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Chapter IV <br /> In the Coal Basin affected area, the Upper Sandstone is approximately 50 feet thick., <br /> the Middle Sandstone is about 120 feet thick and the Rollins Sandstone is about 140 <br /> feet thick. All of these sandstones outcrop on the eastern wall of Coal Basin. This is <br /> presumably where recharge to the aquifers occur. From their ourcrops, the <br /> sandstones dip to the west under Huntsman Ridge and eventually extend deep under <br /> the Piceance Basin. There are no known users of water in the vicinity of the mine from <br /> the three sandstone units because of their depth (over 2,000 feet). <br /> Sediment loads within the Coal Basin are naturally high. This is due to the geology <br /> (large expanses of exposed Mancos shale), steep terrain and large volumes of runoff <br /> generated primarily by snowmelt. <br /> The Coal Basin mine plan is designed to minimize the impacts on the surface and <br /> ground water of the area. Drainages from all mine disturbed areas are routed through <br /> one or more sediment ponds. <br /> In the sediment pond series are 30 sediment ponds, 6 Best Available Technology <br /> Ponds, and 3 sediment ponds approved but not yet constructed, with a total capacity of <br /> 50.84 acre feet. <br /> The system, except for the two approved tunnel ponds, was designed to handle <br /> sediment loads from an operation of five mines, with heavy traffic along the 13.7 miles <br /> of haul roads., and the coal refuse pile. <br /> b. Adit/Rock Tunnel. <br /> During the preceding permit term, the Adit/Rock Tunnel became operational to both <br /> coal seams mined at Coal Basin, and is the major transportation artery for the workings <br /> of Nos. 1 and 2 Main Entries (previously referred to as Mines No. 1 and 2). The <br /> workings of Nos. 3, 4 and 5 Main Entries (previously referred to as Mines No. 3, 4 and <br /> 5) are inactive at the time of permit application submittal. <br /> The Adit/Rock Tunnel has been operational since the fall of 1987. The use of the <br /> Adit/Rock Tunnel for transport to and from the active workings is beneficial in terms of <br /> the hydrologic consequences of mining, as sediment generated by mine operations will <br /> be reduced. <br /> c. Haul Roads. <br /> A substantial benefit derived from the Adit/Rock Tunnel is a reduction in traffic to the <br /> portals over the extensive road system developed for coal haulage. <br /> As noted in the mid-term review, which was done prior to the Adit/Rock tunnel having <br /> become operational: <br /> 8 <br />