SR0084051 (4) - Laserfiche WebLink

Home Browse Search

Groundwater Well Installation Work Plan Sharpe Army Depot Lathrop, California Ahtna Environmental, Inc. 12 9. Run the data logger self-test routine (if available) to check that the data logger and transducers are operating properly. If the self-test indicates that the instrument is not operating correctly, the test will not be started, and a backup transducer will be installed. 10. Measure and record the water level in the pumped well and each observation well. Record measurements taken as part of the test on an aquifer constant-rate test field data sheet (Appendix A). Record water levels prior to the start of the test. Then record levels during the pumping period at an interval of 5 to 10 minutes (depending on the rate of drawdown and using professional judgment). Finally, record levels after the pump has stopped until the water level in the test well is within 10 percent of its initial (pre-pumping) water level. 11. Check that the power supply or generator for the submersible pump is ready, piping is in place, the discharge rate has been determined and set, and the data logging equipment is ready. The initial discharge rate for the step-drawdown test is 5 gpm for the A Zone well and 40 gpm for the C Zone well. The discharge rate for the constant rate test will be determined based on the results of the step-drawdown test. 12. Turn on data loggers for all transducers before starting the pump in the test well. Record the test start time. 13. Begin to measure water levels periodically using a manually operated water level meter to check the accuracy of the transducer readings and to provide backup data if the data logger fails. Check water levels more frequently at the beginning of the test when levels are changing rapidly (i.e., every minute for the first 10 minutes, and every 2 minutes for the next 10 minutes, etc.). 14. Begin to check the pumping discharge rate periodically using the flow meter to check that the well is being pumped at the appropriate discharge rate. Also, check the flow rate by comparing it to the totalizer flow meter reading. Record the flow rate on the aquifer constant-rate test field data sheet (Appendix A). 15. After pumping the well for the specified test duration, set the data logger to begin recording recovery, and then shut off the pump. 16. After monitoring recovery until the water level in the test well is within 10 percent of its pre- pumping water level, remove the pump and transducers from the wells. 17. Transfer the test data from the data logger to an appropriate data storage device (such as a personal computer or tablet) using the downloading procedures from the data logger. Pumping test data will be analyzed using AQTESOLV™, an industry-standard software package used for the design and interpretation of aquifer tests. Analyses may include one or more of the following: • Neuman type curves for delayed yield analysis (Neuman, 1975) • Leaky Aquifer Method (Hantush, 1956), Distance-Drawdown (Jacob, 1963), or Residual Drawdown Method (Jacob, 1950) for transmissivities and hydraulic conductivities • Leaky Aquifer Method (Hantush, 1956) method for storativity values • Other methods as applicable, based on site conditions and test results Data from the constant rate tests will be used to calculate transmissivity and storativity.