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Work Plan for Phase II Subsurface Investigation 434 Dr.Martin Luther King Jr.Boulevard Stockton,California 95206 Partner Project Number 17-191672.3 August 22,2017 Page 13 Objective The main objectives of the project will be to identify the potential location of on-site USTs,former tankholds, and/or other associated features and to investigate the potential impact of petroleum hydrocarbons and fuel-related volatile organic compounds (VOCs) to soil and/or groundwater as a consequence of a release or releases from the historical on-site gasoline service stations. To investigate the identified REC, Partner will conduct a Phase II Subsurface Investigation.The investigation scope will include a geophysical survey and the advancement of five borings (B1 through B5) to facilitate the collection and analysis of soil and/or groundwater samples. If soil and/or groundwater impacts are observed/recorded, the investigation scope may not be sufficient to evaluate the extent and magnitude of subsurface impacts and additional laboratory analysis and/or sampling beyond the proposed scope may be required Scope Sampling procedures will generally conform to the requirements of the San Joaquin County Environmental Health Department(SJCEHD),the SWRCB, 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: • Perform a review of available regulatory agency files pertaining to the subject property; • Prepare a site-specific health and safety plan; • Notify Underground Service Alert(USA)a minimum of 48 hours 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. • Advance a total of five exterior borings in the vicinity of the former fuel USTs and/or associated features (based on data from the geophysical survey and/or historical records) to a terminal depth of 30 feet bgs or groundwater, whichever is shallower, collecting soil samples in five-foot intervals from five feet to the terminal depth and a grab groundwater sample at the terminal depth • Soil samples will be collected using a two-foot long by 1.5-inch diameter sampler with a two-foot long acetate liner and sampling point. The sampler will be advanced by a direct-push drill rig using four- foot long (three-foot long for the limited-access rig) by 1.25-inch diameter hollow rods with the inner rods in place. At approximately one foot above the desired sampling depth, an inner rod was removed and the sampler was advanced to the desired sampling depth to allow undisturbed soil to enter the sampling liner. The sampler will be retrieved from the subsurface and the soil-filled liner will be removed; PARTNER