Laserfiche WebLink
During the Division's adequacy review of this permit revision <br />(PR-Ol), questions regarding modeling assumptions used 'to <br />design these two sediment ponds were raised. The applicant <br />has committed to re-evaluating the modeling methodology by <br />August 31, 1992. The only hydrologic structures to be built <br />during that time are the Prospect Pond and a portion of the <br />South Collection Ditch. These structures are adequately <br />sized to treat any additional runoff from disturbance to be <br />created during the next year. Should modifications be <br />required following re-evaluation of the hydrologic modeling, <br />they can be implemented by modifying structures or building <br />additional structures. <br />Acid-forming and Toxic-forming Spoil <br />Overburden sampling and regraded spoil sampling plans were <br />approved for the East Pit and Section 11 Pit during the first <br />two permit terms. These plans are discussed in Exhibit G and <br />Section 2.05 of the permit application. Results from past <br />sampling are included in the mine's Annual Reclamation <br />Reports. These programs were instituted primarily due to <br />concerns about high sodium adsorption ratios (SAR) in some <br />over- and interburden materials. Analogous sampling will be <br />performed in the West Pit and Section 16 Pit. <br />Sampling during the past nine years of the upper and lower Y <br />seam overburden in the East Pit has encountered only one <br />sample with a suspect SAR value. Approximately seven percent <br />of the overburden samples in the Section 11 Pit have had <br />suspect SAR values; all of which were automatically placed at <br />the bottom of the pit by the dragline. Only one of 99 <br />samples of regraded spoils has had a suspect SAR value. One <br />sample of regraded spoil is collected for each five acres of <br />reclaimed area. No evidence of toxic effects to vegetation <br />on reclaimed areas has been reported to date on the mine site <br />(4.05.8). <br />Impoundments <br />The applicant proposes to construct cattle-watering <br />impoundments on the reclaimed mine area. Prior to <br />construction of any of these structures, design plans and <br />locations must be submitted to the Division and approved. <br />The only impoundment within the permit area, other than the <br />approved sediment ponds, is the Taylor Pump Holding Pond, <br />which existed prior to August 3, 1977 (4.05.9). <br />G. Ground and Surface Water Monitoring <br />Information on Surface and Ground Water Monitoring is found in <br />Section 4.05.13 of the permit application. <br />_17_ <br />