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4 0 CONCLUSIONS AND RECOMMENDATIONS <br /> Between March 19, and .lune 26, 2002, the groundwater surface dropped an average of 3 84 feet, <br /> the groundwater gradient increased from 0 0053 to 0 0095 foot/foot, and the groundwater flow <br /> direction shifted less than five degrees to the east Over the past eight quarters, the groundwater <br /> flow direction has shifted between north-northwest and north-northeast, over a range of <br /> approximately 45 degrees <br /> Consistent with previous results, gasoline compounds in the groundwater monitoring wells are <br /> tconcentrated in MW-2, on the north side of the dispenser island complex For the first time, the <br /> groundwater sample collected from MW-4 was free of detectable concentrations of MTBE Over <br /> the past eight quarters, the concentrations of gasoline compounds in the groundwater monitoring <br /> ' wells have declined significantly, possibly due to previous source removal efforts The plume of <br /> MTBE at the groundwater table appears to be contracting, declining in concentration, and limited <br /> to the vicinity of MW-2 The plume remains undefined to the north <br /> Based on the sample results from the water supply and residential wells, and CPT and discrete <br /> groundwater sampling data, the vertical and horizontal extent of impacted groundwater appears to <br /> be defined to the first groundwater beneath the site Concentrations of MTBE detected below the <br /> groundwater table at CPT-4 in September 2000 were not found in the same interval at CPT-4A in <br /> June 2002 This decline in concentration may also be a result of source removal efforts, natural <br /> attenuation, and/or dissolution processes <br /> Based on these results, Ramage Environmental recommends that the two approved groundwater <br /> ' table monitoring wells be installed, as proposed Installation of these monitoring wells is currently <br /> pending encroachment permitting and contractor scheduling <br /> 16 <br /> 1 <br />