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1995 Reclamation Bids July 7, 1995 page 9 <br /> Task 3 Silt Fencing <br /> My concerns regarding installation, maintenance and cost of silt fencing <br /> from Task 2 of Bid PKA-5-356 apply to this project also. If there are areas <br /> where sediment control is required (such as the outslope areas from which <br /> backfill is procured), alternatives to silt fencing should be considered. The <br /> use of small berms, containment ditches, vegetative brush or rock filters, <br /> and the existing sediment ponds/traps below the outslopes could be used to <br /> control runoff not directed to sediment ponds. <br /> CDMG does not specify the quantity of material to be used for backfill at <br /> the Mine # 3 bench. Based on the nominal highwall dimensions of 800 feet <br /> long, 30 feet high and 211:1 V maximum backfill slope, estimated backfill <br /> volume is 53,333 cubic yards. The intermediate coal transfer area backfill <br /> volume would be 2,592 cubic yards and the volume of highwall backfill <br /> required for the lower bench area would be 4,815 cubic yards. <br /> Clarification is in order regarding construction of contour furrows at the <br /> Mine# 3 benches. CDMG proposes construction of contour furrows on <br /> the bench remnants. If the term bench remnants means the relatively flat <br /> bench areas in front of the highwall backfill, there should not be a <br /> problem. The construction of these furrows would be consistent with that <br /> proposed in TR25. However, no furrows should be constructed on the <br /> backfill proper, as it would be impossible to construct the number and <br /> shape of furrow on the backfilled area. Based on discussions with Mr. <br /> Lewicki, we both concluded that the proposed size of the furrows is <br /> probably excessive, as these are not conveyance ditches, but sediment and <br /> runoff traps. <br /> Task 5 Surface Drainage <br /> This task encompasses construction of the contour furrows described in the <br /> prior task. As stated before, concern over the furrows centers around <br /> location and size. Furrows should not and could not be constructed as <br /> designed on the highwall backfill. Furrow size (1.5' deep and 2' bottom <br /> width) and configuration (trapezoidal) as proposed appear excessive, as the <br /> function of these furrows is to catch and hold sediment and runoff. <br />