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generated by the mining operations in the East Pit, West Pit and Section 16 Pit. Please <br />revise the text references accompanying the chart to summarize the current status of the <br />fills and to indicate that no additional spoil will be placed into the fills. <br />Colowyo's Response: <br />Colowyo will submit a minor revision by the end of August, 2010 to address this issue. <br />6. On Page 2.05-3 Colowyo provides an overburden monitoring plan, which was updated <br />with the approval of Technical Revision 62. This overburden monitoring plan was <br />approved based on the average topsoil replacement depth of at least eight inches. In <br />Technical Revision 82, Colowyo is proposing a variable topsoil replacement depth, which <br />could lead to less than four inches of topsoil being replaced on some of the regraded areas. <br />With the more shallow topsoil replacement depth proposed, the suspect levels for pH and <br />electrical conductivity become more important. Based on the proposed change in topsoil <br />replacement depth, the Division requests that Colowyo change the suspect levels for pH <br />and electrical conductivity. The Division requests that Colowyo change the pH suspect <br />level from "less than 5 and greater than 9 standard units" to "less than 5.5 and greater than <br />8.8 standard units". The Division also requests that Colowyo change the electrical <br />conductivity suspect level from "greater than 12 millimhos/cm" to "greater than 8.0 <br />millim.hos/cm". <br />Colowyo's Response: <br />Colowyo doesn't believe this change is warranted. Only 20-40% of the remaining <br />disturbed acres are scheduled to receive less than or equal to four inches of topsoil. This <br />means that 60-80% of the remaining disturbed area may receive more that the previous <br />eight inches of topsoil, which at a minimum would directly counter any potential impact of <br />the areas receiving less than or equal to four inches. Furthermore, after review of <br />Colowyo's historical spoil suitability analyses data, a change in the pH and eC suspect <br />levels is not supported based on the fact that Colowyo has not had past compliance issues <br />with overburden suitability. <br />Rule 2.04.7 - Hydrologic Description <br />In the probable hydrologic consequences section of the Colowyo permit there is no <br />discussion regarding spoil springs. Numerous spoil springs have been identified by both <br />aerial photographs and on the ground inspections in the East Pit. Additionally, it is <br />assumed that the continual discharge from the Streeter Pond, even during the dry summer <br />months, is a result of a spoil spring(s). Please include a detailed discussion of the spoil <br />springs that have developed in the East Pit as well as those that are expected to develop in <br />the West Pit and the South Taylor Pit. Please include a discussion of the probable <br />hydrologic consequences from these spoil springs, including discussions on the anticipated <br />changes in the quality and quantity of surface and ground water. <br />Colowyo's Response: <br />The development of alleged spoil springs in or around reclaimed areas is very limited, <br />both in extent and volume of water generated. In specific instances such as the Streeter <br />Fill, pre-existing springs are likely the major source for the nearly continual low level <br />discharge from the Streeter Pond. Many years of NPDES discharge monitoring at this <br />location does not support the notion that water quality is being negatively affected by <br />water that is/has managed to migrate through the reclamation areas and associated <br />spoils. Colowyo believes that the previously stated probable hydrologic consequences