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Phase II Subsurface Investigation Proposal 1029-1045 North EI Dorado Street Stockton, California 95205 Partner Proposal Number P21-338831.3 November 10, 2021 Page 12 surface (bgs) with an inferred flow direction to the northeast. The subsurface is expected to consist of a varying combination of clay, silt, and sand from the ground surface to at least 25 feet bgs. Objective The main objective of the project will be to evaluate the potential impact of petroleum hydrocarbons and/or volatile organic compounds (VOCs) to soil, soil gas, and/or groundwater as a consequence of a release or releases from the historical on-site automobile service facility operations. To investigate the identified REC, Partner will conduct a Phase II Subsurface Investigation.The investigation scope will include the advancement of three borings to facilitate the collection and analysis of soil, soil gas, and/or groundwater samples, as well as the installation of three temporary sub-slab soil gas probes to facilitate the collection and analysis of soil gas samples. The proposed investigation scope is designed to evaluate the objective. Based on the investigation results, regulatory conditions, and/or client requirements, subsequent investigation and consulting may be necessary. Scope Sampling procedures will generally conform to the requirements of the San Joaquin County Environmental Health Department (SJCEHD), the SWRCB, the Department of Toxic Substances Control (DTSC), and the United States Environmental Protection Agency (EPA). A state-certified laboratory will analyze the samples and the project will be performed under the responsible charge of a qualified Partner representative. Laboratory results will be compared with San Francisco Bay Regional Water Quality Control Board (RWQCB) Environmental Screening Levels (ESLs). Partner will perform the following tasks for the Phase II Subsurface Investigation: • Prepare a site-specific health and safety plan; • Notify Underground Service Alert North (USAN) a minimum of three business days prior to drilling activities to clear public utilities; • Secure the necessary drilling permit from the SJCEHD. Permit acquisition will involve submitting a completed application and site plan to the SJCEHD for review and approval and remitting the necessary fees.The turnaround time of the SJCEHD to issue the permit is expected to be no more than two weeks; • Notify the applicable regulatory agencies a minimum of 48 hours prior to drilling/backfilling activities; • Clear boreholes of utility lines through a geophysical survey. Boring placement will be modified as necessary based on the geophysical survey results to avoid damaging underground features. Additionally, to the extent practical based on subsurface lithology, clear boring locations using hand tools; • Advance three exterior borings at the subject property to a terminal depth of 25 feet bgs or groundwater, whichever is shallower, collecting soil samples at 2 feet bgs and at 5-foot intervals from 5 feet bgs to the terminal depth and a grab groundwater sample at the terminal depth; • Field-screen each soil sample using a photoionization detector (PID); • Prepare up to 18 soil samples and three groundwater samples for laboratory analysis; PARTNER 4 O O O