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f DDJ*Acy OU 1 Pesticide Reme liation Groundwater Extraction Well Installation Woi k Plan System, Zone 3,North American Datum of pump test and the start of the second 24-ho it 1983. Ground surface elevations will be pump test. obtained to the closest 0.1 foot and 0.01 foot, respectively. These elevations will be referenced 6.3.5 To comply with regulatory standard for to the National Geodetic Vertical Datum of addressing potential pesticide impacts,ground- 1988.If temporary piezometers are converted to water generated during aquifer testing will permanent piezometers, the top-of-casing require treatment by carbon adsorption and air elevations will also be measured and referenced stripping methods already in place at the sil e. To to the National Geodetic Vertical Datum of maximize the pumping rates used during t step 1988. and constant rate aquifer tests, groundwate generated during the tests will be conveyed 6.3 Aquifer Testing through a 2-inch diameter discharge hose to a tank for temporary storage. The groundwa r 6.3.1 The set-up and performance of the aquifer will be simultaneously pumped out of the testing will follow the procedures outlined in the storage tank and through a carbon adsorption DDJC-SharpelTracy Comprehensive Field Work vessel located near EW022A,approximate) 600 Plan(URS, 2001)and as modified in this work feet south of the TP 2. The water will then be plan. Pressure transducers will be placed in each conveyed to TP 2 through the existing of the temporary piezometers during the test. groundwater conveyance pipeline. Additional transducers will be installed in existing nearby wells(i.e.,EW040AU and 6.3.6 Drawdown and recovery data from t oth EW041AU)to supplement the water level pumping tests will be evaluated using measurements collected in the observation AQTESOLVTm to estimate aquifer paramet rs. piezometers.Water levels in all instrumented In addition to analysis methods and procedures wells will be backed up with manual measure- outlined in the DDJC-Sharpe/Cracy Comp - ments.Well EW043AU will be used during the hensive Field Work Plan(URS,2001),the tests to provide background water level trend drawdown data should be evaluated with th data. Neuman (1975)analysis for wells with delayed yield.The Neuman method is not described in 6.3.2 Barometric pressure changes and the DDJC-Sharpe/Cracy Comprehensive Fi ld potential influence on groundwater levels will be Work Plan but should be considered for thi test evaluated by recording the air pressure using a because delayed yield may occur near the barometric probe.The probe will collect air pumping well.The Neuman method of analysis pressure data at the same measurement was developed for testing of wells construci ed in frequency as the water levels. anisotropic aquifers that are unconfined, wl ich is the aquifer condition expected at the loca ions 6.3.3 Separate stepped pumping rate tests on of PEW-1 and PEW-2. This analysis metho PEW-1 and PEW-2 will consist of at least four employs curves representing drawdown ver us progressively higher pumping rates with a time that allow analysis of both the initial y eld minimum duration during each step of 60 and the delayed yield from an unconfined minutes. Specific procedures for stepped aquifer during an aquifer test. pumping tests are outlined in the DDJC- Sharpe/Tracy Comprehensive Field Work Plan 6.4 Temporary Piezometer (URS,2001). Abandonment 6.3.4 Following the stepped pumping rate tests, 6.4.1 Upon completion of the aquifer tests the 24-hour constant rate pumping tests will be temporary observation piezometers will either be conducted separately on PEW-1 and PEW-2, abandoned or converted to permanent piez e- with a delay of 24 hours to allow water level tern,depending on the results of the aquifer tests. recovery between the end of the first 24-hour Abandonment will be performed according to the general procedures described in the DD C- K102237\OU I—Pest-Rem\fnal\GW-EW-WrkPIn.duc 9 Juj e2002