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City of Pleasanton 475 and 493 St. John Street Mixed-Use Project 40 As determined in the Final EIR for the DSP, the DSP area does not overlie a known earthquake fault or landslide hazards areas; therefore, the proposed project would not cause potential substantial adverse effects, including the risk of loss, injury, or death involving rupture of a known earthquake fault or landslides. However, as discussed in the Final EIR, the DSP area is within a seismically active region, and the proposed project would be subject to strong seismic ground shaking. Risks associated with ground shaking would be minimized by compliance with CBC engineering design and construction measures, which require foundations and other structural support features to resist or absorb damaging forces from strong ground shaking. Although nothing can ensure that proposed structures do not fail under seismic stress, proper engineering can minimize the risk to life and property. Additionally, as described above, the project would be required to incorporate recommendations made in the Geotechnical Investigation. These recommendations would minimize the impacts of ground shaking, including but not limited to recommendations for subgrade preparation, materials for fill, compaction of fill, and foundation construction, and the impacts of localized erosion along Arroyo del Valle (Appendix D). The Geotechnical Investigation identified that some subsurface soils at the project site are prone to liquefaction during seismic ground shaking. The Geotechnical Investigation recommends including post-tensioned slab foundations in proposed structures, which would accommodate settlement during liquefaction (Appendix D). Additionally, the Geotechnical Investigation includes other recommendations to reduce risks associated with liquefaction, including but not limited to soil moisture content control and selection of fill material. As described above, the project would be required to incorporate recommendations made in the Geotechnical Report, and risks associated with liquefaction would be minimized to the extent feasible. Therefore, the project would not cause potential substantial adverse effects, including the risk of loss, injury, or death involving liquefaction. Impacts would be less than significant. As described further in Section 4.8, Hydrology, Drainage, and Water Quality, the project site is greater than one acre and would be subject to the National Pollutant Discharge Elimination System (NPDES) General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities (Order No. 2022-0057-DWQ) adopted by the State Water Resources Control Board (SWRCB). Compliance with the NPDES permit requires each qualifying development project to file a Notice of Intent with the SWRCB. Permit conditions require the development of a stormwater pollution prevention plan (SWPPP), which must describe the site, the facility, erosion and sediment controls, runoff water quality monitoring, means of waste disposal, implementation of approved local plans, control of construction sediment and erosion control measures, maintenance responsibilities, and non-stormwater management controls. Inspection of construction sites before and after storms is also required to identify stormwater discharge from the construction activity and to identify and implement erosion controls, where necessary. Compliance with the Construction General Permit is reinforced through the PMC in Chapter 9.14, Stormwater Management and Discharge Control. Section 9.14.090(b)(3) of this chapter prohibits development within 20 feet of the top of a bank or within 30 feet of the creek centerline unless a written permit has been obtained from the Public Works Director. The project would be required to include recommendations made within the Geotechnical Investigation, including the installation of stitch piers along the top of the existing creek bank to retain the soil and surcharge forces from behind the piers. Compliance with the Construction General Permit and PMC would ensure that the project would not result in substantial soil erosion or the loss of topsoil. Impacts would be less than significant.