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<br /> <br />PROBABLE HYDROLOGIC CONSEQUENCES OF MINING <br />A. The Golden Eagle Mine <br />Mining activities at the Golden Eagle Mine began in 1976. Most of the <br />activity has been in the development of surface facilities and mains in <br />anticipation of future coal production. Hydrologic effects from this <br />operation would be expected to increase with future mining activities. <br />Many of these effects have been assessed in the applicant's hydrologic <br />analysis provided in Exhibit 6 of the permit renewal application. <br />The area of mine discharges measured during the first half of 1988 at the <br />Golden Eagle Mine are higher than the estimates of inflow to the mine <br />presented in Exhibit 6. The present discharge rate is in excess of <br />300 gpm and has ranged up to nearly 500 gpm. Earlier estimates ranged <br />from 179 gpm to 193 gpm depending on the transmissivity of the coal. The <br />current increase in discharge, however, is due primarily to the inflow <br />experienced when a water bearing fracture zone was encountered in the <br />Second Right entries in early 1988. No such point source flow was <br />anticipated in the earlier study. <br />The most recent inflow study for the Golden Eagle Mine was conducted in <br />September 1987 and is included in Exhibit 10. The study consisted of <br />mapping all mine inflows at the time, measuring or estimating inflow <br />rates, and determining inflow sources. This study was made prior to the <br />mine encountering the water bearing fracture zone in the Second Right <br />entry. A total of 13 sources of inflow were reported, including 5 new <br />points of flow, and a total inflow of 45.4 gpm was estimated. A figure <br />of 26.4 gpm had been recorded during a 1986 study. At this point, the <br />mine was experiencing inflow well within the preliminary estimates. None <br />of the sources identified at that time were fault related; significant <br />faults or fracture systems had not been encountered in the Golden Eagle <br />Mine prior to early 1988. <br />Impact by the mine on the quantity of water available on the artesian <br />bedrock aquifer being tapped by the fracture zone in the Second Right <br />entry area is probable. The identity of this aquifer is uncertain, but <br />the Trinidad Sandstone is a possibility. The Trinidad Sandstone is a <br />regional aquifer with potential recharge areas at appropriate elevations <br />southwest and west of the mines. <br />In excess of 500 gpm was estimated as initially issuing from the fracture <br />zone. This flow exceeded the capacity of the mine's pumping system and a <br />section of the mine was flooded for some period of time. Ultimately the <br />flow from the fracture zone was controlled, and the flooded section <br />cleared. Currently the water flow from the fracture zone totals somewhat <br />less than 200 gpm. Such flow will reduce the potentiometric surface for <br />the aquifer over a significant surrounding area. The apparent depth of <br />the aquifer is, however, such that no wells in the area apparently <br />produce from it. As a result no reduction of use of water from this <br />aquifer has occurred or is anticipated for the future. <br />-18- <br />