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�'� �»x� J �,• t �.. �, �� -� .r .u 4i�'' ��+ ,;k i rT�U �.� ',r`u "ft..�. x(^� <br /> goa- <br /> On October 10, 1985, EMCON Associates sampled all wells for hydrocarbon <br /> contamination. An acrylic thief bailer was used to determine if a <br /> second liquid phase (gasoline or a gasoline derivative) was floating on <br /> the ground water. Five wells (E-2, E-4, E-6, E-10 and E-11) had <br /> evidence of floating petroleum product, which ranged from 1/16 to <br /> 3/16-inch (see Figure 8). <br /> In wells where no floating petroleum product was observed, a ground- <br /> water sample was collected for laboratory analysis of dissolved constit- <br /> uents. Prior to sampling, the wells were purged by removing <br /> approximately three casing volumes of ground water. The samples were <br /> obtained with a teflon bailer and were labeled, recorded on a chain-of- <br /> custody form, and transported to the laboratory on ice. The samples <br /> were analyzed for benzene, toluene, and xylene isomers (BTX), and for <br /> _. total hyerocarbons. This analysis was performed according to EPA <br /> Method 602, a purge-and-trap/gas chromatography technique using a photo- <br /> ionization detector (Appendix 8, Chemistry Data). Total dissolved <br /> ry-ti gasoline constituents ranged from 430 ppb in Well E-7 to 80,000 ppb in <br /> E-3. Figure 8 shows the distribution of floating product thickness and <br /> dissolved gasoline constituents at the site in October 1985. <br /> A review of the Gettler-Ryan monitoring data shows a significant reduc- <br /> tion in the levels of floating product (see Table 1), since the system <br /> has been operating. Initial thicknesses of free product ranged from <br /> v .16 to 3 feet in seven of the monitoring wells before extraction began <br /> In May 1984. During the latest monitoring in January 1986, product <br /> thickness in all wells has been reduced to nearly non-detectable. <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> The present recovery system at the site appears to be sufficiently <br /> capturing water from all the wells on site. It is anticipated that <br /> little or no additional floating product is available for capture by <br /> -- this system, in the future. Therefore, EMCON recommends that ARCO <br /> PJO 438-22.04 g <br /> EM(On Associates <br />