontal and yet highly warped. In our opinion, the Monta Vista Fault within the relatively small-scale area of the subject site as well as the larger area of northern Los Altos Hills has been distorted by tectonic uplift, and in the vicinity of the site appears to no longer be a definitive feature capable of rupture in the manner which previouslyresulted in the thrusting of older Franciscan Complex rocks over the younger Santa Clara Formation. Although studies elsewhere along this fault indicate that it is capable of sub- and ground surface rupture, the segment in the site vicinity in our opinion is no longer a discrete feature capable of rupture along the current boundary between the two rock units. In particular, the up-thrown Franciscan block at the subject site does not appear to be of sufficient thickness and mass to move as. a coherent block if movement were to occur at depth west of the site along the Monta Vista Fault. However, because of the low potential for sympathetic movement on.the fault in response to more distant deep-seated earthquakes or to movement elsewhere along,the Monta Vista Fault, we conservatively recommend that the foundations of the proposed residences be designed to avoid extending below the fault plane. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 23 of 36 Faulting and Seismicity The San Francisco Bay Area is, however, an active seismic region. Earthquakes in the region.result from strain energy constantly accumulating because of the northwestward movement of the Pacific Plate relative to the North American Plate. On average about 1.6-inches of movement occur per year. 'Historically, the Bay Area has experienced large, destructive earthquakes in 1838, 1868, 1906 and 1989. The faults considered most likely to produce large earthquakes in the area include the San Andreas, San Gregorio, Hayward, and Calaveras faults. The San Gregorio fault is located approximately 14 miles southwest of the site. The Hayward and Calaveras faults are located approximately 16 and 20 miles northeast of the site, respectively. These faults and significant earthquakes that have been documented in the Bay Area are listed below in Table 1. Table 1. Earthquake Magnitudes and Historical Earthquakes Lands of Stirling Subdivision Los Altos Hills,California Maximum Historical Estimated. Fault Magnitude(Mw) Earthquakes Magnitude San Andreas 7.9 1989 Loma Prieta 6.9 1906 San Francisco 7.9 1865 N. of 1989 Loma Prieta Earthquake 6.5 1838 San Francisco-Peninsula Segment 6.8 1836 East of Monterey 6.5 Hayward 7.1 1 868 Hayward 6.8 1858 Hayward 6.8 Calaveras 6.8 1984 Morgan Hill 6.2 1911 Morgan Hill 6.2 1897 Gilroy 6.3 San Gregorio 7.3 1926 Monterey Bay 6.1 In the future, the subject property will undoubtedly experience severe ground shaking during moderate and large magnitude earthquakes produced along the San: Andreas or other :active Bay Area fault zones. The Working Group On California Earthquake Probabilities, a panel of experts that are periodically convened to estimate the likelihood of future earthquakes based on the latest science and information, concluded there is a 63 percentchance for at least one earthquake of Magnitude 6.7 or larger in the Bay Area before 2038 (Working Group, 2008). The San Andreas fault has the second highest likelihood of a large earthquake in the Bay Area, estimated as a 21 percent chance of a Magnitude 6.7 or larger earthquake by 2038, while the Hayward fault hasthe highest likelihood of a similar event(31 percent). ROMIG ENGINEERS,INC. • Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 24 of 36 Earthquake Design Parameters The State of California requires that all buildings be designed in accordance with the seismic design provisions presented in the 2010 California Building Code, and in ASCE 7, "Minimum Design Loads for Buildings and Other Structures." Based on site geologic conditions, and on information from our subsurface exploration at the site,the site may be classified as Site Class C, very dense soil and soft rock, in accordance with Table 1613.5.2 in the 2010 California Building Code. Spectral Response Acceleration parameters Ss and S1, and site coefficients Fa and Fv, may be taken directly from the • figures and tables in the 2010 California Building Code and in the lookup tables at the U.S.G.S. website based on the longitude and latitude of the site. For the site latitude (37.3718) and longitude (-122.1575) and Site Class C, Fa = 1.0, Fv = 1.3, SDs = 1.684 and SD1 =0.874. Additional Geologic Hazards Summary • We briefly reviewed the potential for geologic hazards, other than fault rupture and landsliding, which were discussed earlier, to impact the site, considering the geologic setting and the soils encountered during exploration. Our review is summarized below: • Ground Shaking - The site is located in an active seismic area. Moderate to • large earthquakes are probable along several active faults in the greater Bay Area over a 30 to 50 year design life. Strong ground shaking should therefore be expected several times during the design life of the residence, as is typical for sites throughout the Bay Area. Future structures should be designed and constructed in accordance with current earthquake resistance standards. • • Differential Compaction - Differential compaction occurs during moderate and large earthquakes when soft or loose, natural or fill soils are densified and settle, often unevenly across_a site. Since the soils encountered in our borings were generally stiff to hard clays and weathered bedrock, in our opinion, the likelihood of significant differential compaction of the native soils and rock encountered is low. Structures supported,on the planned moderately thick fills required for the central swale mitigation or fills required for general grading/development purposes should be designed to accommodate the expected seismic and static settlement from fill compression. • Liquefaction -Liquefaction occurs when saturated sandy soils densify and lose strength during earthquake shaking. Ground settlement often accompanies liquefaction. Soils most susceptible to liquefaction are saturated, loose, silty sands, uniformly graded sands, and sandy silts. Loose silty sands and other soils prone to liquefaction were not encountered at the site. Due to the relatively shallow depth to bedrock across the site, thelikelihood of liquefaction occurring at the site is low. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 25 of 36 CONCLUSIONS AND DISCUSSION OF FINDINGS From a geotechnical engineering and geologic viewpoint, the site is suitable for the proposed subdivision development provided the recommendations presented in this report are followed during design and construction. Specific recommendations for the proposed development are presented in the following sections of this report. A trace of the Monta Vista Fault was encountered during our subsurface exploration. As discussed earlier, in our opinion, the Monta Vista.fault is a remnant feature, a distorted and warped plane that is no longer capable of surface rupture within the site. Although • we do not anticipate ground surface rupture along this fault trace, we recommend that the foundations of the proposed residences be designed to avoid extending below the fault plane, to reduce the potential for damage to the residences from secondary sympathetic movement on the fault plane from major earthquakes effecting the area. The other geologic and geotechnical constraints for the proposed development are the presence of highly expansive near surface colluvial soils,the moderately sloping nature of the property, and the dormant landslides observed on the northwest section of the site. Feasibility level discussion concerning construction of residences at the subdivision lots is presented below. Once specific development plans are available for each of the lots, site specific recommendations can be developed on a lot by lot basis as discussed below. Two dormant landslides were identified on along the Lot 5 and 6 property line. In our opinion, the upper landslide may be left in place if structures are placed no closer than 20 feet from the slide margin, with a series of subdrains installed centering on the spring area located centrally in the dormant slide. Based on the scope of the current development, in our opinion, there is no need to address or mitigate the lower area of landsliding at this time. The colluvial swale on Lot 7 should be mitigated during development of the lot. We recommend that the colluvial soil deposits be removed and replaced with a properly benched and compacted engineered fill across the lower portion of the lot with appropriate surface and subsurface drainage. Specific recommendations for mitigation are presented in the following sections-of this report. Because subsurface conditions may vary from those encountered at the locations of our borings and test pits, and to observe that our recommendations are properly implemented, we recommend that we be retained to.1) review the project plans for conformance with our report recommendations and 2) observe and test during earthwork and foundation construction. ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 26 of 36 • FEASIBILITY OF PROPOSED RESIDENCE SITES In our opinion,.from a geologic and geotechnical viewpoint, the site is suitable.for construction of the future subdivision residences. Final foundation recommendations can be established after the residence locations are finalized and additional subsurface investigations are conducted. Detailed foundation design criteria should be developed based on subsurface investigation and laboratory testing performed as part of a design- level geotechnical investigation on a lot by lot basis. Seismic design criteria will need to be developed based on guidelines in the version of the California Building Code that is in effect at the time the plans are submitted for review and approval. Subdivision Lots 1 Through 4 The primary geotechnical concern for development of Lots 1 through 4 is the presence of up to approximately 5 feet of highly expansive surface soil overlying weathered Franciscan Complex bedrock encountered at the locations of these lots. On a preliminary basis, in order to reduce the risk of differential movement due to the highly expansive near surface soil, the at-grade portions of future residences on these lots should be supported on relatively deep and stiff conventional spread footing foundations with additional reinforcing to help mitigate potential differential movement with basement areas supported on structural mat foundations. We expect that relatively minor cuts and fills may be required during grading of the building pads and perimeter yard and driveway areas. In addition, a layer of*non-expansive fill will need to be placed below concrete slab-on-grade floors and exterior flatwork. As mentioned earlier, the foundations of these residences should be designed to avoid extending below the Monta Vista Fault. Because the fault plane is 15 feet or deeper at the residence sites on Lots 2 through 4, basements are feasible at these locations. At Lot 1, the fault plane was located at a depth of 11 feet at the front of the residence envelope. A basement may be feasible on this lot depending upon its depth and location; during the site specific geotechnical investigation, the depth of the fault plane at the location of any proposed basement areas should be determined to confirm feasibility. Subdivision Lots 5 Through 8 The primary geotechnical concerns for Lots 5 through 8 are thepresence of moderately to highly expansive near surface soils which may also be subject to downslope creep, the expansion potential of the bedrock at the site and the sloping nature of these sites. An additional geotechnical concern is the dormant landslide located on Lots 5 and 6 and the colluvial swale located across Lot 7; recommendations formitigation of the dormant landslide and colluvial swale are presented in the next section of our report below. ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 27 of 36 Due to the sloping nature of these lots, the expansion potential of the surface soil and bedrock and the potential for downslope creep of the surfacecolluvial soils, it should be assumed that residences on these lots will need to be supported on moderately deep pier and grade beam foundations; which extend about 12 feet into weathered bedrock below the expansive surface and colluvial soils (or in structural-. fill where placed for the reworked colluvial swale below Lot 7). Depending upon the residence layout and grading plans, basement areas can probably be supported on structural mat foundations founded in weathered bedrock. The final foundation system and design will need to be established as part of the site specific geotechnical investigations for each lot. In addition, a layer of non-expansive fill will need to be placed below concrete at-grade slab-on-grade floors and exterior flatwork. The foundations of residences on Lots 5 and 8 should be designed to avoid extending below the Monta Vista Fault. Because the fault plane is 17 to 20 feet deep at our exploration at these residence sites, basements and moderately deep pier and grade beam foundations are feasible. As discussed earlier, the proposed residences at Lots 5 and 6 are currently located further than 20 feet from the slide margin, and therefore, the dormant landslide features may remain in place and landslide, mitigation measures consisting of installing subdrains through the upper dormant landslide should implemented as discussed below. Concentrated surface drainage should also be directed away from these dormant landslides. We expect that some grading will be required for the building pads, driveways and yard areas, possibly requiring some retaining walls to support cuts and fills. In general, fills will need to keyed and benched well into competent bedrock with subdrains installed. Retaining walls supporting fills probably will require pier foundations while retaining walls supporting cuts into competent bedrock may be able to use shallow foundations. Drainage measures in hillside areas should be carefully designed by the project civil engineer. The drainage design should include surface and subsurface drainage systems to prevent erosion or'concentrated discharge of surface water onto building pads, fills and hillside areas. As discussed earlier, active and inactive wells were observed along the upslope portion of Lot 7. If the wells will not be used for the development, they will need to be properly demolished and grouted following the Santa Clara Valley Water District and State of California guidelines for well removal. ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 28 of 36 Subdivision Lot 9 We previously prepared a geotechnical investigation for Lot 9. There are no additional improvements planned to Lot 9 that require additional recommendations at this time. UPPER DORMANT LANDSLIDE&COLLUVIAL SWALE MITIGATION To repair the colluvial swale on Lot 7 (and upper dormant landslide on Lots 5 and 6 if the residences are relocated closer than 20 feet from the landslide margin), we recommend excavating the colluvial soil in the swale and any areas of potentially unstable material and rebuilding the hillside with a properly keyed, benched and compacted engineered fill containing proper surface and subsurface drainage, as discussed below. The approximate depth and extent of the remedial grading on Lot 7 (and potential fill for the building pad) is shown on the Lot 7-Conceptual Grading Plan, Figure 15 and on a cross-section through Lot 7,Figure 16. • Generally, the fill should be built to an inclination matching grades on either side of the repair area, although if desired, a level fill building pad could be incorporated into the remedial grading at the residence site as shown on Figure 16. Due to the presence of numerous well.established trees between the planned roadway and building pad on Lot 7 and the shallow thickness of the colluvium on the upper portion of the lot, in our opinion, thelimits of the remedial grading may be adjusted to allow the trees to remain as shown • on Figure 15. In our opinion, the mitigation of the colluvial swale should extend from near the downslope side of the trees and to approximately 100 feet downslope of the .proposed residence and associated improvements. A portion of the colluvial swale extends into the northeast side of Lot 6, which might remain in place after the remedial grading at Lot 7 is completed. In order to buttress the fill upslope of the remaining colluvium on Lot 6, we recommend a keyway be constructed along the property boundary as discussed below. Based on the subsurface conditions encountered within the approximate limits of the colluvial swale on Lot 7, the colluvium extends to a maximum depth of approximately 15 feet. The exact depth of overexcavation will need to be established during construction based on the conditions encountered during grading and as directed by our field staff. Since the existing colluvium upslope of the residence is to remain in place, if overly wet or soft areas of weathered bedrock are encountered'at the excavation of the upper benches, we may recommend a deeper keyway be excavated and/or more extensive- drainage at the upper bench in order to buttress the remaining colluvium. ROMIG ENGINEERS,INC. Ms. Avigale.McLoughlin Lands of Stirling Subdivision Page 29 of 36 Slope Grading The structural fill should be benched into competent bedrock, and a key excavated into the underlying competent weathered bedrock with subdrains installed as discussed below. A keyway with a minimum width of 10 feet should be constructed at the base of the fill (approximately 100 feet downslope of the improvement area) and a keyway should be constructed to the southwest of the residence location along a portion,of the Lot 6 and 7 property boundary, as conceptually shown on Figure 15. The keyways should extend a minimum of 4 feet into weathered rock at the toe of the keyway and slope at a minimum of 2 percent into the hillside. .A generalized benching detail is shown in Figure 17. Fill should be placed and compacted on level benches as engineered fill to reach final grades in accordance with the recommendations presented in the section of the report titled "Earthwork". The location and depth of the keyways and benches should be approved by our field representative. We should be retained to observe the earthwork operations, including excavation of the keyway and benches, placement and compaction of the fill and installation of subdrains. Subdrains Subdrains should be utilized in the mitigation of the colluvial swale and should also be installed within the upper dormant landslide feature, as discussed below. The subdrains should be included at the base key and at the back of several of the benches, as directed by our field representative during construction. The subdrains should consist of an 18- inch width of Caltrans Class 2 Permeable Material. Four-inch diameter rigid plastic pipe (Schedule 40 PVC, SDR 35 or equal) should be placed with perforations down on a 4- inch thick bed of Permeable Material. The Permeable Material should be continued up to -at least 12-inches above the elevation of the next bench. However, the subdrain located at the highest bench should continue up to within about 2 to 3 feet below the finished grade or as needed to be compatible with the intended future use. A solid pipe should be used to direct the subdrain to a suitable discharge location. Cleanouts should be provided at appropriate locations. We should review the location of subdrains during the development stage of the project and confirm subdrain locations during grading operations. It is essential to develop an accurate as-built plan showing the final locations of the subdrains which can be used during foundation design where structures are planned above the repaired slope. We also note that indications of spring activity and significant seepage were observed within Test Pits TP-8 and TP-12 at the upper dormant landside feature. We 'recommend that a subdrain system be installed within the upper dormant landslide. On a preliminary basis, the subdrain system should include a subdrain line downslope roughly through the ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 30 of 36 middle of the dormant landslide in the area of the observed spring and TP-8 and TP-12; including several laterally installed subdrains lines. We recommend a minimum of two subdrain lines extending laterally through the width of the landslide. The subdrains should be extended through the upper colluvial soil and perched seepage zones (likely 8 to 10 feet in depth). The depth of the perforated pipes and number of lateral subdrains lines will depend on the seepage and ground water conditions exposed during installation of the subdrain system. The dissipation outfall for the subdrains should be located to the north (not directly upslope) of the lower dormant landslide feature. SUBDIVISION ROAD PAVEMENTS Based upon the laboratory test results and the plasticity of the surface soils at the site, an . R-value of 5 is appropriate for design.of the proposed road.. Using estimated traffic indices for various pavement loading conditions depending on the expected traffic conditions, we developed the minimum pavement section thicknesses presented in Table 2 below based on Procedure 608 of the Caltrans Highway Design Manual. The Traffic Indices used in our pavement thickness calculations are considered reasonable values for this development and are based on engineering judgment rather than on detailed traffic projections. Asphalt concrete and aggregate base should conform to and be placed in accordance with the requirements of the Caltrans Standard Specifications, latest edition, except that compaction should be based on ASTM Test D1557. Table 2. Minimum.Pavement Section Thicknesses Lands of Stirling Subdivision Los Altos Hills,California General Traffic AC Thickness Aggregate Base* Total Section Traffic Condition Index (inches) (inches) (inches) Automobile Access 4.5 3.0 8.0 11.0 Light Truck Access 5.0 3.0 10.0 13.0 Moderate Truck Access 6.0 3.0 13.5 16.5 3.5 12.5 16.0 Heavy Truck Access 7.0 3.5 16.5 • 20.0 4.0 15.5 19.5 *Caltrans Class 2 Aggregate Base (minimum R-value=78). ROMIG ENGINEERS,INC. • Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 31 of 36 We recommend that measures be taken to limit the amount of surface water that seeps into the aggregate base and subgrade below vehicle pavements, particularly where the pavements are adjacent to landscape areas. Seepage of water into the pavement base material tends to soften the subgrade, increasing the amount of pavement maintenance that is required and shortening the pavement service life. Deepened curbs extending 4-inches below the bottom of the aggregate base layer are generally effective in limiting excessive water seepage. Other types of water cutoff devices or edge drains may also be considered to maintain pavement service life. Preferably, the upper 1 feet of backfill of utility trenches should consist of native soil. During grading for the subdivision road, the expansive subgrade soils should be moisture conditioned to well above the laboratory optimum moisture content. The contractor will also need to either cover the compacted subgrade with base rock quickly to lock in the moisture or continually water the subgrade to prevent excessive desiccation.. . The road will extend across the upper portion of the colluvial swale near Lot 7. The colluvial soils should excavated in this area and replaced with a compacted fill that is keyed and benched at least 2 feet into bedrock following our earthwork guidelines. SLABS-ON-GRADE General Slab Considerations The near surface soils at the site have a moderate to high expansion potential. Expansive soils have a tendency to expand due to increases in moisture content and shrink as they dry. This can result in, some slab cracking and heave regardless of the geotechnical measures implemented. Our recommendations below will help mitigate the impacts of the expansive soils beneath slabs-on-grade, but will not eliminate the risk entirely. To reduce the potential for movement of the slab subgrade, at least the upper 6-inches of expansive soil should be scarified and compacted at a moisture content at least 3 percent above the laboratory optimum. The native soil subgrade should be kept moist up until.the time the non-expansive fill, crushed rock and vapor barrier, and/or aggregate base is placed. Slab subgrades and non expansive fill should be prepared and compacted as recommended in the section of this report titled "Earthwork." Exterior flatwork and interior slabs-on-grade should be underlain by a layer of non expansive fill as discussed below. The non expansive fill should consist of aggregate base rock or a clayey soil with a plasticity index of 15 or less. . ROMIG ENGINEERS,INC. • Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 32 of 36 • • In areas where slab-on-grade will be constructed directly on excavated weathered bedrock or where the expansive near surface soils are removed, the non-expansive fill section recommended below may be reduced as established by our representative in the field during construction. Considering the potential for expansive soil movements of the surface soils, we expect that a.reinforced slab will perform better than an unreinforced slab. Consideration should also be given to using a control joint spacing on the order of 2 feet in each direction:for each inch of slab thickness. Exterior Flatwork If any concrete walkways, sidewalks, or exterior flatwork are to be constructed as part of the subdivision road construction, the concrete flatwork should be at least 4 inches thick and should be constructed on at least 12 inches of Class 2 aggregate base. The potential for distress to exterior slabs due to expansive soil movements could be reduced by placing and compacting at least 6 inches of non-expansive fill, or aggregate base, below the minimum 12-inch thick layer of aggregate base recommended above; We recommend that exterior slabs-on-grade be constructed with a thickened edge to improve edge stiffness and to reduce the potential for water seepage under the edge of the slabs. EARTHWORK RECOMMENDATIONS Clearing and Subgrade Preparation All deleterious materials, such as existing foundations, slide debris, slabs, pavements, utilities, existing fill, vegetation, topsoil, and root systems, should be cleared from areas to be built on or paved. The actual stripping depth should be established by us at the time of construction. Excavations that extend below finish grade should be backfilled with structural fill that is water-conditioned, placed, and compacted as recommended in the section titled "Compaction." After the site has been properly cleared, stripped, and excavated to the required grades, exposed soil surfaces in areas to receive structural fill or concrete slabs-on-grade, should be scarified to a depth of 6 inches, moisture conditioned, and compacted as recommended in the section of this report titled "Compaction." On-site soils should be kept in a moist condition throughout the construction period to mitigate the potential effects of the expansive on-site soils on the proposed improvements. ROMIG ENGINEERS, INC. • Ms. Avigale McLoughlin Lands,of Stirling Subdivision Page 33 of 36 Compaction Scarified surface soils and all structural fill should be compacted in uniform lifts no thicker than 8-inches in uncompacted thickness, conditioned to the appropriate moisture content, and compacted as recommended for structural fill in Table 3 below. The relative compaction and moisture content recommended in Table 3 is relative to ASTM Test D1557; latest edition. Table 3. Compaction Recommendations Lands of Stirling Subdivision Los Altos Hills,California Relative Compaction* Moisture Content* General • Scarified subgrade in areas 88-92 percent At least 3 percent to receive structural fill.,' above optimum • Structural fill composed 88-92 percent At least 3 percent of native soil. above optimum • Structural fill composed ' 90 percent Above optimum of non-expansive fill. • Fills below a depth 92 percent 2 to 3 percent of 4 feet. above optimum • Pavement Areas • Upper 6-inches of soil 8.8-92 percent 2 to 3 percent below baserock. above optimum • Aggregate baserock. .95 percent Near optimum Utility Trench Backfill . • On-site soil. 88-92 percent At least 3 percent above optimum • Imported sand 95 percent Near optimum * Relative to ASTM Test D1557, latest edition. Material For Fill On-site soil containing less than 3 percent organic material by weight (ASTM D29.74) should be suitable for use as structural fill. Structural fill should not contain rocks or pieces larger than 6 inches in greatest dimension and no more than 15 percent larger than 2.5 inches. Imported non-expansive fill should have a plasticity index no greater than 15, should be predominately granular, and should have sufficient binder so as not to slough or cave into foundation excavations or utility trenches. Imported fill to be used within the upper.2 feet of pavement subgrade elevation should have an R-Value of at least 15. Our representative should approve proposed import materials prior to their delivery to the site. ROMIG ENGINEERS, INC. • • Ms. Avigale McLoughlin Lands of Stirling Subdivision . Page 34 of 36 General Hillside Grading Fill may be required.to raise grades along moderately steep sloping terrain in the central portion of the site beneath the roadway. Where fills are required as part of the site development (for areas outside the landslide or colluvial swale mitigation as described earlier), fill slopes should be designed and constructed as presented below. Prior to placing fill on the existing slope, we recommend that all deleterious materials, topsoil, roots, vegetation, etc., be cleared from theareas to receive the fill. Where placing fill on existing slopes having an inclination steeper than 6 horizontal to 1 vertical, the fill should be benched, and a key excavated into the underlying competent supporting material or weathered bedrock. Several subdrains within the keyways and benches•are anticipated to be needed. A generalized benching detail is shown in Figure 17. The location and depth of the keyways, benches, and subdrains should be approved by our field representative in the field•at the time of the.grading. We should be retained to observe the earthwork operations, including excavation of the keyway and benches, subdrain installation, and placement and compaction of the fill. Temporary Slopes and Excavations The contractor should be responsible for the design and construction of all temporary • slopes and any required shoring. Shoring and bracing should be provided in accordance with all applicable local, state and federal safety regulations, including the current OSHA excavation and trench safety standards. Temporary slopes less than 4 feet deep excavated in the native soils should be capable of standing near-vertical for short construction periods with minimal bracing. Field modification of temporary cut slopes may be required. Unstable materials encountered on slopes during excavation should be trimmed off even if this requires cutting the slopes back to a flatter inclination. Excavations that extend below ground water will require flatter inclinations. Construction dewatering may be required depending on the depth of cuts and the ground water level at the time of excavation. Protection of structures near cuts should also be the responsibility of the contractor. Finished Slopes It would be preferable for finished slopes to be cut or filled to an inclination no steeper than about 2:1 (horizontal:vertical). Exposed slopes may be subject to minor sloughing and erosion that may require periodic maintenance. We recommend that all slopes and soil surfaces disturbed during construction be planted with erosion-resistant vegetation. ROMIG ENGINEERS, INC. Ms. Avigale McLoughlin Lands of Stirling Subdivision Page 35 of 36 Surface Drainage Finished grades should be designed to prevent water ponding and to direct surface water away from foundations, edges of slabs and pavements, and toward suitable collection and discharge points. Slopes of at least 2 percent are recommended for flatwork and pavement areas with 5 percent preferred in landscape areas within 8 feet of the structures, where possible. Preferably, downspout drainage from the residences should be collected in a closed pipe drainage system that is routed to a suitable discharge point. Concrete lined surface swales or unlined swales and channels should be planned above or along the upslope side of the subdivision road and future improvements. Surface water collected should be directed to a suitable discharge location. The creek and swale area in the central portion of the site may be a practical location. Concentrated discharge should be directed away from the dormant landslide features shown on Figure 4. The drainage facilities should be observed to verify that they are adequate and that no adjustments need to be made, especially during first two years following construction. We recommend that an as-built plan showing the location of the subsurface and surface drain lines and clean outs be developed. The drainage facilities should be periodically checked to verify that they are continuing to function properly. FUTURE SERVICES Plan Review Romig Engineers should review the completed grading and foundation plans for conformance with the recommendations contained in this report. We should be provided with these plans as soon as possible upon completion in order to limit the potential for delays in the permitting process that might otherwise be attributed to our review process. In addition, it should be noted that many of the local building and planning departments now require "clean" geotechnical plan review letters prior to acceptance of plans for their final review. Since our plan reviews often do result in recommendations for modification of the plans, our generation of a "clean" review letter often requires two iterations. At a minimum, we recommend the following note be added to the plans: • ROMIG ENGINEERS,INC. Ms. Avigale McLoughlin Lands.of Stirling Subdivision Page 36 of 36 "Earthwork, pavement and slab subgrade preparation, aggregate base placement and compaction, slope and colluvial swale grading and mitigation, subdrain installation and site drainage should be performed in accordance with the geotechnical report prepared by Romig Engineers, Inc., dated May 12, 2014. Romig Engineers should be notified at least 48 hours in advance of any earthwork or foundation construction and should observe and test during earthwork andfoundation construction as recommended in the geotechnical report." Construction Observation and Testing The earthwork and foundation phases of construction should be observed and tested by us to 1) establish that subsurface conditions are compatible with those used in the analysis and design; 2) observe compliance with the design concepts, specifications and recommendations; and 3) allow design changes in the event that subsurface conditions differ from those anticipated. The recommendations in this report are based on a limited amount of subsurface exploration. The nature and extent of variation across the site may not become evident until construction. If variations are exposed during construction, it will be necessary to reevaluate our recommendations. Oi ••'• •'• •Oi Oi ♦ ♦ o • • ROMIG ENGINEERS,INC. REFERENCES Aerial Photographs . Pacific Aerial Surveys, Oakland, California (PAS); United States Geologic Survey Library, Menlo Park, California (USGS); WAC Corporation (WAC), Eugene, Oregon; United States Department of Agriculture (USDA): vertical stereo pairs. Black and white unless otherwise noted. Source Imagery Comment Date Scale • • USDA C1V-286-66/67 B/W 8/1/39 1:20,000 PAS AV-170-20-15/16 B/W 6/8/55 1:10,000 WAC 9-3/4 Color 6/25/74 1:20,000 PAS AV-2670-18-14/15 B/W 10/15/85 1:12,000 PAS SCL-AV-6600-18-14/15 B/W 6/26/00 1:12,000 Publications and Reports Al Atik,L., and Sitar,N.,2010, Seismic Earth Pressures on Cantilever Retaining Structures, Journal of Geotechnical and Geoenvironmental Engineering,ASCE Vol. 136,No. 10. American Society of Civil Engineers, 2013, Minimum Design Loads for Buildings and Other Structures,ASCE Standard 7-10. Association of Engineering Geologists (AEG), 2004, Seismic Hazard of the Range Front Thrust Faults, Northeastern Santa Cruz Mountains/Southwestern Santa Clara Valley, Field Trip Guidebook, March 27, 2004. Brabb, E.E, R.W Graymer, and D.L. Jones, 2000, Geologic Map and Database of the Palo Alto 30 X 60 Minute Quadrangle, California: U.S. Geological Survey Miscellaneous Field Studies Map 2332,Map Scale 1: 100,000. California Division of Mines and Geology, 1974, State of. California Special Studies Zones,Mindego Hill Quadrangle,Map Scale 1:24,000 (1 inch=2000 feet). California Geological Survey, August 11, 2005, State of California, Seismic Hazard Zones Map, Mindego Hill 7.5-Minute Quadrangle, Santa Clara and San Mateo Counties, California, Seismic Hazards Zone Report 109. California Building Standards Commission, and International Code Council (2009), 2010 California Building Code, California Code of Regulations, Title 24,Part 2. ROMIG ENGINEERS,INC. . • California Department of Conservation, Division of Mines and Geology (DMG), 1994, Fault-Rupture Hazard Zones in California,Special Publication 42. Cotton, Shires & Associates, 2004, Geotechnical and Seismic Hazard Zones, Los Altos Hills, California, Scale 1:7200. Cotton, Shires & Associates, 2005, Geologic Map of Los Altos Hills, California, Scale 1:7200. Lew,M.,Al Atik,L., Sitar,N.,Pourzanjani,M., &Hudson,M., 2010, Seismic Earth Pressures on Deep Building Basements, SEAOC 2010 Convention Proceedings. Romig Engineers, Inc, Geotechnical Investigation, Lands of Stirling, Garage Addition, 28030 Natoma Road, Los Altos Hills, California, Project No. 2559-1A. Murray Engineers, Inc., September 30, 2010, Engineering Geologic & Geotechnical Investigation, Yong Residence, 13456 South Fork Lane, Los Altos Hills, California,Project No. 1101-1R1. Terratech, Inc., October 1990, Concentrated Damage from the Loma Prieta Earthquake in the Monta Vista Fault Study Area, Santa Clara County, California,Project No.4745. The County of Santa Clara, 2002, Santa Clara. County Geologic Hazard Zones, Fault Rupture Hazard Zones,Plate 09. The County of Santa Clara, 2006, Santa Clara County Geologic Hazard Zones, Landslide Hazard Zones,Plate 09. The County of Santa Clara, 2006, Santa Clara County Geologic Hazard Zones, Liquefaction Hazard Zones,Plate 09. U.S.G.S.,2007, Ground Motion Parameters Calculator, http://eqhazmaps.usgs.gov/ • Working Group ,on California Earthquake Probabilities (WGCEP), 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2), U.S. Geological Survey Circular Open File Report 2007-1437. ♦♦♦ •♦♦♦ •o♦e •.♦♦ •♦♦♦ ♦ ♦ e • • ROMIG ENGINEERS,INC. EXHIBIT 4 Revised Arborist: Report 28030 Natoma Road Los Altos Hills, CA Prepared for: Los Altos Property LP 333 Edmondson Avenue Sarasota, FL 34242 Prepared by: HortScience, Inc. 325 Ray Street Pleasanton CA 94566 November 2014 HORT SCIENCE Revised Arborist Report 28030 Natoma. Road, Los Altos Hills CA Table of Contents Page Introduction and Overview 1 Assessment Methods 1 Description of Trees 2 Oak-Bay Woodland Census 4 Suitability for Preservation 4 Evaluation of Impacts and Recommendations for Preservation 6 Sudden Oak Death 12 Tree Preservation Guidelines 13 List of Tables Table 1. Condition ratings and frequency of occurrence for trees 2 Table 2. Oak-Bay Woodland Census 3 Table 3. Tree suitability for preservation 5 Table 3. Trees recommended for removal 7 Table 4. Recommended Tree Protection Zones for future lot develop. 11' Attachments Tree Assessment Form Tree Assessment Map Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page .1 • Introduction and Overview The Los Altos Property LP is proposing to subdivide the property at 28030 Natoma Rd., in Los Altos Hills, California. The project includes subdivision of the property, construction of a new road, improvementof the access road leading to the property and installation of utilities to:service the new lots. HortScience, Inc.was asked to prepare an Arborist Report for the project for review by the Town of Los altos Hills. This report provides the following information: 1. An assessment of the health and structural condition of those trees identified by the project's Civil Engineer, Wilsey Hamm. 2. Identification of Heritage trees as defined by the Town of Los Altos Hills Ordinance #12-2. 3. An assessment of the impacts of constructing the proposed project on the trees. 4. A discussion of sudden oak death, its presence in the area and potential impacts to the site. 5. Guidelines for tree preservation during the design, construction and maintenance phases of development. Assessment Methods Trees were assessed on November 8, 2012 and April 15, 2014. The assessment included trees 6"and greater in diameter(19" in circumference). The survey procedure consisted of the following steps: 1. Identifying the tree as to species; 2. Measuring the trunk diameter ata point 48"above grade; 3. Evaluating the health and structural condition using a scale of 1 —5: 5-A healthy, vigorous tree, reasonably free of signs and symptoms of disease, with good structure and form typical of the species. 4-Tree with slight decline in vigor, small amount of twig dieback, minor structural defects that could be corrected. 3-Tree with moderate vigor, moderate twig and small branch dieback, thinning of crown, poor leaf color, moderate structural defects that might be mitigated with regular care. 2-Tree in decline, epicormic growth, extensive dieback of medium to large branches, significant structural defects that cannot be abated. • I-Tree in severe decline, dieback of scaffold branches and/or trunk; most of foliage from epicormics; extensive structural defects that cannot be abated. 5. Rating the suitability for preservation as"high", "moderate"or"low". Suitability for preservation considers the health, age and structural condition of the tree, and its potential to remain an asset to the site for years to come. • High: Trees with good health and structural stability that have the potential for longevity at the site. Moderate: Trees with somewhat declining health and/or structural defects than can be abated with treatment. The tree will require more intense management and monitoring, and may have shorter life span than those in 'high' category. Low: Trees in poor health or with significant structural defects that cannot be mitigated. Tree is expected to continue to decline, regardless of treatment. The species or individual may have characteristics that are undesirable for landscapes, and generally are unsuited for use areas. Arborist Report, Los Altos Property LP. HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 2 Description of Trees One-hundred and fifty-eight(158)trees were assessed, including 135 trees on the development site and 23 along the access road connecting the site to Natoma.Road. Descriptions of each tree are found in the Tree Assessment Forms, and locations are shown on the Tree Assessment Map(see attachments). Walnut and eucalyptus trees were not included in the assessment. The site sits at the edge of the oak-bay woodlands that extend down the east side of the coastal mountain rage in this area. A closed canopy forest of coast live oak exists along the western edge of the property,with a small finger extending east and south to the driveway entrance(Photo 1,following page). The northeastern half of the site was an open oak woodland, dotted with open-grown valley.oaks(Photo 2,following:page). Three(3)species of oaks were assessed at the site(Table 1). The most frequently occurring species was coast live oak(116 trees, or 73%of the population). Valley oak,with 41 trees (26%),was the second most frequent species assessed. One blue oak(#157)was also assessed. Tree size ranged from 6"to 46"in diameter. Forty-one(41)trees had multiple trunks arising below 48". Table 1: Condition ratings and frequency of occurrence of trees. 28030 Natoma Rd., Los Altos Hills Common Name Scientific Name Condition Rating No.of Poor Fair Good Trees (1=2) (3) (4-5) Coast live oak Quercus agrifolia 6 51 59 116 Blue oak Quercus douglasii - - 1 1 Valley oak 'Quercus lobata 2 22 17 41 Total 8 73 77 158 5% . 46% 49% 100% Coast live oaks were growing in groups, or stands,where one or two trees were dominant and the rest were subordinate. Dominant trees tended to be mature to over-mature,with diameters from 24"to 46", and in good to excellent condition. Subordinate trees were typically young to semi-mature(<24" in diameter) and growing at the edge of the group or beneath their larger neighbors. The competition for light and resources among this group often produced trees in fair condition,that leaned or had asymmetric or one sided crowns. Fifty-nine(59)of the coast live oaks were in good or excellent condition, 51 were in fair and six(6)were in poor(Table 1). Mature valley oaks dominated the northeast half of the site,with young to semi-mature trees located in the grove between Lots 1 and 2. The remaining seven (7)valley oaks were along the access road. Condition of the valley oaks was fair(22 trees)to good (17 trees). Two(2) of the valley oaks were in poor condition. There were fewer young valley oaks than coast live oaks(22 valley:oaks with diameters <24".vs. 85 coast live oaks with diameters <24"), indicating that the valley oaks are not regenerating_naturally and may slowly disappear from the landscape. Overall, tree condition was good (77 trees or 49%)to fair(73 trees or 46%). Eight(8)trees (5%of the population),were in poor condition, including tree#51, a 42"diameter coast live oak with a several cavities and extensive trunk decay. The Town of Los Altos Hills defines all oaks with a diameter of 12" (circumference of 36")as Heritage Oaks.. Based on this definition, 132 of the 158 trees qualified as Heritage Oaks. Heritage Oaks are identified in the Tree Assessment Forms(see attachments). Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page.3 • aye ▪ �•� . ,.U a .♦ jam r� '' 7S • `S' ., , c i`G acs } t ,17,',^ y+.._!1r• a' -:.6.-r.,/.1"?'". 1�Y%•'1K‘'CCS'" f 1•F. e- e:,1v ' ,. .le y-„_ • .; ,51......:„ 3:" 4, _• `1::-r.,.'"}-..,-:`1"4". 3' �.t,',` •-r, ,.,.,•i t t• � : �fy fix , r z'•� �.!<la t - • a 'i •`S y •`•. f£ �` - �It7-'•• .� • r4,,, '"'N ',_ .. F. f'a......4 ' 4i• 4,r✓ 4-,r,•ils7;tr f• lit '! "L. fC.h ,r5ffi "r.' st 4.4.,-'.'.04.'1' • %1 f "A': t �.`%ai ! '' !:'-,S-..5,0 Ff tV. r a'f,i --a-f tY, • :/tom „, `a`7• t,, 7,--,14,„4`' . t 'Fr r` ., ..��..s • v`.i,,,, Y,. -,,'�''� -.•. r' n_ .� p M r -6,-4; `sf �3C:� a. '- �',e qtr_ r,,- :�,h t '.•x . •._. x:, e• 'i . t t t! ,���/ - — i. AC- • 'atyz•�t�_ 1 prtD• 4 ]n••.�:>flKr..�^ R- ___r• L•.._,h. ';e11,':! ... '* "l�'' ra..s .- - — - - -''►:`1 f-.-.. :l4 ;'- ...,c .r.i'�..' 'r L. Photo 1 (above):A group of coast liveoaks near the entrance to the property(looking east): This grove was dominated by mature coast live oaks#16 and 17,with smaller-diameter. trees growing at the edge of their canopies. Photo 2(below): Open-grown valley oak#58 was growing on the northeast half of the site. The location and growing conditions were typical of the other valley oaks assessed. ;'c ' ' 1 `�. • tZL � ' G�x r41 1, T�',.4Sg: 1; ." . • r� . N1 0 _ l •• y v. k' -flew.,.-:t:° -P' .,�� - -, -...-%.!%.•,, -f;4:4' • V V '1,4:_e4.12.- ! N� )� /;•.a.rvt i.1 t- y c t ..:• iY `A�i pV! K ,1"1".r: " 4 1 •4 n-1 -, g C t`<!y:' .' 'cri.-:,c•~ . "- :,„.6".?:::!-A, m - '* .F Cly .-"••• 4, ,„.Y�F4 - 1 '�,'” l,.-1 E T--.:4-.A.';rdF.t t¢ ,.•r , . • +• tt��eC'. 'I'-iii. }r: .T T� -. tay,., , e • r sem" e. /,l r. . , .' \fit'•,4.'Se -Y .7� kyi ^`f*.. A T !! Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 4 Oak-Bay Woodland Census For the remainder of the site, we performed a census of all trees 6" and greater in diameter. The census procedure consisted of the following steps: 1. Identifying the tree as to species; 2. Counting the number of trees of each species in the following diameter classes: 6-11", 12-17", 18-23", 24-32", and z32". The remainder of the site was a west-facing slope with a dense cover of oak-bay woodland. The property boundary was defined by the creek running along the southern and western boundaries, except in the northwestern corner where the boundary extended over the creek (see attached Tree Assessment Map). Table 2 provides a summary of the census data by species and diameter class. The majority of trees were coast live oaks (316 trees, or 63%of the census trees)and California bays (106 trees or 21%). Two-hundred and eighty-five(285) of the trees in this. area qualified as Heritage Oaks, including 253 coast live oaks, 23 valley oaks and 9 blue oaks. Table 2: Oak-Bay Woodland Census. 28030 Natoma Rd., Los Altos Hills Common name Scientific name Diameter Classes Total 6-11 12-17 18-23 24=31 Calif. buckeye ' Aesculus californica 11 14 - 2 1 28 Toyon Heteromeles arbutifolia - - 1 - - 1 Coast live oak Quercus agrifolia 63 94 63 52 44 316 Valley oak Quercus lobate 9 10 7 2 4 32 Common elderberry Sambucus nigra 2 5' - - - 7 Calif. Bay Umbellularia californica 80 19 . 5 1 1 106 Blue oak Quercus douglasii 2 4 - 4 1 11 Total 167 146 76 ' 61 51 501 Suitability for Preservation Before evaluating the impacts that will occur during development, it is important to consider the quality of the tree resource itself, and the potential for individual:trees to function well over an extended length of time. Trees that are preserved on development sites must be carefully selected to make sure that they may survive development impacts;adapt to a new environment and perform well in the landscape. Our goal is to identify trees that have the potential for long-term health, structural stability and longevity. For trees growing in open fields or creek channels, away from areas where people and property are present, structural defects and/or poor health presents a low risk of damage or injury if they fail. However,we must be concerned about safety in use areas. Therefore, where development encroaches into existing plantings,we must consider their structural stability as well as their potential to grow and thrive in a new environment. Where development will not occur, the normal life cycles of decline, structural failure and death should be allowed to continue. Arborist Report, Los Altos Property LP HortScience,:Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page. 5 Evaluation of suitability for preservation considers several factors: • Tree health Healthy, vigorous trees are better able to tolerate impacts such as root injury, demolition of existing structures, changes in soil grade and moisture, and soil compaction than are non-vigorous trees. • Structural integrity Trees with significant amounts of wood decay and other structural defects that cannot be corrected are likely to fail. Such trees should not be preserved in areas where damage to people or property is likely. Coast live oak#51 is an example of such a. tree. • Species response There is a wide variation in the response of individual species to construction impacts and changes in the environment. In our experience,for example, valley oak is moderately sensitive to site disturbance,while coast live oak is more tolerant of root loss. • Tree age and longevity Old trees,while having significant emotional and aesthetic appeal, have limited physiological capacity to adjust to an altered environment. Young trees are better able to generate new tissue and respond to change. • Species invasiveness Species which spread across a site and displace desired vegetation are not always. appropriate for retention. This is particularly true when indigenous species are displaced. None of the species surveyed at the Natoma Rd. property are considered invasive. Each tree was rated for suitability for preservation based upon its age, health, structural condition and ability to safely coexist within a development environment. Table 3 provides a summary of the suitability ratings. Suitability ratings for individual trees are included in the Tree Assessment Form(see attachments). Table 3: Tree Suitability for Preservation 28030 Natoma Rd., Los Altos Hills High These are trees with good health and structural stability that have the potential for longevity at the site. Thirty-five(35)trees were highly suitable for preservation; including 25 coast live oaks and 10 valley.oaks. Moderate Trees in this category have fair health and/or structural defects that may be abated with treatment. Trees in this category require more intense management and monitoring, and may have shorter life-spans than those in the"high"category. Ninety(90)trees were of moderate suitability for preservation, including 68 coast live oaks,21 valley oaks and one(1) blue oak. Low Trees in this category are in poor health or have significant defects in structure that cannot be abated with treatment. These trees can be expected to decline regardless of management. The species or individual tree may possess either characteristics that are undesirable in landscape settings or be unsuited for use areas. Thirty-three(33)trees were of low suitability for preservation, including 23 coast live oaks and 10 valley oaks. 1 Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 6 Evaluation of Impacts and Recommendations Appropriate tree retention develops a practical match between thelocation and intensity of construction activities and the quality and health of trees. The Tree Assessment Form was the reference point for tree condition and quality. Potential impacts from construction were evaluated using the Proposed Subdivision Map and Access Road Improvement Plan prepared Wilsey Ham(dated July 17, 2014). The plan proposes to subdivide the property into nine(9) lots,with the existing house to remain on Lot 9. Building envelopes and potential building and driveway locations were . shown on the plans. The existing dirt driveway will be improved and extended to the north. The new road would be 22'wide,with a 3'curb and gutter and a 5'wide pathway installed along the eastern edge. Utilities are not shown on the plan but are proposed to be placed within the new road. Accurate tree trunks were shown on the plans for most, but not all, of the trees. In addition, theaccess road from Natoma Rd.to the development:site will be widened to 22', with a 2'gutter and a 5'wide pathway installed along the northern edge. The path is proposed to be constructed of decomposed granite and will be designed to meander through the trees. Potential impacts from construction of the new road were estimated for each tree. The most significant impacts to the trees would occur as a result of the road grading, access road widening and curb and gutter installation. For the Development Site: Based on my evaluation of the plans and associated impacts on the trees, I recommend preservation for 120 trees, including 97 Heritage Oaks. Preservation is predicated on establishing a Tree Protection Zone and other recommendations listed in the Tree Preservation Guidelines(page 12). Removal is recommended for 15 trees, including nine(9)that fall within the proposed road alignment and six(6)that were adjacent to the new road but which would be impacted beyond their tolerance. Of the 15 trees recommended for removal, five(5) had low suitability for preservation and 14 qualified as Heritage Oaks. Table 3 (following page)provides the recommended action for each tree, along with their Heritage Oak status and a description of impacts. Twenty-two(22)•of the trees identified for preservation had low suitability for preservation. Most of these were suppressed trees with poor structure; however, some were structurally unstable including#11, 50, 51 and 64. All of these trees had some amount of decay andhad experienced limb or stem failures. While the current plan does not impact trees#11, 50, 51 and 64, these trees are structurally unstable and are inappropriate for retention in a development environment. These trees should be protected in such a way as to limit their potential to do damage when they fail,or they should be removed with the development of individual lots. In anticipation of the development of individual lots, I have provided recommended Tree Protection Zones for those:trees that are shown as being within, or adjacent to the proposed building envelopes(Table 5, page 8). This information is provided to help with the design of improvements on individual lots and distances provided representradii in all directions. Thirteen (13)of the trees recommended for preservation will be in close proximity to the new road alignment and may require pruning for construction and vehicle clearance. These include trees#1, 3, 4, 7, 23, 25-27, 28,'33, 66, 95 and 101. Pruning recommendations are provided in the Tree Preservation Guidelines(page 13). Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 7 For the Access Road: • Based on my evaluation of the plans and associated impacts on the trees, I recommend preservation for 15 of the 23 trees along the access road, including 13 Heritage Oaks. Preservation is predicated on establishing a Tree.Protection Zone and other recommendations listed in the Tree Preservation Guidelines(page 13). Removal is recommended for eight(8)trees, all of which qualified as Heritage Oaks. Table 3 provides the recommended action for each tree, along with their Heritage Oak status and a description of impacts. Impacts were as follows: • Tree#107 had failed at the base and will need to be removed to construct the path. • Four.(4)trees fell within the proposed access road alignment, requiring their removal. • Trees#111, 118 and 119 were adjacent to the new access road but would be impacted beyond their tolerance. Ten (10)of the trees recommended for preservation will be in close proximity to the new access road alignment, including trees#109, 110, 112, 113, 115, 121, 122, and 124-126. Root loss associated with construction of the access road will remove roots and may lead to decline, such as dieback of twigs and branches,for some trees. This is especially true for trees#122 and 125,which are large-diameter trees in very close proximity to construction. In addition, these trees may require pruning for construction and vehicle clearance. In summary, a total of 135 trees can be preserved (120 on the subdivision site and 15 along the access road), including 109 which qualified as Heritage Oaks. Twenty-three(23)trees will require removal (15 on the subdivision site and 8 along the access road), 22 of which qualified as Heritage Oaks. Table 4: Recommendations for action 28030 Natoma Rd., Los Altos Hills Tree# Species Trunk Heritage Impact Diameter Oak? (in.) 1 Coast live oak 14,9,9,6 Yes Preserve, 8' N. of 5' new rd. 2 Coast live oak 13 Yes Remove, impacted by new rd. alignment 3 Coast live oak 13 . Yes Preserve, 6' N. of 5'path. 4 Coast live oak 11 No Preserve, 6' N. of 5' path. 5 Coast live oak 12,10,10,9,8 Yes Preserve, 18' N. of 5' path. 6 Coast live oak 8 .No Preserve, 20' N. of 5'path. 7 . Coast live oak 17 Yes Preserve, 6' N. of 5'path. 8 Coast live oak 8 No Preserve,20' N. of 5'path. 9 Coast live oak 13 Yes Preserve, 20' N. of 5'path. 10 Coast live oak . 17 Yes Preserve, outside impacts 11 Valley oak 32 Yes Preserve, outside impacts. 12 Coast live oak 12,10 Yes Preserve, outside impacts • 13 Coast live oak 7 • No Preserve, outside impacts 14 Coast live oak 17,9 Yes Preserve, outside impacts 15 • Valley oak ' 17,17 Yes Preserve, outside impacts 16. Coast live oak 35 Yes Preserve,within Lot 1 bldg. envelope 17 Coast live oak 25,22,18 Yes Preserve,within Lot 1 bldg. envelope 18 Coast live oak 10 No Preserve,within.Lot 1 bldg. envelope 19 . Valley oak 10 No Preserve,within Lot 1 bldg.envelope. 20 Valley oak , 17,8 Yes Preserve,within Lot 1 bldg. envelope 21 Coast live oak 28 Yes Preserve,within Lot 1 bldg. envelope 22 Coast live oak 21,18 . Yes Remove; within new rd. alignment (Continued,following page) , Arborist Report, Los Altos Property LP. HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page:.8 Table 4: Recommendations for action,continued 28030 Natoma Rd., Los Altos Hills Tree# Species Trunk Heritage Impact Diameter Oak? - (in.) 23 Coast live oak 12,10 Yes Preserve, 6'W. of new rd. . 24 Coast live oak 18 Yes Preserve, 20'W. of new rd. 25 Coast live oak 18,16 Yes Preserve, 18'W. of new rd.; 12' N. of Lot 8 dr. 26 Coast live oak 20 Yes Preserve, 8'W. of new rd. 27 Coast live oak 16,12,11 - Yes Preserve, 15'W. of new rd. 28 Coast live oak 20 Yes Preserve, 10'W. of new rd. 29 Coast live oak 18,17 Yes Preserve, outside impacts 30 Coast live oak 29 Yes Preserve, outside impacts 31 Coast live oak 40 Yes Preserve, outside impacts . 32 Coast live oak 46 Yes Preserve, outside impacts 33 Coast live oak 8 No Preserve, 8'W. of new rd. 34 Valley oak 16 Yes Remove, impacted by new rd. alignment. 35 Coast live oak :.12 Yes Remove,within new rd. alignment 36 Coast live oak 11,10 Yes. Remove,within new rd. alignment 37 Coast live oak 8,8 . Yes Remove,within new rd. alignment 38 Valley oak 14 Yes Remove,within new rd. alignment 39 Coast live oak 12 Yes Preserve, outside impacts 40 Coast live oak 8 No Preserve, outside impacts 41 Coast live oak 20 Yes Preserve, 25'W. of new rd. 42 Coast live oak 9 No Preserve, outside impacts . 43 ; Coast live oak 14 Yes Preserve, outside impacts . . 44 Coast live oak 8,8 Yes Preserve, outside impacts 45 Coast live oak 17 Yes Preserve, 25'W. of new rd. 46 Coast live oak 20 Yes Preserve, 20'.S.of Lot 7 drive 47 Coast live oak 18 Yes Preserve,within Lot 7 bldg. envelope _ 48 Coast live oak 25 Yes Preserve,within Lot 7 bldg. envelope 49 Coast live oak :42 Yes Preserve, within Lot 7 bldg. envelope 50 Valley oak 32 Yes Preserve,within Lot 8 bldg. envelope 51 Coast live oak 42 Yes Preserve, declining and high risk 52 Coast live oak 29 Yes Preserve,within Lot 8 bldg. envelope 53 Valley oak . 28 Yes Preserve,within Lot 8 bldg. envelope 54 Coast live oak 28 Yes Preserve,outside impacts 55 Valley oak 20 • Yes Preserve, outside impacts 56 Valley oak 30 Yes Preserve, outside impacts 57 Valley oak 28 Yes Preserve, outside impacts 58. Valley oak 23 Yes Preserve, outside impacts 59 Valley oak. 16 Yes Preserve, outside impacts 60 Valley oak 23 Yes Preserve,within Lot 4 bldg. envelope 61 , Valley oak 38 Yes Preserve,within Lot 4 bldg. envelope 62 Valley oak 26 Yes Preserve, 35'SE. of Lot 4 drive 63 Valley oak 28 Yes Preserve, 35'SE. of Lot 4 drive 64 Valley oak 44 Yes Preserve, 35' NW. of Lot 4 drive 65 Valley oak 44 Yes Preserve, 20'W. of Lot 4 drive 66 Valley oak 36 Yes Preserve, 15'NE. of rd., 15'S. of Lot 4 drive 67 Coast live oak 20,18,18 Yes Preserve,within Lot 6 bldg. envelope 68 Coast live oak 40 Yes Preserve,within Lot 6 bldg. envelope (Continued,following page) • Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page .9 Table 4: Recommendations for action,continued 28030 Natoma Rd., Los Altos Hills Tree# Species Trunk Heritage Impact Diameter Oak? (in.) . . 69 Coast live oak 19,19 Yes Preserve, outside impacts 70 Coast live oak 7,5 Yes Preserve, outside impacts 71 Coast live oak 8 No Preserve, outside impacts_ 72 Coast live oak 9 No Preserve, outside impacts 73 Coast live oak 35 Yes Preserve, outside impacts 74 Coast live oak 18,18,15 Yes Preserve, outside impacts 75 Coast live oak 16 Yes Preserve, outside impacts 76 Coast live oak 10,10 Yes Preserve, outside impacts' 77 Coast live oak 14 Yes Preserve, outside impacts 78 Coast live oak 17 Yes Preserve, outside impacts 79 Coast live oak 8 No Preserve, outside impacts 80 Coast live oak 9 No Preserve, outside impacts 81 Coast live oak 12 Yes Preserve, outside impacts 82 Coast live oak 20 Yes Preserve,within Lot 7 driveway 83 Coast live oak 20 Yes . Preserve,within Lot 7 driveway 84 . Coast live oak 14 Yes Preserve, 3' N. of Lot 7 bldg. 85 Coast live oak 26 Yes Preserve,within Lot 7 bldg. 86 Coast live oak 6 No Preserve,within Lot 7 bldg. 87 Coast live oak 32 Yes Preserve, 15' E. of Lot 7 drive, 12'N. of Lot 7 bldg. 88 Coast live oak 17 Yes Preserve, 3' E. of Lot 7 bldg. 89 Coast live oak . 11 No Preserve, within Lot 7 bldg. 90 Coast live oak 9 No Preserve, 5' E. of.Lot 7 bldg. 91 Coast live oak 14 Yes Preserve, 10' E. of Lot 7 bldg. 92 Coast live oak 9 No Preserve,withinLot7 bldg. 93 Coast live oak 9,44 Yes Preserve, outside impacts 94 Valley oak 1 ": Yes Remove, impacted by new rd.alignment 95 Coast live oak 33''J Yes Preserve, 15' E. of new rd., 10' E'of path 96 Coast live oak 10 No Remove,within new rd. alignment 97 Coast live oak 13,11 Yes Remove,within new rd. alignment 98 Coast live oak 16 Yes Remove, impacted by new rd. alignment 99 Coast live oak 14,10 Yes Remove, within new rd. alignment 100 Coast live oak 18 Yes Remove, impacted by new rd. alignment 101 Coast live oak 22,21 Yes Preserve, 15' E. of new rd., 10'E'of path 102 Coast live oak 21;20 Yes Remove, impacted by new rd. alignment 103 Valley oak 9 No Preserve, outside impacts 104 Coast live oak 15 Yes Remove,within new rd. alignment 105 Coast live oak 27 Yes Remove,within access rd. alignment 106 Coast live oak 25,24,22,19,1 Yes Remove,within access rd. alignment 7,12,6 107 Coast live oak . 17,14 ,12,6 Yes Remove, tree failed at base. 108 Coast live oak 21,19 Yes Remove,within access rd. alignment 109 Coast live oak 33,8 Yes Preserve, 7' N. of access rd., 5'S. of path. 110 Coast live oak 25 Yes Preserve, 10' N. of access rd., 3'S. of path 111 Coast live oak 22 Yes Remove, impacted by newaccess rd. alignment (Continued,following page) Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 10 • • Table 4: Recommendations for action, continued 28030 Natoma Rd., Los Altos Hills • Tree# 'Species Trunk Heritage Impact ' Diameter Oak? (in.) 112 Coast live oak 21,20 Yes Preserve, 15'.N. of access rd., 5' N. of path 113 Coast live oak 33,13 Yes Preserve, 15' N. of access rd.,3' N. of path 114 Valley oak 10,6 Yes Preserve, 20' N. of accessrd., 3. N'of path 115 Coast live oak 23,22,13,12,9 Yes Preserve, 13'N. of access rd:,2'S.of path 116 Coast live oak 12 Yes Preserve, 10' N. of access rd., 10' S. of path 117 Valley oak 11 •. No Preserve, 10`N;.of access rd., 10' S. of path 118: Valley oak 16,9 Yes Remove, impacted by new access rd. alignment ' . • • • 119 Coast live oak 29 Yes Remove,within access rd.alignment 120 Valley oak . 25 Yes Remove,within access rd. alignment • - 121 Coast live oak 19 • Yes Preserve, 10' N;-of access rd., 6' S. of path 122 Valley oak 35, Yes Preserve, 5' N. of access rd., 5' S. of path 123 Coast live oak 6 No Preserve,4' N. of path 124 Coast live oak 18 Yes Preserve, 10' N. of access rd., 5' N. of path • 125 Valley oak 28 . Yes Preserve, 6' S. of access rd. l 126 Coast live oak 15,14,8 Yes Preserve, 14' S. of access rd. 127 Valley oak 14 Yes Preserve, 10' N. of path 128 Coast live oak 22;14,10 Yes Preserve, outside impacts 129 Coast live oak 35,19 Yes Preserve, outside impacts 130 Valley oak 18 Yes Preserve, outside impacts 131: Valley oak 14 • Yes Preserve, outside impacts 132 Coast live oak 18 Yes Preserve,within Lot 1 bldg. envelope . 133. Coast'live oak 28,10 Yes Preserve,within Lot 1 bldg. envelope . 134 Coast live oak • 30 Yes Preserve,within Lot 1 bldg. envelope 135 Coast live oak 29 Yes Preserve, outside impacts 136 Valley oak .8,4 . Yes Preserve, outside impacts 137 Valley oak 11 ' No Preserve, outside impacts 138 Valley oak 9 No Preserve, outside impacts . 139 Valley oak 12 Yes Preserve, outside impacts 140. Coast live oak 19 Yes Preserve, outside impacts 141 Coast live oak 12 • Yes Preserve, outside impacts.- 142 Valley oak 29 Yes Preserve, outside impacts 143 Valley oak 21 Yes ' Preserve, outside impacts • 144 Coast live oak 9 • No Preserve, outside impacts .• 145 Coast live oak 22 Yes Preserve, outside impacts 146 Coast live oak 26 Yes Preserve,within Lot 1 bldg. envelope 147 Valley oak- 8 No Preserve,within Lot 1 bldg. envelope 148 Valley oak 15 Yes Preserve,within Lot 1 bldg. envelope• 149 Coast live oak 10,9,8 yes Preserve,within Lot 1 bldg. envelope • 150 Coast live oak 17 Yes Preserve, outside impacts 151 Coast live oak 20 Yes Preserve, outside impacts 152 Coast live oak 29,23,19,10 Yes Preserve, outside impacts 153 Coast live oak 23 Yes Preserve, outside impacts 154: Coast live oak 16,11 Yes Preserve, outside impacts 155 Valley oak 18 Yes Preserve, outside impacts 156 Coast live oak 22 Yes Preserve, outside impacts 157 Blue oak • 9 No Preserve, outside impacts • 158 Valley oak 16 'Yes Preserve, 15' E.of new rd. Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 11 ' Table 5: Recommended Tree Protection Zones for future lot development 28030 Natoma Rd., Los Altos Hills Tree# Species Trunk ' Heritage Tree Protection Zones Diameter Oak? . (in.) •: . • 12' Coast live oak 12,10 Yes 10'in all directions 13 Coast live oak . ‘7 No 10'in all directions 14 Coast live oak 17,9 Yes 12'in all directions 15 Valley oak 17,17. Yes 12'in all directions 16 Coast live oak 35 Yes 20'in all directions 17 Coast live oak 25,22,18 Yes 20'in all directions 18 Coast live oak 10 No 8'in all directions 19 Valley oak 10 No 10'in all directions 20 Valley oak 17,8 Yes 15'in all directions 21 Coast live oak 28 Yes 15'in all directions 46 Coast live oak 20. Yes 15'in all directions 47 Coast live oak 18 Yes 12'in all directions 48 Coast live oak 25 Yes 18'in all directions 49 Coast live oak 42 Yes 20'in all directions 50 Valley oak 32 Yes 20'in all directions 52 Coast live oak 29 Yes 20'in all directions 53 Valley oak 28 Yes 20'in all directions. 54 Coast live oak 28 Yes 15'in all directions 55 Valley oak 20 Yes 15'in all directions 56 Valley oak 30 Yes - • • 25'in all directions 57 Valley oak 28 Yes 25'in all directions 58 Valley oak 23 Yes 20'in all directions 59 Valley oak 16 Yes 15'in all directions 60 Valley oak 23 Yes 20'in all directions . 61 Valley oak 38 Yes 25'in all directions 62 Valley oak 26 Yes 20'in all directions 63 Valley oak 28 Yes 20'in all directions 64 Valley oak 44 Yes 30'in all directions 65 Valley oak 44 • Yes 7 20'in all directions 66 Valley oak 36 Yes 20'in all directions 67 Coast live oak 20,18,18 Yes 15'in all directions 68 Coast live oak, 40 Yes 20'in all directions 82 Coast live oak 20 Yes 12'in all directions 83 Coast live oak 20 Yes 12'in all directions 84 Coast live oak 14 Yes 10'in all directions • 85 Coast live oak 26 Yes 15'in all directions 86 Coast live oak. 6 No 5'in all directions 87 Coast live oak 32 Yes 20'in all directions 88 Coast live oak 17 Yes 15'in all directions 89 Coast live oak 11 No 8'in all directions 90 Coast live oak 9 No 8'in all directions ' 91 Coast live oak 14 Yes 10'in all directions 92 Coast live oak 9 No 8'in all directions 132 Coast live oak 18 Yes DL in all directions 133 Coast live oak 28,10 Yes 18'in all directions 134 Coast live oak 30 Yes 20'in all directions 146 Coast live oak 26 Yes DL in all directions 147 Valley oak 8 No DL in all directions 148 Valley oak 15 • Yes DL in all directions 149 Coast live oak 10,9,8 Yes DL in all directions Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 12 Sudden Oak Death was asked to provide some information on the current state of the disease„its presence in the region and the potential for it to affect trees at the 28030 Natoma Rd. site. Sudden Oak Death (SOD)is caused by Phytophthora ramorum, a fungal pathogen (actually a water mold) affecting oaks in the red oak group, including coast live oak. Valley oak, in the white oak group, is not affected. The disease was first recognized in Santa Cruz and Marin counties in the mid 1990's. Research indicates it was likely introduced through the nursery industry and may have been in the environment for many years before it'escaped'into the forest. The disease requires water to grow and spread, and has many host species that are not affected by the disease but play a critical role in its spread. The disease has been shown to move from plant to plant via wind-driven rain, water, plant material, and human activities. The disease typically lands on the foliage of a susceptible plant and migrates with water movement onto the trunk. Trunk lesions and foliar dieback ensue, eventually girdling the trunk, but the tree may remain green for several months or even years before it suddenly turns brown (hence the name). Bleeding cankers and dieback are not sufficient to make a positive SOD identification. Lab analysis of plant material is required before the suspected case can be confirmed. In general, SOD is a forest disease and has had limited impact in the urban-wildland interface. However,there are thousands of confirmed cases of SOD in Santa Clara County (mostly in the forested areas), but there are dozens within the immediate area around the 28030 Natoma Rd. site. We did not see any indications of SOD during our November field work, however, several precautions are recommended to help limit the possibility of infection. A"detailed list of susceptible and host species, management and monitoring guidelines and prophylactic treatments are provided on the California Oak Mortality Task Force website(link provided below). The greatest potential for the disease to move onto the site will be during the development process, including the road construction and development of the lots. Current research indicates that the wet months(typically Novemebr through March)are when the disease is most active,with the highest probability of infection occurring in March. The same research has revealed that the presence of Calif. bay laurel (Umbellularia californica)within 20 meters of a susceptible oak species is the best indicator of a high probability for infection. Should the disease become established at the 28030 Natoma Rd. site, all coast live oaks would be at risk, representing approximately 2/3 of the tree population. Although not included in the current assessment, other species, such as black oak, tan oak and madrone are also at risk for infection and death. Several species such as Calif. bay laurel are host speciesand do not decline as a result of the infection,but are important vectors in the movement of the disease. Following is a brief list of the most important steps to take to limit the chances of SOD becoming established. I have also included the Best Management Practices for minimizing the chances of infection on individual trees and the movement of infected material, provided by theCalifornia Oak Mortality Task Force(see attachments). • Monitor the coast live oaks and other susceptible species for indicators of the disease. • If susceptible species are showing SOD indicators, have the presence of the disease confirmed through a recognized laboratory. Contact the Project Arborist or the County Agriculture Commissioner:for assistance with sampling of oaks. • Avoid the purchase and movement of host plants, including several ornamental plants commonlyavailable in the nursery trade. Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natomand., Los Altos Hills, November 2014 Page 13 • Avoidconstruction activities and major tree removal during the wet months (typically Novemebr through March). • Make sure arborist performing tree work are aware of and follow all sanitation guidelines for personnel and equipment during the course of their work. • The movement of infested soil and plant material is regulated by the state and federal government. Avoid movement of plant material, including dead and downed woody_ debris. Debris from tree removal, whether confirmed to have SOD or not, should be left on site. It can be chipped and spread as mulch but cannot be moved off site without contacting your County Agricultural Commissioner. • Certain phosphate containing-compounds have been registered for use as prophylactics against infection from SOD. These compounds are not a cure but can be used on individual, high-value trees as a preventative against infection. Where appropriate, consider the use of these compounds to help protect trees. Current information on susceptible species can be found at the US Dept. of Food and Agriculture website: http://www.aphis.usda.gov/plant health/plant pest info/pram/index.shtml Information on the current research can be found at the California Oak Mortality Task Force • website: http://www.suddenoakdeath.orq/ Information on the local presence of the disease can be found at the Oak Mapper website: - http://oakmapper.orq/ . Tree Preservation Guidelines The goal of tree preservation is not merely tree survival during development but maintenance of tree health and beauty for many years. Trees retained on sites that are either subject to extensive injury during construction or are inadequately maintained become a liability rather than an asset. The response of individual trees will depend on the amount of excavation and grading, the care with which demolition is undertaken, and the construction methods. Coordinating any construction activity inside the Tree Protection Zone can minimize these impacts. The following recommendations will help reduce impacts to trees from development and maintain and improve their health and vitality through the clearing,grading and construction phases. • Design recommendations 1. All plans affecting trees shall be reviewed by the Consulting arborist with regard to tree impacts. These include, but are not limited to, demolition plans, grading and utility plans, landscape and irrigation plans. 2. Evaluate the design of the path to minimize grading and provide as much room from . trees#109, 110, 112, 113, 115-1.18, 121 and 122 as possible: By placing the path on grade, or as close to existing grade as possible, and providing as much room from trees as possible, root loss will be minimized. 3. Underground services including utilities, sub-drains, water or sewer shall be routed around the TREE PROTECTION ZONE. Where encroachment cannot be avoided, special construction techniques such as hand digging or tunneling under roots shall be employed where necessary to minimize root injury. 4. A TREE PROTECTION ZONE must be established for trees to be preserved, in which no disturbance is permitted. TREE PROTECTION ZONES for trees identified for preservation are identified in the following table. No grading, excavation, construction or storage of materials shall occur within that zone. Trees Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 14 Specific Tree Protection Zones Tree No. TPZ • #123 4'S., DL in all other directions #125 5' N. DL in all other directions #122 5'S., 5' N., DL in all other directions _ #3,4 and 7 6'S. and DL in all other directions. #23 6' E. and DL in all other directions. #26, 33 7' E. and DL in all other directions. #1 8'S. and DL in all other directions. #6, 8 and 127 10'S. and DL in all other directions. #110 10'S., 2' N. DL in all other directions #109 and 124 10'S., 5'N., DL in all other directions _ #28: 10' E. and DL in all other directions. #12.1 10'S., 6' N. DL in all other directions #116 and 117 10'S., 10' N. DL in all other directions #9 12'S. and DL in all other directions. #126 14'N., DL in all other directions #5, 10, 112 and 113 15'S. and DL in all other directions. #24 and 27 15'E. and DL in all other directions. #25 15' E., 12'S. &DL N. &W. #95, 101 and 158 15'W. DL in all other directions. #115 > 13'S., 2'N. DL in all other directions #41, 45 and 65 20' E. DL in all other directions #114 20'S. DL in all other directions #46 20' N. DL in all other directions #66 25'S. DL in all other directions #62 and 63 35' NW. DL in all other directions 64 35'SE. DL in all other directions 3. As trees withdraw water from the soil, expansive soils may shrink within the root area. Therefore, foundations,footings and pavements on expansive soils near trees should be designed to withstand differential displacement. 4. No underground services including utilities, sub-drains,water or sewer shall be placed in the TREE PROTECTION ZONE. 5. Tree Preservation Notes, prepared by the Consulting Arborist, should be included on all plans. 6. Do not lime within 50'of any tree. Lime is toxic to tree roots. 7. Any herbicides placed under paving materials must be safe for use around trees and labeled for that use. 8. Irrigation systems must be designed so that no trenching will occur not within the TREE PROTECTION ZONE. Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 15 Pre-construction treatments and recommendations 1. The construction superintendent shall meet with the Consulting Arborist before beginning work to discuss work procedures and tree protection. 2. Fence all trees to be retained to completely enclose the TREE PROTECTION ZONE prior to demolition, grubbing or grading. Fences shall be 6 ft. chain link or equivalent as approved by Consulting Arborist. Fences are to remain until all grading and construction is completed. 3. Pruning trees to provide construction and access clearance will be required. Trees#3, 4, 7,23,25, 27, 28, 33, 66, 95, 101, 121, 122 and 125 have been preliminarily identified for pruning to provide construction and road clearance. Additional trees may require pruning for pedestrian clearance over the path. 4. Prune trees to be preserved to clean the crown and to provide clearance. All pruning shall be done by a State of California Licensed Tree Contractor(C61/D49). All pruning shall be done by Certified Arborist or Certified Tree Worker in accordance with the Best: Management Practices for Pruning (International Society of Arboriculture, 2002)and adhere to the most recent editions of the American National Standard for Tree Care Operations (Z133.1)and Pruning (A300). 5. Have brush from the pruning and removal operations chipped and spread beneath the trees within the TREE PROTECTION ZONE. Mulch shall be 2"to 4"in depth and kept a minimum of 3'from the base of the trees. Recommendations for tree protection during construction 1. Prior to beginning work, the contractors working in the vicinity of trees to be preserved are required to meet with the Consulting Arborist at the site to review all work procedures, access routes, storage areas and tree protection measures. 2. No grading, construction, demolition or other work shall occur within the TREE PROTECTION ZONE. Any modifications must be approved and monitored by the Consulting Arborist. 3. Fences have been erected to protect trees to be preserved. Fences define a specific TREE PROTECTION ZONE for each tree or group of trees. Fences are to remain until all site work has been completed. Fences may not be relocated or removed without permission of the Consulting Arborist. 4. Construction trailers,traffic and storage areas must remain outside fenced areas at all times. 5. Prior to grading, pad preparation, excavation for foundations/footings/walls, trenching, trees may require root pruning outside the TREE PROTECTION ZONE. Any root pruning required for construction purposes shall receive the prior approval of, and be supervised by, the Consulting Arborist. 6. If injury should occur to any tree during construction, it should be evaluated as soon as possible by the Consulting Arboristso;that appropriate treatments can be applied. 7. No excess soil, chemicals, debris, equipment or other materials shall be dumped or stored within the TREE PROTECTION ZONE. 8. Any additional tree pruning needed for clearance during construction must be performed by a Certified Arborist and not by construction personnel. Arborist Report, Los Altos Property LP HortScience, Inc. 28030 Natoma Rd., Los Altos Hills, November 2014 Page 16 Maintenance of impacted trees Preserved trees will experience a physical environment different from that pre-development. As a result, tree health and structural stability should be monitored. Occasional pruning, fertilization, mulch, pest management, replanting and irrigation may be required. In addition, provisions for monitoring both tree health and structural stability following construction must be made a priority. As trees age, the likelihood of failure of branches or entire trees increases. Therefore, annual inspection for hazard potential is recommended. HortScience,Inc. • 4f:_,. .1036 John Leffingwell Board Certified Master Arborist WE-3966B Registered Consulting Arborist#442 Attached: Tree Assessment Form Tree Assessment Map - Tre• e Assessment 28030 Natomas Rd. Los Altos,California November 2012 • HORT SCIENCE • TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches) 5=EXCELLENT PRESERVATION 1 Coast live oak 14,9,9,6 Yes 3 Poor Multiple attachments at base;topped for overhead utilities. 2 Coast live oak 13 Yes 3 Poor Topped for overhead.utilities; poor form. 3 Coast live oak 13 Yes 4 Moderate Side pruned for overhead utilities;fair structure. 4 Coast live oak 11 No 3 Poor Topped for overhead utilities; one sided south. 5 Coast live oak 12,10,10;9,8 Yes 3 Poor . Multiple attachments at base; all but one stem topped for overhead utilities. 6 Coast live oak 8 No 3 Moderate Suppressed; crown bowed east. 7 Coast live oak 17 Yes 3 Moderate Side pruned for overhead utilities; one sided S. 8 Coast live oak 8 No 3 Poor Topped for overhead utilities; lateral south. 9 Coast live oak 13 Yes 3 Poor- . Topped for overhead utilities; poor form. 10 Coast live oak 17 Yes 3 Poor Topped for overhead utilities; poor form. 11 Valley oak 32 Yes 3 Poor Codominant trunks at 6'; N. stem failed at 10'; S. stem with trunk wound&decay. 12 Coast live oak 12,10 . Yes 4 Moderate Codominant trunks at 3'; multiple girdling ropes on 13 Coast live oak 7 No . 3 : Moderate Suppressed form; small crown. 14 Coast live oak 17,9 Yes 3 Moderate Side pruned for overhead utilities;fair structure. 15 Valley oak 17,17 Yes 4 Moderate Codominant trunks at 3'; N.stem upright; S. stem topped for overhead utilities. 16 Coast live oak . 35 Yes 5 Good Codominant trunks at 6'; one sided S.; branches to the ground S. &W. 17 Coast live oak 25,22,18 Yes 4 Good Multiple attachments at 2'; included bark &narrow attachments. 18. Coast live oak 10 No 5 Good Good young tree; upright form. 19 Valley oak 10 No 3 Moderate Suppressed form; epicormic shoots;dieback. 20 Valley oak 17,8 Yes 3 Moderate 17"stem upright; epicormic shoots; dieback. 21 Coast live oak 28 Yes 4 Moderate Multiple attachments at 6'; included bark;twig dieback in upper canopy. Page 1 • • 28030 Natomas Rd. • Tree Assessment Los Altos,Califomia C November 2012 HORT SCIENCE • TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches), 5=EXCELLENT PRESERVATION 22 'Coast live oak 21,18 Yes 4 Good Codominant trunks at 2'; included bark; one sided E. 23 . Coast live oak 12,10 Yes 3 Moderate Codominant trunks at 2'; basal wOund with decay; asymmetric crown. 24 Coast live oak 18 Yes 3 Moderate Codominant trunks at 6'; lateral N.;fair structure. 25 Coast live oak 18,16 Yes 4 Moderate Codominant.trunks at 2';very one sided S. , 26 Coast live oak 20 Yes 3 Moderate Lateral W. at 6'; one sided S. ; thin canopy. 27 Coast live oak 16,12,11 Yes 4 Moderate Multiple attachments at 3'; seam in attachment;thin canopy. 28 Coast live oak 20 Yes 4 Good Codominant trunks at 12'; upright form. 29 Coast live oak 18,17 Yes . 4 Moderate Codominant trunks'at 4'; one stem upright; one stem extends SW.; dieback. 30 Coast live oak 29 Yes 4 Moderate ' Codominant trunks at 6'; good form and structure; • thin canopy. 31 Coast live oak 40 Yes 4 Moderate ,Multiple attachments at 12'; leans SE.;_thin canopy; . . ' cabled. . .. • 32 . Coast live oak '• 46 Yes. 4 Moderate Multiple attachments at-7'; crown one sided SW.;' thin canopy; adding wood on large branches. 33 Coast live oak 8 No 4 Good Good young tree; slight lean W. 34 Valley oak, 16 • Yes . .5 Good Upright form. 35 Coast live oak 12 . Yes 4 Moderate ' Leans E.; small crown. 36 Coast live oak 11,10 Yes 4 Moderate Codominant trunks at 2'; stems kiss at 6'; one stem . upright. . 37 Coast live oak • 8,8 Yes - 3 Moderate Codominant-trunks at 2'; suppressed;one sided NE.. 38 Valley oak 14 Yes 5 Good Upright form. 39 Coast live oak 12 Yes 5 Good Good young tree. . 40 Coast live oak 8 No 4 Moderate Slight crook at base; crowded&one sided N. Page 2 Tree Assessment 28030 Natomas Rd. Los Altos,California tO November 2012. HORT SCIENCE TREE . SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches) 5=EXCELLENT PRESERVATION • 41 . Coast live oak 20 Yes 4 Good Trunk sweeps at 3-4'; one sided S. 42 Coast live oak ' 9 No 3 Poor Suppressed form; Leans S.; small crown. 43 Coast live oak 14 Yes 4 Moderate One sided &leaning E. 44 Coast live oak 8,8 Yes 3 Poor Codominant trunks at 4';suppressed; leans W.; small crown. 45 Coast live oak 17 Yes 4 Good Upright form; a little thin in upper canopy. 46 Coast live oak 20 Yes 3 Moderate Leans E.; twig dieback. 47 Coast live oak 18 Yes 4 Moderate One sided N.;twig dieback. 48 Coast live oak 25 Yes 4 Moderate Codominant trunks at 5'; included bark; rodent damage. 49 Coast live oak 42 Yes 4 Moderate Multiple attachments at 18'; basal cavity W.;twig dieback. 50 Valley oak 32 Yes 3 Poor Codominant trunks at 10'; E. stem with trunk wound &decay; lateral S. 51 Coast live oak 42 Yes 2 Poor ,Hollow with extensive trunk decay; lost several main leaders. 52 Coast live oak 29 Yes 3 Moderate Very one sided S.; long laterals S.to the ground. 53 Valley oak 28 Yes 4 Good Multiple attachments at 10';fair branch structure; twig dieback. 54 Coast live oak 28 . . Yes 4 Good . Multiple attachments at 5'; spreading form; heavy lateral limbs. 55 Valley oak 20 Yes 4 Moderate Multiple attachments at 7'; twig and branch dieback. 56 Valley oak 30 Yes 5 Good Upright; good form an structure; lateral S.; engulfed in poison oak. 57 Valley oak 28 Yes 4 Moderate One sided S.; lost upright limb; engulfed in poison oak. 58 Valley oak 23 Yes 5 Good Multiple attachments at 12'; good form and structure. Page 3 Tree Assessment 28030 Natomas Rd. Los Altos,Californiato November 2012 . HORT SCIENCE TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches) 5=EXCELLENT PRESERVATION 59 Valley oak 16 , Yes 5 Good Multiple attachments at 7'; good form and structure; laterals. 60 Valley oak 23 Yes , 5 Good Multiple attachments at 7'; good form and structure; branches to the ground. 61 Valley oak 38 Yes 4 Moderate Multiple attachments at 12'; narrow attachments; one sided with branches to the ground S. 62 Valley oak 26 Yes 4 .Moderate. Codominant trunks at 8'; one stem upright; one stem bowed W.to horizontal. 63 Valley oak 28 Yes 3 Moderate Codominant trunks at 8'; suppressed; crown bowed W.to horizontal. 64 Valley oak 44 Yes 3 Poor Codominant trunks at 7'; large trunk wound/cavity N.; lost limb W. 65 Valley oak 44 Yes 4 Good Codominant trunks at 6'; spreading form; branches to ground S. 66 Valley oak 36 Yes 4 Moderate History of branch failure; lateral N.; engulfed in • poison oak. 67 Coast live oak 20,18,18 Yes 5 Good Multiple attachments at 4'; good form; included bark. 68 Coast live oak 40 Yes 4 Moderate Multiple attachments at 10'; narrow attachments;fair - • structure; engulfed in poison oak. 69 Coast live oak 19,19 Yes 4 Good Codominant trunks at 3'; seamin attachment. 70 Coast live oak • 7,5 Yes 5 Good Codominant trunks at 3'; good young tree. 71 Coast live oak 8 No 4 Moderate Crowded;fair structure. 72 Coast live oak 9 No 5 Good Crowded;one sided W. 73. Coastlive oak 35 Yes. 4 _ Good Multiple attachments at 20'; lateral W.to ground; thin canopy/oak moth damage. 74 Coast live oak 18,18,15 Yes 5 Good Multiple attachments at 3'; good form; included bark/seam. 75 Coast live oak 16 Yes 3 Moderate One sided W.; poison oak. Page 4 _ Tree Assessment 28030 Natomas Rd. Los Altos,Califomia November 2012 HORT SCIENCE TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS • . No: DIAMETER 1=POOR FOR . (in inches) 5=EXCELLENT PRESERVATION .. .. 76 ..Coast live oak. 10,10 Yes • 2 Low Suppressed; crown bowed W.to horizontal:: • . . 77 Coast live oak •.• 14 • Yes • .3 Low .• Suppressed; one sided SE. 78 Coast live oak 17 - Yes 3 Moderate Sparse canopy; one sided E. 79 Coast live oak 8 No 5 High Slight lean N.; good young tree. 80 Coast.live oak 9 No 5 High .Good young.tree. . 81 Coast live oak 12 Yes 3 Low Trunk sweeps S.; crook at 3'; poor form.and structure. 82 Coast live oak 20 Yes 4 Moderate Multiple attachments at 7'; crowded &one sided N. 83 Coast live oak 20 Yes 4 Moderate Crowded; high crown; lateral S. 84 Coast live oak . 14 Yes 3 Moderate Trunk leans NW.; one sided W. 85 Coast live oak 26 Yes 4 Moderate Crowded &one sided S.;fair branch structure. 86 Coast live oak 6 No 3 Moderate Suppressed; branch wounds. 87 Coast live.oak 32 Yes 4 High . Slight lean N.; good form and structure; dead wood. 88 Coast live oak 17 Yes 3 Low Leans W.;trunk wound at 15'. 89 Coast live oak 11 No 3 Moderate Suppressed; crown bowed E. 90 Coast live oak 9 No 3 Moderate Leans W.; small crown. 91 Coast live oak 14 Yes 3 Low Leans S.; embedded barbed wire. 92 Coast live oak 9 No 5 High Good young tree. • . 93 Coast live.oak . 9,4,4 Yes 5 High Good young tree. . . . 94 Valley oak 17 Yes 3 Low Codominant trunks at 6'; narrow crown; dieback. 95 Coast live oak 33 Yes 4 Moderate Multiple attachments at 5'; one sided E.; laterals & dead wood. 96 Coast live oak 10 No 3 Low Suppressed; small, high crown. 97 Coast live oak 13,11 _ Yes 3 Moderate Codominant trunks at 3'; high crown. 98 Coast live oak 16 Yes 3 Moderate Codominant trunks at 10'; leaning &one sided S.; cavity E. • Page 5 Tree Assessment 28030 Natomas Rd. Los Altos,Califomia ,C0 November 2012 HORT SCIENCE TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR • FOR (in inches) 5=EXCELLENT PRESERVATION . ' 99 Coast live oak 14,10 Yes 3 Low Codominant trunks at 1'; crown.bowed S.to. horizontal. 100 Coast live oak 18 Yes 3 Moderate Codominant trunks at 10';fair structure; high crown. 101 Coast live oak 22,21 Yes 4 Moderate Codominant trunks at 3'; one sided E.; laterals & • dead wood. 102 Coast live oak 21,20 Yes 4 Moderate Codominant trunks at 3';good form; large pruning wounds. 103 Valley oak 9 No ' 3 Low Codominant trunks at 5'; suppressed; crown bowed E.to horizontal. 104 Coast live oak 15 Yes 3 Moderate High•crown; sunscald S. • 105 Coast live oak 27 Yes 4 Moderate Crowded; crown bowed W. 106 Coast live oak i,24,22,19,17,12 Yes 2 Low Multiple attachments at 3; history of stem failure E.; . ganoderma at base W. 107 Coast live oak 17,14 ,12,6 Yes 2 Low Failed at base; laying on ground. 108 Coast live oak 21,19 Yes 3 Moderate Overtopped; crown bowed W. 109 Coast live oak 33;8 Yes 3 Moderate Codominant trunks at 10'; overtopped; crown bowed W. 110 Coast live oak 25 Yes 3 Moderate Overtopped; crown bowed W.to horizontal. 111 Coast live oak 22 Yes 3 Low Crowded; one sided S. 112 Coast live oak • 21,20 Yes 3 . Moderate Codominant trunks at 3';W. stems bowed VV. 113 Coast live oak 33,13 Yes 4 Moderate One sided N.; dominant tree. 114 Valley oak 10,6 Yes 3 Low Codominant trunks at 2'; suppressed; poor form. 115 Coast live oak 23,22,13,12,9 . Yes 3 Moderate Multiple attachments at 3'; some stems upright; some stems bowed N. 116 Coast live oak 12 Yes 2 Low Small crown; dieback. 117 Valley oak 11 No 3 Low Codominant at base w/#116; high crown; dieback. 118 Valley oak 16,9 Yes 3 Moderate Codominant at 2'; high crown; deadwood Page 6 • Tree .Assessment 28030 Natomas Rd. Los Altos,California fill\)) . November 2012 HORT SCIENCE TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches) 5=EXCELLENT PRESERVATION . 119 Coast live oak 29 Yes 3 . , Moderate Leans E.to horizontal 120 . Valley oak 25 Yes 4 Moderate• . High crown; one sided S. 121 Coast live oak 19 Yes 2 Low Leans E.to horizontal; bark checking; trunk wounds. 122 Valley oak 35 Yes 3 Moderate Multiple attachments at 6'; sparse crown; spreading form. 123 Coast live oak 6 No 5 High Good young tree. 124 Coast live oak 18 Yes. 4 High Multiple attachments at 8'; good form and structure. 125 Valley oak 28 Yes 4 High Multiple attachments at 10'; good form; recently pruned. 126 Coast live oak 15,14,8 Yes 3 Moderate Suppressed;•one sided SE. 127 . Valley oak 14 Yes .3 Moderate Pruned N.; one sided S. 128 Coast live oak 22,14,10 Yes 4 Moderate Multiple attachments at 3'; one sided S. 129 Coast live oak 35,19 Yes 4 Moderate Multiple attachments at 5';wide attachment; 19" stem is low lateral W. 130 Valley oak 18 • Yes. 3 Moderate Upright form; dieback; powdery mildew. 131 Valley oak 14 Yes, 3 Low Leans N.;asymmetric crown; embeddedbarbed • wire; dieback to 4". 132 Coast live oak 18 Yes 4 Moderate Codominant trunks at 6'; included bark; sap flow at - attachment. • 133 . Coast live oak 28,10 Yes 4 Moderate Multiple attachments.at 8'; beetle activity along trunk; 10"stem is low lateral. 134 Coast live oak 30 Yes 4 Moderate Multiple attachments at 5'; heavy lateral E. 135 Coast live_oak 29 Yes 4 Moderate Multiple attachments at 8'; low lateral S. 136- Valley oak ' 8,4 Yes. . 3 Moderate One sided E.;twig dieback. 137 Valley oak 11 No , 3 Moderate Crowded; crown bowed NW. 138 Valley oak 9- No 3 Moderate Crowded; slight lean W. 139 Valley oak 12 Yes 3 - Moderate Crowded; leans N.to horizontal then turns upright. Page 7 • Tree Assessment 2$030 Natomas Rd. to Los Altos,California November 2012 • . HORT SCIENCE • TREE SPECIES SIZE HERITAGE? CONDITION SUITABILITY COMMENTS No. DIAMETER 1=POOR FOR (in inches) 5=EXCELLENT PRESERVATION .. 140 Coast live oak 19 Yes • 3 Moderate Crowded;:reaching through the canopy of#142. 141 Coast live oak 12 Yes .3 Low Crowded; leans E.to horizontal over fence. 142 Valley oak 29 Yes 4 High Multiple attachments at 10'; dominant tree; laterals • W. 143 Valley oak 21 Yes 3 Moderate Codominant trunks at 5';asymmetric crown. 144 Coast live oak 9 No 3 Moderate Crowded; growing through canopy of#142. 145 Coast live.oak .. 22 Yes 4 High Upright form; high canopy. 146 Coast live oak 26 Yes 3 Moderate _ Codominant trunks at 4'; one sided S. . 147 Valley oak • 8 No 2 Low Suppressed; crown formed by epicormics. 148 Valley oak . 15 Yes 2 Low One sided S.; dieback; crown formed by epicormics. 149- Coast live oak 10,9,8 Yes 4 Moderate Multiple.attachments at 2'; narrow attachments. 150 Coast live oak 17 Yes 3 Moderate Crowded; high crown bowed SW. 151 Coast live oak 20 Yes 3 Moderate Crowded; asymmetric crown. 152 Coast live oak 29,23,19,10 Yes 4 High Multiple attachments at 3'; dominant tree; beetle • activity at base. 153, Coast live oak 23 Yes 4 Moderate , Codominant trunks at 15'; upright; one sided W. 154 Coast live oak 16,11 Yes 3 Moderate Codominant trunks at 3';wide attachment; crown bowed S. 155 Valley oak - 18 Yes 3 Moderate Multiple attachments at 10'; good form;thin canopy. 156 Coast live oak 22 Yes 3 . . Moderate Codominant trunks at 5'; asymmetric crown. 157 Blue oak 9 No 4 Moderate Good young tree; lower branches covers in lichen. 158 Valley oak 16 Yes 3 • Moderate One sided S.;twig dieback;wires attached to trunk at 10'. Page 8 i ' —iremelazir Tree Assessment Map •• V;TZ..,4.1 28030 Natoma Road • ,r,"9 Los Altos Hills,CA �c.� Prepared for: Los Altos Property,LLC Sarasota,FL i4 •'ao December 2012 4. m m ,. ♦ F,. CY C,otca 4txrva Updated April 2014 1, ) . . SCN•a n•• PAPS_ SAKAA1oro „w,•MIIRAKAlO el b 43= 132e3 YON LANE le 13313 SUCK UNE '�, 1.r 0,F AC 1.•.AC 1.'•AC �i. 2e0Z7 NATQJA RD SLOSS No Scale 6. 12094 / Z59 AC A.., ,r .�� , a oo•.T'991.a5y�e taw ,a, .,r ,:a .e♦ - 1 1AC.T-_ / aa .� ' Ifir// � � 12400 NElOOY lJtO1.10 �� , , �, ♦ / 1t. AEE AC • aay//, S. Notes: 4' ' ...1,~r"♦e ,,/e/ I Rase map provided by. • . lDT3 e , Qementl&Assodates s-ioix .I 1915.I ill ul�� I \ m ams,CA _ .019 ., SmO. , \ Numbered treemat locations are approximate. 1-111741111. 4a10'm _ I •I• ,,111 ,0arei0V----.4••••" ..-----. k.Z":"4,.. . : - iSr//7 . 1 1\ YONO � , R'ea / ' I Trees that have no point were apprOtlmawly located. FORK- LANE , a _ t _ 9 40 AC ;'--WOW, ��_." M • / • 1 ---:..4: 11.- ..11,011:17-411&114 .0i.,." 41....." *. 114:111/4411*' -0•0"-- . . 017 . ..,...„.14 . ...........,..t0 4.. . .-- --,.4itirw, AL.:, •.• <> 401/ ''' / . . . � / Imo._✓• � -.ZN ;IS.N fe/ t „.$ / • .„,, .z.0 , . , 2.54.A. . • yr............ ,. .....r..., ..,...44,y,ii,16".... .7.• . .. .s. � HORT SCIENCEI c• ^/`'./ 315 Ray Street \�♦ t e Pleasanton,CA 94566 P� Phone 915.184.0231 • ��,'.4 Fax 915.484.0596 RANAC - - \ / • --- LOT 0 — i%//�..:/c/��i- .www.hortsdence.wm S.FORK LANE • 1.7E AC EXHIBIT 5 Page 1 of 245 • Final 2010 Integrated Report(CWA Section 303(d) Statewide CATEGORY 5 List/305(6)Report) USEPA Final Approval:October 11,2011 2010 CALIFORNIA 303(d)LIST OF WATER QUALITY LIMITED SEGMENTS* Category 5 criteria:1)A water segment where standards are not met and a TMDL is required,but not yet completed,for at least one of the pollutants being listed for this segment. •USGS HUC=US Geological Survey Hydrologic Unit Code.Calwater=.State Water Resources Control Board hydrological subunit area or even smaller planning watershed. ••TMDL requirement status definitions for listed pollutants are:A=TMDL still required,B=being addressed by USEPA approved TMDL,C=being addressed by action other than a TMDL - •••Dates relate to the TMDL requirement status,so a date for A=TMDL scheduled completion date,B=Date USEPA approved TMDL,and C=Completion date for action other than a TMDL WATERSHED* • POLLUTANT ESTIMATED FIRST TMDL REGION WATER BODY WATER CALWATER/ ° POTENTIAL SOURCES AREA YEAR REQUIREMENT DATE*** NAME TYPE USGS HUC Relevant Notes ASSESSED LISTED STATUS** 1 Bodeqa HU,Bodeqa Bay& 11522000 / • Invasive Species 810 Acres 2006 5A 2019 Harbor HA Harbor 18010111 Source Unknown • Nutrients 1 Bodega HU,Estero River& 11530000 / 38 Miles 1996 5A 2019 Americano HA, Stream 18010111 Dairies Americano Creek ° Intensive Animal Feeding Operations • o Manure Lagoons o Pasture Grazing-Riparian o Range Grazing-Riparian o Range Grazing-Upland • The Bodega HU,Estero Americano HA,Americano Creek includes the following Calwater Super Planning Watersheds(SPWs):115.30010 and 115.30011.A Water Quality Attainment Strategy is attempting to increase voluntary measures for attainment of standards&objectives,as was done in the Estero de San Antonio/Stemple Creek TMDL Water Quality Attainment Strategy,adopted by North Coast RWQCB in December 1997. • Nutrients 1 Bodeqa HU,Estero Estuary 11530012 / Manure Lagoons 199 Acres 1996 5A 2019 estuary Americano HA, • 18010111 • ° Range Grazing-Riparian and/or Upland The Bodega HU,Estero Americano HA,Americano Creek includes the following Calwater Super Planning Watersheds(SPWs):115.30010 and 115.30011.A Water Quality Attainment Strategy is attempting to increase voluntary measures for attainment of standards&objectives,as was done in the Estero de San Antonio/Stemple Creek TMDL Water Quality Attainment Strategy,adopted by North Coast RWQCB in December 1997. - • Sedimentation/Siltation 199 Acres 1992 • 5A 2019 ° Erosion/Siltation • Hydromodification o Nonpoint Source • ° Range Grazing-Riparian o Removal of Riparian Vegetation ° Streambank Modification/Destabilization A Water Quality Attainment Strategy is attempting to increase voluntary measures for attainment of standards&objectives,as was done in the Estero de San Antonio/Stemple Creek TMDL Water Quality Attainment Strategy,adopted by North Coast RWQCB in December 1997. 1 Campbell Cove Coastal& 11522000 / • Indicator Bacteria 0.22 Miles 2006 5A 2019 Bay 18010111 ° Source Unknown Shoreline 1 Clam Beach Coastal& 10820012 / • Indicator Bacteria 1.3 Miles 2006 5A 2019 Bay 18010102 ° Source Unknown Shoreline 1 Copco Lake 776 Acres 2006 5A 2019 http://www.waterboards.ca.gov/water issues/programs/tmdl/2010state it reports/category...- 1/12/2016 Page 27 of 245 WATER BODY WATER WATERSHED* • POLLUTANT ESTIMATED FIRST TMDL REGION NAME TYPE CALWATER/ 2 POTENTIAL SOURCES AREA YEAR REQUIREMENT DATE*** USGS HUC Relevant Notes ASSESSED LISTED STATUS** • Source Unknown Lake& 20210010 / Reservoir 18050006 This listing was made by USEPA. • • Source Unknown 299 Acres 2002 5A 2019 This listing was made by USEPA. • 2 Lake Merritt .Lake& 20420040 / Organic Enrichment/Low Dissolved Oxygen 142 Acres 2002 5A 2019 Reservoir 18050004 • Source Unknown This listing was made by USEPA. • Trash • Urban Runoff/Storm Sewers 142 Acres 1998 5A 2019 • Indicator Bacteria 2 Lawsons Landing Coastal& 20112030 / • Source Unknown 3.2 Miles 2006 5A 2019 Bay 18050005 Shoreline This listing was made by USEPA for 2006. 2 Marina Lagoon(San Estuary 20440040 / • Coliform Bacteria 169 Acres 2002 5A 2019 Mateo County) 18050004 ° Nonpoint Source • Urban Runoff/Storm Sewers • Diazinon 2 Matadero Creek River& 20550040 / o Urban Runoff/Storm Sewers 7.3 Miles 1998 5B 2007 Stream 18050003 This listing was made by USEPA for the 1998 303(d)list.For 2006,diazinon was moved by USEPA from the 303(d)list to this being addressed list because of a completed USEPA approved TMDL. • Trash Illegal dumping 7.3 Miles 2010 5A 2021 • Urban Runoff/Storm Sewers • Indicator Bacteria 2 McNears Beach Coastal& 20610010 / 0.18 Miles 2006 5A 2019 Bay 18050002 Source Unknown Shoreline This listing was made by USEPA for 2006. 2 Millerton Point Coastal& 20112032 / • Indicator Bacteria 0.25 Miles 2006 5A" 2019 Bay 18050005 • Source Unknown Shoreline This listing was made by USEPA for 2006. 2 Mission Creek Estuary20440010 / • Ammonia • Combined Sewer Overflow 8.5 Acres 2002 5A 2019 18050004 o Industrial Point Sources • Chlordane(sediment) 8.5 Acres 2002 5A 2013 Combined Sewer Overflow o Industrial Point Sources • Dieldrin(sediment) 8.5 Acres 2002 5A 2013 o Combined Sewer Overflow o Industrial Point Sources • Hydrogen Sulfide 8.5 Acres 2002 5A 2019 http://www.waterboards.ca.gov/water issues/programs/tmdl/2010state it reports/category... 1/12/2016 EXHIBIT 6 4. lir... • �1 Santa Clara Valley Urban Runoff,Pollution Preven 'lost , aYJ,- 1. i ii I. ea .t Search it;+ Home About SCVURPPP -Management•.Committee :Program Components + Resources ? Watersheds , ' ,-.:.4#..4i. ---,1--,...',,l..tt..-4."•",-- ' Y. :. ‘,t'..v7.}'',^..4',.4. 4-4%,..,'may ' ' e- ;..1,4–.... t;) Matadero Watershed �: ; * :The Matadero Creek watershed covers an area of about li i 4r t r / •, 7 14 square miles,of which approximately 11 square miles .1-• i 1 ! •`„ }^ ', ,Y ,' are mountainous land,and 3 square miles are gently r 1 ',; . 3K' ~F-, Z.",-'4}tsr,; sloping valley floor.Matadero Creek originates in the , *3 � x _;, rel foothills of the Santa Cruz Mountains and flows in a . / ' -+'� snortheasterlydirection for approximately eight miles until it i ,�,�-'4–'4 ,. " - r PP Y 9 4-'4\ -"":' --""'2.'' discharges into the Palo Alto Flood Basin,and then drains Santa Clara Basin into the Lower South San Francisco Bay.Major tributaries I Watersheds to Matadero Creek are Arastradero and Deer Creeks and Adobe Stanford Channel. ( ../.- - 1 Barron Through the foothills Matadero Creek traverses through ) d. low-density residential development in the town of Los y r 1 Calabazas Altos Hills.As it nears the valley floor it flows through the , I ''Coyote Stanford University Preserve and Campus,and then through residential,commercial,and industrial areas of , Guadalupe Palo Alto.The portions of the watershed that fall in the , / I northern part of City of Palo Alto are predominantly ;'- ,� i`: r I Lower Penitencia :- :i. 1 residential,commercial and public/institutional. f Matadero ;�, -' ti ..,.. ) , I • Five species of native fishes have been collected and/or �'- ;; \ I Permanente =%.`. a, f 1 observed from Matadero Creek during the last 20 ears: „r California roach,Sacramento blackfish,Sacramento •. ` ' •'1 " 'San FrancisguiEo -: _. ' } — sucker,threespine stickleback,and prickly sculpin. San Tomas Aquino f' f, I Stevens Watershed Facts 1 Sunnyvale East • Watershed area:14 square miles 1 Sunnyvale West • Number of tributary creeks:3 I ,TMDLs • Miles of natural creek bed:18 —' • Local towns and cities:Santa Clara County,Palo Alto,Los Altos Hills Glossary of Watershed Terms • Percent area by land use: (Beneficial Uses' ° Residential 57.1% I - • Industrial/Commercial 5.8% Watershed Links/ ° Forest 8.9% Resources ° Rangeland 8.2% I • • Other 20% - i • Percent Impervious Area:60.3% • Beneficial Uses:Cold Freshwater Habitat(COLD),Warm Freshwater Habitat(WARM),Fish s Migration(MIGR),Fish Spawning(SPWN),Wildlife Habitat(WILD),Water Contact Recreation (REC-1),Noncontact Water Recreation(REC-2) • • Water Quality Impairments:Urban Pesticide Toxicity(Diazinon),Trash back to watersheds map I l I 1 ,I li EXHIBIT 7 • .i e Fix re: C.3. Handbook Santa Clara Valley Urban Runoff. Pollution Prevention Program • ATTACHMENT II-7 CEQA Guidance Related to Provision C.3 Stormwater Requirements • Table: CEQA Initial Study Guidance for Project Applicants • Additional Resources for Environmental Review Process • Table: Guidance for Co-Permittee Review/Modification of CEQA Procedures and Local CEQA Guidance II.Project Review Attachment II-7 • l FINAL F:�SC46\SC46.241C.3.Guidance AlonuolFinnl May 2004\pupa 2Wch Madman ii-7 FLY_Muy 2004 dnc May 20,2004 Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program SCVURPPP Guidance for Project Applicants in Addressing Stormwater Quality Concerns During CEQA Review The following table provides supplemental guidance to project applicants in completing the initial study checklist to address urban runoff water considerations during project environmental review. CEQA Guidelines Question Additional Issues to Address Stormwater Quality Concerns within.the CEQA Initial Study Checklist CHECKLIST CHAPTER IV: BIOLOGICAL RESOURCES IV.b)Will the project have a substantial The evaluation of a project's effect on sensitive natural communities should adverse effect on any riparian habitat or encompass aquatic and wetland habitats.Consider"aquatic and wetland other sensitive natural community habitat"as examples of sensitive habitat. identified in local or regional plans, policies,regulations or by the California Department of Fish and Game or US Fish and Wildlife Service? CHECKLIST CHAPTER VIII: HYDROLOGY AND WATER QUALITY VIII.a) Will the project violate any water The evaluation of a project's compliance with water quality standards should quality standards or waste discharge consider the project's potential effect on water bodies on the Section 303(d) requirements? list',as well as the potential for conflict with applicable surface or groundwater receiving water quality objectives or degradation of beneficial uses. VIJI.d) Will the project substantially alter the The evaluation of a project's effect on drainage patterns should refer to the existing drainage pattern of the site or final approved SCVURPPP Hydromodification Management Plan(HMP), area, including through the alteration of where applicable,to assess the significance of altering existing drainage the course of a stream or river,or patterns and to develop any mitigation measures.The evaluation of substantially increase the rate or amount hydromodification effects should also consider any potential for streambed or of surfacerunoff in a manner which would bank erosion downstream from the project. result in,flooding on-or off-site? VIII.e)Will the project create or contribute The evaluation of a project's potential to create or contribute runoff should runoff water which would exceed the consider whether the project meets the NPDES permit's Group 1 or Group 2 capacity of existing or planned stormwater criteria.The response to this question will indicate how.Provision C.3 drainage systems or provide substantial requirements will be met.Applicants must address Provision C.3 requirements additional sources of polluted runoff? in environmental documents for projects that meet Group._1 or Group 2 criteria. VIII.,f) Would the project otherwise The evaluation of a project's potential to degrade water quality should consider substantially degrade water quality? whether a project has the potential to result in a significant impact to surface water quality,marine,fresh,or wetland waters,or to groundwater quality.As with every category of environmental impact,effects must be considered both during and after construction.The evaluation of water quality impacts should include a description of how the project will comply with the requirements of SCVURPPP's NPDES permit and the State's Construction General Permit. The description should also include a statement that the project should avoid creation of mosquito larval sources that would subsequently require chemical treatment to protect human and animal health. Available at:http://www.swrcb.ca.gov/rwgcb2/tmdlmain.htm II.Project Review Attachment H-7 Page 1 FINAL F:1SC461SC46241C.3.Guidance ManuallFinal May 20041Chapter 2tAttachment iii-7 CEQA Guidance May 2004.doc May 20,2004 • Santa Clara Valley • C.3 Stormwater Handbook • Urban Runoff Pollution Prevention Program Additional Potential Water Quality Impacts Additionally,the San Francisco Regional Board staff has expressed the concern that the following potential water quality impacts not be overlooked during CEQA review: - • Seasonal creeks; . • Stream crossing impacts; • Turbidity limitation for discharged water; • Whether increased runoff from increasing impervious surface will impact water ecology(along with storm drain capacity and flood control); • Hydrograph modification; • Endangered species; • Off-site impacts to channels;and • Appropriateness of runoff mitigation. • . Additional Resources for the Environmental Review Process Staff planners, engineers and consultants responsible for environmental reviews may find the following references useful for evaluating water quality impacts. 1. San Francisco Bay Regional Water Quality Control Board, 1995 Basin Plan and Amendments: (http://www.swrcb.ca.gov/rwqcb2/basinplan.htm). 2. Bay Area Stormwater Management Agencies Association, Start at the Source, 1999: (http://www.scvurppp.org). 3. California BMP Handbooks(New Development and Redevelopment, Construction Maintenance): (http://www.cabmphandbooks.com/). 4. Santa Clara Valley Urban Runoff Management Program,NPDES Permit Order No.01-024 and NPDES Permit Order No. 01-119: (Appendix A and http://www.scvurppp- w2k.com/NPDES Permit.htm) 5. 303 (d)Impaired Water Body List and TMDLs: (http://www.swrcb.ca.gov/rwqcb2/tmdlmain.htm) 6. San Jose Council Policy on Post-Construction Urban Runoff Management: (www.ci.san- jose.ca.us/planning/sjplan/counter/stormwater/pol_stormwater.pdf) 7. Santa Clara Valley Water District, Soils Data Mapping,2003. (CDs have been provided to Co- permittees). 8. Santa Clara Valley Water District,Results of the Water Resources Collaborative that provides guidance on Water District review of projects near streams(under development): (http://www.valleywater.org/index.htm). • II.Project Review Attachment II-7 Page 2 FINAL F:1SC461SC48.241C.3.Guidance ManuallFinal May 20041Chapter 2\Attachment u-7 CEOA Guidance_May 2004.doc May 20,2004 Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program Guidance for Co-permittees' Review/Modification of CEQA Procedures and Local CEQA Guidance Corresponding C.3.mCE A Guidelines Question Example Question(s) Recommended Action CHECKLIST CHAPTER IV: BIOLOGICAL RESOURCES IV.b)Will the project have a substantial x.Will the project impact aquatic, The evaluation of a project's effect on adverse effect on anyriparian wetland,or riparian habitat? sensitive natural communities should habitat or other sensitive natural encompass aquatic and wetland habitats. community identified in local or Co-permittees may revise any local regional plans,policies,regulations CEQA guidance to identify"aquatic and or by the California Department of wetland habitat"as examples of sensitive Fish and Game or US Fish and habitat.It is also recommended that Co- Wildlife Service? permittees evaluate,as an adverse impact,changes to sensitive habitats that favor the development of mosquitoes and other biting flies that may pose a threat to public health. CHECKLIST CHAPTER VI: GEOLOGY AND SOILS VI.b)Will the project result in substantial v.Will the proposed project result in No change is recommended in Co- soil erosion or the loss of topsoil? increased erosion in its watershed? permittees'procedures for responding to Checklist question VI.b.The issue raised by the C.3.m example question is addressed under Checklist question VIII.d. CHECKLIST CHAPTER VIII: HYDROLOGY AND WATER QUALITY VIII.a)Will the project violate any water vi.Is the project tributary to an already The evaluation of a project's compliance quality standards or waste discharge impaired water body,as listed on the with water quality standards should requirements? Clean Water Act Section 303(d)list?If consider the project's potential effect on so,will it result in an increase in any water bodies on the Section 303(d)list, pollutant for which the water body is as well as the potential for conflict with already impaired? applicable surface or groundwater ix.Will the proposed project cause orreceiving water quality objectives or contribute to an exceedance of degradation of beneficial uses.Co- contribute surface or permittees may revise any local CEQA pp groundwater guidance to specify that these water receiving water quality objectives or quality standards be considered. degradation of beneficial uses? VIII.d)Will the project substantially alter iv.Will the proposed project create a The evaluation of a project's effect on the existing drainage pattern of the significant adverse environmental drainage patterns should refer to the final site or area,including through the - impact to drainage patterns due to approved SCVURPPP alteration of the course of a stream changes in runoff flow rates or Hydromodification Management Plan or river,or substantially increase the volumes? (HMP),where applicable,to assess the rate or amount of surface runoff in a significance of altering existing drainage manner which would result in v.Will the proposed project result in patterns and to develop any mitigation flooding on-or off-site? increased erosion in its watershed? measures.The evaluation of hydromodification effects should also consider any potential for streambed or bank erosion downstream from the project.Co-permittees may revise any local CEQA guidance to include these instructions regarding the evaluation of hydromodification effects. • II.Project Review Attachment 1I-7 Page 3 FINAL F:ISC461SC46.241C.3.Guidance ManuallFinal May 20041Chapter 21Attachment ii-7 CEQA Guidance_May 2004.doc May 20,2004 . Santa Clara Valley C.3 Stormwater Handbook Urban Runoff Pollution Prevention Program Guidance for Co-permittees' Review/Modification of CEQA Procedures and Local CEQA Guidance Corresponding C.3.m • CEQA Guidelines Question Example Question(s) Recommended Action VIII.e)Will the project create or iii.Will the proposed project result in The evaluation of a project's potential to contribute runoff water which would increased impervious surfaces and create or contribute runoff should exceed the capacity of existing or associated increased runoff? consider whether the project meets the planned-stormwater drainage NPDES permit's Group 1 or Group 2 systems or provide substantial criteria.The response to this question additional sources of polluted will indicate how Provision C.3 runoff? requirements will be met.Co-permittees should advise applicants of the need to address Provision C.3 requirements in environmental documents for projects that meet Group 1 or Group 2 criteria. VIII.f)Would the project otherwise i.Would the proposed project result in an The evaluation of a project's potential to • substantially degrade water quality? increase in pollutant discharges to degrade water quality should consider receiving waters?Consider water whether a project has the potential to quality parameters such as result in a significant impact to surface temperature,dissolved oxygen, water quality,marine,fresh,or wetland turbidity and other typical stormwater waters,or to groundwater quality.As pollutants(e.g.,heavy metals, with every category of environmental pathogens,petroleum derivatives, impact,effects must be considered both synthetic organics,sediment,nutrients, during and after construction.The oxygen-demanding substances,and evaluation of water quality impacts trash)• should include a description of how the • ii.Would the proposed project result in project will comply with the significant alteration of receiving requirements of SCVURPPP's NPDES water quality during or following permit and the State's Construction construction? General Permit.The description should also include a statement that the project • vii.Would the proposed project have a should avoid creation of mosquito larval potentially significant environmental sources that would subsequently require impact on surface water quality,to chemical treatment to protect human and marine,fresh,or wetland waters? animal health. viii.Would the proposed project have a Co-permittees may include these potentially significant adverse impact instructions in any local CEQA guidance. on ground water quality? • • II.Project Review Attachment I1-7 Page 4 FINAL F:1SC45\SC46.241C.3.Guidance ManuallFinal May 20041Chapter 21Attachment 1-7 CEQA Guidance_May 2004.doc May 20,2004 EXHIBIT 8 TOWN OF LOS ALTOS HILLS PLANNING COMMISSION AGENDA REGULAR MEETING,THURSDAY,FEBRUARY 16,2006 at 7:00 p.m. Council Chambers,26379 Fremont Road, Los Altos Hills www.losaltoshills.ca.gov ASSISTANCE FOR PERSONS WITH DISABILITIES In compliance with the Americans with Disabilities Act,if you need special assistance to participate in this-meeting, please contact the City Clerk at(650)941-7222.. Notification 48 hours prior to the meeting will enable the'City to make reasonable arrangements to ensure accessibility to this meeting. 1. ROLL CALL AND PLEDGE OF ALLEGIANCE 2. PRESENTATIONS FROM THE FLOOR Persons wishing to address the Commission on any subject not on the agenda are invited to do so now. Please note, however, that the Commission is not able to undertake extended discussion or take action tonight on non-agendized items. Such items will be referred to staff or placed on the agenda for a future meeting. 3. PUBLIC HEARINGS Persons wishing to address the Commission should obtain a copy of the request form located at the table at the back of the Council Chambers and leave the completed form at the podium;this ensures that names and addresses are recorded accurately in the minutes. Please limit remarks to three minutes. This will assure time for all persons wishing to speak. Also,in the interests of time,please avoid redundancy with remarks made by previous speakers. If a large group wishes to express its views,the group should try to,have one spokesperson. If you challenge the proposed action(s) in court, you may be limited to raising only those issues you or someone else raised at the public hearing described below, or in written correspondence delivered to the Planning Commission at,or prior to,thepublic hearing. Any interested party may appeal a determination of the Planning Commission to the City Council by filing a written notice of appeal with the City Clerk within twenty-three (23) days of the decision. A nonrefundable filing fee and a deposit for services shall accompany each.notice of appeal,except that any member of the Council may file such an appeal without payment of a fee. >Planning Commission.Ex Parte Contacts Policy Disclosure 3.1 LANDS OF GRAHAM, 2344 Old Page Mill Road(238-05-ZP-SD); A.request for a Site Development Permit for a 682 square foot addition and major remodel including 236 square feet added to the second story (no proposed change to the height of the building). The project includes alterations to the existing driveway. The applicant also requests a minimum setback of 10' from the top of Matadero Creek bank where 25' is the minimum per Section 10-2.702 (e) of the Site Development Code. CEQA status-Categorically Exempt per 15301(e) (staff-Brian Froelich); Planning Commission Agenda February 16, 2006 Page 2 • 3.2 LANDS OF GOESE, 13480.Wildcrest Drive (254-05-ZP-SD); A request for a Site Development Permit and a development area credit pursuant to the Town's Development Area Policy for a 1,637-square-foot array of free-standing solar panels(staff-Leslie Hopper); 4. OLD BUSINESS-none 5. NEW BUSINESS 5.1: Discussion to consider amending Zoning and Site Development codes with regard to effective date, appeal, and Council review of actions for Zoning and Site Development Permits (Sections 10-1.1108-1110, 10-2.1305 and 10-2.1313) (staff- Debbie Pedro). 5.2 Proposed Amendment to the Basement Ordinance (Section 10-1.208) (staff-Brian Froelich) 6. REPORT FROM THE CITY COUNCIL MEETING 6.1 Planning Commission Representative for February 9th-Commissioner Collins 6.2 Planning Commission Representative for February 23`d-Cancelled 6.3. Planning Commission Representative for March 9th-Commissioner Cottrell 6.4 Planning Commission Representative for April 13th-Commissioner Kerns 7. APPROVAL OF MINUTES 7.1 Approval of February 2, 2006 minutes 8. REPORT FROM FAST TRACK MEETING-FEBRUARY 14, 2006 8.1 LANDS OF ALLEGRA, 26721 Taaffe Avenue (202-05-ZP-SD-GD); A request . for a Site Development Permit for a 1,141 square foot first and second story addition (maximum height 24'4" feet). (staff-Debbie Pedro) 9. REPORT FROM SITE DEVELOPMENT MEETING-FEBRUARY 14,2006 9.1 LANDS OF IRANI, 24008 Oak Knoll Circle (257-05-ZP-SD); A request for a Site Development Permit for a landscape screening plan (staff-Debbie Pedro). 10. . ADJOURNMENT EXHIBIT 9 Draft Initial Study for the Matadero Creek Restoration and Bank Stabilization Project LOS ALTOS HILLS, SANTA CLARA COUNTY, CALIFORNIA Prepared For: Town.of Los Altos Hills 4to 1,. 26379 Fremont Road } Los Altos Hills, CA 94022 4. • ` � •; atr - Prepared By: „ rd i,•••WRA, Inc. 2169-G East Francisco Boulevard _ „ _ San'Rafael, California 94901 - �~ �� ;` Date: ���Rr •� f; `�{ ” .r � • � � `� October 2015 i pax1$*1 • �`” -" jA goik w ra ENVIRONMENTAL CONSULTANTS a result, sensitive receptors in the vicinity of the project would.not be exposed to substantial pollutant concentrations, and impacts would be less than significant. e) Less Than Significant Impact. Construction activities would involve the use of gasoline or diesel-powered equipment that emits exhaust fumes.. These activities would take place intermittently throughoutthe workday, and the associated odors are expected to dissipate within the immediate vicinity of the work area. Persons near the construction work area .may find these odors objectionable. However, the proposed project would not include uses that have been identified by BAAQMD as potential sources of objectionable odors, such as restaurants, manufacturing plants, landfills, and agricultural and industrial operations. The infrequency• of the emissions, rapid dissipation of the exhaust and other:odors into the air, and short- term nature of the construction activities would-result in less than significantodor impacts. 4.4 Biological Resources Less than Potentially Significant Less thano - BIOLOGICAL RESOURCES—Would the Significant with Significant. I pact Source Impact Mitigation Impact project: Incorporated a) Have a substantial adverse effect, either ® ❑ 1,7,8 directly or through habitat modifications, on any species identified as a candidate, sensitive, or special-status species in local. or regional plans, policies, or regulations, or by the California Department of Fish and ' Wildlife or U.S. Fish and Wildlife Service? b) Have a substantial adverse effect on any ❑ ® ' : El LI : 1,7,8 riparian habitat or other sensitive natural community identified in local or regional plans, policies, or regulations or by the California Department of Fish and Wildlife . or U.S. Fish and Wildlife Service? c) Have a substantial adverse effect on ® 1111,7,8 federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.)through direct removal, . flling, hydrological interruption, or other means? d) Interfere substantially with the movement of 1110 1,7,8 any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or . impede the use.of native wildlife nursery sites? Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 25 October 2015 Less than Potentially Significant Less than Significant with Significant No Source BIOLOGICAL RESOURCES—Would the Impact Mitigation , Impact Impact . project: Incorporated e) Conflict with any local policies or ® ❑ ❑ 1,7,8 ordinances protecting biological resources, such as a tree preservation policy or ordinance? f) Conflict with the provisions of an adopted LI , 0 ® 1,7,8 Habitat Conservation Plan, Natural 'Community Conservation Plan, or other approved local, regional, or state habitat conservation plan? The following analysis of biological resources is based on the Biological Resources Assessment (BRA) prepared by WRA, Inc. (Appendix A). Regulatory Setting Sensitive Biological Communities . Sensitive biological communities include habitats that fulfill special functions or have special values, such as wetlands, streams, and riparian habitat. These habitats are regulated under federal regulations (such as the Clean Water Act [CWA]), state'regulations (such as the Porter- Cologne Act, the California Department. of Fish and Wildlife (CDFW) Streambed Alteration Program, and CEQA), or local ordinances or policies (such as City or County Tree Ordinances, Special Habitat Management Areas, applicable Local Coastal Programs [LCP], and General Plan Elements). Waters of the United States The U.S. Army Corps of Engineers (Corps) regulates "Waters of the United States" under Section 404 of the CWA. Waters of the United States are defined in the Code of Federal Regulations as waters susceptible to use in commerce, including • interstate waters and wetlands, all otherwaters (intrastate waterbodies, including wetlands), and their tributaries (33 CFR 328.3). Potential wetland areas are identified by the presence of(1) hydrophilic vegetation (or hydrophytes), (2) hydric soils, and (3) wetland hydrology. Areas that are inundated at a sufficient depth and for a sufficient duration to exclude growth of hydrophilic vegetation are • subject to CWA Section 404 jurisdiction as "non-wetland waters" (also referred to as "other waters") and are often characterized by an ordinary high water mark (OHWM). Non-wetland waters, for example, generally include lakes, rivers, and streams. The placement of fill material into Waters of the United States generally requires an individual or nationwide permit from the Corps under Section 404 of the CWA. . Waters of the State The term "Waters of the State" is defined by the Porter-Cologne Act as "anysurface water or groundwater, including saline waters, within the boundaries of the state." The Regional Water Quality Control Board (RWQCB) protects all waters in its regulatory scope and has special responsibility for wetlands, riparian areas, and headwaters. These waterbodies have high resource value, are vulnerable to filling, and are not systematically protected by other programs. The RWQCB jurisdiction includes "isolated" wetlands and waters that may not be regulated by Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 26 October 2015 the Corps under the CWA. Waters of the State are regulated by the RWQCB under the State Water Quality Certification Program which regulates discharges of fill and dredged material under Section 401 of the CWA and under the Porter-Cologne Water Quality Control Act. Projects that require a Corps permit, or that fall under other federal jurisdiction, and that have the potential to impact Waters of the State, are required to comply with the terms of the Water Quality Certification. If a proposed project does not'require a federal permit, but does involve dredge or fill activities that may result in a discharge to Waters of the State, the RWQCB has the option to regulate the dredge and fill activities under its state authority in the form of Waste Discharge Requirements. Streams, Lakes, and Riparian'Habitat Streams and lakes, as habitat for fish and wildlife species, are subject to jurisdiction by the CDFW under Section 1600-1616 of the California Fish and Game Code (CFGC). Alterations to or work within or adjacent to streambeds or lakes generally require an application for a Section 1602 Lake and Streambed Alteration Agreement. The term "stream", which includes creeks and rivers, is defined in the California Code of Regulations as "a body of water that flows at least periodically or intermittently through a bed or channel having banks and supports fish or other aquatic life [including] watercourses having a surface or subsurface flow that supports or has supported riparian vegetation" (14 CCR 1.72). In addition, the term "stream" can include ephemeral streams, dry washes, watercourses with subsurface flows, canals, aqueducts, irrigation ditches, and other means of water conveyance if they support aquatic life, riparian vegetation, or stream-dependent terrestrial wildlife (CDFG 1994). "Riparian" is,defined as "on, or pertaining to, the banks of a stream" (CDFG 1994). "Riparian vegetation" is defined as vegetation which occurs in and/or adjacent to a stream and is dependent on, and occurs because of, the stream itself" (CDFG 1994). Removal of riparian vegetation also requires an application for a Section 1602 Lake and Streambed Alteration Agreement from the CDFW. Other Sensitive Biological Communities Other sensitive biological communities not discussed above include habitats that fulfill special functions or have special values. Natural communities considered sensitive are those identified in local or regional plans, policies, regulations, or by the CDFW. The CDFW ranks sensitive communities keeps records of their occurrences in its California Natural. Diversity Database (CNDDB;: CDFW 2014). Sensitive plant communities are also identified in other reports prepared by the CDFW (CDFG 2003, 2007, 2009). California Natural Diversity Database vegetation alliances are ranked 1 through 5.based on NatureServe's (2014) methodology, with those alliances ranked globally (G) or statewide (S) as 1 through 3 considered sensitive. Impacts to sensitive natural communities identified in local or regional plans, policies, or regulations, or those identified by the CDFW or the U.S. Fish and Wildlife Service (USFWS), must be considered and evaluated under CEQA (CCR Title 14, Div. 6, Chap. 3, Appendix G). Specific. habitats may also be identified as sensitive. in city or county general plans or ordinances. Special-Status Species . . . Special-status species include those plants and wildlife species that have been formally listed, are proposed as endangered orthreatened, or are candidates for such listing under the federal Endangered Species Act (ESA). or California Endangered Species Act (CESA). These acts afford protection to both listed and proposed species. In addition, CDFW Species of Special Concern, which are species that face extirpation in California if current population and habitat trends continue, USFWS Birds of Conservation. Concern, and CDFW special-status invertebrates are all- considered special-status species. Although CDFW Species of Special Concern generally have no special legal status, they are given special consideration under Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 27 October 2015 CEQA. In addition to regulations for special-status species, most birds in the United States, including non-status species, are protected by the Migratory Bird Treaty Act of 1918. Under this legislation, destroying active nests, eggs, and young is illegal. Plant species on California Native Plant Society (CNPS) Inventory of Rare and Endangered Plants (CNPS 2014) with California Rare Plant Ranks (Rank) of 1 through 4 are also considered special-status plant species and must be considered:under the CEQA. Relevant Local Policies, Ordinances, and Regulations Town of Los Altos Hills Tree Protection Ordinance Chapter 2 of the Los Altos Hills Municipal Code requires a permit for the alteration or removal of any street tree, shrub,or plant in any street, park, or public place in the Town. Permits are also required for certain activities, such as excavation or placement of concrete, with a distance of 10 feet from the center of the trunk of any street tree. Permits are also required by the Town for the removal of Heritage Oaks, which are defined asany tree of the genus Quercus that has a trunk or multiple trunks measuring 36 inches in circumference (approximately 12' inches in diameter) at a point 4 feet above the root crown (LAHMC 5-8.02(2)). Trees deemed by the Town to be Heritage Trees cannot be removed or damaged except with approval of the Town following a public hearing. Biological Communities in the Project Area WRA, Inc. biologists conducted a site assessment on October 21, 2014. See Appendix A, Figure 2, for a map of biological communities and for lists of observed or documented species within or near the project.area. Non-sensitive biological communities in the project area include developed land and disturbed/landscaped areas (e.g., roadside shoulder or adjacent mown areas). Three sensitive biological communities occur in the project area: perennial wetland, perennial stream (Matadero Creek), and mixed riparian woodland. The developed and disturbed/landscaped portions of the project area include a two-lane paved road and adjacent mowed areas lacking substantial tree cover. Approximately 0.03 acre of perennial freshwater wetlands occur in vegetated portions of Matadero Creek northwest and southeast of Page Mill Road. These wetlands are dominated by cattail (Typha sp.) upstream (southeast) of Page Mill Road and by watercress (Nasturtium officinale) and creeping bentgrass (Agrostis aff. gigantea) downstream (northwest) of Page Mill Road. The perennial wetlands in the project area fit the description of Holland's coastal and valley freshwater marsh (1986) and contain elements of Sawyer's Typha sp. Alliance (cattail marshes) and Agrostis gigantea Semi-Natural Herbaceous Stands (bent grass meadows) (Sawyer et al. 2009). An approximately 333-foot-long stretch of.Matadero Creek (approximately 0.04 acre, excluding areas mapped as in-stream perennial wetlands) occurs within the project area. Matadero Creek is a perennial USGS blue-line stream and was flowing during the site visit conducted for this assessment. The creek was mapped based on the location of the OHWM, as evidenced by scouring and sediment/drift deposits along the streambed. The creek is daylighted within the project area. Upstream -(southeast) of Page Mill Road, the creek has a relatively shallow gradient and contains a large area of cattail wetland adjacent to the road. Downstream (northwest) of Page Mill Road, the creek has a steeper gradient and is covered by a dense riparian canopy dominated by arroyo willow (Salix lasiolepis) .and northern California black walnut (Juglans hindsii). The creek is armored by concrete sack walls within the immediate vicinity of Page Mill Road. Downstream (northwest) of Page Mill Road, where the concrete armoring ends, a nick-point.'has developed, resulting in a steeply incised channel with substantial erosion, undercutting, and bank slumping. Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 28 October 2015 In the project area, approximately 0.54 acre of mixed riparian woodland occurs along Matadero Creek up= and downstream of Page Mill Road. Dominant tree species include arroyo willowand northern California black walnut; valley oak (Quercus lobata) and coast live oak (Quercus agrifolia) are also present at lower density. Downstream (northwest) of Page Mill Road, the riparian canopy cover density is generally greater than 80 percent. The understory is dominated by non-native annual grasses and other native and non-native species such as fringed willowherb (Epilobium ciliatum), Himalayan blackberry (Rubus armeniacus), California blackberry (Rubus ursinus), upright snowberry (Symphoricarpos albus var. laevigatus), and poison oak (Toxicodendron diversilobum). Many of the species found within the riparian woodland are listed as having "moderate" to "high" potential for invasiveness by the Cal-IPC (2014). The understory also contains a large number of naturalized horticultural species. Upstream (southeast) of Page Mill Road, the riparian canopy is less dense and is dominated by a similar suite of tree species, but with relatively higher cover of valley oak and coast live oak. The understory upstream of(Page Mill Road was dominated by non-nativeannual grasses and other weedy vegetation that was mowed or otherwise maintained at 3 to 4 inches in height. Mixed riparian woodland within the project area can be classified as Central Coast Arroyo Willow Riparian Forest with elements of Central Coast Live Oak Riparian Forest (Holland 1986). The mixed:riparian woodland fits the description of Sawyer's Salix lasiolepis Shrubland Alliance (arroyowillow thickets) (Sawyer et al. 2009). Special-Status Species in the Project Area Plants Forty-seven special-status plant species have been documented from within the vicinity of the project area (Appendix A, Figure 1). Many of these species occur in habitats that are not present in the project area, such as coastal habitats, broadleaved or coniferous upland forests, chaparral, valley and foothill grasslands, vernal pools, or serpentine soils. Special-status species that occur in habitats not present in the project area were determined to have no potential to occurin the project area. For special-status species known to occur in riparian woodland (e.g., western leatherwood, Dirca occidentalis, CNPS 16.2 or Loma Prieta hoita, Hoita strobilina, CNPS 16.1) or perennial wetlands (e.g., Hoover's button-celery, Eryngium aristulatumvar. hooveri,,CNPS 1 B.1, alkali milk-vetch, Astragalus tener var. tener, CNPS 1 B.2, or legenere, Legenere limosa, CNPS 1B.1), the project area may contain elements of suitable habitat. However, no special-status plant species were identified within the project area during the site visit (with the exception of northern California black walnut, see discussion below), and it was determined that the fragmented, disturbed nature of habitat within, the project area, including .the high cover of non-native, invasive species, greatly reduces the potential for special-status plant species to occur there. As such, it was determined that no special-status plant species are likely to occur within the project area and no additional plant surveys are recommended. Northern .California black walnut has a California. Rare Plant Rank of 16.1 (CNPS 2014) indicating:that it is.rare, threatened, or endangered in California and elsewhere. However, this ranking is intended for those individuals found within naturally occurring stands and within the natural range of the species. Stands of this species from areas thatpreviously contained walnut orchards or naturalized individuals that occur as a result of dispersal by wildlife or humans, as well as_planted landscape specimens, are not regarded as a natural community or as special- status plants. Northern California black walnut individuals observed during the site visit are not within any known natural community, according to the CNPS (2014) or Sawyer et al. (2009), and thus are not considered to be special-status. As a native tree, northern California black walnut grows only in central California, being limited to a few isolated stands very much restricted.in area and in nearly every case present near historical Native American village sites Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 29 October 2015 or camping grounds (Jepson 1923, CNPS 2014). The Juglans hindsii and Hybrids Special and Semi-Natural Woodland Stands (Hind's walnut and related stands)identified by Sawyer et al. (2009) occurs in native groves near the town of Walnut Creek in Contra Costa County and on the banks of the Sacramento River in Sacramento County. Although the walnut,trees within the project area are not considered special-status, they are protected as riparian woodland by the CDFW and may also be protected by the Town's tree protection ordinance. Wildlife Of the.61 special-status wildlife species with potential to occur within the vicinity of the project area, 51 species were determined to occur in habitats not present in the project area or in habitats that may be present in the project area but which are of poor quality and unsuitable for the species (Appendix A). The nest structure of one special-status wildlife species, dusky footed woodrat (Neotoma fuscipes annectens; CDFW Species of Special.. Concern) was observedwithin the project area during the site assessment. Additionally, eight special-status wildlife species were determined to have a moderate to high potential to occur within the project area. Species that were observed within the project area or determined to have the potential to occur there are discussed in detail below. One federal-listed species for which the project area provides ostensibly suitable habitat but which is unlikely to occur there is also discussed. Species with the Potential to Occur San Francisco dusky-footed woodrat (Neotoma fuscipes annectens). CDFW Species of Special Concern. High Potential. This subspecies of the dusky-footed woodrat occurs in the Coast Ranges between San Francisco Bay and the Salinas River (Matocq 2003). Occupied habitats are variable and include forest, woodland, riparian areas, and chaparral. Woodrats feed on woody plants, but will also consume fungi, grasses, flowers, and acorns. Foraging occurs on the ground and in bushesand trees. This _species constructs robust structures/houses made of sticks and twigs in areas with moderate cover and a well-developed understory containing woody debris. Breeding takes place from December to September. Individuals are mostly nocturnal and are active year-round. Riparian woodland within the project area provides suitable habitat for the San Francisco dusky- footed woodrat, and one woodrat nest structure was observed within the project area during the site assessment. Woodrats are presumably present in the project area year-round. White-tailed kite (Elanus leucurus). CDFW Fully Protected Species. Moderate Potential. White-tailed kite is resident in open to semi-open habitats throughout the lower elevations of California, _including grasslands, savannahs, woodlands, agricultural areas, and wetlands. Vegetative structure and prey availability are more important habitat elements than associations with specific plants or vegetative communities (Dunk 1995). Nests are constructed mostly of twigs and are placed in trees, often at the edges of habitats. Nest trees are highly variable in size, structure, and immediate surroundings, ranging from shrubs to trees greater than 150 feet tall (Dunk 1995). This species preys upon a variety of small mammals, as well as other vertebrates and invertebrates. . White-tailed kite may nest within or adjacent to the project area, most likely in large riparian trees; however, use of other trees, including those directly adjacent to development, is also possible. Allen's hummingbird(Selasphorus sasin).: USFWS Bird of Conservation Concern. High Potential. Allen's hummingbird, common in many portions of its range, is a summer resident along the majority of California's coast and a year-round resident in portions of coastal southern California and the Channel Islands. Breeding occurs in association with the coastal fog belt, and typical habitats used include coastal scrub, riparian, woodland and forest edges, and Matadero Creek Restoration and Bank Stabilization Project . Draft Initial Study Town of Los Altos Hills 30 October 2015 • • eucalyptus and cypress groves (Mitchell 2000). The species feeds on flower nectar and forages for insects and spiders. Riparian woodland within the project area provides suitable habitat for this species, including for nesting. Nuttall's:woodpecker (Picoides nuttallii). USFWS Bird of Conservation Concern. High Potential. Nuttall's woodpecker, common in much of its range; is a year-round resident throughout most of California, west of the Sierra Nevada Range. Typical habitat is oak or mixed woodland,:including riparian areas (Lowther 2000). Nesting occurs in tree cavities, principally those of oaks and larger riparian trees. This species forages on a variety of arboreal invertebrates. Nuttall's woodpecker occurs regularly in and near developed areas of the San Francisco Bay area where suitable habitat is present. This species may occur within the project area's riparian woodland. . Oak titmouse (Baeolophus inornatus).: USFWS Bird of Conservation Concern. High Potential. This relatively common species is resident throughout much of California including most of the coastal slope, the Central Valley and the western Sierra Nevada foothills. Primary habitat is woodland dominated by oaks; local populations have adapted to woodlands of pines and/or junipers in some areas (Cicero 2000).. The species nests in tree cavities, usually natural cavities or those excavated by woodpeckers; birds may partially excavate their own cavities. The species forages for seeds and arboreal invertebrates. As with Nuttall's woodpecker, this species is relatively common throughout much of the San Francisco Bay area and may occur among riparian trees and oaks within the project area. (Brewster's) Yellow warbler (Setophaga petechia brewsteri). .CDFW Species of Special Concern, USFWS Bird of Conservation Concern. Moderate Potential. Yellow warbler is a neotropical migrant bird that is widespread in North America. The Brewster's (brewsten) subspecies is a summer resident and represents the vast majority of yellow warblers that breed in California. In California, west of the Central Valley, typical yellow warbler breeding habitat consists of dense riparian vegetation along watercourses, including wet meadows, with willow growth being particularly favored (Shuford and Gardali 2008). Insects compose most of the • diet. Riparian woodland within the project area provides suitable nesting habitat for yellow warbler. San Francisco (saltmarsh) common yellowthroat (Geothlypis trichas sinuosa). CDFW Species of Special Concern, USFWS Bird of Conservation Concern. Moderate Potential. This subspecies of the common yellowthroat is endemic to the greater San Francisco Bay area and is present year-round in and near marshes (salt, brackish, and fresh), riparian thickets, and coastal swales. Yellowthroats require thick, continuous vegetative cover, preferring wetland vegetation and adjacent transitional areas (Shuford and Gardali 2008). Nesting occurs in dense vegetation, usually on or near the ground. Arthropods (insects, spiders) compose most of the diet. Riparian woodland and emergent marsh vegetation (cattails) within the project area provide suitable habitat for this species, including for nesting. Western pond turtle (Actinemys marmorata). CDFW Species of Special Concern. Moderate Potential. Western pond turtle is the only native freshwater turtle in California, occurring in suitable aquatic habitats throughout California, west of the Sierra-Cascade crest and Transverse Ranges (Jennings and Hayes 1994). Occupied habitats are both annual and perennial water bodies and include coastal lagoons, lakes, ponds, marshes, rivers, and streams Matadero Creek Restoration and Bank.Stabilization Project Draft Initial Study Town of Los Altos Hills 31 October 2015 • from sea.level to 5,500 feet in elevation. Manmade habitats such as stock and wastewater storage ponds, percolation ponds, canals, and reservoirs are also used. This species requires low-flowing or stagnant freshwater with*basking structures, including rocks, logs, vegetation mats, mud.banks, and sand. Whereas pond turtles require suitable aquatic habitat for most of the year, features that become seasonally unsuitable are also used. To escape periods of high water flow, high salinity, or prolonged dry conditions, pond turtles may move upstream and/or take refuge in vegetated, upland habitat for up to four months (Rathbun et al. 2002). Nesting occurs from late April through July; nesting habitat consists of open, dry, unshaded'upland areas with friable soils near suitable aquatic habitat, where females excavate nests and lay eggs (Rathbun et al. 1992). Within the project area, Matadero. Creek provides suitable aquatic habitat for,westernpond turtle, provided that water is present. Thus, turtles mayoccur only seasonally and/or dependent upon annual precipitation levels, rendering the habitat of limited quality overall. Nesting within the project area is unlikely due to the highly-incised and steep banks along the creek. California red-legged frog (Rana draytonii). Federal Threatened, CDFW Species of • Special Concern. Moderate Potential. ' California red-legged frog (CRLF),is the only native "pond frog"found throughout much of California and was listed as Threatened by the USFWS in 1996. Suitable CRLF breeding habitat is characterized by deep (approximately two feet), still or slow-moving water associated with emergent marsh and/or overhanging riparian vegetation (USFWS 2010). Such habitats must hold water for a minimum of 20 weeks, and include ponds (ephemeral and perennial), streams/creeks (ephemeral and perennial), seasonal wetlands, springs, seeps, man-made features (e.g., stock ponds, roadside ditches), marshes, and lagoons. Dependent upon local conditions, CRLF may complete its entire life cycle in a particular habitat patch (e.g., a perennial pond suitable for all life'stages), or.utilize multiple habitat types. In aquatic habitats that dry-down seasonally, CRLF often undergo aestivation (a period of inactivity) during the dry months, over-summering in small mammal burrows, moist leaf litter, incised stream channels, or large cracks in'the bottom of dried ponds (Jennings and Hayes 1995). Adult and sub-adult (newly metamorphosed) CRLF may disperse from breeding habitats to nearby.riparian and/or aestivation habitats in the summer. Conversely, during the rainy season, CRLF may disperse from estivation sites to suitable breeding habitat. During such dispersals, frogs can travel over one mile through upland areas (Bulger et al. 2003); such upland dispersal habitats are variable and typically include riparian corridors, grasslands, and oak savannas. The majority of creeks in developed areas of the San Francisco Bay Area do not typically provide,suitable breeding habitat for the CRLF due to unsuitable hydrology, the presence of aquatic and/or terrestrial predators, and/or other factors: However, CRLF breeding has recently been documented approximately 1.2 miles north of the project area within Deer Creek, a tributary to Matadero Creek (CDFW 2014). There are also additional recent occurrences (including breeding occurrences) within five miles to the west.(TRA Environmental Sciences 2011 [no additional documentation provided], CDFW 2014). Within the project area, Matadero Creek is narrow and highly incised, and therefore the stream current during typical winters is expected to be strong, with limited to non-existent still, deeper water suitable for CRLF breeding. However, given the :occurrences in the general vicinity, and because riparian corridors are often used by dispersing/migrating CRLF, this species was determined to have moderate potential to occur in the project area. The potential for CRLF to occur is greatest during breeding migrations and dispersal events, particularly during the rainy season. • Matadero.Creek Restoration and Bank Stabilization Project , Draft Initial Study Town of Los Altos Hills 32 October 2015 Federal-Listed Species Unlikely to Occur Steelhead(Oncorhynchus mykiss irideus) - Central California Coast DPS. Federal Threatened. Unlikely. Steelheadis the native rainbow trout of coastal California that spends part of its life cycle in freshwater and part in the ocean. The Central California Coast Distinct Population Segment (DPS) includes all naturally spawned populations (and their progeny) in California streams from the Russian River to Aptos Creek and the drainages of San Francisco and San Pablo Bays eastward to the Napa River(inclusive); the Sacramento-San Joaquin River Basin is excluded. Steelhead typically migrates to marine waters after spending two years in freshwater, though . they may stay there for up to seven years. Individuals then reside in marine waters for two or - three years prior to returning to their natal stream to spawn as 4- or 5-year-olds. Steelhead adults typically spawn between December and June. In California,females typically spawn two times before they die. Successful reproduction requires abundant riffle areas (shallows with . gravel orcobble substrate) for spawning, and deeper pools with sufficient riparian cover for rearing. High-quality spawning habitat occurs in perennial streams with cool to cold water temperatures, high dissolved oxygen levels, and fast-flowing water. A technical report by Leidy (2005) summarizes known distribution information for steelhead in Santa Clara County streams. Although Matadero Creek is believed to have historically supported a steelhead population, the creek was surveyed for steelhead in 1981 and 1997 and none were found in either year. Additionally, when operated, the tide gates at the mouth of the creek can prohibit passage by anadromous fishes. For these reasons, Leidy (2005) concluded that steelhead is absent from Matadero Creek. Discussion of Impacts a) Less than Significant with Mitigation Incorporated. The project area has potential to support nine special-status wildlife species: San Francisco dusky-footed woodrat, white-tailed kite, Allen's hummingbird, Nutall's woodpecker, oak titmouse, San Francisco common yellowthroat, yellow warbler western pond turtle and California red-legged frog. If anyof these special-status wildlife species are present in the project area, impacts to these species are possible duringconstruction and would potentially be, significant. Implementation of Mitigation Measures BIO-1 through BI0-4 would reduce potentially significant impacts to a less-than-significant level. Because no special-status plants are likely to occur in the project area, no impacts to special-status plants are anticipated and no mitigation measures are required. Mitigation Measure BIO-1: San Francisco Dusky-footed Woodrat Prior to vegetation removal and/or ground disturbance within the project area, a pre- . . construction survey .for woodrat structures would be conducted by a qualified biologist. Any woodrat structures found during the survey would be flagged and subsequently avoided to the fullest extent feasible. . If avoidance is not possible, thenstructures to be impacted would be dismantled by hand under the supervision of a qualified biologist. • If woodrat young are encountered during the dismantling process, the material would be placed back on the house,'and a work exclusion buffer of at least 10 feet would be implemented around the structure. The structure would remain undisturbed for at least two weeks to allow the young to mature and leave the nest of their own accord. Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills '. 33 October 2015 After the avoidance period, the nest dismantling process may begin again. Nest materialwould be moved to adjacent vegetated areas that will not be disturbed. Mitigation Measure BIO-2:Nesting Birds To the fullest extent feasible, initial ground disturbance and/or vegetation removal would occur duringthe non-breeding season (September 1 to January 31). Preconstruction nesting bird surveys.are typically not required during this period. (Note, however, that some birds have the potential to nest year-round; if nests are observed during project activities, a biologist would be consulted, and the nest avoided as described below.) If initial ground disturbance and/or vegetation removal occurs during the breeding season (February 1 through August 31), a qualified. biologist would conduct a breeding bird survey no more than 14 days.prior to ground disturbance to determine whether any birds are nesting within or adjacent to project impact areas. If active nests are found within project impact areas or close enough to these areas to. affect breeding success, the biologist would establish an appropriate work exclusion zone around each nest. Exclusion zone sizes vary dependent upon bird species, nest location, and existing visual buffers and ambient sound levels. A buffer radius may be as small as 25.feet for common species and 100 feet or more for special-status species and raptors. Once all young have become independent of the nest (or the nest otherwise becomes inactive), work may recommence within the exclusion zone. If initial ground disturbance is delayed or there is a break in project activities of greater than 14 days within the bird nesting season, then a follow-up nesting bird survey would be performed to ensure no nests have been established in the interim period. Mitigation Measure BIO-3: Western Pond Turtle • A pre-construction survey for western pond turtles shall be conducted by a qualified biologist within 48 hours of the initiation of work activities in or near the streambed. If western pond turtles are present, they would be captured and relocated to suitable habitat outside of the project area by a qualified biologist. The biologist would require specific approval from the CDFW to conduct such activities. • Mitigation Measure BIO-4: California Red-legged Frog Pre-construction CRLF surveys would be performed within 48 hours of the initiation of work activities, including exclusion fence installation and initial work activities. Biological sensitivity training would be conducted for-project construction personnel focused on CRLF identification and the project-specific avoidance and minimization measures to be implemented. Installation of a wildlife exclusion fence (or sections of fencing) would be done to prevent CRLF (dispersing or otherwise) from entering project work areas during construction. Such fencing would, be maintained throughout project activities. All pits or trenches would be covered at the end of each work day, or wildlife escape ramps would be installed. Daily inspections of the work area would be conducted by trained project personnel to ensure no CRLF are present.. b) Less than Significant with Mitigation Incorporated. The project area contains three sensitive biological communities: perennial wetland, perennial stream, and mixed riparian woodland. Wetlands and waters in the project area are subject to Matadero Creek Restoration and Bank Stabilization Project . . Draft Initial Study Town of Los Altos Hills 34 October 2015 Corps jurisdiction as Waters of the U.S. under CWA Section 404, RWQCB jurisdiction under CWA Section 401, and CDFW jurisdiction under Section 1600 of the CFGC. Mixed riparian woodland in the project area is also potentially subject to RWQCB and CDFW jurisdiction. The proposed project would temporarily impact perennial wetland, perennial stream, and mixed: riparian woodland. Existing conditions are a negligible sized wetland dominated by non-native species. Wetland functions from the existing conditions provide little to no value for wildlife in terms of typical wetland functions (e.g., water quality). Temporary impacts would be the result of grading activities, installation of a grade control structure and revetment, installation of a soldier pile wall, and construction access and staging: The project would help to restore the natural • hydrology of the stream by repairing a 3-foot headcut:.that would otherwise move upstream and undermine more of the structure of the riparian canopy and eventually the roadway. The project is designed to address erosion and bank slumping in the stream, thus project activities will restore natural hydrological processes in the stream and improve upon pre-disturbance conditions, as the project wouldrestore natural functions to the stream, which would also result in the development of instream wetland habitat at suitable locations. Construction activities would also require the removal of riparian trees (Table 3); however, all riparian trees will be replanted at project completion, and therefore, the impact to mixed riparian woodland habitat is also considered temporary. The concept for riparian plantings was developed by analyzing the existing conditions with the project area, the extent of proposed impacts to riparian trees, anticipated natural dieback of planted trees, and the particular constraints and opportunities at the site. Over time, plantings would return the mixed riparian woodland habitat to near pre-disturbance conditions. The extent of potentially significant temporary impacts to sensitive habitat is provided in Table 2 and Table 3. Implementation of Mitigation Measure BIO-5 would reduce potentially significant impacts to a less-than-significant level. • Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 35 October 2015 Table 2. Summary of Impacts to Wetlands and Waters Temporary Impacts Jurisdictional Feature (acres) Impacts to Corps Jurisdiction Perennial Wetland <0.01 acre Non-wetland Waters(up to Ordinary High Water Mark) 0.02 acre(333 linear feet) Total Area of Impacts to Corps Jurisdiction <0.03 acre Impacts to RWQCB and CDFW Jurisdiction Perennial Wetland <0.01 acre Non-wetland Waters(up to Top of Bank) 0.05 acre(333 linear feet) Total Area of Impacts to RWQCB and CDFW Jurisdiction <0.06 acre Table 3. Summary of Impacts to Mixed Riparian Woodland 1 Tree Species Number of Trees to be Removed Northern California black walnut 7 Arroyo willow 6 Total 13 Mitigation Measure 8/0-5: Sensitive Habitat Impacts to federally protected wetlands and non-wetland waters in the project area will require a Corps CWA Section 404 Nationwide or Individual Permit and a RWQCB CWA Section 401 Water Quality Certification. Impacts to areas subject to CDFW jurisdiction will require application for a CFGC Section 1600 Lake and Streambed:Alteration Agreement from the CDFW. Prior to issuance of construction and grading permits the applicant shall obtain a Corps Section 404 Nationwide Permit, RWQCB Section 401 Water Quality Certification, and CDFW 1602 Lake and Streambed Alteration Agreement. Best management practices to be implemented during construction include, but are not limited to the following activities: • Work in the creek below the level of top-of-bank (TOB) shall be restricted to June 1 through October 31 to correspond with the dry period. No equipment shall be operated in areas of flowing or standing water and no fueling, Matadero Creek Restoration and Bank Stabilization Project Draft Initial Study Town of Los Altos Hills 36 October 2015 • cleaning, or maintenance of vehicles or equipment shall take,place within any areas where an accidental discharge into the creek may occur; • Burlap bags filled with drain rock will be installed:around storm drains to route sediment and other debris away from the drains; • Earthmoving or other dust-producing activities will be suspended during periods of high winds; • All exposed or disturbed soil surfaces will be watered or covered to control dust as necessary; • Stockpiles of.soil or other materials that can be blown by the wind will be watered or covered; • All trucks hauling soil, sand, and other loose materials will be covered and all trucks will be required'to maintain at least two feet of freeboard; • All paved access roads, parking areas, staging areas, and residential streets adjacent to the construction sites will be swept daily with water sweepers; • The use of suitable erosion control materials, including straw wattles, erosion control blankets, etc., will be employed to reduce potential erosion associated with excavation and grading; • No debris will be allowed to enter into or be placed where it may be washed • by rainfall or runoff into the stream and all such debris will be picked-up daily and properly disposed at an appropriate site; • Equipment access to the creek will be restricted to as few locations as possible and will be sited to avoid impacts to wetland and riparian vegetation to the greatest,extent feasible; • Prior to the start of construction, or the introduction of machinery into the aquatic portion of the project site, a qualified biologist shall inspect the area to determine if invasive species are present. All equipment that may have come in contact with invasive plants or the seeds of these plants will be carefully cleaned before arriving on the site and shall be carefully cleaned before removal from the site; • Disturbance or removal of vegetation will not exceed the minimum necessary to complete construction; and • The work area will be delineated where necessary with orange construction fencing (or similar)to minimize impacts to habitat beyond the work limit.. c) -Less than Significant with Mitigation Incorporated. The project area contains federally-protected wetlands subject to the jurisdiction of the .Corps pursuant to Section 404 of the CWA. The extent of potentially significant impacts to federally protected wetlands is provided above in Table 2. The 435 square feet of perennial wetland has little to no ecological value and its loss will be compensated by the increase in stream area, as well as the increase in stream function. Therefore, there will be no loss of Waters of the U.S. .and no loss in functional value.. Once the natural hydrology and stream.morphology. are returned, instream wetlands. may develop in,suitable locations. In addition, implementation of Mitigation Measure BIO- 5 (above), including. obtaining authorization from the Corps via a Section 404 Nationwide Permit, would further reduce less than significant impacts to federally- protected wetlands. d) Less than Significant Impact. No migratory corridors or nursery sites are anticipated to be affected by the project. Because project activities have been limited by design to the dry season, no impediments to fish passage are anticipated • Matadero Creek Restoration and Bank Stabilization Project .Draft Initial Study Town of Los Altos Hills 37 October 2015 as a result of project activities and any impacts to potential migratory corridors or nursery sites would be less than significant. e) Less than Significant with Mitigation Incorporated. The Town of Los Altos Hills Tree Protection Ordinance requires a permit for the removal of any protected trees. Any tree located within a public right-of-way is considered protected under the' ordinance. The proposed project includes the removal of 13 trees that would be considered protected under this ordinance (Figure 7). Implementation of Mitigation Measure BIO-6 would ensure that the project would not conflict with any local policies or ordinances protecting biological resources and impacts would be less than significant. Mitigation Measure BIO-6: Tree Removal Prior to issuance of construction permits the applicant shall obtain a tree removal permit. Additional avoidance and minimization measures recommended in these permits shall be followed. This ratio shall be two to one or as defined in the tree removal permit, the stricter standard shall be followed. f) No Impact. No state, regional, or federal habitat conservation plans or Natural Community Conservation Plans have been adopted for the project area. 4.5 Cultural Resources Less than Significant • CULTURAL RESOURCES—Would the Potentially with Less than Significant Mitigation Significant No project: Impact Incorporated Impact Impact Source a) Cause a substantial adverse change in the 0 ® 1,2 significance of a historical resource as identified in Section 15064.5? b) Cause a substantial adverse change in the ❑ ® 1,2 significance of an archaeological resource pursuant to Section 15064.5? c) Directly or indirectly destroy a unique ® • L 1,2 paleontological resource or site or unique geologic feature? d) Disturb any human remains, including ® ❑ 1,2 those interred outside of formal cemeteries? Environmental Setting • Discussion of Impacts a) Less than Significant Impact. No historic properties/cultural resources listed, determined, or potentially eligible for inclusion on the NRHP (36 CFR Part 800.4) and/or California Register of Historic Resources (CRHR) (California Public Resources Code Section 5024.1) were identified within or immediately adjacent to the proposed project's APE. The Town's General Plan was consulted to identify potential cultural resources. Impacts would be less than significant and not mitigation is required. Matadero Creek Restoration and Bank Stabilization Project • Draft Initial Study Town of Los Altos Hills 38 October 2015 EXHIBIT 10 - {!IWO. ,V• t 4.:,'..70.. .:d0 Ii•. I .. 10,l4-(1 ,tx -m "Mir". ..' ' ,, gq'1,040 ; 1 1 {,.. ..i '� of .ol' •r•»*Tt .1, ,,,. �' � �•r I.'•1,yt.;. � } .>�.Y• 1,.. i� �..�'.' ,h`• � n1 � i.j t.1'! ,}}-. ` 1, ♦� a. •1^ tr ..w..1>�,. . ,`r'I' l M�:1 .•4' ' y y 4 4 •.' Ill.f.' 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