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STaTE OF CoLOR.~aO eit ~~po o, ~•"++. tw•...a DEp~RTMENT Of NGTURAL RESOURCES o, IAOne• h.to., Ea.art,vt O~retar e~ i i'""J h1INED LAND RECI,A.-IATION 423 Centennial Buildiny.1313 Sherman Street Denver. Colorado 80203 7~i.{303) 839-3567 June 30, 1983 TO: Eob L.iddle FROM: Jim Pendleton SUBJECT: Geotechnical as s of Energy Fuels No ~;Z~ a David C. Shelton J-~ Director , ~~i-•~ ,y.¢,,t. r,~, :.~ ;. `~' c ~ ~ Cn ? 3 Permit Application Pursuant to your request I have reviewed the Energy Fuels No. 3/Middle Creak pe_-autnent program permit application. 7 forward the tolloaing commenu regarding the geotechnicel aspects of the permit fot your consideration. Grading and Backfilling The application states that it is the apalicant's intent to backfill the surface pits and the portal area pit to approximate original contour. The applicant further requests a variance from required cortemaoraneous reclamation within the portal and surrounding area. The purposes for this request are to allow portal access and to facilitate placement for underground waste rock j2 ft. of roof rock removed to assure roof stability) throughout the 10-year projected life span of the Middle Creek L~derground mine. The application is dufficient in two facets of its backfilling and grading proposal, First, the material bulking calculations are based upon very limited materials field density testing which utilizes "'wet density" results. I do not believe this deter:uinatton is sufficient. The applicant should conduct additional testing including determination and comparison of results using dry material densities. Comparison of dry densities wilt eliminate the possibility of confusion due to moisture variation between the samples. The testing submitted within the application is v:mited to one in-place overburden test and approximately a half dozen spoil sample sites. She applicant should expand the testing program to include multiple in-place undisturbed overburden samples designed to test the representative overburden stratigranhic types. Furthermore, testing of disturbed spoil should include both the permanent and temporary overburden piles, which have been consolidated to varying degrees. Secondly, the application contains only a brief calculation of overall spoil bulking, including allowance for coal removal. The application should be amended to detail volume calculations for the separate project pits, the portal area and the pe_-manent and temporary overburden piles. Further, a detailed calculation summary of the projected underground waste material volume should be included. This should allow verification of the applicant's statements re- garding :he excess nature of the various overburden piles and verification of their projection of regraded approximate original contour.