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• III Ililllllllllllll • <br />STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION of ~o~ <br />Department of Natural Resources ~w-'~> <br />e/ <br />1313 Sherman St.. Room 215 ~ ~ <br />Denver, CO 80203 ••ri4"„ys~•~ <br />303 666-3567 • rg~g <br />FAx 303 632-6106 <br />fioY Romer. <br />Governor <br />Michael B. Long, <br />Orvison Director <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 exposures in <br />the upper tailings impoundment during our Apr11 1-5 inspections. At that <br />time, Mr. Ron Zumwalt of BMG said the liner cap would be covered over 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-drain layer <br />P^~ s covering the liner was designed to be fairly permeable so that no more than 1 <br />S~D-'~ foot of head pressure could build up on the synthetic liner. If BMG covers <br />the liner with tailings, this will compromise the integrity of the liner by <br />reducing permeabiiity of the sub-drain cover. <br />I recommend that during the next inspection, the liner cover be inspected to <br />1~~~+'~ ssure that tailings were not placed over the liner. I also recommend that <br />~ s~,,,,,~~ he permit file be checked to assure that permeability tests of the gravelly <br />i {1~/r, ,r/ ub-drain layer assure the degree of drainage that would be necessary 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 permeabiiity of such a material would be. <br />It would be appropriate to test the permeability of the new patches of <br />sub-drain material. IoM 7wr„ ,1h,...f d <br />HPlern <br />cc: B. Keffelew ~_ <br />L. Oehler I ~~/~ <br />J. Pendelton <br />J. Stevens ,, <br />9980E ~ r <br />~~ <br />