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' approximately 65 feet at 5 GPM Utilizing the Distance-Drawdown Method, a �) pp Y g transmzssivity was calculated at 205 ftZ/day (equivalent to 1,536 gallons per day/ft) and a ' storativity value was calculated at 0 054 • Based on a transmissivity value of 205 ft'/day and the extraction well screen thickness ' equal to 25 ft (screen interval at EW-1), a hydraulic conductivity value was calculated at 6144 ft/day, or 0 022 cm/s, a hydraulic conductivity of 0 022 cm/s is consistent with a screened interval located within a well sorted sand to clean sand ' Laboratory analysis of extracted water during the pumping test detected elevated concentrations of TPH-g, BTEX and MTBE ' On 05 and 06 June 2001 four ground water monitoring wells were installed off-site as part of the investigation Borings MW13 through MW16 were completed as ground water monitoring wells ' MW-13 through MW-16 MTBE was detected in the soil samples collected from thirty feet bsg from borings MW15 and MW16, these concentrations may be more reflective of impacted ground water in the pore spaces of the soil than of adsorbed MTBE ' The highest concentration of dissolved hydrocarbons quantified as TPH-g, TPH-d and overall BTEX compounds occurs in the areas east and northeast of the dispenser islands, on-site The highest concentration of MTBE detected in the ground water occurs in monitoring well MW-11, which is situated in the median of Pacific Avenue Lower or non-detectable concentrations in the ' .y down-gradient and cross gradient wells define the dissolved MTBE plume toward the north and west This suggests that the dissolved MTBE plume is detaching from the TPHBTEX hydrocarbon plume ' In September and October 2001, a low-flow, ground water extraction and treatment system was installed at the site The system utilizes the newly installed ground water extraction well on site and a small volume treatment system As of March 2005 a total of 2,712,799 gallons of water have been extracted since the inception of ground water treatment in October 2001 and a total of 10 54 lbs of MTBE, 4 81 lbs of BTEX and 73 12 lbs of TPH-g have been removed since October ' 2001 On 04 and 05 February 2003 two additional ground water monitoring wells were installed off- site as part of the investigation Boring MW17 was completed as ground water monitoring well MW-17 using two-inch diameter PVC casing with 0 020-inch slotted screen installed from approximately 25 feet to 45 feet bsg and boring MW18 was completed as ground water monitoring well MW-18 using two-inch diameter PVC casing with 0 020-inch slotted screen installed from approximately 60 feet to 65 feet bsg anct with blank casing extended to the surface