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12/06/00 WED 17:40 FAX 916 387 0802 DAMES & MOORE SAC Z013 DDJC-Tracy OU 1 Groundwater Treatment for Pesticides,Pump Test Work Plan be removed from any wrappings until barometric probe. The probe will collect air immediately before it is to be placed into the pressure data at the same measurement interval boring- as for the water levels. 2.1.5 The well screen for the observation 2.2.3 Stepped pumping rare tests will consist of piezometers will be I '/2-inch diameter PVC with at least four progressively higher pumping rates 0.010-inch slots. The well screen surface will be with a minimum duration during each step of 60 free of solvents, oils,grease,paint and dirt and minutes. Specific procedures for stepped will be certified clean from the factory or steam pumping tests are outlined in the Comprehensive cleaned prior to installation. Screen sections Field Work Plan. , will not be removed from any wrappings until immediately before being placed into the boring. 2.2.4 Monitoring well LW 174AU(future EW The screen length for the piezometer will depend 045AU)will first be evaluated for conversion upon how close it is to the test well. To into an extraction well. A stepped pumping rate accommodate projected drawdowns, observation test will be conducted to estimate the optimum piezometers 50 feet or closer to the pumping pumping rate and anticipated drawdown. If the well will have at least 10 feet of screening. results are favorable,a 24-hour constant rate Observation piezometers greater than 50 feet pumping test will be conducted to evaluate the will have 5 feet of screen. Final screen length long-term performance of the well and aquifer. determination will be made in the field based upon the observed conditions. For all 2.2.5 Well EW 040AU will be pumped at a completions,the top of the screen shall be no constant rate of approximately 9 gallons per higher than the top of the water table. minute(gpm)for at least 24 hours. This pumping rate is based upon previous pumping 2.1.6 Each piezometer will be tests conducted on the well in 1999(Radian developed after installation. Development International, 1999). No stepped pumping test is procedures will generally follow those outlined planned because this test was conducted in 1999. in the Comprehensive Field Work Plan. To develop a natural filter pack,piezometers will be 2.2.6 Drawdown and recovery data from both bailed using a sand bailer or similar device to pumping tests will be evaluated using remove sand and fine sediment from the bottom AQTESOLVTm to estimate aquifer parameters. of the piezometer. in addition to analysis methods and procedures outlined in the Comprehensive Field Work Plan, 2.2 Aguifer Testing the drawdown data should be evaluated with the Neuman(1975) analysis for wells with delayed 2.2.7. The set-up and conduct of the aquifer yield. The Neuman method is not described in testing will follow the procedures outlined in the the Comprehensive Field Work Plan but should Comprehensive Field Work Plan and as be considered for this test because delayed yield modified here. Pressure transducers will be may occur near the pumping well. placed in each of the observation piezometers during the test. Additional transducers will be 2.3 Location Surveying installed in existing, nearby wells to supplement the water level measurements collected in the Location and elevation surveying is observation piezometers and to provide recommended for the 13 temporary piezometers, background measurements. Water levels in all according to the procedures outlined in the instrumented wells will be backed up with Comprehensive Field Work Plan. manual measurements. 2.2.2 Barometric pressure changes and potential influence on groundwater levels will be evaluated by recording the air pressure using a OU-1 Pump Test WP 6 Nwemba 2000