ARCHIVED REPORTS_XR0006041 - Laserfiche WebLink

Home Browse Search

I04 February 2004 AGE-NC Project No 95-0173 IPage 7 of 10 3 2 CONSTANT RATE GROUND WATER PUMPING TEST The constant-rate pumping test consisted of extracting ground water from well EW-1 at a rate of 5 GPM, the pumping test was terminated after 500-minutes hours (8 3 hours) due to the apparent stability of ground water draw-down at well EW-1 and the surrounding observation wells Therefore, AGE determined that the data collected from the 500-minute aquifer pumping test was adequate to evaluate general ground water aquifer characteristics at the site At the termination of the 500-minute constant-rate pumping test, the maximum ground water drawn-down in well EW-1 was measured at 7 71 feet, and draw-down was measured in wells AW-1A/AW-1B, AW-2A/AW-2B, AW-4, MW-2 and MW-3 at between 0 27 feet and 0 56 feet (Table 3), significant draw-down was not observed at well MW-1 Utilizing the draw-down data collected at 500 minutes of pumping operation, the ground water draw-down in observation wells AW-1 (A and B), AW-2 (A and B), AW-4, MWA, MW-2 and MW-3 versus the distance of each well from the extraction point were graphed on semi-loganthmic paper Utilizing the Distance- Drawdown Method (Jacob straight-line method), general transmissivity, storativity and hydraulic conductivity values were determined (Appendix K) Ground water levels in all observation wells except MW-1 appeared to be influenced with measurable draw-down during the pumping test Utilizing data collected from extraction well EW-1 and the above referenced observations wells, a I transmissivity value was calculated at 565 W/day, a storativity value calculated at 0 11, a hydraulic conductivity value of 0 008 cm/s and a radius of influence projected at 62 feet utilizing a semi- logarithmic plot of draw-down versus distance (Appendix K) Results of the aquifer ground water pumping test are summarized in Table 4, a site plan depicting the radius of influence during the 11 July 2003 pumping test is depicted in Figure 4 33 EXTRACTED WATER SAMPLING PROCEDURES I Approximately 7,500 gallons of extracted ground water was generated from the 09 and 11 July 2003 ground water aquifer pump testing activities Prior to discharge into the 10,000-gallon Baker tank on 1.1 July 2003,grab ground water samples were collected at the 45-minute time interval(0830 hr), at the 240 minute time interval(1145 hr)and at the 333-minute time interval(1318 hr)utilizing three 40-m1 EPA-approved VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative Following sample collection,each preserved sample was logged on a chain-of-custody form,placed in a chilled container and transported to a California Department of Health Services(DHS)-certified laboratory for analysis for • TPH-g by EPA Method 5030/8015Cm, Advanced GeoEnvironmental,Inc