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3. The Division has approved the use of vegetation and organic material as mulch or as an <br />amendment to topsoil to control erosion, promote growth, or increase moisture <br />retention. (4.09.1(4)). <br />4. The Division has approved of the location of the disposal azea. (4.09.1(6)). <br />5. The applicant has proposed an alternative method for disposal of excess durable rock by <br />gravity placement in single lifts. The alternative method is certified by a qualified <br />registered professional engineer as resulting in a fill which will be stable and will meet <br />all other applicable requirements, including Rules 4.09.1 and 4.09.3. The excess rock <br />spoil consists of at least 80% by volume, durable non-acid and non-toxic forming rock <br />that does not slake in water and will not degrade to soil material. The fill is designed to <br />attain a minimum long-term safety factor of ] .5 and an earthquake safety factor of 1.1. <br />Surface water runoff from areas adjacent to and above the fill shall be diverted away <br />into stabilized channels designed to meet the requirements of 4.05.3 and safely pass a <br />100-yeaz, 24-hour precipitation event. Therefore, the Division has approved use of the <br />alternative method for rock disposal. (4.09.4). <br />Construction of the underdrain and placement of fill was completed in August 1987. At <br />that time, inspection reports regazding construction ofthe underdrain were conducted by <br />Seneca Coal Company. Submittal of those reports was in compliance with Stipulation <br />No. 4 of the 1987 permit. Therefore, that stipulation is no longer required on the <br />permit. Final reclamation of the fill has been completed. Quarterly inspections of the <br />fill were conducted by Seneca Coal Company during reclamation activities and for at <br />least one year following revegetation. <br />Additional information on the excess spoil fill is located in Tab 12 of the permit <br />application. <br />VIII. Backfilling and Grading <br />Details of the backfilling and grading plan at the Seneca II Mine are found in Volume 10, <br />Tab 12 and Volume 12, Tab 13 of the permit application. A backfilling and grading <br />timetable is presented on Exhibit 13-2, and in the permit application. <br />All areas affected by surface coal mining operations, except specifically exempted by the <br />Division, were returned to approximate original contour as shown on Exhibit 12-9. This <br />includes the drainage channels which were returned to approximate original locations to help <br />maintain appropriate downstream water rights. The spoil was cast by the dragline into the <br />adjacent open pit and compacted by the reclamation equipment. All spoils were graded, <br />highwalls reduced and spoil piles and depressions eliminated except those depressions that <br />existed prior to mining. Cut and fill terraces were not proposed at the Seneca II Mine. <br />The following findings were made regarding backfilling and grading practices at the mine: <br />32 <br />