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r <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Naiu rat Resources <br />1313 Sherman SI., Room 215 <br />Denver, Colorado 80203 <br />Phone: 13071 866-3567 <br />FA%:14D7)832.8705 <br />~I~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Roy Rumer <br />Governor <br />DATE: August 30, 1995 <br />TO: Gregg Squire <br />FROM: Allen Soreneon -J-YG/' <br />RE: Reservoir Liner, Connell Resources, Inc., Wellington Downs Pit, <br />File No. M-95-035 <br />lames S. lochheaA <br />Executive Direcw. <br />M¢hael N. Lang <br />Division Director <br />In the applicant's adequacy response dated Auguat 25, 1995, the commitment is made to <br />conduct one moisture/density test for each 10,000 cubic yards of clay liner material <br />placed. No justification ie provided for deviating from the Division's recommendation <br />to conduct one moisture/density test for each 1000 cubic yards of material placed. <br />Since it ie critical to assure an adequate degree of compaction of the clay liner to <br />prevent seepage into the proposed reservoir, and given the relative difficulty involved <br />in repairing a leaky liner compared to proper initial installation, and because <br />moisture/density testing is trivial once a nuclear density gauge is mobilized to the <br />site, the Division should require that a frequency of one test per 1000 cubic yards be <br />adhered to. <br />In the applicant's adequacy response dated Auguat 25, 1995, it ie stated that the <br />applicant's understanding ie that compaction testing and moisture/density testing are <br />the same. This misunderstanding comes out of my failure to better define the <br />nomenclature used in a memo dated Auguat 12, 1995. By compaction testing, I was <br />referring to Proctor testing. The applicant should commit to one Proctor teat for each <br />5000 cubic yards of liner material placed. <br />Sn the applicant's adequacy response dated Auguat 25, 1995, it is stated liner material <br />characterization through sieve and Atterberg limits analysis would not be necessary <br />because the character of the material is not expected to change from that described in <br />the application (Exhibit E-1). The reason for on-going sieve and plasticity testing ie <br />to assure that the liner material ie sufficiently consistent, and falls within specified <br />parameters for plasticity and gradation. The applicant should commit to Atterberg <br />limits testing and sieve testing at a frequency of one sample tested for each 5000 cubic <br />yards of liner material placed. The specification for plasticity would be a plasticity <br />index greater than 10, ae recommended in my memo dated Auguat 12, 1995; the <br />specification for gradation of the liner material should be ouch that the percentage of <br />large particles (greater than 3/4'•) is minimized, and such that a significant percentage <br />of particles are retained on the /200 sieve, coupled with a minimum percentage of <br />material passing the #200 sieve, i.e., a well graded material. The applicant should <br />propose a gradation specification based on their knowledge of the material available. <br />STATE OF COLORADO <br />