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Cl III 'lll�llll��I11�� L • CONSTRUCTION • COMPLIANCE <br /> 999 <br /> RECE"VED <br /> jU! 0 2 20-01 <br /> Division of Minerals and Geology <br /> June 26, 2000 <br /> Mr. Roger Doak <br /> Colorado Department of Public Health and Environment (CDPH&E) <br /> Hazardous Materials and Waste Management Division <br /> 4300 Cherry Creek Drive South <br /> Denver, CO 80246-1530 <br /> RE: Response to Comments <br /> Proposed Varra Coal Ash Proposal — Work Plan and Analytical Data <br /> Weld County, Colorado <br /> CORS No. 1-135-2755 <br /> Dear Mr. Doak: <br /> This letter address issues presented in )'our correspondence and attachments dated May 3"'. 1999. <br /> regarding our submittal for performing a pilot test for gravel quarry reclamation utilizing coal ash <br /> in saturated conditions. I have attached your letter for reference. My comments to your issues are <br /> provided below. <br /> Your comment that "analytical data submitted unequivocally shows degradation to groundwater" is <br /> over simplistic and does not account for the different testing performed. The comparison of SELP <br /> data to drinking water standards was lot comparison purposes to show elemental makeup of <br /> extracts from a highly agitated test with a three to one dilution ratio (for comparison the TCLP lent <br /> requires a 20 to one dilution). In addition, none of the leachates were filtered with a 0.45 micron <br /> filter and some of the samples were not filtered at all. The SELP test showed that materials <br /> considered inert have elemental compositions similar to that of coal ash. <br /> As agreed upon with the State, we have conducted additional leaching tests as presented in our <br /> Quality Assurance Project Plan (QAPP) dated March 13, 2000 and in our January 26. 2000 letter <br /> to you. The results of the leaching tests are presented it. Table 1. The leaching test was designed to <br /> reflect to the extent possible the conditions that will be encountered by placing ash at the Varra <br /> property. As stated in the QAPP the leaching test was a modification of IIS7A9 D 4874-95 <br /> Standard Test Metlrnd for Leaching Solid Material in Column Apparatus. <br /> The column was filled with fly ash and sand and gravel obtained from the Varra property in the <br /> vicinity of the proposed trench. Prior to filling the column with fly ash (a combination of Class I <br /> silo ash with gypsum and Cherokee 4 fly ash with sodium) and sand and gravel, a divider was <br /> placed in the column to allow a vertical separation of the materials. This divider was removed as <br /> the eclumn was filled. Approximately 70 percent of the column was filled with fly ash and the <br /> P.O. BOX 1489 • FORT COLLINS, COLORADO 80522 R�4,-. 'L 970-493-77S3 FAX: 974-493-7986 <br />