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-53- permanent ground water dewatering system and backfilling many of the surface facilities with the retaining structures left in place. Merrick and Company's analyses have been found to conform with the current state-of-the-art. The Division finds that the operation is in compliance with the requirements of this section. XVIII. WECC initially proposed the disposal of waste rock within two waste piles. One pile, the "initial waste rock pile", will contain approximately 1.25 million cubic yards and will be located on the lower facilities bench. The second waste pile, the "upper waste pile", will be significantly larger and be located on the bench above the portal area. Since the submittal of the original application; the initial waste pile was removed from the plan. All waste is now proposed for disposal in one, permanent pile. The original permit application contained limited descriptions of both waste piles, lacked engineering detailed design and plans, and proposed that the waste be considered "durable rock". The Division expressed concern that the waste rock would qualify as "durable rock" and, because of generation via separation through a rotary breaker, may actually constitute "coal processing waste".; Concern was also expressed that the delineated slope stability problem area within the surface facility complex might compromise the upper waste pile's structural integrity. The applicant was directed to analyze the slope and foundational stability of the proposed waste piles and to submit appropriate detailed engineering plans for review. WECC subsequently revised page 3-43 of the original permit application to state "for the purpose of expediting the permitting procedure the waste rock shall be tentatively specified as 'coal processing waste', and the initial waste pile shall be designed as though this were the case". WECC also submitted a letter proposal for preliminary design of the waste pile utilizing existing geotechnical data, and redesign or revision of the design if later geotechnical data indicated significant variance from preliminary material assumptions. Further, WECC revised the permit application to indicate that the upper waste pile design would be submitted several years in the future, following delineation of the waste material classification, completion of appropriate stability analyses of the slope and foundational area, and the completion of the final detailed engineering design plans. -WECC has subsequently submitted a report entitled "Report, Preliminary Design Recommendations, Initial Waste Rock Pile, Mt. Gunnison Coal Mine, Somerset, Colorado, for ARCO (WECC) Coal Company", prepared by Geo-Hydro Consultants, Inc. This report, which constitutes Phase I of. the studies proposed on page 3.43c of Exhibit letter 3.2.8.A of the revised permit application, is t M1,.