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7kadwell&Rdlo <br /> encountered, but the geophysical signature of the anomalies did not appear to be ferrous metal <br /> objects such as a UST. <br /> On 5 August 1999, Treadwell & Rollo observed the quarterly groundwater monitoring conducted <br /> by Wallace Kuhl &Associates Inc. at Area 21, and collected duplicate samples from monitoring <br /> wells MW-1 through MW-6 for laboratory analyses. The locations of the monitoring wells are <br /> shown on Figure 7. Analytical results are given in Tables 5, 6, and 7. <br /> On 20 September 1999, a geoprobe direct push rig was used to collect 15 soil samples at five <br /> locations. Soil borings 21B-1 through 21B-5 were pushed to a depth of 10 feet. Soil samples <br /> were collected at the depths shown in the boring logs in Appendix C and locations shown on <br /> Figure 9 and analytical results are presented in Table 1 of the Treadwell & Rollo report. <br /> Significant concentrations of petroleum hydrocarbons are present at Area 21. Three of the five <br /> groundwater monitoring wells sampled during the 1999 Treadwell & Rollo investigation. MW-0 <br /> had detectable concentrations of TPH-g, TPH-d and BTEX compounds. The highest • <br /> concentrations of TPH-g and TPH-d were encountered in MW-5 at 20.9 and 1.74 mg/1 <br /> respectively. Benzene was detected in monitoring wells MW-4 and MW-5 at from 3.36 to <br /> 3.31 mg/I respectively. Minor amounts of non-chlorinated volatile and semi-volatile organic <br /> compounds were detected in groundwater at monitoring well MW-5. <br /> No petroleum fuel hydrocarbons or volatile organic compounds were detected in soil analyzed <br /> during the Treadwell & Rollo 1999 investigation. However, it should be noted that this study did <br /> not include investigation of the immediate area of the former UST, where soil contamination is <br /> known to exist. A minor amount of semivolatile organic compounds were detected in one soil <br /> sample but at concentrations below EPA Residential PRGs. One surface soil sample had a total <br /> lead concentration of 440 mg/kg, while 10 other samples contained less than 36 mg/kg. <br /> 16 • <br /> 25970309.DGD 24 August 2000 <br />