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• ABOVE. THE REVISED TEXT (PAGE 4.3-5) TO INDICATE THAT A COVER CROP IS USED IN-LIEU OF MULCH I5 ENCLOSED AND MAY BE SVBTITUTED DIRECTLY INTO THE PERMIT FOR EXISTING PAGE 4.3-5. D. For the inactive topsoil stockpiles on the Moffat Area, P&M should construct containment ditches around the entire perimeter of the stockpiles. These containment ditches would direct overland flow away from the inactive stockpiles and keep the topsoil medium in the stockpile area rather than eroding away. The discussion under Section 4.3.4 should be revised to reflect a commitment to these containment ditches. A REVISED PAGE 4.3-8 IS ENCLOSED STATING THAT CONTAINMENT BERMS WILL BE PLACED AT THE BASE OF ALL TOPSOIL STOCKPILES. THIS PAGE MAY BE SUBSTITUTED DIRECTLY INTO THE PERMIT FOR EXISTING PAGE 4.3-8. E. The discussion on page 9.3-8 pertaining to the active stockpiles on West Ridge Area specifies "Acceptable erosion control practices will be applied as necessary." P&M should e::pand upon this statement to clarify the erosion control practices that will be implemented. • A REVISED PAGE 4.3-B IS ENCLOSED CLARIFYING THE EROSION CONTROL PRACTICES TO BE IMPLEMENTED. THIS PAGE MAY BE SUBSTITUTED DIRECTLY INTO THE PERMIT FOR EXISTING PAGE 4.3-8. VI. Ponds, Impoundments and Diversions - 2.05.3(4) A. A review of the design methodology and assumptions used in the design of Pond 1 indicates that the pond may not be sufficiently, sized to contain the design flows. Pittsburg and Midway should review the following discussion prior to re-evluating the pond size and design. The description states Pond 1 will receive the outflows from Ponds 2B through 7B after they are constructed in year 3. Pond 1 was designed considering only the contributing runoff from the area between Diversion Ditch No. 1 and the inflow collection ditches to the pond during year Z. The runoff and sediment generated from this area were modelled using Sedimot II. It was assumed that the design condition would be year 2 and that the year 1 disturbed area would be topsoiled, with contour furrows at 150 foot spacing, mulched and seeded with a temporary cover for at least 60 days. The following two conditions should be re-evaluated to determine the sizing requirements for Pond 1: 1. The sediment and runoff generated in the contributing areas during year 1 of mining with spoil and when topsoil has been removed (CP=1.0); and • 2. The sediment and runoff routed to Pond 1 from Ponds 2B-7B at their design condition (Appendix 4.6-B) added to the contribution from the basin area below these ponds at year 3. The larger of these two runoff and sediment storage requirement