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The ventilation shaft was constructed as a bleeder for the mined out area of longwall panels <br />located northeast of the shaft location. Mining ceased approximately midway through the <br />third panel north of the Purgatoire River valley The vent shaft was constructed using the <br />raised bore method. A ten-foot diameter shaft was bored and completed to eight foot in <br />diameter, lined with perforated steel plate backed by a pea gravel fill in the one-foot annulus <br />Prior to drilling the shaft. grout was injected in the overburden in four drill holes adjacent to <br />the shaft location to attempt to minimize inflows to the shaft after construction. The location <br />of the shaft, windmill well, bunkhouse, and Purgatoire River are as identified in Photograph <br />#1 <br />Photograph #1 <br />Ge logy <br />The geology at the shaft location is fairly basic. Raton Formation rocks outcrop immediately <br />below the thin mantle of soils as evidenced by geologic logs completed during shaft <br />construction, The formation consists of sandstones, siltstones, mudstones, and <br />carbonaceous shales interbedded with various seams of coal from the surface to the total <br />depth of the shaft. The vertical shaft reaches total depth of 620 feet in the Maxwell coal <br />seam floor at an elevation of 6749 feet AMSL South of the shaft location is the alluvial valley <br />of the Purgatoire River. Visible in photograph #2 are the bedrock outcrops in the Highway <br />12 road cut within close proximity to the Purgatoire River channel. <br />