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• 2.05.6 <br />(3) Protection of Hydrologic Balance <br />(a)(I) The applicant has prepared a drainage and sediment control system which will minimize <br />changes to the surface water and to the prevailing hydrologic balance in the facilities area by <br />detaining run-off in sediment ponds or treating runoff with alternative sedimentation control. <br />The sediment ponds are designed to contain the run-off from the 10 year precipitation event. <br />The sedimentation control plan is presented in Volume III, Exhibit 6, and on Maps 20, 21-1, <br />21-2, 21-3, 21-4, 22-B, 22-C, 22J, 35, 36, 36a and Volume IV. <br />There is very little if any beneficial use made of surface run-off from the ephemeral drainages <br />in the permit and adjacent areas. These ephemeral drainages typically only flow during <br />spring snowmelt and significant precipitation events. Sediment ponds B & C should alleviate <br />the problem of the ditches (Deer Trail Ditch & Fire Mountain Canal) plugging with sediment <br />andlor completely washing out do to previously uncontrolled runoff events. <br />The construction of mine entries, ventilation shafts and the mining of the coal could cause <br />water to move from formations above the coal seam into the mine. This potential water <br />migration would be magnified by roof collapse and fracturing caused by subsidence. <br />Although the permeability of the coal seam and surrounding strata is low and the quantity of <br />water stored in the formation is also low, some water will occasionally seep into the mine. <br />The Freeman Gulch vent shale will be raise bored to an 8-foot diameter. The shaft will be <br />lined with a 6-foot diameter steel casing. The steel casing will be grouted through the water <br />bearing zone which is approximately 0 to 140 feet deep. The grout liner through this zone will <br />we approximately 1-foot thick. To prevent surface drainage from entering the shaft, the steel <br />liner will be extended at least 3-feet above the ground surface (see Map 35). A screen will be <br />placed on the top of the steel liner. <br />The Hubbard Creek vent shaft will be blind drilled to a 14-foot finished diameter. The shaft <br />will be steel lined to a finished diameter of 12-feet. The 500 foot deep shaft will be grouted <br />through water bearing zones. To prevent surface drainage from entering the shaft, the <br />concrete collar will be extended above the ground surface. During idle periods, a screen will <br />be placed on the top of the concrete shaft. Water that flows into the shaft during shaft <br />construction will be pumped into a tank(s), located on the surface, that will be used to allow <br />sediment to settle. The quantity of water will be measured as it is discharged out of the <br />tank(s). Additionally, after shaft construction is complete, flow at the bottom of the shaft will <br />be monitored and results submitted to the DRMS on a monthly basis. <br />The quality of ground water that comes in contact with coal seams and surrounding strata is <br />generally degraded. Bear Coal Company prepared a study of the potential effects of mining <br />on the B-Seam aquifer (J. E. Stover & Associates letter to DMG dated October 23, 1995). A <br />correlation was made between the geochemical characteristics of the roof, coal and <br />interburden and the degradation of the quality of water in the coal seam. Soluble calcium, <br />magnesium and sodium appears to degrade the quality of ground water that comes in <br />contact with the disturbed coal seam and surrounding strata. This degradation of ground <br />water quality is considered typical for water which seeps into the mines in the Paonia <br />Somerset area. <br /> <br />TR-47 2.05 - 67 07/07 <br />~PP>QOvE~ <br />7 / 17/0'7 <br />