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27 February 1997 <br /> AGE-NC Project No. 96-0273 <br /> • Page 4'of 5. <br /> L.. <br /> 4.1 LABORATORY RESULTS OF PROBING GROUND WATER SAMPLES <br /> TPH-g was detected in two of three grab water samples at concentrations as high as 28,000 parts per <br /> r billion (ppb, reported as micrograms per liter)..BTE&X were also detected in two of three grab <br /> ground water samples at concentrations up to 4,700 ppb (toluene, P2). The maximum benzene <br /> concentration was 140 ppb(P2). Low concentrations of TPH-g and toluene,ethylbenzene and xylene <br /> were detected in.the water sample collected from probe boring P3. . <br /> Detectable concentrations of petroleum hydrocarbons were not present in the water sample collected <br /> 3 from probe boring P 1. MTBE was not detected in any of the grab water samples collected. <br /> Analytical results from the grab ground water samples are summarized on Table 2 - Analytical <br /> Results of Water Samples:The laboratory report(MAI LaboratoryID 71349 through 7135. 1),'QA/QC <br /> report and chain-of-custody are presented in Appendix-A. <br /> R <br /> 5.0. CONCLUSIONS AND RECOMMENDATIONS <br /> w <br /> 5.1. CONCLUSIONS <br /> The following conclusions were drawn from the results of this investigation: <br /> • On 18 November 1996, ground water depth at the site was approximately 12 feet bsg. <br /> • Hydrocarbon-impacted soil has been encountered at a depth of 10 feet bsg,just on or above <br /> LM the capillary fringe or saturated zone. Hydrocarbon-impacted soil appears to be limited to the <br /> former 350-gallon UST excavation area. <br /> +— Based on analytical results of ground water samples collected from probe borings, <br /> hydrocarbon-impacted ground water is limited to the immediate area surrounding the former <br /> 350-gallon UST excavation. <br /> R <br /> �.. 5.2. RECOMMENDATIONS <br /> Based on the results of this investigation, AGE recommends the following: <br /> • The agricultural well 30 feet from UST, a domestic well is 90 feet from UST are both <br /> sensitive receptors, especially since reported ground water-flow direction is toward the <br /> northeast, toward the wells. We recommend an expedited additional assessment of ground <br /> v - <br />