ARCHIVED REPORTS_MONITORING WELL INSTALLATION REPORT - SITE ASSESSMENT WORK PLAN

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' 25 February 2005 AGE-NC Project No. 98-0500/04-1127 Page 5 of 7 generally encountered from 30 feet to 55 feet bsg. Silty sand or sand was observed from 55 feet to 65 feet bsg. Silt and clay were encountered from 65 feet to 85 feet bsg,where no soil was recovered except for heaving sand.Generally,silt and clay was encountered below a depth of 90 feet bsg,until silty sand was encountered at approximately 185 feet bsg to the total depth of the soil boring. 3.2. FIELD EVIDENCE OF HYDROCARBON-IMPACTED SOIL Hydrocarbon vapors was detected in samples collected below a depth of 50 feet bsg.Samples above 50 feet bsg did not generally exhibit hydrocarbon odor or have detectable readings on an OVM.The t samples from 55 feet to 65 feet bsg had detectable reading as high as 1,400 parts per million(ppm) in sample MW37-65.This reading overwhelmed the organic detector in the OVM and readings were no longer collected. Generally,hydrocarbon odors were observed in samples collected from 55 feet to 95 feet bsg. 3.3. ANALYTICAL RESULTS OF SOIL SAMPLES '• TPH-g was detected in two soil samples collected from boring MW37-60 and MW37-70 bsg, at concentrations of 470 milligrams per kilogram (mg/kg) and 5.4 mg/kg,respectively. BTEX compounds were detected in the two soil samples MW37-60 and MW37-70 with the TPH-g detections; the highest concentration of BTEX were 1.6 mg/kg benzene, 6.1 mg/kg toluene, 3.4 mg/kg ethylbenzene and 23 total xylenes. TBA was detected in one soil sample, MW37-70 at a concentration of 0.036 mg/kg.In addition, 1,2-DCA was detected in nine soil samples. The highest detection of 1,2-DCA was in sample MW37-60 at 0.19 mg/kg, while concentrations decreased in the deeper soil samples. A total of nine sample of the ten analyzed contained low, yet detectable, ' concentrations of 1,2-DCA. EDB was detected in the sample MW37-60 at 0.052 mg/kg. No other target analytes were detected in the soil samples analyzed. Analytical results are ' summarized in Table 1. The laboratory report(MAI Work Order 0501154), quality assurance and quality control (QA/QC) and chain of custody are included in Appendix D. 3.4. GROUND WATER ELEVATION AND GRADIENT The depth to ground water for intermediate monitoring MW-36 was 56.33 feet bsg and the ground water in the well only re-charged to a depth of 140 feet after the well was purged approximately 30 ' gallons. The depth to ground water for the deeper monitoring MW-37 was 52.86 feet bsg and the ground water in the well re-charged to a depth of 52.92 feet after the well was purged approximately • 70 gallons. ' Advanced GeoEnvironmental,Inc.