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■0 A E I January 10, 2024 San Joaquin County Environmental Health Department Soil Boring Permit Application 1868 E Hazelton Avenue Stockton, California 95205 Re: Work Plan for a Limited Phase II Subsurface Investigation 1535 East Pescadero Avenue Tracy, California 95304 Dear Mr. Wong: AEI Consultants (AEI) has provided this work plan outlining a 59TLimited Phase II Subsurface Investigation at 1535 East Pescadero Avenue in Tracy, California 95304 (Site). The November 11, 2023, draft Phase I Environmental Site Assessment (ESA) for the Site identified former uses at the Site as recognized environmental conditions (RECs). We have prepared this proposal to assess whether the identified RECs have significantly affected the Site. The purpose of this investigation is to evaluate whether the subsurface at the Site (i.e., soil and groundwater) has been significantly impacted by the former users at the Site identified in the Phase I ESA. AEI proposes to complete the following to assess the subsurface. • Prepare a Site-specific health and safety plan (HASP) for the project. • Obtain a drilling permit for the proposed exploratory borings from the San Joaquin County Environmental Health Department. • Conduct a pre-field Site walk to identify boring locations and access restrictions. • Notify 811 (DigAlert) who in turn, will contact subscribing utility companies to mark the locations of their underground utilities along site boundaries and near proposed investigation locations, as appropriate. • Arrange for a private utility locator to clear each of the planned drilling locations from subsurface features at the proposed subsurface sample locations using ground penetrating radar (GPR), electromagnetic induction and possibly utility tracing instruments. In addition, perform hand auger clearing to a depth of at least four (4) feet beneath ground surface (bgs) to check the planned drilling location(s) for possible utilities. • AEI will contract a licensed driller to advance seven (7) soil borings at the Site with a truck-mounted direct-push drilling rig. The locations of the proposed borings are shown on the attached figure. The borings will be advanced to the planned depth of 24 feet below ground surface (bgs), first encountered groundwater, or refusal, whichever is encountered first for the collection of soil and/or grab-groundwater samples. • Each boring will be logged by AEI staff, soil core will be logged and described in general accordance with the Unified Soil Classification System (USCS); soils will be screened with a portable organic vapor meter (OVM) or photoionization detector (PID) and for sensory perception. Soil samples will be collected for laboratory analyses from the intervals that represent the highest likelihood for contamination based on the field screening results. The remaining soil samples will be held at the laboratory. • It is anticipated that one (1) soil sample collected from each boring will be selected for analysis for total petroleum hydrocarbons (TPH), volatile organic compounds (VOCs), and polychlorinated biphenyls (PCBs). • After drilling, a temporary well will be constructed using well materials consisting of 1-inch diameter, 0.010 slotted, poly vinyl chloride (PVC) piping installed in the boreholes to facilitate collection of a groundwater sample. It is anticipated that one (1) groundwater sample will be collected from each of the borings and selected for analysis for the same parameters listed above. If no groundwater is encountered or is not readily available for collection of a groundwater sample; a soil sample will be collected (in place of a groundwater sample) from the boring and analyzed for the same parameters as listed above. • Samples collected for potential laboratory analysis will be sealed, labeled, and entered onto chain-of-custody documentation for transportation for analysis to a California state-certified laboratory. • The following types and number of soil analyses are anticipated: • TPH as gasoline (TPH-g), diesel (TPH-d), and oil (TPH-o) using EPA Testing Method 8015B ......7 samples • VOCs using US EPA Testing Method 8260B.................................................................7 samples • Polychlorinated biphenyls (PCBs) using US EPA Testing Method 8082 ................................4 samples • The following types and number of groundwater analyses are anticipated: