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,~ t s ~ ~•. <br />affirmed that these previous agreements with Sunbelt Mining would be <br />applicable to La Plata Coal Corporation. <br />The proposed permit area lies in the upper rim of the San Juan Structural <br />Basin, an asymmetric structural basin in northwestern New Mexico and <br />southwestern Colorado. Sedimentary rocks within the basin are of both marine <br />and non-mari rte origin. <br />The formation of interest in the area of the mine site is the Cretaceous <br />Mesaverde Group. The Mesaverde Group is composed of three major units (in <br />ascending order): Point Lookout Sandstone, Menefee Formation and Cliffhouse <br />Sandstone. <br />The coal seam to be mined occurs in the Menefee Formation. This formation is <br />composed of interbedded sandstone, shale, carbonaceous shale, and coal. The <br />La Plata No. 1 Mine will remove the upper ("A") coal seam from the Menefee <br />during the course of its operation. <br />Ground water occurs in the Hay Gulch alluvium adjacent to the mine site and in <br />the Point Lookout Sandstone underlying the proposed mine. The Hay Gulch <br />alluvium is nearly saturated year round. The Point Lookout Sandstone aquifer, <br />nearly 275 feet below the mine floor, will be unaffected by mining operation. <br />There are no perennial streams within the permit area. Surface water within <br />the small ephemeral drainage basin is limited to runoff from rainfall and <br />snowmelt events. Runoff is conveyed through a system of culverts and ditches <br />to a single sediment pond at the base of the 11.2 acre watershed. Discharge <br />from the pond enters Hay Gulch, a tributary of the La Plata River. There is <br />no flowing stream within the valley of Hay Gulch at the location of the mine. <br />Historically, streamflow has been diverted into an irrigation ditch on the <br />north side of Hay Gulch. Runoff from upland areas enters the ditch or <br />recharges the alluvium. <br />Climatological information was presented from a nearby reporting station <br />located in Durango, Colorado (approximately twelve miles east of the proposed <br />permit area). Data were presented for both precipitation and temperature for <br />the period 1971 to 1986. The average annual precipitation calculated from the <br />reported data was 19.4 inches with an average annual temperature of 46.9oF. <br />As stated, the soil in the area has been disturbed by previous coal mining <br />operations. During site clean-up activities during the first part of 1987, <br />La Plata Coal Corporation stockpiled 388 cubic yards of suitable soil <br />material. This material will be used during reclamation activities. <br />Two soil associations were previously mapped by the Soil Conservation Service <br />in the areas surrounding the disturbed area: <br />Camborthids-Torriorthents-Haplargids Association and Witta-Falfa-Potts <br />Association. The first association encompasses the area surrounding most of <br />the facilities area; whereas, the second association surrounds the sediment <br />pond area. <br />-6- <br />