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Mineral Creek Watershed <br /> Longfellow and Koehler Mines (Main Stem) <br /> Upper Mineral Creek is degraded by mining impacts near the headwaters <br /> immediately below Red Mountain Pass. Acid mine drainage from the Longfellow, <br /> Koehler and an unidentified mine flows into the stream near sampling point <br /> MC-2 (Figure 2) . The Koehler Tunnel was observed to be draining approximately <br /> 25-30 gpm of pH 5.0 water in June, 1992. The southern mine (unidentified) was <br /> also observed to be draining, but flow could not be estimated because of large <br /> rubble in the collapsed adit. The water flowing from the southern mine <br /> quickly infiltrated the mine waste pile and emerged at the toe of the pile as <br /> a series of springs. The pH's of these springs varied from 2.6 to 2.8. <br /> In addition to the two draining mines, the Longfellow waste rock pile has <br /> dammed the small stream above the mine, and the southern mine waste rock pile <br /> is partially inundated by a pond between the two mines. The blocked drainage <br /> results in a spring flowing from the toe of the Longfellow waste rock pile. <br /> The pH of this spring was measured at 2.6. The southern mine waste rock pile <br /> also is believed to be a significant source of metals through oxidation of the <br /> pyritic waste as the water level in the pond fluctuates. <br /> The aggregate flow into the pond from the three sources was estimated to be <br /> 120 gpm. <br /> There are many possible treatment alternatives for this site. Several of the <br /> alternatives such as aqueous lime injection have not been tested sufficiently <br /> at this time. However, since this site has a clean water source, aqueous lime <br /> injection should be considered. Based upon our current knowledge of the site, <br /> the preferred remediation method is to enlarge the existing pond; construct <br /> anoxic limestone drains in the Koehler and southern adits; cap the mine waste <br /> rock piles with soil; and divert clean drainage around the site, with the <br /> exception of the clean water needed for the aqueous lime injection system. <br /> To enlarge the pond, the existing pond will have to be treated, then drained <br /> into Mineral Creek, and allowed to dry for approximately one month. After the <br /> pond has dried sufficiently for equipment to drive on the bottom, the bottom <br /> material will be excavated along with the south mine waste rock pile in the <br /> pond. The material excavated from the pond will be incorporated with either <br /> the south or Longfellow mine waste rock piles. The soil along the edges of <br /> the pond will be excavated to enlarge the pond, build the dam embankment, and, <br /> if suitable, topdress the waste rock piles. The entire pond will then be <br /> lined and partially filled with organic substrate such as cow manure, or <br /> mushroom compost. The organic substrate is proposed to allow some sulfate <br /> reduction in the pond. <br /> -6- <br />