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• SENECA COAL COMPANY <br />HISTORY AND BACKGROUND <br />Seneca Coal Company (SCC) has operated the Seneca II, Seneca II-West, and the Yoast Mines in Northwest <br />Colorado beginning with coal production in 1968 at the Seneca II Mine. The mining progressed to Seneca II- <br />West in 1990 and to Yoast in 1996. The three mines are known collectively as the Seneca Mining Complex <br />and produced coal for the Hayden Generating Station. Coal production totally ceased in 2005 leaving 4,000 <br />acres of reclaimed land within the Seneca mining complex. The success of the reclamation program at SCC is <br />evident even within a climate of changing regulations, high altitude, and very steep slopes. <br />The terrain and climate provide interesting, and intriguing challenges to mining and reclamation technology, <br />equipment operation, post mine contouring and revegetation. The coal lies in a 20-35% pitching grade. The <br />terrain varies in elevation from 6,300 feet to 8,500 feet. The climate in Northwest Colorado provides a 65- <br />day growing season. The annual precipitation is 17 inches of moisture, mostly in the form of snow. The <br />summer growing season tends to be relatively dry. <br />The post mine land use for SCC reclamation is wildlife habitat and livestock grazing, similar to premine uses. <br />Most of this land was overgrazed prior to mining and invasive weeds continue to be a challenge. The re- <br />establishment of shrubs and trees has also proven difficult. The post mine terrain is steep, up to 33%, <br />resulting in significant erosion potential and the necessity for intensive reclamation best practices and <br />permanent drainage channel construction. <br />Even with these adverse conditions, successful reclamation is achievable and nearly 3500 acres have been <br />successfully revegetated at the three mine sites to date. The following narrative describes the overall <br />reclamation practices at the Seneca II-West Mine and the successful efforts to reestablish shrubs and aspen <br />on reclaimed lands. <br />GENERAL OPERATIONS <br />Normally, area surface mining is restricted to coal reserves which he in a relatively level plane below a level or <br />gently rolling surface terrain. However, at Seneca II-West, the geologic structure is such that the coal seam <br />outcrops at the top of the mountain and dips at 20 to 35 percent, while the overlying surface dips at <br />approximately 18 to 30 percent. This results in areas of overburden thicknesses ranging from 15 to over 100 <br />feet, which lends itself to area surface mining by dragline. Mining was conducted with a BE 770 dragline (18 <br />cu. yd. bucket) with maximum digging depth of 100 feet. The relatively high angle of dip on the coal seam <br />and surface require some creative modification of conventional dragline-mining methods. <br />RECLAMATION PRACTICES <br />All backfilled spoils are graded to create irregular topographic undulations and achieve the approximate <br />original contour. In addition, reclaimed areas with an overall slope grade of 30% or more require special <br />attention. Permanent drainage channels are constructed to control and prevent undue erosion while <br />revegetation is established. <br />Topsoil handling is conducted with dozers and scrapers. Live handling of topsoil has only been done on <br />limited basis due to mining area configurations. The majority of the topsoil has been placed in storage <br />stockpiles for periods of three years or more before replacement. Topsoil is replaced to a depth of ±11-18 <br />inches overall with thicker placement (up to 4 ft.) in tree establishment plots. With the exception of tree and