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5. The permanent diversion shall make use of artificial structural controls in order to allow it to <br />remain in dynamic equilibrium with the drainage basin system. Riprap channel lining will be used in <br />most of the permanent drainage channels on the reclaimed area. The Division approves the use of <br />such structures (4.05.4(4)(6)). <br />D. Sedimentation Control Measures, Ponds and Discharge Structures -Rules 4.05.5, 6 & 7 <br />Ten sediment ponds are in place as approved by the Division and treat disturbed area surface water <br />runoff. These are the Streeter Gulch, Work Area, Gulch A, Loadout, Stoker, Railway Loop, Prospect, <br />West Pit, East Taylor, and Section 16 Ponds. Three additional ponds, the West Taylor Pond, the <br />Section 21 Pond and the Section 28 Pond are approved by Permit Revision 02. Designs for these <br />ponds are included in Exhibit 7, and locations of the ponds are shown on Maps 12, 41 and 41A. <br />1. The Division does not approve of any sediment pond in a perennial stream (4.05.6(1)(6)). <br />2. The Division proposes to approve the submittal of reports required by Rule 4.05.9(17) on other <br />than a quarterly basis. The timing of report submittal shall be annual in the Annual Hydrology <br />Report. <br />3. Alternative design criteria and specifications have been approved for use in sediment pond design <br />and/or construction. This decision is based on a thorough analytical demonstration by a qualified <br />professional engineer that the resulting sediment pond will be as environmentally sound and <br />structurally stable taking into consideration physical, climatological and other characteristics ofthe <br />site (4.05.6(11)). <br />E. Acid-forming and Toxic-forming Spoil -Rule 4.05.8 <br />No significant acid-forming spoil exists within the overburden or coal seams to be mined (PAP, page <br />2.05-57). Overburden sampling and regraded spoil sampling plans were approved for the East Pit and <br />Section ] 1 Pit during the first two permit terms. These plans aze discussed in Exhibit G and Section <br />2.05 of the PAP. Results from past sampling are included in the mine's Annual Reclamation Reports. <br />These programs were instituted primarily due to concerns about high sodium adsorption ratios (SAR) <br />in some over- and interburden materials. Analogous sampling is performed in the West Pit and <br />Section 16 Pit. During nine years of sampling of the upper and lower Y seam overburden in the East <br />Pit, only one sample had a suspect SAR value. Approximately seven percent of the overburden <br />samples in the Section 11 Pit had suspect SAR values; all of which were placed at the bottom of the <br />pit by the dragline. Only one of 99 samples of regraded spoils has had a suspect SAR value. One <br />sample of regraded spoil is collected for each five acres of reclaimed area. No evidence of toxic <br />effects to vegetation on reclaimed areas has been reported to date on the mine site (review ofAnnual <br />Reclamation Reports through 2005 report and inspections to date). See Section 6 of Exhibit 6 of the <br />PAP and Annual Reclamation Reports for explanations and additional information. Additionally, <br />drill holes for the South Taylor Pit were analyzed in conjunction with PR-02. Several holes were <br />found with suspect SAR levels in the interburden. These interburdens aze well below the surface and <br />Proposed Decision and Findings of Compliance 4 May 2007 <br />Permit Revision 02 Page 34 <br />