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4 May 1995 <br /> >: AGE-NC-95-0118 <br /> Page 3 of 4 <br /> i. <br /> 3.2. GROUND WATER SAMPLE COLLECTION AND ANALYSIS <br /> Water samples were collected from each well using a new disposable plastic bailer. Samples <br /> were collected in 40-m1 EPA vials. The samples were logged on a chain-of-custody form, <br /> placed in a chilled container and transported to McCarnpbell Analytical Inc. (MAI) in <br /> Pacheco, California. Each sample was analyzed for TPH as gasoline and BTE&X in <br /> accordance ivitli EPA methods 5030 and 602, respectively. <br /> The laboratory report and chain- <br /> of-custody are presented in Appendix B. <br /> . 4.0. FINDINGS <br /> 4.1. RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The relative elevation of ground water in each well was calculated by subtracting the ground <br /> ak water depth frons the surveyed relative casing elevation (Table 1). The ground water <br /> elevation rose approximately two feet between December 1994 and.March 1995. <br /> 'a The hydraulic gradient was calculated to be 0.0097 ft/ft directed S 37° W (Figure 3). The <br /> flow direction has shifted 180° from the flow direction measured in December 1994. <br /> r,..� <br /> 42. LABORATORY EVIDENCE OF GROUND WATER CONTAMINATION <br /> TPH as gasoline was detected in water samples from MW-1, MW-2 and MW-3 at <br /> concentrations of 61 ppb, 29,0.00 ppb and 780 ppb, respectively. Elevated concentrations of <br /> BTE&X were detected in samples from NIW-2 and MW-3 at concentrations ranging from <br /> 94 ppb (etlrlybenzene, MW-3) to 5000 ppb, (toluene, MW-2). Toluene was the only <br /> purgeable aroirratic detected in MW-1 at 0.85 ppb. The analytical results of the samples are <br /> f listed in Table 3. The laboratory report and. chain-of-custody are included in Appendix B. <br /> 5.0. CONCLUSIONS & RECOMMENDATIONS <br /> 5.1. HYDROCARBON-IMPACTED SOIL <br /> Hydrocarbon-impacted soil remains at the site in the area of the former UST excavation. <br /> Based upon analytical results of soil samples, it likely that MW-3 is near the edge of the <br /> impacted soil plunge. <br /> The proposed monitoring well borings should establish the lateral extent of impacted soil. <br /> Subsequently, rerrledial options for the impacted soil will be addressed. <br />