2020-10-22_PERMIT FILE - C1981012A (4)

Home Browse Search

34 conditions. The Middle Fork of the Purgatoire low flow is generally from mid- August through mid-April. Peak flows occur from mid-April through July. Gravels removed from the riverbed will be used as road base, riprap or bedding for underground rails. Excavation of gravels will naturally alter the streambed. Every effort will be made to minimize disturbance. The operator will either use rubber -tired or crawler loading equipment to remove gravels from the upstream portion of the culverts. The amount of time for maintenance activities will be dependent on the amount of gravel deposited. The operator estimates 1 to 2 days will be necessary to facilitate cleaning. The volume of gravel will be dependent upon the amount of deposition. Normally, the operator will not stockpile the gravels removed from culvert maintenance. They will be used for road base or ballast. If necessary, potential stockpile areas at the New Elk will be located just east of the culverts being cleaned and to the north of the scrap yard outside of the buffer zone to the river. The action of cleaning the culverts is a mitigative action to comply with the surface mining rules and regulations. During 1981 and 1982 a new ventilation shaft was designed, permitted and constructed in Apache Canyon (see Map 3, Mine Plan). A description of the facility is presented in Exhibit 25, Apache Canyon Ventilation Shaft. All appropriate rules and regulations concerning operation, maintenance and reclamation have been included under this permit term. During 2006 plans were submitted to MSHA for approval to re-enter the New Elk underground mine to evaluate the feasibility of reopening the operation. As determined by measuring water levels in the East Portal airshaft, the mine has flooded to an elevation of 7220 feet. Prior to re-entry, a temporary vertical turbine pumping system will be installed in the east portal airshaft to dewater the mine to an elevation of 7180 feet (the elevation of the bottom of the airshaft and slope entries) allowing entry into and exploration of the mine. Initial pumping capacity is planned at 4,000 gpm. Location of the pumping system is shown on Map 11 -Surface Facilities and Roads East Portal. At this rate dewatering may take from 6-9 months dependent on actual quantities of water encountered. After dewatering to 7162 foot elevation, pumping will continue to occur from pumps located underground and the temporary system will be removed. Prior to mine closure, mine water quality allowed discharge directly into the Purgatoire River with no treatment. Since closure in 1989, mine water samples were periodically extracted from the East Portal airshaft and boreholes into the mine workings (NEW -2 and NEW -4 of the hydrologic monitoring plan). Sample results collected at these sites indicated that direct discharge can be resumed in compliance with NPDES permit limitations. Additional samples were collected at the pump head and analyzed for the parameters listed in the NPDES permit 2008 renewal for Outfall 001 C, page 8 (Exhibit 22 of the New Elk permit) when pumping started and prior to discharge to the Purgatoire River. These test results demonstrated compliance and the Section 2.05 RN -6 10/17/2016