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Ms.Margaret Lagorio, SJCEHD October 21,2003 Joe's Truck Plaza Project No.2033-15600-01 Work Plan for Additional Site Assessment Page 13 until groundwater level stabilization occurs or a trend in drawdown versus time can be plotted and extrapolated. The pumping rate selection for the constant-discharge test will be achieved by identifying the flow rate from the step test that exhibits appreciable water level drawdown in the well, with some stabilization of the drawdown by the end of the step. The selected pumping rate will be estimated to sufficiently stress the water-bearing zone during the constant-discharge test,without dewatering the pumping well. One set of groundwater samples will be collected during the step test, and submitted to a state-certified laboratory on a 24-hour turnaround time, for chemical analysis under strict chain-of-custody procedures. The groundwater samples will be analyzed for TPHG, TPHD, methanol, BTEX, MTBE, ETBE, TAME, DIPE, TBA, 1,2-DCA, EDB, and ethanol as described in Task 3. Strict chain-of-custody procedures will be followed. Constant-Rate Discharge Test A constant-rate discharge test will be performed on well EX-1 to estimate the hydraulic properties (transmissivity, specific yield) of the water-bearing zone. Groundwater will be pumped from the pumping well, at flow rates determined by the step-discharge test, for approximately 72 hours. The test will be conducted long enough to overcome borehole storage effects, and to induce appreciable drawdown in the nearby observation wells. The exact start up time of the test will be recorded, and any adjustments of the pumping rate required to maintain a nearly constant pumping rate throughout the test will be noted. In addition to the pressure transducers placed during the baseline monitoring, a hand held electronic sounding device will be used to measure depth to water in wells MW-9, MW-10, DW-1, and DW-3. A minimum of two additional groundwater samples will be collected during the constant discharge test and forwarded to a state-certified laboratory for chemical analysis of TPHG, TPHD, methanol, BTEX, MTBE, ETBE, TAME, DIPE, TBA, 1,2-DCA, EDB, and ethanol as described in Task 3. Strict chain-of-custody procedures will be followed. Recovery Period The post-pumping recovery test will involve monitoring water levels in the pumping well and observation wells after termination of pumping. Water levels will be recorded as they return to static levels, using pressure transducers and electronic data loggers, until 95%recovery in pumping well EX-1 is observed. P:\Joe's Truck Plaza\Work Plans\Joes workplan 102103.doc