1994-05-02_REVISION - C1981017 - Laserfiche WebLink

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The pre -law trommel screen reject contained a significant percentage of coal, therefore, this slope is the least vegetated and contains gullies that continue unbroken from the top of the slope to the bottom. Screening operations ceased prior to 1977. The spoil slope extends from the portal bench to a point approximately 450 feet below. The enclosed photo shows the downslope area in detail. The overall grade is roughly 1.OH:1.OV. Approximately 16 gullies exist ranging in depth from 2 feet to 7 feet. A crust has built up on the surface of the slope over the years which is helpful in controlling erosion. Close site inspection reveals no evidence of significant recent (last five years) erosion. Most of the gullies have reached a relative equilibrium and are not expected to produce significant erosion during normal runoff events. 3) Mine #1 Mine #1 contains two significant and two minor pre -law spoil slopes created when the portal bench was excavated. The enclosed photo shows the 2 southernmost downslope areas in detail. These are the two significant slopes. The natural slope located to the left of the spoil slope looks very similar to the disturbed slope and it.also contains little vegetation. The enclosed map section shows all four downslope areas. The slope material consists of Mancos Shale, weathered coal from the seam outcrop and some sandstone material from minor beds excavated above the coal seam. The spoil slopes in the photo extend from the portal bench to a point approximately 400 feet below. The overall grade is roughly 1.OH:1.OV. Although some clump grasses have been established naturally on the slope, very little vegetative cover exists. Approximately 30 gullies of depths greater than 3 feet exist, with lengths greater than 100 feet. A few gullies exist over 8 feet in depth, however, for the most part, the gully depths do not exceed 5 feet. The two southernmost downslope areas are located directly in avalanche paths and have been difficult to naturally vegetate. Due to the avalanche paths and heavy snowfall, these slopes are more active than the others in the area and the protective crust which exists at the other areas is not as prevalent on the slopes at Mine #1. The two minor downslope areas to the north are less than 150 feet in length. The slopes are milder, approximately 1.3H:1.OV and gullies in excess of 2 feet are rare. Clump grasses also exist on these slopes but no appreciable vegetative cover exists.