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-23- The general area of the Twin Pines No. 2 Mine has been considered to be the Chandler Synclinal Basin, which coincides with the Canon City Co a] Field. The surface water and ground water general areas for this CHIS coincide because of the geologic structural basin. Figure 1 illustrates the locations of the mines within the general area of the Canon City Coal Field. All of the mining operations considered in this assessment are located near the axis of the Chandler Syncline and are mining coal from the middle portion of the Cretaceous Uermejo Formation. Eleven mineable coal seams occur in this formation and have thicknesses ranging from 1 to 16 feet. It is difficult to correlate the strata between mines because each mine uses different terminology for the individual coal seams. Figure 4 gives a general correlation of the relationship of the seams being mined. In view of the descriptive correlation inconsistencies, terminology used by the individual mines will be used in this discussion. These anticipated and existing permitted operations, include: the Twin Pines No. 2 G.E.C. Strip, Newlin Creek, and Dorchester No. 1 Mines. The proposed Twin Pines underground mine is in the west central portion of the Canon City Coal Field and proposes to mine the Brookside coal seam. The Newlin Creek underground mine is permitted to mine the uppermost seam, the Rex Carbon, and the second highest economic seam, the Shamrock. Both seams are shallow and the workings are currently above the piezometric surface, as is.shown on Map 2.04.78 of the Newlin Creek application. The G.E.C. surface mine will be removing five seams. The maximum depth of extraction will be 100 feet and the pit will, therefore, be above the piezometric surface. No inflows from bedrock strata to the pit have been observed by Division personnel during monthly inspections for the past three years. As stipulated in the G.E.C. permit, additional monitoring is underway to verify the mine's impact to the hydrologic balance. The Dorchester tJo. 1 underground mine lies on the southern terminus of the Chandler Syncline, and is currently mining the Red Arrow and the Dirty Jack O'Lantern Seams of the Vermejo Formation. These seams are stratigraphically the lowest seams proposed to be mined in the general area. A. Impacts on Ground lJater The three underground mines and one surface mine anticipated within the Canon City Coal Field may impact ground water quantity by one or more of the following: 1) Dewatering of the coal, roof and floor with the advance of mining; 2) Subsidence-induced flows into the mines; and 3) Degradation of water recharging ground water aquifers.