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Cortments - Continued The operator had backfilled numerous rills and gullies prior to the inspection and contour furrow installation was in progress during the inspection. Furrow installation was completed by the evening of May 24th. All major rills and gullies had been regraded, although shallow rill erosion (1-3 inches deep) was evident in several areas. Actual damage (topsoil loss) is difficult to quantify since gully reclamation had already been completed. Photos 5/85/D-20 and 5/85/D-21 show at least 6 reclaimed gullies. Assuming an average gully length of 1,000 feet, depth of 18 inches and width of 24 inches, a total volume of 111 cubic yards or less than 1/10 acre foot would have been lost through gully erosion. Loss of topsoil resulting from rill erosion is also difficult to quantify. My estimate based on observation and photographs is that rill erosion averaging 2 inches deep occupied approximately 5% of the surface. Approximately 1/2 acre foot of topsoil may have been lost through rill erosion. Over a 50 acre area, the amount of topsoil lost to erosion during the spring of 1985 cannot be considered significant with respect to the ultimate achievement of successful revegetation. The operator's reasoning for not installing contour furrows in the fall of 1984 as required was that snow and wet conditions prevented equipment operation. The operator felt it was reasonable and prudent to delay soil stabilization until after spring runoff had abated. The fault with this reasoning is that snow and wet conditions are always a possibility when topsoiling and stabilization is delayed until fall. If soils are replaced and smooth graded in the fall, but stabilization practices are not implemented there is potential for significant erosion during the subsequent spring runoff. The practice of topsoiling large areas in the fall is somewhat risky. The following statement is from Page 2.05.74, Volume 1 of the Mine 3 Permit Application: "Reclaimed areas will be drill seded with a rangeland drill. Immediately following seeding, the entire area will be contour furrowed according to the specifications contained in Figure 13, Design of Typical Contour Furrow." The area was drill seeeded in Fall, 1984, but was not furrowed until May, 1985. 3. NOV C-85-045 was issued for failure to construct sediment control facilities in compliance with approved design. The NOV has subsequently been modified to read "failure to construct and maintain..." Specifically, collection Ditch P-1 along the base of the Middle Creek Pit rough graded spoils had not been constructed and the Middle Creek Detention Basin had not been dewatered as required. Photos 5/85/D-17, 5/85D-18 and 5/85/D-19 show the Middle Creek Detention Basin and its emergency spillway. A small amount of water (less than 5 gpm) was discharging through the emergency spillway when the photos were taken on May 23, 1985. It was apparent from highwater marks in the spillway channel that a considerable volume of water had discharged through the emergency spillway earlier this spring (high water mark approximately 2 feet above channel bottom).