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s ~ • • <br />{page 2I <br />MINE ID # OR PROSPECTING ID # M-77-300 <br />INSPECTION DATE 9/22/99 INSPECTOR'S INITIALS ACS <br />This inspection was conducted in conjunction with the Division's review of technics:. revision TR-04 to <br />the Schwartzwalder Mine reclamation permit (permit no. M-77-300). Technical revision TR-04 was <br />submitted on April 15, 1999 to revise certain elements of the reclamation plan in sac tions E-3 and E-4 <br />(Surface Hydrology) of the permit amendment approved in 1983 and to provide notice that components of <br />the debris from demolition of the ore sorter facility would be disposed of in the underground workings <br />of the mine. The Division issued authorization to proceed with the ore sorter 3ebris disposal by <br />letter dated May 19, 1999. The ore sorter debris disposal was also au thorize~d by the Colorado <br />Department of Public Health and Environment under Radioactive Materials License No. 369-D3. Cotter <br />Corporation personnel met with Division staff on June 3, 1999 to discuss the status of technical <br />revision TR-04. It was agreed at that time that Cotter's consultant, Shepherd Miller, would prepare <br />revised designs and provide quality assurance criteria to address the issues listed in the Division's <br />May 14, 1999 letter. It was further agreed that the Division would inspect the s:.te to evaluate the <br />condition of Ralston Creek through the mine reach. The pending decision date for technical revision <br />TR-04 is October 21, 1999. <br />This inspection was focussed on three elements of the mine site proposed for revision under TR-04: 1) <br />Ralston Creek, 21 the west and east mine waste and ore sorter reject dumps, and 3i the location of a <br />proposed runoff energy dissipater on the top of the east dump. <br />Ralston Creek flows from northwest to southeast through the reach affected by surface disturbances at <br />the Schwartzwalder Mine. Most of the mine facilities and surface disturbances arz on the right bank <br />or west side of the creek. These include the underground mine portals and the adit and borehole access <br />road, shops, warehouses, offices, water treatment plant and ponds, parking lot, ~:he west mine waste <br />dump, and the former location of the demolished ore sorter. Mine disturbances on the east side of the <br />creek include the east dump, water treatment sludge evaporation trenches, a helipad and bone yard. The <br />main road through the site is on the west side of the creek until it crosses over to access the east <br />dump near the north end of the permit area. <br />The reclamation plan for the Schwartzwalder Mine approved through an amendment tc the permit in 1983 <br />specifies the installation of eleven riprap check structures in the creek bed. The purpose of these <br />structures is to afford local control of erosion in the vicinity of the mine waste piles and to assist <br />the creek, during intermediate and low flows, to rebuild the natural step-po~xl system. In the <br />technical revision TR-04 submittal, results of a study of the condition of the stream through the mine <br />reach is provided. Cotter proposes the elimination of the requirement to iris tall riprap check <br />structures based on the conclusions from the study that the step-pool sequencing through the mine reach <br />is similar to upstream and downstream areas and stream bank vegetation is well es t~sblished. The study <br />concludes that "Measures taken in an attempt to improve the stability of the creek will not improve <br />that Situation already established naturally..." The Surface Hydrology Study provided with TR-04 <br />contains quantitative information to support these conclusions in the form of bed grain size <br />distribution data and stream cross section and longitudinal profile surveys. This quantitative <br />information indicates that Ralston Creek through the mine reach is dynamically stable mountain stream. <br />That is, long term changes in the stream may occur, but they would be in response to high recurrence <br />interval floods or geologic events and not to the normal stream flow. <br />During this inspection, qualitative observations were made of the stream bed, stceam banks, and bank <br />vegetation to supplement the data and discussion provided in the technical revision TR-04 application <br />and aid in making the determination to approve the plan to eliminate the requirement to install riprap <br />check dams. The creek was walked from the location of the 1" staff gauge south of the guard shack up <br />to the area north of the east waste dump location. The following specific observations were made: <br />• The installation of the mine access road along the west side of the creek has confined the channel <br />between the access road fill and the east canyon wall. This channelization is particularly evident <br />in the reach from the 1" staff gauge north to the employee parking lot. For example, at the <br />location of staff gauge no. 3 it was observed that the channel has bedrock con'=rot on the left bank <br />and is confined by a substantial road fill on the right bank. Ore haulage on the access road is <br />limited no more than 15 ore trucks per day, and is currently operating at approximately 4 trucks <br />