SITE INFORMATION AND CORRESPONDENCE

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An extraction pipe will be connected to the pump in RW-1 and extend into the east end of the Basin. The pipe will terminate at a manifold located approximately 5 feet below existing grade. The manifold will contain several lawn-type spray heads capable of emitting a minimum combined flow of 100 gallons per minute. The manifold will be located below the surrounding surface grade to minimize the amount of spray escaping the Basin and traveling outside site boundaries. To allow sampling and control of the effluent, the extraction pipe will be fitted with a flow meter, sampling port, and gate valve near the wellhead (Figure 3). Static water levels will be collected from all site related wells for the two days prior to start-up and immediately before starting the test on day three. Operation. Groundwater will be extracted from RW-1 at a minimum rate of 75 gallons per minute (gpm) and discharged back to the Basin. The static water level in RW-1 and the effluent flow rate will be monitored every 15 minutes for the first two hours of the test, every 30 minutes for the next two hours, and every hour thereafter. Static water levels will be collected from monitoring wells immediately surrounding the Basin every hour. Because the effects of the pilot test are not expected to be seen more than 150 feet downgradient of the pumping well, wells in the neighborhood north of the canal, and background well BC-6, will not be monitored during the pilot test. A sample of the effluent will be collected from the sample port at the beginning of the test, at four hours, eight hours, and twenty-four hours into the test, and immediately before shutting down the pump at the end of the test. Grab samples of the water ponded in the bottom of the Basin will be collected at the same intervals. A sampling point will be constructed by suspending a 1-liter wide mouth sample bottle approximately three to five feet above the Basin floor in the center of the spray field. Samples will be collected from the bottle following the schedule proposed above. Termination. Static water levels in wells BC-18, BC-19, and BC-3 are expected to stabilize within the first 8 hours of the pilot test. However, the test will be run for a minimum of 24 hours to monitor the affects of recharge on groundwater elevation in the vicinity of the Basin. If the static water level in the wells appears to be stable after the first 24 hours, then the test will be terminated. Otherwise monitoring will continue. The duration of the test will not exceed 36 hours. Analyses. All samples collected during the pilot test will be submitted to a California Department of Health Services certified laboratory for analysis of volatile organic compounds following United States Environmental Protection Agency Method 8010. Reporting. A report describing the pilot test, field measurements, and analytical results will be presented to the RWQCB for review within 30 days following cessation of the pilot test. 05/07/98\e:Urc\2092\2092-14\Rspnslt2.doc\(pn) Page 2