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Award Nomination for Excellence in Surface Coal Mining and Reclamation - USDf, OSMRE - 1990 September, 1990 B. Site Desc~tion Trapper Mine is a surface coal mine located approximately 6-12 miles south of the city of Craig, CO, along the northern slope of the Williams Fork Mountains. The climate is semi-arid steppe and is charac- terized by cold winters and moderately warm summers. The average annual precipitation is 13.9 inches, one-third of which falls in the form of snow and is the principal source of stream Oow for the region. Soils are generally deep and formed in alluvium and colluvium derived from sandstone and shale. The topo- graphy is described as rolling hills with relativity steep slopes (average - 14%). The prevalent vegetation type is mountain shrub which interfaces with stands of big sagebrush at lower elevation and aspen types at higher elevations. Stream Channel Reconstruction and Erosion Control Measures Introduction During surface mining activity, drainage systems are altered in that natural bedrock drainage control is o[ten replaced with unconsolidated spoil material that is relatively homogeneous in nature. The frac- tured spoil material may produce a modification to what would naturally develop in terms of drainage pat- tern or hillslope and channel gradients. To compensate for this geologic change, hillslopes and channel gradients could be reduced or appropriate conservation technique could be incorporated to reduce the potential for accelerated erosion. In 1987, Trapper began a program to control the heavy runoff and to consequently minimize the sedimen- tation problems that were catued by the high rate of erosion, particularly in postmine drainageways. A variety of erosion control materials and methods were evaluated for the stabilization of reconstructed drainageways. Additionally, sediment reducing landforms were studied and applied on the reclaimed sideslopes that Oanked the reclaimed channels. By September , 1990, 7.3 miles of permanent postmine channel reconstruction was completed in five major drainageways within Trapper Mine's permit area. This paper presents the results o[ a four-year erosion control study and describes viable conservation alternatives to successfully reconstruct drainage channels on drastically disturbed lands in a cost effective manner. Vegetation Samoline Methods Herbaceous plant canopy wver, annual herbaceous primary production and woody stem densities were measured on seven postmine reclaimed drainage sites and on two undisturbed premine drainage locations in 1988, 1989, and 1990. Plant canopy coverwaz estimated in 3,100-m transects spaced 10-m apart at each site. Herbaceous plant canopy cover and percent mulch cover were estimated by species using the point- hit technique (Optical Point Bar). Herbaceous production was estimated by clipping 6,1/4-m plots (20-m spacing) on each of the three line transects at each site. Woody stem density on undisturbed drainage segments waz calculated using the point-center-quarter (PCQ) method. Five PCQ's were wnducted on each line transect at 20-m spacing. Distances Crom the center of each PCQ to the nearest live stem in each quarter was recorded. Woody stem densities in reconstructed drainage segments are an approximation of the actual seedlings planted at each site. Erosion Control Stratceies A wide variety of soil erosion control materials, methods and sediment reducing measures were used in reconstructed drainageways, on reclaim sideslopes and on regraded spoils. The following list of measures and/or materials were applied in combination to decrease the likelihood of accelerated erosion, to reduce Oow rates and to reduce the sediment loading in downstream sedimentation structures.