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topmost seam mined in the area. Coal from the Brookside seam is ahigh-volatile bituminous coal that: is up to six feet thick with a shale split that can vary between two inches to three feet. Overlying the Vermejo sediments is the Raton Formation of Tertiary age, consisting primarily of resistant cliff-forming sandstones of yellowish grey color. The immediate area has been dissected by the perennial streams of Oak Creek, Lewis Gulch acid South Oak Creek. These streams have carved the landscape leaving mesas capped with alluvial pediments and many short and steep ravines. Quaternary alluvial and colluvial sediments, ranging from boulders to gravel, blanket the surface of the landscape. Hydrology Review of the both the ground and surface water hydrology can be found in permit section 2.04 of the permit application, pages JFSA 5, 13 to 17, 28 to 42, and pages 25 to 27. Ground A'ater -Groundwater information can be located in the permit application on pages 28 through 45. In general, three categories of potential groundwater aquifers occur in the mine area. These are the Trinidad Sandstone, the lenticular discontinuous sands of the Vermejo Formation, and the alluvial deposits found along the drainages. The first aquifer is the Trinidad Sandstone, the most extensive aquifer in the region. Domestic wells in the general area that are located four miles upstream from the permitted area yield 20 to 100 gpm. Permeability is high, ranging from 1 to 200 millidarcys. The impact by mining at the Twin Pines No. 2 Mine on the Trinidad Sandstone is negligible due to the stratigraphic distance between the coal seams and the aquifer. The lowest of the coal seams is 350 feet above the contact with the Trinidad Sandstone member. Tl~e second water-bearing zone, the Vermejo Formation, contains perched and discontinuous sandstone lenses that may act as aquifers. Production in these sandstone lenses is less than 10 gpm, signifying their low yield character. Further information on this Formation and impact on the aquifers can be found in the original Findings Document dated November 1983. The third type of aquifer in the region includes the alluvial drainages. Most of these drainages expose coal seams which have been mined historically since the late 1800's, thereby causing widespread channel disturbance. Underground waste was also deposited in these local drainages. Due to these mining practices, there is little baseline information available for these alluvial drainages. The original Findings Document stated that the potential for impacts to the alluvial aquifers as a result of mining at the Twin Pines No. 2 Mine is considered negligible. In general, ground water for the region is derived from the recharge areas near the Wet Mountain fault. The ground water moves downdip, controlled by the structure of the Chandler Syncline, moving along its axis and discharging through the Trinidad Sandstone and Vermejo Formation aquifers and retrace deposits adjacent and beneath the Arkansas River. 10