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Stream Buffer Zones - <br />No disturbance is anticipated within 100 feet of a stream with a <br />biological community. <br />Probable Nvdroloaic Consequences - <br />Ground Water <br />The Orchard Mine has the potential to affect ground waters in <br />three ways - degradation of water quality, mine consumption of <br />water, and'dewatering of insignificant bedrock aquifers. Each of <br />these cases will be discussed in detail in the following <br />paragraphs. <br />Degradation of ground water quality could occur in three <br />locations. The train loadout and auxiliary coal stockpile are <br />located on an alluvial terrace of the North Fork of the Gunnison. <br />Runoff infiltration could result in the dissolution of salts. The <br />operator installed and monitors three wells downgradient from <br />these facilities and has not detected any significant water <br />quality changes. The Division has expressed some concern about <br />the narrow band of alluvium found downdip of the underground waste <br />development stockpile. The operator has installed a well (Node <br />22) and 1s monitoring that location for impacts. No impacts have <br />been detected to date. Lastly, there is a slim probability that <br />subsidence-related impacts to springs might result in the <br />modification of springs water quality due to a change in routing <br />of the water. The operator is monitoring springs in currently <br />affected areas quarterly for major cations and anions, and no <br />changes have been detected. <br />Water utilized for mine operations is obtained from a well in the <br />Steven`s Gulch well field. Consumption from this alluvial/ <br />colluvial deposit is measured with a wellhead gage. From <br />July 1990 through June 1991, COVCC produced 720,000 tons of coal <br />and imported approximately 18,000 gpd from the Steven's Gulch <br />well. Water quality information is also collected and reported to <br />the Division. In 1986, CWI produced 333,292 tons of coal and <br />consumed 8,700 gpd while in operation. In 1983, Orchard Valley <br />Mine produced 1.3 million tons of coal and consumed 27,400 gpd. <br />There has not been any detectable impact to the <br />groundwater/surface water regime in this well field since they <br />initiated pumping at the site. <br />Dewatering will occur at the Orchard Valley Mine but will be <br />insignificant in extent. Mine inflows may be derived from <br />fractures associated with perched aquifers within the overlying <br />Mesaverde, surficial alluvial/colluvial sediments, and stream <br />flows associated with fracture systems as well as from dewatering <br />of the coal aquifer itself. In 1983, approximately 300,000 <br />gallons of water flowed into the mine from perched, discontinuous, <br />water-bearing sandstones overlying the D seam. A Division <br />_28_ <br />