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In the past, the West Elk Mine has experienced three <br />types of mine inflows. The first type of inflow is due <br />to primary permeability which is ground water flow <br />through the competent portions of the F seam and lower <br />Barren member. The second type of inflow occurs in the <br />coal seam and overlying Barren member in areas of <br />shallow overburden. This is secondary permeability and <br />is the result of ground water flow through the <br />fractured and weathered portions of these strata. The <br />fractured rock acts as a conduit to the surface <br />colluvial aquifers. The third type of inflow is also <br />due to secondary permeability and it is the result of <br />ground water flow along fault zones. These fault zones <br />may be in contact with surface aquifers or with water <br />bearing zones in the overburden. The streams in the <br />North Fork area are generally fault controlled and may <br />be a source of recharge for fault related inflows. <br />Prior to the construction of the mine entries, <br />piezometers were installed in the colluvial/landslide <br />strata immediately upslope of the entries. All <br />piezometers but one were destroyed during construction <br />of the entries. <br />Three of the five entries experienced inflows during <br />construction, which began in September of 1981. Adit <br />entry No. 4 experienced the greatest inflow, about <br />5 gpm, which decreased to less than 1 gpm and dried up <br />within a week. The No. 1 entry produced a small <br />quantity of water from the bottom of the coal at a rate <br />of less than 1 gpm and dried up within two weeks. <br />However, the sandstone roof at entry No. 1 was dry. <br />Entry No. 5 produced drips, approximately 0.1 gpm, for <br />about one week. The other two entries were dry. <br />During the period from August to December 1981 water <br />levels dropped in some of the piezometers located above <br />the portals. In all cases the drop was not greater <br />than two feet. Water levels have changed very little <br />since January 1982. <br />MCC has submitted two plans for the sealing of the <br />portals upon closure of the mine. The first plan calls <br />for sealing the portals to allow gravity discharge of <br />mine inflows. MCC anticipated, from water samples <br />taken in the Oliver Mine, that mine waters will not be <br />toxic. This plan calls for the construction of a block <br />wall at the portal and a four-inch PVC pipe to drain <br />the collected mine waters. The second plan is <br />contingent on the mine producing toxic mine waters. <br />This plan calls for the construction of several <br />engineered seals located within the mine designed to <br />withstand pre-mining head pressures. <br />The experience near the F seam subcrop indicates that <br />the colluvium, coal and bedrock are recharged locally. <br />-37- <br />