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MID-CONTINENT RESOURCES <br /> P.O.Box 1298 <br /> Glenwood Springs, CO 81602 <br /> July 20, 1993 JUL 21 1993 <br /> if1Vl$K1i it i�in it;t ta. .. .�:,. ,yi y <br /> Anthony J. Waldron <br /> Reclamation Specialist <br /> Division of Minerals & Geology <br /> 1313 Sherman St. <br /> Room 215 <br /> Denver, C 0203 <br /> RE: M . Coal Basin Mine - C-81-017. <br /> Dear Mr. Waldron: <br /> Minor Revision #38, which you issued on June 18 allowed for extension of an <br /> interceptor/clean water diversion ditch beyond the upper perimeter of the old refuse <br /> pile, (Refuse Pile #1), extending around the outer perimeter of an adjacent area which <br /> had previously been cleared for topsoil. <br /> The ditch has been installed. Attached please find calculations as to necessary size to <br /> pass a 100 year flood event from the undisturbed hillside above the ditch, and <br /> measurements of the ditch as constructed. <br /> MR-38 had also directed the installation of monitoring points for what were thought to <br /> be tension cracks; however, it was later determined during a subsequent site visit by <br /> Dr. Pendleton, (the Division's Engineer/Geologist) that the surface cracks noted were <br /> not tension cracks. We believe, therefore, that monitoring points are not necessary. <br /> Flows from the southwestern-most section of the area will be passed through a gravel <br /> filter installed in a berm, as indicated on the attached site sketch, and water sampling <br /> will be done when sufficient flow passes through the gravel filter, for an SAE <br /> demonstration. <br /> Subsequent work has been done, as approved by Minor Revision#39, issued by Mr. <br /> Routten on July 7, 1993, which involved obtaining additional soil material which was <br /> used to establish positive drainage toward the sediment pond for most of the area. <br /> MR-39 requires a further submittal, as does Office of Surface Mining (OSM), which has <br />