ARCHIVED REPORTS_XR0003771 - Laserfiche WebLink

Home Browse Search

15 February 2000 AGE-NC Project No 98-0448 Page 12 of 33 ' 51 PROCEDURES The pump test consisted of extracting ground water from well EW-1 utilizing a 4-inch diameter Grundfos Redl-flo pump into a 6,500-gallon aboveground Baker storage tank The pump test utilized ' pressure transducers that were deployed in wells MW-1, MW-2, MW-4A and EW-1 to measure difference In ground water levels during ground water pumping, ground water level measurements ' were continuously recorded utilizing an Aqulstar data logger(Appendix A) The pumping rate was determined by measuring the time required to fill a 5-gallon bucket from the Ipumping discharge hose Initially, ground water was pumped from EW-1 at a rate of 13 gallons per minute (gpm) but was decreased to 8 GPM afer 8 minutes of pumping operation and was then increased to 10 GPM after 40 minutes Approximately 4,500 gallons of purged ground water were ' removed from EW- 1 during operation of the pump test Draw-down versus time for wells MWA, MW-2, MW-4A and EW-1 was graphed on semi- lognthmnc paper (Appendix J) Utilizing the Jacob straight-line method, the transmnssivity and storativnty for each well were determined(Appendix K) The radius of influence was then determined by graphing the draw-down in each well at a specific time versus distance (Appendix J) Following the ground water pump test, a ground water sample was collected from the 6,500-gallon aboveground storage Baker Tank utilizing a new, disposable polyethylene bailer and four 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a preservative Care was taken to ensure that visible air bubbles were not present in the vials after filling and capping Ground water sample containers were labeled with the sample location, date, time, and sampler's Initials Each ground water 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 I, for TPH-g by EPA Method 8015 Modified and BTEX/MTBE by EPA Method 8020 52 GROUND WATER PUMP TEST RESULTS Pumping rates fluctuated between 8 and 13 GPM during the pump test The greatest draw-down from Iextraction well EW-1 was observed at 22 5 feet after 160-minutes of pumping operation, however, at this time draw-down from MW-4A(located 4 feet to the south) was observed to be approximately 1 22 feet, draw-down from MW-2 (located 10 feet to the northwest) was observed to be approximately 1 15 feet, and draw-down from MW-1 (located 15 feet to the west-southwest) was observed to be 0 74 feet The transmissnvlty value for well EW-1 was calculated at 347 5 gai/day-ft , transmnsslvlty values from MW-1,MW-2 and MW-4A ranged between 4,185 gal/day-ft and 9,533'gal/day-ft Calculations Advanced GeoEnviron mental,Inc I .