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i <br /> IDISTRIBUTION OF 1,2-DCA <br /> • A release of 1,2-DCA mostly likely occurred from dispenser line releases However no <br /> samples from the UST removal or soil bonngs until the most recent had been analyzed for this <br /> compound <br /> • Five soil sample collected from the below the former UST area,from a boring for a deep well <br /> installation have detections of 1,2-DCA These sample were collected from between from <br /> between sixty-five and eight-five feet bsg The true distribution of 1,2-DCA within the vadose <br /> rzone is uncertain Once released to the subsurface, the 1,2-DCA contaminant migrated to a <br /> vertical depth of approximately 85 feet bsg at the former UST area The 1,2-DCA, has <br /> physical properties (readily higher vapor pressure, low Henry's Law Constant and higher <br />' aqueous solubility or the tendency to remain dissolved)which cause the highest impact to site <br /> to remain in the dissolved phase 1,2-DCA is the most widespread contaminant released at <br />' the site 1,2-DCA extends vertically to a depth of 130 feet bsg at concentrations of 100's, <br /> while lower concentrations in the 10's,remain at the depth of 150 feet bsg in the former UST <br /> area Laterally, 1,2-DCA extends into almost ever well on site, at low concentrations west <br />' and south Significant concentrations are detected in the wells established directly west of the <br /> former UST area, lower concentrations in the magnitude of the 10's are present in the wells <br /> established in the western end of the building and further west of the building The 1,2-DCA <br /> tis defined north and east of the site,though momtonng well sampling and soil boring samples <br /> • 1,2-DCA was detected in samples at concentrations ranging from 4 2 µg11 to 1,600 �ug/l, <br /> which are above the MCL of 0 5 µg/1 for drinking water The investigations to date suggest <br />' that the source of the 1,2-DCA is the former UST site <br /> The vertical extent, and the lateral extent between intermediate- and deep-screen ground <br /> water depths, of 1,2-DCA have not been defined <br /> ' Advaneed GeoEnvrronmental,Inc <br />