2014-08-13_PERMIT FILE - C1981018A (2)

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As a result of the pumping tests conducted during 'baseline studies" and the analysis of water level data, all three zones should be classified as "aquitards" in that they will yield water but at very slow rates. As of November 1998, mining in the D Seam has produced approximately 16.0 million tons of raw coal. The void volume created by this tonnage is about 380 million cubic feet. Considering an average mining height of 9 feet, 42.2 million square feet (or 968.9 acres) of opening have been created. From water balances and direct measurements, water inflow into the mine from seeps is about 34.28 gpm. Averaged over the entire mine, seeps produced about 0.035 gpm per acre of mine opening. As projected from baseline studies, the mine is essentially dry. As stated previously (II.B.2), the Deserado Mine Permit Area is located on the southwest flank of the northwest/southeast trending Red Wash syncline. This syncline is asymmetrical with strata on the southern flank dipping to the northeast at about 7 degrees. These moderately dipping strata form cuestas, with more resistant layers forming dip slope surfaces. strata along the north flank of the syncline dip to the south at up to 70 degrees. These steeply dipping strata are expressed topographically as the east -west trending hogback, Coal Ridge. The Red Wash syncline plunges to the southeast at about 2.7 degrees into the Piceance basin. The three stratigraphic intervals identified as separate hydrologic zones (upper sandstone facies, siltstone /coal facies and lower sandstone, see II.C.3.b) outcrop continuously along the flanks and around the western end of the syncline. These strata form a typical topographic basin with the lower elevations located near the structural axis of the syncline. The north -south width of this "basin" is about 6 miles. However, this "simple" structural syncline and topographic basin has been breached (incised) by three drainages: the White River, Red Wash and Scullion Gulch. These three drainage features and their tributaries note: Red Wash and Scullion Gulch are tributary to the White River) greatly complicate the geo- hydrology of the "simple" structural syncline. Baseline hydrologic data (see II.C.3.c) show the flanks of the Red Wash syncline (west and north of the mine area) to be the areas of recharge with the area of discharge being the area adjacent to and between the mouths of Scullion Gulch and Red Wash on the White River. The reason the piezometric gradient is toward the mouths of Scullion Gulch and Red Wash instead of down dip toward the axis of the syncline is that the three drainages have incised the strata and provide an area of low elevation (a spill point). This spill point allows the syncline to discharge or drain. The Deserado Mine workings are located in the siltstone /coal facies stratigraphic interval (hydraulic zone). However, monitoring has indicated a rapid decline in water level in response to mining and subsequent dewatering in all three hydrologic zones. The mine began in areas near the discharge for the three hydrologic zones and therefore, the piezometric gradient has always been toward the mine workings. As the mine advances down dip the cone of depression created by the workings maintains the piezometric gradient toward the workings. Baseline data for the lower sandstone facies indicated that the deepest (or structurally lowest) monitoring point, 310136 -2, actually had lower dissolved solids content than did monitoring holes located up dip. As with the piezometric gradient data, this suggests that recharge is coming (Permit Renewal #3 1/99) II.13-8