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Geotechnical Investigation Scope of Services (Revision No. 3) BSK Proposal GL21-22459 PFAS Treatment and Wells Rehabilitation Project November 10, 2021 Pleasanton, California Page 1 Environmental, Geotechnical, Construction Services, Analytical Testing - An Employee-Owned Company ATTACHMENT C BSK Associates Pleasanton PFAS Treatment and Wells Rehabilitation Project Geotechnical Investigation Scope of Services SCOPE OF SERVICES Our scope of services, as described below, includes pre-field activities, subsurface investigation, preparation of a geotechnical data report and a geotechnical engineering report , perform a geotechnical review of the project plans and specifications, provide post-report consultation, perform a site-specific ground motion hazard analysis for the Centralized Treatment Facility, perform analytical testing of groundwater and soil samples, and perform additional exploration associated with the alternative Well 9 and 10 locations and pipe alignment along the eastern boundary of Alisal Elementary School. Our findings will be summarized in reports prepared under the supervision of a California registered Geotechnical Engineer. ANTICIPATED SUBSURFACE CONDITIONS According to the U.S. Geological Survey, the project site (Site) area is mapped as Holocene alluvial fan deposits, fine-grained facies – fine-grained alluvial fan and flood plain overbank deposits that are rich in clay and silt with interbedded sand and occasional gravel. According to the California Geological Survey (CGS), historical high groundwater in the area surrounding the Site ranges from about 30 to 50 feet below the existing ground surface (BGS). In addition, as shown on Figure 1, the western approximately two-thirds of the Site is located within a Seismic Hazard Zone for liquefaction. However, the Site is not located within an Alquist-Priolo Earthquake Fault Zone. Task 1 – Pre-Field Activities This task will include project coordination, project set up/administration for BSK’s services, utility clearance, locating exploration points in the field, and filing drilling permits with Zone 7 Water Agency and an encroachment permit with the City of Pleasanton (City). A reconnaissance of the project area and immediate vicinity will be conducted to observe existing conditions and features that may impact our investigation or project geotechnical design/construction. BSK will mark the locations of the borings and CPTs during the site reconnaissance. The explorations will be located where they do not conflict with overhead/underground utility lines, trees, or other obstructions and are readily accessible to drill/CPT rigs. We will call Underground Service Alert (USA North 811) a minimum of 72 hours prior to our field exploration for utility clearance. It should be noted that USA North 811 will only check for utilities on the public right-of-way and does not include private property. Therefore, we will hire a private utility locator to help locate detectable underground utilities near our proposed explorations outside City streets only.