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20 October 1995 <br /> AGE-NC Project No 95-0111 <br />' Page 2 of 4 - <br />' Prior to March 1995, ground water samples have been collected on three occasions from each well W <br /> at the site The depth to ground water at the site is approximately 8 feet, with a prevailing flow <br /> direction to the north to northeast <br /> 3.0. PROCEDURES <br />' 3 1 MONITORING WELL PURGE PROCEDURES <br /> IOn 13 July 1995, the water level in each monitoring well was measured relative to the top of the <br /> casing using a Solinst water level meter Free product was present in MW-4, therefore an MMC <br />' interface probe was used to measure free product thickness After water levels were measured;a <br /> two-stage submersible pump was used to purge each well Three to five gallons (minimum.three well <br /> volumes) of water were removed from each well until temperature, pH and conductivity had <br />' stabilized(Appendix A) A bailer was used to remove free product from MW-4 prior to purging with <br /> the submersible pump Stabilization parameters were measured at one-gallon intervals using an ICM <br /> water analyzer Purged water was stored on-site in 55-gallon DOT drums <br /> 3 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each well using a new disposable plastic bailer Each water <br /> sample was collected in two 40-m1 VOA vials and one 1-liter amber bottle After collection, the <br /> I samples were placed in a chilled container and transported under chain-of-:custody procedures to <br /> McCampbell Analytical, Inc (MAI) in Pacheco, California Each sample was analyzed for total <br /> petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d) and volatile aromatics <br /> (benzene, toluene, ethyl benzene and xylenes BTE&X) in accordance with EPA methods <br /> 5030/8015m and 602, respectively <br /> 4.0. FINDINGS <br />' 4 1 GROUND WATER GRADIENT AND DIRECTION <br /> The relative elevation of ground water in each well was calculated by subtracting the depth-to-water <br /> from the surveyed relative casing elevation (Table 1) All wells were surveyed relative to MW-1 The <br /> relative ground water elevation ranges from 10 53 feet in MW-4 to 1125 feet in MW-3 Ground <br /> water elevation decreased an average of 0 75 feet at the site between March 1995 and July 1995 Free <br /> product thickness was measured in MW-4 at 1 5 inches <br /> 4 <br /> IThe ground water gradient was calculated`to be 0 0053 ft/ft directed N 34° E (Figure 3) The <br />