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recognizes that after the overlying limestone has been removed, the exposed sandstone slab will be relatively resistant to erosion. As previously stated, erosion control structures will be necessary to prevent rapid runoff from the sandstone slab from impacting downslope areas. The applicant is required to address the impact which surface runoff, originating on the permit area, will have on the adjacent downslope land east of the permit. The adequacy review of July 14, 1993 asked for sizing and locations of all erosion control structures. Sizing is based on whether they would be temporary of permanent. The applicant states that temporary erosion control structures, including stone berm filters and check dams, will be used at the base of the disturbed area in the natural drainage:;. Each structure needs to be designed and sized appropriately to handle the peak runoff. from a 10 year/24 hour storm event. The calculations included in the addendum for the #98 runoff curve should be used with the acreage of the watershed which will impact each structure. Permanent erosion control structures include the tree pads and sandstone benches. Each of these structures must be sized and designed to handle peak runoff form a 100 year/24 hour st~~rm event using t e #98 curve mentioned above. ~d }~ ~'he Division maintains that,_ ice the area is disturbed, •a3~3 "."H - . -- ~s~t or should be accounted in the site specific storm water permit. •If '~r ~ city of the runoff exceeds F feet per second, the checnnelized will require riprap. Please state how any runoff will be r (y"•Sf( u,R.P~ addressed. ~-Q.~,4 ~tt~ ~j~a_~,{-~ GCcM 4fY` 1-~'(.Gl'~-C~~(1~ ~.~,p,+""c^~'LRp,{-'~" ~ivl,l .•~C..~j +u.-tfp k;' c~Y~ LL ~lU[.d ~ y ~,, ~ ~ ~ p 5. Stability Of Loadout Benches - Tfie application s atesat~,~ ^p~p~, permanent erosion control will be handled by inward sloping Loadout ~ 1 ~ benches. Some questions have been raised regarding the stability of the Loadout benches on such a steep slope. The use of gak~bions or rock buttresses has been discussed as one possible means of stabilization. Please state the method that will be used to stabilize these benches and provide the design to be followed to ensure the means of stabilization will be adequate. 6. Sediment Control - All sediment control features, including Loadout benches, rock berm filters and check dams need to be located on Exhibit C and engineered to retain the appropriate peak runoff for the specific drainage area to be retained. The runoff ~t the base of the disturbance must be no greate~7 The operator must provide geotechnical documentation to demonstrate that the Loadout benches will be stable both during dry and saturated conditions. The check dams must also be engineered to retain the appropriate runoff. 7. Soil Salvage - The application states that sandy overburden will 2