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e <br />The general approach will be as follows: <br />1. For all No. 6 Mine longwall mining, the zone area computer program <br />that we have used for the No. 5 Mine longwalls at Empire Energy <br />and Dorchester's old Fruita property, will be used to predict the <br />subsidence resulting from the proposed mining. <br />2. Where multiple seam mining is projected to occur, the following <br />methodologies will be utilized: <br />a. Mine No. 6 longwall mining under No. 5 Mine longwall mining -the <br />principles of superpostion will be applied. The total amount of <br />subsidence for a surface point from both episodes of longwall mining will <br />simply be the sum of the subsidence resulting from each individual <br />episode of longwall mining. <br />b. Mine No. 6 longwall mining under No. 5 Mine room-and-pillar workings. I <br />propose to use a conservative approach here. The No. 5 Mine <br />room-and-pillar workings have not been retreat mined. The worst <br />possible consequence of subsidence from the No. 6 Mine longwall panels <br />would be the failure of the 5 Mine pillars with the subsequent caving of the <br />roof. Should this occur, the total subsidence above the No. 6 Mine <br />longwall would also include subsidence resulting from the caving of the <br />No. 5 Mine workings. Again, the principles of superposition will be <br />applied. The subsidence contribution from the No. 6 Mine longwalls will <br />be calculated with the zone area computer model. The subsidence from t <br />the No. 5 Mine room-and-pillar areas will be calculated with the Lee and <br />Abel equation utilized in the No. 5 Mine permit application. <br />3. The zone area computer model will be modified slightly to reflect the actual <br />subsidence data that Empire has collected over their full-extraction <br />room-and-pillar panels and the first longwall panel. <br />4. Asite-specific draw angle of 19o will be used. This is still conservative with <br />~ J~~" respect to overburden subsidence effects, the zone model that we used <br />in the No. 5 Mine permit will be used. This will be modified slightly to <br />specifically address the possible consequences of multiple seam mining <br />subsidence impacts. <br />