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Work Plan for Additional Phase II Subsurface Investigation 434 Dr.Martin Luther King Jr.Boulevard Stockton,California 95206 Partner Project Number 17-191672.4 September 25,2017 Page 1 3 Objective The main objective of the project will be to further evaluate the identified impacts of petroleum hydrocarbons and fuel-related VOCs to soil, soil gas, and/or groundwater as a consequence of a release or releases from the historical on-site gasoline service stations. To further investigate the identified impacts, Partner will conduct an Additional Subsurface Investigation. The investigation scope will include a geophysical survey and the advancement of six step-out borings to facilitate the collection and analysis of soil, soil gas, and/or groundwater samples. Please note that contamination delineation is an iterative process and that the investigation design was based on currently available information.Therefore, additional sampling and/or laboratory analysis beyond the proposed scope of work may be required to fully characterize the contamination in the vicinity of previously detected impacts. 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 Additional 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 six step-out borings (four exterior and two interior borings) in the vicinity of the previously identified impacts to a terminal depth of 30 feet bgs or groundwater,whichever is shallower, collecting soil samples at five-foot intervals from five feet bgs 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