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September 26, 1990: Alton Geoscience personnel supervised the <br /> installation of ground water Monitoring Wells AW-1 through AW-4. <br /> The monitoring well locations are shown in Figure 2. The <br /> findings and conclusions from this and past site investigative <br /> work, and from the results of laboratory analyses and field <br /> observations of the preliminary ground water investigation, are <br /> presented in the Alton Geoscience report dated December 14 , 1990. <br /> April 30 and May 1, 1991: Alton Geoscience conducted a <br /> supplemental site investigation by drilling additional soil <br /> borings (B-1 through B-9) . Soil Borings B-2, B-3, B-4 , and <br /> B-9 were subsequently converted to ground water Monitoring Wells <br /> AW-5, AW-7, AW-6, and AW-8. The monitoring well locations are <br /> shown in Figure 2 . <br /> May 7, 1991: Alton Geoscience performed monitoring and sampling <br /> of ground water Monitoring Wells AW-1 through AW-8. Ground water <br /> samples were analyzed for TPH-G, TPH-D, and BTEX, except AW-1 and <br /> AW-3, which were also analyzed for fecal coliform. Petroleum <br /> hydrocarbon constituents were not detected above method detection <br /> limits in the samples, except AW-3, which had detectable <br /> concentrations of TPH-G (210 ppb) , ethylbenzene (0.3 ppb) , and <br /> total xylenes (0. 8 ppb) . The findings from the supplemental <br /> investigation are presented in the Alton Geoscience report dated <br /> July 9, 1991. <br /> August 21, 1991: Alton Geoscience monitored and sampled <br /> Monitoring Wells AW-1 through AW-8. Results of this sampling <br /> event were reported in a quarterly report dated January 21, 1992 . <br />