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' 09 October 2001 • AGE-NC Project No 95-0144 Page 4 of 5 ' 2 5 PURGED GROUND WATER DISPOSAL On 13 June 2001, the ground water extracted during the pumping test was pumped from the ' aboveground storage Baiter tank into a vacuum truck(supplied by Amencan Valley Waste Oil), the purged water was transported off-site under non hazardous waste manifest to Industnal Service Oil Co Inc , a waste treatment facility located in Los Angeles, California Documentation and uniform hazardous waste manifest for disposal of the pump test purged water is contained in Appendix F ' 3.0. SUMMARY AND CONCLUSIONS ' The implications from the May 2001 aquifer ground water pumping test are • Ground water draw-down of at least 6 90 feet was observed in extraction well EW-1 following 7 hours of continuous pumping operation at a rate of 6 gpin, ground water draw- down was observed in well MW-21A (located 14 feet to the northeast) at 0 48 feet, well MW-19A(located 30 feet toward the south) at 0 18 feet,well EW-2(located 45 feet toward E ,i the north) at 0 09 feet and in well MW-20A (located 60 feet toward the north) at 0 07 feet (Table 2, Appendix B) • Utilizing a semi-logarithmic plot of ground water draw-down vs observation well distance ' to pumping well(Jacob straight-hne method), a best-fit line can be utilized to project a radius of influence of approximately 65 feet at 6 gpm(Appendices C and D) ' • Utilizing the Distance-Drawdown Method(Jacob straight-line method), a transmissivity was calculated at 636 ft2/day (equivalent to 4,750 gallons per day/ft) and a storativity value calculated at 0 019 (Appendix D) ' • Based on a transmissivity value of 636 ft'/day and the upper water zone aquifer thickness equal to 25 ft (screen interval'at EW-1), a hydraulic conductivity value was calculated at ' 190 ft/day, or 0 067 cm/s (Appendix C), a hydraulic conductivity of 0 067 cm/s is consistent with a screened interval located within silty to clean sand (Appendix G) • Laboratory analysis of extracted water during the pumping test detected elevated concentrations of TPH-g, TPH-d and BTEX compounds (Appendix E) • The,increased depth to ground-water observed in the deeper-screened observation wells (MW-19B, MW-20B, MW-2113) does not appear to be pumping-induced draw-down The similar values recorded (MW19B - 0 21 feet, MW20B - 0 20 feet, MW21B - 0 22 feet) despite vaned distances from the pumping well(15 to 60 feet) suggest an external influence ' not related to the pumping test (i e , tidal effect, other local ground water pumping) Advaneed GeuEnvtronment4 Inc 1