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January 1993 Raton Creek Mine * Adequary Response ~ 4 <br />panial reduction, grading to blend with surrounding terrain with limited slope breaks, <br />retention of minor stable highwall segments, etc.) should be considered. <br />The proposed regulatory changes would definitely be beneficial, since they establish <br />pazameters for evaluating highwall reduction alternatives. EFMC would like to further <br />explore possible options relative to both timing and extent of highwall reduction with <br />the Division to achieve the best potential overall reclamation outcome. <br />4. Far Response (BJ(1) of CML-RD Commenu of 4/22/91: <br />Page 468 of the permit sutras that the refuse will br compacted to at least 90 percent of the <br />maximum dry density. Rule 4.10.4(3J(cJ sates that "compaction testing shall be performed <br />to verify that the minimum required compaction is achieved " Rule 4.10.4(3J(b) cites the <br />method, or iu equivalent, that shortld be used The Division requests that the resulu of an <br />appropriate compaction testing program be submined. /f compaction teeing has not bran <br />done, then please submit the details ofa proposed compaction testing program for the Division <br />to review. <br />Page 493 of the permit stares that 30,000 cubic yards of refuse will be taken from the refuse <br />pile and placed into the Helen portal area, topped by 3.3 feet of overburden and 6 inches of <br />topsoil. Map 17-B, "Pon Mining Topography -Worst Case ;shows the refuse pile to have a <br />final elevation of 6413 feet However, in your current submittal, no refuse is taken off the <br />refuse pile, resulting in a final elevation of 6460 feet for the refuse pile. Please submit a <br />reclamation plan that will lower the top elevation of the refuse pile to 6415 feet. <br />Response: No compaction test data is available for the existing refuse pile. Pile <br />construction, has however, proceeded in a manner consistent with the original <br />construction practices documented by the summary of inspection reports included in the <br />permit application. <br />In order to provide the required documentation of ongoing compliance with compaction <br />requirements, EFMC plans to develop and submit, for OMLR review and approval, a <br />technical revision outlining specific plans for determining in-place material densities. It <br />is anticipated that the proposed evaluation approach will involve spot testing using a <br />drive-hammer to determine refuse material densities at various locations and depths in <br />the existing stockpile. <br />The reclamation plan review referenced in the previous response to Comment 3 resulted <br />in a determination that use of an alternate borrow source (Borrow Source 1) would offer <br />several advantages over removal of material from the north end of the refuse pile, as <br />originally proposed. Use of the alterna[e borrow source would potentially limit any <br />drainage impacts which could result from creation of a Swale at the contact between the <br />toe of the refuse pile and the adjacent steep natural slope, facilitate establishment of a <br />smooth slope transition in the azea below the reclaimed portals, and potentially result <br />in better material for reclamation and revegetation of the portal area. <br />There is no inherent advantage in using refuse material rather than the proposed alternate <br />borrow source for final reclamation of the Helen portals and there aze no inherent <br />hazards associa[ed with retention of the refuse pile in it's current configuration. <br />n:~esbarsrtrn <br />01/OS/9J Ipm ACZ /nc. * P.O. Boz 7740]8 * Steamlwat Springs, Colorado 80477 * (303) 879.6260 <br />