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Rule 2.04 <br />• Principal groundwater bearing zones in the general mine azea aze recent alluvial deposits and the coals and <br />massive sandstones of the Williams Fork and Iles formations. Typically, the moderately permeable <br />sandstone units are separated by low permeability shales which act as aquitazds. Groundwater in the <br />region generally moves to the north as the Cretaceous sedimentary units dip to the north. Neaz the mine <br />permit azea, groundwater moves to the northeast following the dip of strata towazd the axis of the <br />Watering Trough syncline which runs north-south just to the northeast of the mine permit azea. Both the <br />20 Mile and Trout Creek sandstones of the Mesa Verde formation constitute significant regional aquifers <br />and aze present below the coal seams at Hayden Gulch. Regional wells in the alluvium reportedly produce <br />up to 1500 gpm and Mesa Verde wells reportedly produce up to 300 gpm. <br />A total of 18 spring and seep azeas were located within one mile of the mine permit boundary. Analysis <br />of water quality data, geology and spring flow data indicated that all but four of the springs or seeps <br />originated from water bearing zones below the mining zone. <br />2.04.6 Site Geology Description <br />The origiualpermit applieatiou described both regional and site speufic geology with respect to physiography, <br />stmcttue, stradgraphy and aquifers in Sectiax 2.04.6 of Volume L A detailed discussion of site and regional <br />geology was also prepared by the MLRD as pazt of the 1987 permit renewal and is included in Appendix <br />E, January 1987 Proposed Decision and Findings of Compliance. <br />Nature of Coal and Overburden <br />The Hayden Gulch mine property contained five coal seams that dipped at approximately 5 to 10 degrees <br />• in a northeasterly direction. The seams varied in thickness from 1.2 - 7.0 feet with a combined average <br />of approximately 2.2 feet. The average overburden and interburden ranged from approxinately 9.0 - 50.0 <br />feet between coal seams. <br />Coal quality was characterized by medium BTU and low sulphur content. Table 2.04-1 presents weighted <br />average proximate analyses results for "typical" H-G coal. <br />TABLE 2.04-1 <br />PROXIMATE ANALYSES <br />las received) <br />Element or Compound Avera a Ran e <br />Moisture 17.51 16.42 - 79.59 <br />Ash 6.24 5.14 - 8.74 <br />Volatile Matter 33.31 32.40 - 34.03 <br />Fixed Carbon 42.93 41.96 - 43.93 <br />Sul hur 0.43 0.34 - 0.79 <br />BTU/Ib 9978 9642 - 10172 <br />r1 <br />~J <br />2.04-5 Revised - 06/01 <br />