Laserfiche WebLink
the permit application, and in the Annual Hydrology Reports submitted by Seneca <br />Coal Company. <br />An extensive ground water monitoring program which was in existence prior to <br />1981, has identified five aquifers a[ or near the Seneca II Mine site: (1) Trout Creek <br />Sandstone member of the Mesaverde Group, (2) Wolf Creek Coal, (3) Wadge Coal <br />and Overburden, (4) Quaternary alluvium, and (5) replaced spoils. <br />With the exception of the Quaternary alluvium and replaced spoils, it is thought that <br />each of the identified aquifers are Hydraulically discontinuous with each other. This <br />is because of the relatively impermeable (confining) nature of the intervening strata. <br />For this reason, each aquifer will be discussed as a separate entity. <br />Trout Creek Sandstone <br />The Trout Creek Sandstone is stratigraphically 70 feet below the Wolf Creek Coal. <br />This 120 foot thick sandstone body is thought to be a significant source of ground <br />water in this region. <br />Water from the Trout Creek Sandstone is used to supply the Seneca II Mine <br />facilities. As the supply well is frequently pumped, reliable depth-to-water <br />information is not available from this site. The Trout Creek Sandstone water is a <br />sodium sulfate type with an average TDS concentration in the range of 900 mg/I. <br />The 70 feet of interbedded sandstone, siitstone, coal and shale act as a confining unit <br />which essentially precludes the vertical migration of water between the Trout Creek <br />Sandstone and the Wolf Creek Coal. Consequently no depletion or degradation of <br />water in this aquifer is anticipated as a result of mining operations at the Seneca II <br />Mine. <br />Wolf Creek Coal <br />The Wolf Creek Coal seam is capable of transmitting and storing small amounts of <br />water. Aquifer tests of the unit were performed at the Seneca II-W Mine site, about <br />5 miles west of Seneca II Mine, in 1980. These tests indicate that the Wolf Creek <br />Coal is a confined aquifer which transmits limited amounts of water. One well was <br />pumped at an average of 1.2 gallons per minute for about 3'/x hours and produced no <br />observable drawdown at an observation well 20 feet away. Transmissivity values <br />calculated for the Wolf Creek Coal vary between 0.02 ftZ per day (0.149 gallons per <br />day per foot) for we113WC and 0.001 ftZ per day (0.007 gallons per day per foot) in <br />the two wells tested. Due to the low water yield and [ransmissivity values, the <br />storativity value of the Wolf Creek Coal is estimated to be about 1 X 10-s. Both <br />21 <br />