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Trapper Mining, Inc. C- 1981 -010; PR7 Adequacy Review No. 2 Page 12 of 15 tlior gli tlie pit depicted iii PRO is sliorter iii llengtli, tlie higllier strip ratio iii thus locatioii results iii a larger pit voud and larger quantity to backfll. As the deptli of tlie cut increases, tlie surface disturbance (and resulting volume required to fill the pit) also increases. This is a f nctioii of the depth aiid highevalll /lose walll slope aiigles. Tlius, tlie backfill volume increases ivitli deptlli iii a iioiillinear eeaY (i.e. parabohcalllly). Cut AE 45 represented iii tlie current PR7 bond calcrilations, is the current pit tlliat exists iii the field today, and is not as deep as the proposed cut estimated iii PRO. Tliis us the primary reason for tlie difference iii AE pit backfill volluune between PR6 and PR7. b. Division's Response: The Division is conducting a cost estimate based on our November 12, 2013 meeting and the subsequent approvals of the SL 14 and SL 15 bond release applications as well as the information provided in the adequacy review response. Thank you for the explanation of the differences in volume. 31. The current cost estimate for the K and G Pits are based on backfilling 3,799,225 cubic yards of material. The new estimate is based on a cost for backfilling 2,169,306 cubic yards of material. This is 1,629,919 cubic yards less than the current estimate. It does not appear areas within K/G Pits has been granted Phase I bond release and it appears the inajority of the projected worst case disturbance used to calculate the current backfill volume amount has occurred. Given that Phase I bond release has not been approved for K/G pit disturbance please explain this large decrease in volume needed to backfill this pit. a. Trapper's Response: As per the meeting on November l2, 20 t3, the tissues regarding the release of liability associated ee ith the Phase bond Release process as tit relates to the PR7 Permit Revusuon iv ere addressed. See explanatuon for itein # 27. With the PR7 bond Estimate, the K, L, & M Pit's regraded surface (P.M.T.) incorporates a lower elevation draiiiage profile that facilitates a lower cost grading plain by reducing the overall volume required to bring the area to a post ininung topographe iflich provudes positive drainage for the worst case bond Year reclaination pllan. This regrade design coinbined eeith the draghne operation 's pllaciiig the M and Q seain iiiterburdeiis "iii pit" (as opposed to hauliiig thus inateriall to the Horse Gulch Fill evith the truck /loader- operation) results iii a lower volume of material required to backfill tlie worst case pit void. The truck /loader operation is utilized to inove inateriall tliat us too dustarit for the dozer grading operations to cost effectie ell' push. Thus inateriall is removed ee ithiri the adjacent pit areas acid does riot take aiie inateriall f oin the Horse Gulch ]Fill as was planned iii the PR6 Worst Case Borid ]Estimate (see item # 33 for truck /loader operations e- ariarice explariatiori). b. Division's Response: The Division is conducting a cost estimate based on our November 12, 2013 meeting and the subsequent approvals of the SL 14 and SL 15 bond release applications as well as the information provided in the adequacy review response. 32. The current cost estimate includes a cost for drilling and blasting the F Pit, Z -Pit, East A Pit and K -Pit. The proposed estimate only includes a cost to drill and blast the highwall associated with K/G Pit. Given that Phase I bond release has not occurred for the areas currently bonded for F Pit, Z Pit and East A Pit and that disturbance did occur in these areas, the proposed cost estimate needs to include a drilling and blasting the highwalls in F, Z and east A pit. Please revise the cost estimate to include this cost. a. Trapper's Response: As per the meeting on November l2, 20 t3, the tissues regarding the release of liability associated ee ith the Phase Borid Release process as tit relates to the PR7 perinit revusuori iv ere addressed (see item # 27 response).