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<br /> <br />(c> The applicant should address the implications of a catastrophic <br />inflow and outline the measures it will take to prevent this from <br />occurring. <br />(d) from observations during recent inspections, the treatment pond <br />(outfall 001) does not appear to offer a sufficient settling time <br />for effluent containing suspended solids discharged from the mine. <br />Somerset should consider the addition of a flocculating system such <br />as a gel log type. This is a low maintenance, passive system that <br />can last several years before needing replacement. The NPDES <br />permit must be amended to show the use of a flocculent if it is <br />used. <br />(e) As stated in the permit application, it is almost impossible to <br />predict inflows from faults or fractures. These flows tend to <br />occur sporadically and have an initially high output. The <br />application should have a value for worst case mine pumpage. <br />(f) Recent mine inflows have occurred, in quantities greater than can <br />be handled by the existing Sanborn Creek settling pond. Future <br />such events will no doubt occur. <br />(g) What contingency plan does the Somerset Mine have for mine inflow <br />that exceeds the pond's treatment capacity? <br />15. The Oliver Mine appears to be flooded and the Hawks Nest Mine in the E <br />seam is at least partially flooded. A June 10, 1987 inspection by Brent <br />Anderson details the sampling of the flooded workings. In his report he <br />said that flooding had made some areas of the mine inaccessible. Oscar <br />Beck, who was working for Western Slope Carbon, accompanied the <br />inspection. The analysis of the sample showed that the water quality of <br />the working was good enough to meet effluent limitations. Iron <br />concentrations were .04 mg/1 and total dissolved solids were 1,642. <br />However, a sample taken in May 1986 showed much higher Concentrations of _ <br />iron (12.2mg/1) and dissolved solids concentrations of 7,020 mg/1. <br />The application did not contain water quality and quantity data for the <br />Oliver or Hawks Nest workings. The Division will need this information <br />to evaluate hydrologic impacts. This can only be collected by the <br />drilling of monitoring wells into the workings of these mines. <br />Monitoring wells located in the downdip areas of each mine workings can <br />be used to find the extent of the flooding and characterize the water <br />quality in the anoxic areas of the workings. The oxygenless areas of <br />these mine workings may have a different water quality than Spring <br />No. 8. This may increase the iron content and create a treatment problem <br />for mine inflows. <br />(a) The Somerset Mine should drill monitoring wells into the abandoned <br />workings of the Oliver Mine and Hawks Nest Mine. <br />(b> The water quality of each flooded working should be characterized. <br />(c> Maps should be drafted to show the extent of the flooding of each <br />working. <br />-a- <br />