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According to the application; the pit may be up to 45 feet in depth if no water is encountered. The Division is concerned of the stability of the Ditch due to the proximity of the pit on both sides of the ditch. The applicant has only provided dimensions of the reclaimed slopes (4h: I v). No anticipated slopes of the pit during mining operations were noted in the application. Typicallc, gravel pity nre mined by excavation at the toe of a gravel bank. whcrebv the hank collapses progressively into [he pit, usually a[ a near vertical slope. It has been the Divisions direct experience that efforts to maintain the mined face at a slope no steeper than l h: l v is rarely successful unless the operator mines the eravel by pushing material down the bank using a bulldozer, in which case safety considerations require that slopes no steeper than 2.Sh: 1 v or 3h: I v be developed. In order for ACA Products to mine within 3 feet to the south of the ditch and within 15 feet to the north of the ditch, the applicant will need to provide an engineering stability analysis for slope configurations as they will occur during mining adjacent to the Templeton Ditch. , The geotechnical stability exhibit shall meet the performance standards of Rule 6.5 in the Construction Material Rttles and Regulations. As an alternative, ACA Products may commit to a greater distance from the edee of the pit to the ditch and a reduced slope during mining to assure slope stability. In either option, the applicant shall infornr the Division as to how the ditch will be lined, the timing of lining, and provide a mitigation plan for the Templeton Ditch in the event of slope failure. ~l. Please inform the Division if the mining operation is expected to directly affect surface or groundwater systems. In particular, please describe how the hydrologic balance will be protected from the asphalt batch plan[ and concrete plant operations. A reclamation cost estimate was included in [he permit application to reclaim all affected areas of the mine, which total nearly 80 acres of disturbance. The estimate provided by ACA includes a cost for topsoil replacement, revegetation, demobilization of the crushing and concrete plant, and 20% overhead addition. The total reclamation bond estimate is $0,89 f .00. The Division's estimate was conducted on November 23, 1998, and vvas based on actual disturbance noted on site during the October inspection. The Division's estimate includes backfilling the pit to achieve a slope of 4h:1 v, ripping, topsoiling the affected area, revegetation, mobilization/demobilization., ar:d indirect cost. The Division's estimate was based on 24.30 acres of disturbance for a total cost of $76,538. It appears that the major differences between the two estimates is the cost for backfilling the slopes to achieve 4h:ly. ACA did not include a cost for backfilling the pit, and the Division calculated $38,631.00 to complete this task. ACA has the following options regarding the bond; Include a cost for reclaiming the entire pit to achieve a slope of 4h: l v. In addition, a cost Yor topsoil replacement, revegetation, mobilizationldemobilization, and an indirect cost percentage of 18.76%, or