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1 Aquifer Testing Work Plan <br /> Former PureGro Facility <br /> t North Broadway Avenue <br /> Stockton, <br /> - <br /> Stockton,California <br /> Sierra-Pacific Project No. 94-055.05 <br /> ' 4.6 Observation Well Development and Step-Draw-Down Pumping Tests <br /> Approximately 72 hours after installation,the observation wells will be thoroughly developed to remove <br /> ' residual drilling materials from the well casing, and to improve well performance by removing fine <br /> material from the filter pack that may pass into the well. Well development techniques used may include <br /> pumping, surging, bailing, swabbing,jetting, flushing, and air-lifting. To minimize the potential for <br /> cross-contamination between wells, all development equipment is either steam cleaned or properly <br /> washed prior to use. The new well will be developed by purging with a pump for a period sufficient to <br /> grade the filter pack and flush fine-grained sediments from the well. The well will then be allowed to <br /> settle and equilibrate for at least 72 hours prior to ground-water sampling and further well testing. <br /> ' The nested test wells will be developed by pumping and swaging. Step-draw-down pumping tests will <br /> be done to estimate potential pumping rates. Pumping test results will also help determine if aquifers <br /> ' are unconfined and connected, leaky, or confined. <br /> The step-draw-down tests will involve isolating a specific aquifer. A relatively low pumping rate will <br /> tbe maintained, and the water level of the well will be documented until the water level reaches <br /> equilibrium. The pumping rate will be stepped-up and pumping will continue until equilibrium is <br /> reached. The greater pumping rate will result in additional draw-down. The process will be repeated <br /> again. An estimate of the maximum pumping rate can be obtained for each aquifer by observing the <br /> ' pumping test results and by graphing the pumping rates versus draw-downs. After performing step- <br /> draw-down tests on all of the isolated aquifers,Sierra-Pacific will estimate the anticipated pumping rate <br /> for the proposed pumping well. <br /> 4.7 Purge Water Storage and Disposal Options <br /> ' Several thousand gallons of purge water will be generated during the installation, development, and <br /> testing of three new wells at the Giglio property. Several large portable polyethylene tanks will be staged <br /> ' at the site to temporarily store purge water. <br /> ' Water generated during the pumping tests will be analyzed for the contaminants known to be present. <br /> Based upon the analytes present in ground water at the site,various options for treatment of purge water <br /> ' SIERRA-PACIFIC GROUP 9 <br /> 1 <br />