AgdaPkt 2017-09-11 Closed and Joint SA PFA

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7.A. - Page 68 LSA ASSOCIATES, INC. ROCKETSHIP REDWOOD CITY ELEMENTARY SCHOOL PROJECT SEPTEMBER 2016 INITIAL STUDY/MITIGATED NEGATIVE DECLARATION With the exception of liquefaction,the potential for ground failure to occur at the project site during a seismic event is considered low. The potential impacts of liquefaction would be reduced to a less- than-significant level through the implementation of Mitigation Measure GEO-1. Therefore the potential of the proposed project to expose people or structures to risk as a result of seismic-induced ground failure is less than significant. b) Result in substantial soil erosion or the loss of topsoil? (Less-Than-Significant Impact) Topsoil is defined as the upper part of the soil profile that is relatively rich in humus and is technically known as the A-horizon of the soil profile.44 The project site is developed and has been mapped as an"urban land"area by the Natural Resource Conservation Service.Areas designated as "urban land"have essentially no soil and are covered by streets,parking lots,buildings,and other structures. Because the project site has no topsoil,the proposed project would have no impact related to the loss of topsoil. The project site and surrounding areas are flat or gently sloped. The elevation of the project site ranges from approximately 8 feet above the National Geodetic Vertical Datum of 1929 (NGVD 29)in the northern corner to approximately 11 feet NAVD 29 in the southern comer.45 The proposed project would not involve topographic changes that could alter the potential of erosion to occur on the project site (e.g.,creation of significant slopes). The redevelopment of the project site would involve demoli- tion and construction activities, such as grading and excavation,which would disturb site soils and could result in temporary soil erosion when the disturbed soils are exposed to wind or rainfall. Soil erosion is discussed further in Section IX,Hydrology and Water Quality.Upon completion of construction,the project site would be covered with structures,pavement,and landscaping and would not include areas of exposed soil. Therefore,the operational phase of the proposed project would not have the potential to result in soil erosion. c) 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-site landslide, lateral spreading, subsidence, liquefaction or collapse?(Potentially Significant Unless Mitigation Incorporated) As previously discussed in Section VLa,above, site soils would not be subject to lateral spreading or landslides,but do have the potential for liquefaction-induced settlement of up to 1 inch. Implementation of Mitigation Measure GEO-1 would reduce the potential risks to people and structures as a result of liquefaction to a less-than-significant level. Subsidence or collapse can result from the removal of subsurface water resulting in either catastrophic or gradual depression of the surface elevation of the project site. The proposed project would connect to the City's water system and would not utilize groundwater at the site.New pavements installed at the site would not introduce new foundation systems that would alter the stability of the existing 44 California State Mining and Geology Board,2014.Surface Mining Reclamation Act(SMARA)Regulations. California Code of Regulations,Title 14,Division 2,Chapter 8,Subchapter 1. 45 K2A Architecture+Interiors,2014.Rocketship Redwood Academy Elementary School Planning Submission Set. Topographic Survey.September 23. P:1RWC1401B Rocketship Sch-I\PRODUCrSUS-MND1Public\Ra ketship Public Review 09-29-16.docx(09/29/16)PUBLIC REVIEW DRAFT 44 ATTY/RESO.0084/CC RESO ADOPTING CEQA-ROCKETSHIP CHARTER SCHOOL APPEAL REV:09-05-17 VR Page 52 of 124