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Ny Dual Phase Extraction Pilot Test Work Plan Former Beneto Facility, 749 East Charter Way, Stockton, California Page 4 'I Based on Advanced GeoEnvironmental' s (AGE' S) report Aquifer Pump Test and Soil Vapor Extraction Pilot Test Report, dated February 7, 2007, prepared for the Super Center Mart (former K & S Gas and Grocery) located at 701 East Charter Way in Stockton, a groundwater pump test was performed at 6 gallons per minute (gpm) upgradient, approximately 250 feet west of the subject site. In the report, drawdown was observed at a maximum of 0 . 62 foot, 42 feet east of the pumping well (EW- 1 ). A plot of drawdown versus distance projected a maximum groundwater ROI in the first water-bearing zone, estimated at 119 feet. During the DPE pilot test, groundwater elevations will be monitored by submersible pressure transducers inserted in monitoring wells MW-7, MW-8, MW-9, and MW- 16 to measure influence on the potentiometric surface affected by the DPE test. METHODOLOGY The thermal/catalytic oxidizer consists of a high vacuum blower for simultaneous groundwater and soil vapor extraction. The high vacuum applied by the vacuum blower creates a vapor-phase pressure gradient that is transmitted directly to the subsurface liquids present. Those liquids will flow toward the vacuum source, and subsequently into the vapor/liquid separator in response to the imposed gradients . The extraction hose, set at a specific depth, and sealed from ambient air at the wellhead allows soil vapor and the entrained groundwater (liquid phase) to be extracted from the desired depth within the well. The soil vapors and entrained groundwater are separated in a vapor/liquid separator. The soil vapor will be incinerated by a thermal/catalytic oxidizer before being released to the atmosphere. Groundwater is pumped from the vapor/liquid separator into an onsite holding tar& All evacuated groundwater will run through a flow totalizer to record flow quantities and calculate flow rates during the test. Groundwater will be routed though to the sanitary sewer for disposal if applicable. GROUNDWATER LEVEL Background groundwater level data will be collected from all wells prior to pressure transducers being introduced into any wells . Manual static groundwater levels will be measured periodically (to the nearest 0 . 01 feet) throughout the test with a depth to water meter of all wells without pressure transducers installed. SAMPLING AND ANALYSIS Apex personnel will collect a groundwater sample and a soil vapor sample immediately after starting the test. Groundwater and soil vapor samples will be collected daily thereafter until the end of the 4-day (96-hour) test. A State-certified laboratory will analyze the groundwater and soil gas samples for the constituents listed in the table below (Note : soil gas samples will not be analyzed for all five fuel oxygenates, only MTBE will be analyzed for). 'JJ