Laserfiche WebLink
The Sanborn Creek workings undermined portions of two abandoned mines - <br />the Oliver Mine and the Hawk's Nest Mine. The Oliver Mine was mined in the <br />1930's and is thought to be flooded. An exposure of the workings adjacent to <br />the old county road formerly dischazged water at a rate of a few gallons per <br />minute. About 90 percent of the workings of this mine lie downdip of the <br />discharge point. <br />The Hawk's Nest Mine lies north of the Oliver Mine and is stratigraphically <br />higher than the Oliver D seam. Hawk's Nest mined in both the E and F seams. <br />The workings of this mine are probably not flooded, as indicated by <br />measurements in an old drill hole. Also, during operation of the Hawk's Nest <br />Mine, there was very little inflow. <br />Because potential exists for subsidence to cause fracturing of the interburden <br />between the B seam and the flooded workings of the Oliver Mine, Oxbow <br />Mining, LLC limited extraction in the Sanborn Creek Tracts under those azeas <br />known to be flooded. <br />4. In the now-abandoned Hawk's Nest Mine several drill holes were drilled down <br />from the active mine into lower seams. It is believed that these holes aze not <br />sealed and could provide a conduit for water to flow into the Sanborn Creek <br />mine; however, as reported in the PHC, there was no evidence of flooding of <br />the mine at the time of this renewal. <br />Mine inflow, except that used in the mining process, will be treated and discharged <br />to the North Fork. The discharge will meet NPDES standards, but it is expected that <br />the dischazge will have an elevated TDS for which there are no discharge standards. <br />From recent water quality analyses, TDS values of 3,200 mg/1 for the dischazge can <br />be expected. During the emergency mine water dischazge of the Sanborn Creek Mine <br />in 1999, water quality analyses of the discharge water showed TDS ranging from a <br />low of 2668 mg/1 to a high of 4785 mg/1. <br />Post-mining impacts are expected to be small. The Sanborn Creek mine is expected <br />to slowly flood to the level of the river, which is below the elevation of the portal. <br />Dischazge from the portal is unlikely. The water quality of the flooded workings is <br />anticipated to be the same as that of the old Somerset Mine. After mine closure, the <br />proposed Sanborn Creek area is not expected to contribute additional dissolved <br />solids to the river. <br />The Elk Creek Mine, based on data from other mines in the vicinity, should not <br />experience problems with inflow or eventual discharge from the portal. Inflows <br />experienced in the vicinity include 1 IS gpm in the B seam at Oxbow, 15 gpm in the <br />23 <br />