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Thompson Creek alluvial ground water in well D-lA. This well is within the expected <br />flowpath of leachate, should leachate flow from the refuse pile to the alluvium. Well D- <br />lAmeets the qualifications of a compliance point. A leachate plume in the alluvium can <br />be expected to extend no more than 1,000 ft. downgradient from the refuse pile, owing to <br />the laterally discontinuous nature of the alluvium and dilution of alluvial water by <br />flowing stream water. If this 1,000-ft. distance is considered to be the "specified area", as <br />this term is defined in the Basic Standazds for Ground Water, then the alluvial water can <br />be tentatively classified as water of Limited Use and Quality because within this specified <br />area, the North Thompson Creek alluvial water is of such small volume that it is not <br />currently used and is unlikely to be used in the future. The Basic Standazds have no water <br />quality standards for the Limited Use and Quality classification; therefore, the mine is in <br />compliance with the Basic Standazds for Ground Water in alluvial formations, at the <br />location of well D-lA. <br />E) Stream Buffer Zones <br />Pre-law surface or underground mining activities within 100 feet or through perennial <br />streams or streams with a biological community within the permit azeas were recognized in <br />the PAP. The approved reclamation plans included restoration of original stream channels, a <br />requirement that water quality and quantity shall not be adversely affected, and a requirement <br />that appropriate riparian vegetation was to be reestablished. Recognized pre-law areas of <br />disturbance are at Portal l and Portal 1 facilities azeas, the underground workings beneath <br />North Thompson Creek, and the conveyor over the Roaring Fork River. The coal mine waste <br />pile and pond, and four water-monitoring flumes were permitted. [Rule 4.05.18(1)] <br />F. Probable Hydrologic Consequences of the North Thompson Creek Mines <br />There is no known underground mine water dischazge from North Thompson Creek Mines in <br />the Middle Thompson Creek drainage. There aze no known impacts to groundwater in the <br />Middle Thompson Creek drainage from mining and reclamation activities or to the Roaring <br />Fork River from the loadout site. <br />1. Ground Water <br />Current discharges indicate that both the North Thompson Creek No. 1 and No. 3 Mines <br />aze experiencing mine inflows. The mine portal discharges represent a redirection in the <br />migration of groundwater from pre-mining conditions. Inflow maps, descriptions of <br />inflows, and water quality analyses of inflows applicable to periods of mining are within <br />the PAP. The inflow water quality analyses indicate that there maybe at least two sources <br />of water. The inflows with low total dissolved solids (TDS) concentrations have water <br />qualities similaz to surface waters. This suggests that these inflows maybe transmitted <br />directly to the mine workings from the surface water system, with very little residence <br />time in the transmitting aquifer, or aze emanating from aquifers with few dissolvable <br />solids. These low TDS inflows aze also generally found emanating from fractures beneath <br />or directly adjacent to the stream valleys of North and Middle Thompson Creeks. High <br />16 <br />