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Groundwater Well Installation Work Plan Sharpe Army Depot Lathrop, California Ahtna Environmental, Inc. 11 allowed to recover to within 10% of its initial water level before proceeding to the constant rate test. During the step test, a sustainable pumping rate will be identified that optimizes drawdown while maintaining a steady water level in the well. This rate will be determined by manually reviewing the drawdown curves generated during the step test, calculating specific capacity, estimating maximum pumping rate, and estimating aquifer transmissivity. Constant-rate tests will consist of pumping at a constant rate (identified by the results of the step- drawdown test) for a minimum of 12 hours and a maximum of 24 hours while collecting drawdown data from the extraction well and nearby wells. The length of the constant-rate test will depend on the response of the aquifer. If at any point after the 12-hour minimum, water level measurements have been asymptotic for a sustained period (at least 2 hours), the constant rate test may be terminated. For extraction well EWA1R, drawdown will be observed at MW445A and EWA3. For the new extraction well EWNC7, drawdown will be observed at monitoring wells MW527BR, MW527CR, and MW527DR. Discharge rates will be monitored and controlled via a flow meter and control valve installed on the discharge hose. Water level data for all tests will be collected and recorded using pressure transducers and a data logger. A manually operated water level meter will be used during the test to confirm the data collected by the transducers. Pumping test activities will include the following: 1. Decontaminate equipment placed in the well. 2. Install a submersible pump and pressure transducer in the pumping well. The pressure transducer and cable can be attached to the submersible pump discharge pipe using ties to prevent the transducer from becoming entangled in the well. 3. Install piping to convey the groundwater to the discharge point. Install a flow meter (with totalizer) and valve to measure and control the discharge rate. 4. Place pressure transducers in each observation well, as applicable. 5. Verify the placement of each transducer in the well by checking depth readings from the transducer data logger as it is lowered below the water surface. Set the transducer at least 5 ft below the maximum drawdown anticipated in the well during pumping (approximately 20 ft in the A Zone and 60 feet in the C Zone), but above the maximum submergence depth for the transducer. 6. Secure each transducer to the well casing at the surface to prevent the transducer from moving during the test. 7. Allow each transducer to equilibrate for 3 to 5 minutes with the temperature of the well water. Then check the functioning of each transducer by moving the transducer up or down a measured distance and noting the resulting change as measured by the data logger. Compare the change to the manually measured distance to check that the pressure transducer is operating properly. 8. Program the test-specific information into the data logger and set it to monitor recovery at the end of the pumping portion of the test. Typical parameters (depending on the data logger selected) include test number, length, measurement intervals, frequency, and start time.