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YM Vicky McCartney 1&Ro1b San Joaquin County Environmental Division 4 November 2004 Page 2 i UST locations and the purnp island. Total petroleum hydrocarbons as gasoline (TPHg) from the August 2004 sampling event are presented in Figure 2 . The proposed soil and groundwater investigation is designed to : i • Delineate the extent of soil contamination at the pump island and fuel lines; • Delineate the lateral extent of groundwater contamination; • Gather sufficient information to recommend appropriate soil and groundwater remedial measures to the City that can be implemented in conjunction with the proposed Site re-development; and • Prepare a characterization report and remedial work plan for SJCEHD approval. This work plan will include a proposal to destroy the groundwater monitoring wells at the site prior to the planned December 2004 Site demolition. The current configuration of the proposed new building has auto parking shown over the entire area with identified groundwater impacts . We anticipate that new monitoring wells that may be required could be placed in this parking garage after construction is completed. PROPOSED SOIL AND GROUNDWATER INVESTIGATION In order to delineate the extent of soil contamination at the pump island and fuel lines, and delineate the extent of groundwater contamination, five borings and three test pits are being proposed. Soil and groundwater sampling locations were selected based on the following rationale. 1 Three borings, SB- 1 , SB-2 and SB-3 (Figure 2) will be located along North Hunter Street to delineate the western extent of the impacted soil and groundwater. One groundwater sample and up to 5 soil samples will be collected from each of these borings every 5-feet from 10 to 30-feet below ground surface (bgs). Soil samples will be screened for organic vapors using a photo ionization detector (PID) . e The two remaining borings S13-4 and SB -5 (Figure 2) will be located in the building northeast and south of the former pump island to delineate the lateral extent of groundwater impacts in those directions. Groundwater samples will be collected from each of these borings. All soil borings are anticipated to be 30-feet deep . Groundwater is encountered at approximately 25 feet bgs .