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I22 July 2002 <br /> AGE-NC Project No 97-0312 <br />' Page 3 of 5 <br /> y <br />' 23 PURGE WATER DISPOSAL <br /> On 05 June 2002, approximately 250 gallons of non-hazardous purge water was pumped from on- _N <br />' site 55-gallon'drums The purge water had been generated during previous ground water monitoring <br /> events Pumping and disposal was completed by American Valley Waste Oil, Inc of Delhi, <br /> California The purge water was disposed at Riverbank Oil Transfer located in Riverbank,California <br />' A copy of the waste disposal manifest is included in Appendix C <br />' 3.0. FINDINGS <br /> } <br /> Ground water elevations were determined by subtracting the measured depths-to-water from the N <br />' surveyed casing elevations (Table 1) Ground water flow direction was determined by contouring <br /> the water elevations on a scaled site plan (Figure 4) Hydrocarbon-impact to ground water was <br /> assessed by laboratory analysis and field observations <br /> 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> Depths to ground water at the site ranged between 60 83 to 61 77 feet below surface grade (bsg), <br /> ground water elevations were between 32 73 feet (UST-1) and 32 85 feet(UST-5)below mean sea <br /> level (MSL) The ground water elevation had decreased by an average of 1 84 feet since the <br /> 11 February 2002 monitoring event <br />' The ground water table occurred within the screened intervals of monitoring wells UST-5 and <br /> UST-6, but was between 3 5 and 4 2 feet above the screened intervals in monitonng wells UST-2 <br />' through UST-4 Monitoring well UST-1 was a deep-screen well (screened between 82 and 102 feet <br /> bsg), the ground water table was approximately 20 2 feet above the screened interval of this well <br /> t <br />' General ground water flow direction at the site was inferred to be easterly with an average gradient <br /> of approximately 0 0001 feet/feet or less Figure 4 depicts the ground water elevation contours for <br /> June 2002 <br /> Monitoring data from UST-2,UST-3 and UST-4 was combined with monitoring data collected from <br /> the adjacent Moore Truck Lines property to determine an,approximate regional ground water flow <br />' direction,however,the two sets of ground water data do not appear to correlate during the June 2002 <br /> monitoring event <br />' l Advanced Geo E nviron mental,Inc <br />