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G E!M Phase II ESA Work Plan March 19,2019 Sampling GEN personnel will oversee a contractor installing a total of four sub-slab soil gas points and advancing a total of 17 borings at select locations. Proposed sampling locations are shown on Figure 2 and proposed sampling locations and depths are summarized as follows: • Four (4) sub-slab soil gas samples will be collected from beneath the floor of the subject building at the old parts washer (not currently being used), the current parts washer and floor drain, the drum storage area in the covered work area, and the floor drain in the covered work area. • Four (4) hand-augered soil borings to approximately 2-feet bgs, or boring refusal, whichever is first encountered, for the collection of eight (8) soil samples at depths of 0.5-feet to 1-foot and 1.5-feet to 2-feet from inside the building at the old parts washer, the current parts washer and floor drain, the drum storage area in the covered work area, and the floor drain in the covered work area. • Three (3) hand-augered soil borings to approximately 5-feet bgs, or boring refusal, whichever is first encountered, for the collection of six (6) soil samples at depths of 2.5-feet to 3-feet and 4.5- feet to 5-feet from the north, east, and west sides of the OWS. • Ten (10) hand-augered soil borings to approximately 1-foot below ground surface (bgs), or boring refusal, whichever is first encountered, for the collection of ten (10) soil samples at depths ranging from of 0.1-foot to 1-foot from the yard in the area of the former auto dismantling activities. Soil gas samples will be collected in 1-liter Summa canisters equipped with manifolds fitted with a vacuum gauge and regulator; soil gas sampling equipment will be provided by the analytical laboratory. Each canister-specific regulator will be pre-set by the analytical laboratory to not exceed a flow rate of 150 milliliters per minute (ml/min). Each canister will be checked, tested, and certified by the analytical laboratory for air tightness and proper vacuum prior to shipping to GSE M. The serial numbers of each manifold and Summa canister used during the investigation and the initial and final vacuum readings will be recorded in the field notes. Soil samples will be collected from the borings and screened in the field with a photoionization detector (PID) and observed for evidence of chemical staining. Soil samples will be collected in new acetate sleeves or glass jars provided by the analytical laboratory at depths noted above. In addition, soil samples will be collected from depth intervals, if any, exhibiting elevated PID readings and/or evidence of chemical staining. The soil samples will be placed on ice in a cooler and the soil gas and soil samples will be transported under chain-of-custody protocols to the analytical laboratory. After completing the sampling activities, each sampling location will be backfilled with soil cuttings, cement grout, and/or bentonite and sealed at grade with concrete. Investigation-derived waste (IDW), including soil cuttings and rinseate, produced during sampling activities will be containerized and left on site. &EN will assist in evaluating appropriate off-site disposal options following receipt and review of the analytical data. Analysis The samples will be analyzed on a normal 5-business-day laboratory response time by a laboratory certified by the State of California to perform the requested analyses. Page 3 of 4