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<br /> <br />XVII. Backfilling and Grading - Rules 2.05.5(6), 2.05.4(2)(a) and (c ), <br />an <br />The application states that the mining plan for Seneca II-W Mine was developed <br />in conjunction with the Seneca II Mining Plan. The pit progression design was <br />based on standard mining practices, tried and proven at the analogous <br />Seneca II Mine. The mining plan and its back filling and grading details are <br />found within Tab 12. <br />The applicant completed projections of overburden bulking, in order to project <br />post-mining topography within the mined area. The projections included within <br />the original application were completed prior to submittal in 1982. <br />Subsequently, in connection with operations at the existing Seneca II Mine, <br />the applicant has completed topographic observations of reclaimed land. These <br />aerophotogrammetric observations have determined that the actual bulking <br />factor slightly exceeded the original projection (19.8% in the operator s <br />terminology, versus 15.3 projection). <br />In completing its review of the amended application, the Division converted <br />the applicant's analytical projections into an analytical format more familiar <br />to the Division. The applicant projects an average overburden swell factor <br />(loose swollen overburden volume divided by bank overburden volume) of 1.32. <br />Further, the applicant projects a bulking factor (swollen backfilled volume <br />divided by excavated pit volume) of 0.91. Considering the average mined depth <br />and extracted seam thickness, this suggests an average post-mining topographic <br />deflation of 4.6 feet. Adjusted for the possible 4.5 percent discrepancy in <br />observed versus original projected bulking discussed above, the post-mining <br />topography might rise by an additional 1.8 feet, resulting in an average <br />post-mining topographic deflation of 2.8 feet. In either case, the projected <br />post-mining topographic configuration is considered by the Division to <br />constitute an acceptable approximate original contour configuration. <br />The amended reclamation plan requests approval for delay in contemporaneous <br />reclamation, as allowed under Rule 4.14.1(1 )(c ). This request is necessitated <br />by the amended mine plan. The original plan called for deposition of boxcut <br />spoil outside the mined pit. However, in response to Division adequacy <br />concerns, that plan was amended to eliminate the deposition of box cut spoil <br />outside the mined area. This mine plan modification resulted in the <br />rehandling of the box cut spoil, which will remain unreclaimed during the <br />first three years of mining. The applicant does not propose to temporarily <br />reclaim this area, because the vegetation would have an insufficient growing <br />season prior to permanent reclamation. Subsequent technical revision <br />approvals have allowed temporary storage of spoil outside the proposed mine <br />pit area. These temporary spoil piles will be protected from erosion by a <br />vegetative cover and are placed in a stable area. <br />A second area for which the applicant requests variance from the normal <br />contemporaneous requirement is northwest of the box cut location, near the end <br />of the 7486 mined area (see Map 12-1 ). At that time the dragline will return <br />to the box cut location. This will leave approximately 3,200 feet of open <br />pit, and at least several rows of ungraded spoil piles. <br />-46- <br />