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THE COLORAL _ .,crARTMENT OF HEALTH <br />Hazardous Materials and Waste R~~,',C~ <br />Management Division gpRl ~ ~Fj~ <br />~;. <br />M E M O R A N D U M ~•' ~. `~ ~99q <br />"'•-~~ . <br />f ~~~ <br />' C~( `~o <br />TO: Derald Lang, WQCD <br />FR: Ken Telleen, HMWMD <br />16 March 1994 /~~ <br />RE: Fate of water extracted from Leyden gas storage facility <br />The old Leyden coal mine west of Arvada (an underground mine, roughly 700' below ground) <br />is currently used as a natural-gas storage facility by Public Service Company of Colorado. PSC <br />pumps water out of the mine in order to make room for the gas, which is stored there as a <br />reserve against high winter demand. In 1990, PSC acquired an NPDES permit so that it could <br />dispose of extracted water into Leyden Creek. <br />Shortly after obtaining the NPDES permit, PSC ceased disposing into Leyden Creek, and so was <br />no longer required to submit regular analyses to CDH. PSC began to pipe the water to Pioneer <br />Sand and Gravel, a nearby operation in Leyden Gulch. Afrer being used for washing at Pioneer, <br />the water either evaporates or seeps into the ground. This seepage may be a basis for WQCD <br />to require that either PSC or Pioneer apply for a groundwater discharge permit. <br />Hazardous constituents in the ground water are of concern here because the old coal mine extends <br />neazly beneath Rocky Flats Industrial Park. RFIP has been the site of an EPA removal of <br />hundreds of drums of used solvents and other hazardous wastes, and both soil and groundwater <br />at the site remain severely contaminated with both chlorinated solvents and metals. Some of tine <br />chlorinated solvents are sufficiently concentrated that they probably exist in sepazate-phase <br />("DNAPL") pools. This contamination raises the possibility that water in the Leyden mine is <br />contaminated, or could become contaminated at any time as the DNAPLs migrate. In that case, <br />analyses of Leyden mine water -possibly done under the requirements of an NPDES permit - <br />would be important indicators of the fate of contaminants in RFIP groundwater. They would also <br />indicate whether segments of the public may be exposed to significant contamination. <br />I would be happy to furnish additional information about the PSC-Pioneer operation or about <br />Rocky Flats Industrial Pazk, if that would be of use to you. <br />wgcdpsc.mmo / p. 1 of 1 <br />