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~ iii iiiiiiiiiiiiiiii <br />MINED LAND RECLAh7AT i0N ui'rliSlCPi <br />Department of Natural Resources <br />t3t3 Sherman St.. Room 2t5 <br />Denver, CO 60203 <br />303 866-3567 <br />Fnx~303 632-6706 <br />~~ <br />I ~~ <br />_ -.~ <br />. i . !-=-{ '; 1. <br />~~~ ~ . <br />~ r87b <br />Foy Gamer. <br />Governor <br />M~chaei B. Long. <br />Division Drreclor <br />DATE: April 24, 1992 <br />T0: H. Bruce Humphries ~,~ <br />FROM: Harry Posey <br />RE: A. Sorenson Memo to you, April 21, 1992, Potential Seepage Through <br />the Tailings Impoundment Liner at BMG San Luis; Permit No.M-88-112 <br />As mentioned earlier, Mr. Keffelew and I noticed several liner expoures in <br />the upper tailings impoundment during our April 1-5 inspections. A that <br />time, Mr. Ron Zumwalt of BMG said the liner cap would be covered ov r with <br />tailings. <br />Y n,,. Having reviewed parts of the permit and particularly Mr. Sorenson's analysis <br />~,,.^ of the liner system, it is now clear that the 2 foot gravelly sub-d Gin layer <br />i'"' ~ s covering the liner was designed to be fairly permeable so that no m re than 1 <br />5Yr' foot of head pressure could build up on the synthetic liner. If BM covers <br />the liner with tailings, this will compromise the integrity of the finer by <br />reducing permeability of the sub-drain cover. <br />~ ~ recommend that during the next inspection, the liner cover be ins ected to <br />~~*:~~"~ ssure that tailings were not placed over the liner. I also recomm nd that <br />Sf,,~.~~ ~he permit file be checked to assure that permeability tests of the gravelly <br />~,. ,,./~5ub-drain layer assure the degree of drainage that would be necessa y to <br />maintain 1 foot of head. I call this into question mainly because, from my <br />observations, the sub-drain layer appears to be a gravelly soil and I don't <br />know what the permeability of such a material would be. <br />It would be appropriate to test the permeability of the new patches~of <br />~~~~ sub-drain material . ~ c.-.~~ ~...~ fin.,.. r z ;~-, . <br />HP/ern <br />cc: B. Keffelew J <br />L. Oehler -~,/ ,~~ <br />J. Pendelton ' <br />J. Stevens / ~ <br />9980E <br />`~ ~ .~~ / <br />