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~: <br />., <br />:: <br />correi-~/ <br />~~M/c~~ <br />RECEIVED <br />~,~ AUG 1_p-2006 <br />GRAND JUNCTION FIEIA OFFICE <br />DMSION OF <br />RECLMMTION MINING & SAFETY <br />July 19, 2006 Permlt #'~~~ <br />Class:~c-fir` <br />From: (_'C~f(t._a <br />Russ Means _ _ Doc. Name: /ti <br />~'Coloi•ado Division of Minerals and Geology! Doc. Date (if no <br />Grand Junction Field Office Specialist: <br />101 S. Third St, Room 301 <br />Grand Junction, Colorado 81501 <br />c~ <br />RE:~Permit No: M-1977-306, JD'-9 Mine, DMO Appeal; Supplemental Geology Report.' <br />Mr. Means: <br />A good general description of the geology of the azea of the JD-9 Mine was included in <br />the report submitted to DMG October 19, 2005 prepared by Geoscience Services entitled <br />"Evaluation of Potential Contaminant Migration for Uranium Mining Operations at the <br />JD-9 Mine". That, and subsequent documents reported on the hydrogeologic properties <br />of the rock units present at the surface and underlying the mine site, including hydraulic <br />conductivity and sorption potentials. <br />Very little needs added to the geologic description for the JD-9 Mine site. However, a <br />new cross-section is attached to show more detail of the relationship of the waste rock <br />dump, mine workings, and perched ground water in the Salt Wash member of the <br />Momson formation. This is a portion of the supplemental information Cotter Corporation <br />is submitting to support Cotter's appeal of the Division's determination that the JD-9 <br />Mine is a Designated Mining Operation. <br />The structural setting of the mine site was also previously described as located on the <br />southwest flank of the Paradox Valley collapsed salt anticline, with rock units dipping <br />southwest at one degree. This flat dip indicates that the mine is near the Dry Creek Basin <br />syncline axis. <br />The initial modeling assumed the waste rock dump sat on Salt Wash sandstone and that <br />groundwater of concern was in the Entrada sandstone, some 400 feet below. The model <br />will be re-run using realistic conditions, i.e. the dump is located in the Brushy Basin <br />member of the Morrison formation and the groundwater of concem is now the perched <br />water at the base of the upper sandstone sequence of the Salt Wash, some 220 feet below. <br />Cotter proposes drilling a well adjacent to the waste rock dump (away from mine <br />workings) and, if goundwater is encountered, sampling of the water to determine the <br />dissolved constituents and age of the water. This hole would then become a monitor <br />well. Cuttings will be analyzed to obtain sorptive properties of the Brushy Basin clays to <br />be incorporated in the realistic model. <br />Cotter Corporation -West Slope Operations - 1 - <br />P.O. Box 700, 28151 DD Road, Nucla, CO 81424 USA <br />Telephone (970) 864-7347 <br />Fax (970) 864-7287 <br />