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Ms.Margaret Lagorio,SJCEHD February 2,2009 Work Plan for Collection of Soil Gas Data Joe's Travel Plaza, 15600 S.Harlan Road Lathrop,California Page 5 Please note that the proposed soil gas survey is an active survey where air is artificially moved across the water table under vacuum conditions. The use of active soil gas collection methods, although widely required by regulatory agencies and therefore proposed herein, changes the in-situ equilibrium between (soil pore space) air and groundwater, thereby causing volatilization of contaminants from water to air that may not occur under normal conditions. Therefore, data gathered during an active soil gas survey is inherently conservative. The proposed scope of work has been subdivided into five tasks, as outlined below. All work will be conducted under the direct supervision of a State of California Professional Geologist or Professional Engineer. Task 1: Pre-Field Activities and Planning f i Following receipt of SJCEHD's concurrence with the activities proposed herein, the following activities will be completed: 1 ■ Obtain boring installation permits from SJCEHD, if needed, ■ Obtain an access agreement to conduct the proposed activities on the Storage Pro facility property, ■ Update the site-specific health and safety plan for the site, ■ Physically mark the proposed boring locations, contact Underground Service Alert and perform a geophysical survey to locate underground utilities in the vicinity of proposed locations, ■ Prior to the proposed sampling event, weather reports will be referenced to verify that a significant rain event (e.g., > 0.5-inch) is not forecasted within 48 hours of the sampling event. If significant rain is forecasted during the scheduled sampling event, the sampling will be rescheduled. Sampling during or just after a rain event can reduce the effective diffusion coefficient and decreases the relative vapor saturation in the unsaturated zone, thereby potentially affecting soil vapor results. i' ■, Notify the SJCEHD and appropriate property owners of the scheduled field activities. Task 2: Soil Gas Sampling Eight (8) shallow soil probes (V-1 through V-9) will be advanced at the approximate locations shown on Figure 7. Stratus intends to subcontract TEG Inc. of Rancho Cordova, California, to provide the drilling equipment and personnel necessary to advance the soil borings and collect the soil vapor samples. A Stratus representative will be on-site during all field activities. Soil borings will be advanced using a direct-push drilling rig (StrataprobeTI) equipped with 1-inch { KAoc's Truck Plaza\Work Plans\Work Plan for Collection of Soil Gas Data 2-2-09.doc