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CLEARWATER ' G R O U P • Env:ronmentai Servoces ' Feasibility Test Results and Discussion ' Groundwater Extraction from DPW-1-March 12, 2002 At the initiation of the test, static depth to water at the initiation of the test was approximately 10 7 feet bgs An initial pumping rate of 1 0 to 1 5 gpm resulted only in a drawdown of less than 5 feet The pumping rate was then ' increased to 1 75 to 2 25 gpm to achieve a drawdown of approximately 15 feet Once this drawdown was achieved, the pumping rate was reduced to 1 75 gpm to attempt to maintain to water level near 25 feet bgs Pumping then ' continued for approximately one hour at a pumping rate of l 75 gpm and the water level was maintained between 24 and 25 feet bgs Over 200 gallons of groundwater was pumped from DPW-1 on March 12,2002 ' Throughout the step testing, drawdown was measured in nearby wells MW-513, MW-1, MW-6, and MW-7 Well MW-5B, which is the nearest to DPW-1 by approximately 10 feet, experienced a maximum drawdown of 1 36 feet ' below the initial water level measurement before pumping in DPW-1 began No drawdown was witnessed in wells MW-1,MW-6 and MW-7 GWE test data is included in Table 3 ' The groundwater sample collected at the end of the step-test contained elevated concentrations of contaminants The • water sample contained TPHg at 42,000 µglL and benzene at 6,300 lig/L, but MTBE was not detected Table 2 ' summarizes the analytical data of collected groundwater samples Table 3 summarizes GWE data The laboratory analytical report and chain-of-custody is included in Appendix C t The results of step-test indicate that a pumping rate of approximately 1 75 gpm could sufficiently dewater the well to P P P S ' provide approximately 15 feet of non-submerged well screen prior to beginning soil vapor extraction It was anticipated that once SVE testing began, a greater pumping rate would be required with each increase in vacuum, since applying a vacuum to the well would draw the water upwards 1 Dual-Phase GWE/SVE Test Results—March 13, 2002 ' Prior to initiating SVE, well DPW-1 was dewatered to approximately 25 feet bgs Once SVE step testing began a pumping rate of 2 1 to 2 2 gpm(10 to 40 in w c)and 2 5 gpm(50 in w c) was required to maintain the water level at 25 feet bgs, so that at least 15 feet of well screen was not submerged for SVE During the combined GWE/SVE ' test, application of moderate vacuums(10 and 20 inches of water)at DPW-1 with 15 feet of screen available resulted in air flows at DPW-1 between 2 3 and 6 0 cubic feet per minute (cfm) from the well Application of vacuums ' ranging from 30 to 40 in w c resulted in flow rates ranging between 6 and 8 5 cfm A vacuum of 50 in w c achieved flow rates between 10 and 11 in w c Therefore, there did appear to be a direct relationship between the ' increase in vacuum and increase in air flow in DPW-1 as demonstrated in Table 4 and the associated chart 1 ZB178C Feas Test Report 6 May 9, 2002