Laserfiche WebLink
MRR 06 '95 12~SSPM DIVi~P.RLS&GEOLOGY <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Netu ral Reroun:cs <br />1313 Sherman Sr., Room ZI S <br />Denver, Colorado Eo203~ <br />Phone+ U03) 966,`3567 <br />FAX: (303) 932.8106 <br />i III IIIIIIIIIIIII III <br />999 <br />STATE OF COLORADO <br />©~CN t~~~.pf~ <br />~f ~14,r b:. <br />R®cetved <br /> <br />MAR 0 6 1995 Roy Romer <br />Gwemor <br />DATSa HaYCh a, 1995 <br /> James S. LOChhoad <br />E.xunveDircoa <br />T0: Tom Oillle DllrBngD Fleld ~~ Michael B. long <br />;FROM, Tom 6chreine Divirion of Minerals 8 Geology olvlt~o~ DucCtor <br />R,6: Hydrology leeview, Final Comments - Incas Mine (110D) Amendment., <br /> Permit No. M-86-076 <br />I have completed my review of Bob Rill's response to my adequacy comments of <br />November 18, 1994 as woll'ae follow-up aommente by Dr. Barry Po¢ey of the DMG. <br />i offer the comments Noted below in addition to Dr. Posey'e comments of <br />Tebruary Z0, 1,995. At this stage in the permitting process, it agpenrs'that the <br />applicant has not adequately addressed all adequacy questions regarding <br />protection of eurfaee and ground water reeoucea, hse not adequately demonstrated <br />a benign filter cake/waste rock mix, has not provided eufficiant baseline <br />hydrologic data, and hse not provided an adequate hydrologic monitoring program <br />sufficient to meet the requirements for a designated mining operation. <br />1. The method proposed for disposal of spent era di~cu~see the use of diversion <br />ditahee to manage eurfaee water flows. However, the operator has not provided <br />engineering designB !or the ditches or construction techniques to be implemented. <br />Also, the operator discusses the installation of a 5' thick compacted cover. The <br />operator hse not characterised the material to be used or provided a permeability <br />to bo expected upon compaction. Finally, a vegetative cover on top of the clay <br />cap may ba3 helpful. However, the operetar may consider placing 6-8 inches of <br />suitable growth medium (soil) on top of the compacted sap in order to achieve a <br />desirable result. <br />2. Tho operator appears to have resolved coneerne for adequate water rights with <br />the 6tate Engineers Office. <br />3. The operator proposes fill of filter cake/mine waste into open cute and <br />shallow depressions while at a moisture content of 25i. The operator further <br />states that the operation will be designed and constructed as a sere discharge <br />facility. Therefore, until the operator hse scoured an NPDEB water discharge <br />permit from the Colorado Department of Health, mater Quality Control Division <br />DGRC/8ab Hill will need to demonstrate that any residual moisture in the filter <br />cake/mine waste placed ae fill will be contained on site and will not discharge <br />toward Little Deadwood Ouleh. <br />