Laserfiche WebLink
COLORADO DEPARTMENT OF HEALTH. Water Quality Control Division <br />Rationale -Page 4 Permit No. CO-0045675 <br />/V. FACILITY DESCRIPTION <br />A. Industry Description <br />Industrial Activity, Contributing Wastewater Sources, and Remediation Water Management Plan: Active mining <br />operations were completed in October of 1996. 77te site Iran been undergoing closure acrd reclamation activities since <br />that time. 7/re prior mining operations at the San Luis Mine were conducted in three open pit raining excavations. <br />Ore and waste x~as removedJrom the East Pit, West Pit, and Pink Gneiss Pit during the active operations period. <br />Overburden xithin the mine consisted of Rito Seco Alluvium and Santa Fe cong[ornerate materials. Each of these are <br />unconsolidated materials above the Precambrian bedrock (ore bearing zone). Ore artd x~aste operations used <br />conventional nwdern nosing methods consisting oj.~ <br />a) Topsoil salvage and stockpile (al[ surface disturbances), <br />b) Overburden removal and deposition, <br />c) Drilling, <br />d) Sampling (ore/waste delineation), <br />e) Blasting, <br />~ Loading ((rant-errd loaders), <br />g) Transpor (diesel fuel haulage trucks), <br />h) Waste rock x~as transposed to one ojfour waste rock facilities (South Waste Rock Facility, Waste Rock <br />Facility B, Waste Rock Facility C, Waste Rock Facility D) x•hich were concurrently reclaimed, <br />i) Ore was transposed to the ROM ore stockpile, <br />j) Backfil[ and reclamation <br />Mill beneficiation operations were comprised of a conventional mill circuit design, which utilized a primary crusher, <br />crushed ore stockpile, SAG mill and single ball mill to dress the ore for precious metal recovery in a sodium cyanide <br />Carbon-in-Leach circuit. Learlred ore tailings jrom the C/L circuit were neutralized using the /NCO cyanide <br />neutralization process (1992 to 1996) prior to placement at a synthetically lined tailings facility (zero disclarge). <br />Loaded carbon Jrorn the C/L circuit x~as firsher benejiciated on-site producing a dare' product which x~as sent off-site <br />jorflnal refining. <br />T/re fanner gold mine is in [he Jinal stages ojreclanra[ion acrd closure in accordance with the Division of Minerals and <br />Geology (DMG) permit number M-88-/12. Active mining was completed at the site in October /996. 7/re mine pits <br />have been partially or canpletely backfilled xith waste rock materials as contemplated in the Technical Revision (/R) <br />Document TR-/8. <br />The events leading to the subrninal ojthis permit application are those associated with completion of the Wesf Pit <br />backfilling. A combination ojsurface rater and groundwater has infiltrated the West Pit. The source of the <br />groundwater is the Precambrian bedrock, the Santa Fe Formation, and the Ri[o Seco alluvium. Groundwater flowing <br />through the West Pit exits the pit through a restricted zone where the backfill material contacts directly the Rito Seco <br />alluvium (r/ee "window "). Groundwater from the West Pit then co-mingles xith Rim Seco alhrvia{ groundwater. One <br />portion oJthe co-mingled groundwater historically emanated as surface seeps adjacent to the Rito Seco in the <br />immediate vicinity of the window. The other portion of the co-mingled groundwater migrates westx~ard in the Rito <br />Seca al(tevinl aquifer. <br />The document tided "TR-26, Water Management in the West Pit Area, Sou Luis Project, Castilla County, Colorado" <br />provides detailed information regarding BMR/'s response to these conditions as required under the current DMG <br />permit. The response plan includes shoe-term and long-term rater management plans. <br />The short-term water management plan includes the operation oja French drain pumping system and physical surface <br />isolation ojany measurable surface seeps xith steel and HOPE curtains anchored info the ground at the seeps. The <br />plan also contemplates pumping of wells in the backfllled pit to produce a final water level that will reverse the <br />groundwater gradient away Jran the Rito Seco such that the seepage into the Rito Seco alluvium jrom rlre West Pit <br />area will be eliminated. The water pumped rill be handled through an evaporation system and/or through treannent <br />by an industrial wastewater plant. <br />This permit is jar die direct discharge from 1lte proposed wastewater treatment plant as well as the seepage front <br />associated x•it/t the backfllled West Pit. As pan of this discharge permit, the permittee will be utilizing best <br />management practices intended to respond to the seepage jiont as described in store detail in Section 6.0 of TR-26. <br />The mine is not currently operating, so no mining or milling processes are contributing to, or could contribute to the <br />waslestrearu being permitted. <br />