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West Elk Mine • In the east panels of the Apache Rocks mining area, only B-Seam mining will occur. Only B-Seam mining will occur in the Box Canyon and West Flat Iron mining areas. In the Apache Rocks western panels (Sections 28, 29, and 30), both B and E-Seam mining will occur. Within the Apache Rocks mining area, the overburden thickness for the B-Seam ranges from 600 to 2,250 feet while the overburden thickness range for the E-Seam is 400 to 1,100 feet. The typical interburden distance between the B and E-Seams is 200 feet. Above the IONS and 11NE longwall panels, the overburden thickness ranges from 600 to 1,200 feet. Within the Box Canyon mining area, the overburden thickness for the B-Seam ranges from 500 to 2,200 feet. Springs (and their sources) can be effected by subsidence in two different ways. First, fractures can extend upwazd from the mine seam and intersect the spring or spring source. As explained in Sections 2.05.6 (6)(e)(i)(C&D), Subsidence Zone Description, the height of the caved/fractured zone extending upward from the mine seam is conservatively estimated at 270 feet. Secondly, there is a small probability of surface cracks developing in association with the mining (see Section 2.05.6 (3)(b)(iii & Viii) Streams for estimate of surface crack probability) and the typical maximum depth of such cracks in the Apache Rocks and Box Canyon mining aeeas is conservatively estimated at 100 to 200 feet. These two distances indicate that, for a spring to avoid any potential impacts, the source of the spring must be at least 270 to 370 feet above the uppermost seam that is being mined and more than 100 to 200 feet below the ground surface. From a practical standpoint, because every spring (by definition) "daylights" at the ground surface, there is an extremely small risk that any given spring • will encounter a surface crack. However, it is essential to recognize the following: Site specific evidence demonstrates that surface cracks aze most likely to occur over chain pillars, barriers and mine boundaries. Consequently, if a spring and its source aze not located in these areas, they will be unaffected by surface cracks. This is true for most of the springs in the Apache Rocks and Box Canyon mining areas. • The spring source could easily be unaffected by a surface crack, even if the spring itself is affected (at the point where it surfaces). In this case, the spring would re-emerge at another location. It is feasible to define which of the springs (and sources) in the permit azea are at least 270 feet above the uppermost coal seam that is being mined, which will leave them essentially immune to mine fracture impacts. This analysis has been conducted, and all of the springs in the Apache Rocks and Box Canyon mining areas are at least 270 feet above the B-Seam (in those aeeas where only the B- Seam is being mined) and at least 250 feet above the E-Seam (where both B and E- Seam mining is being conducted. Above the IONE and 11NE longwall panels, all springs are at least 270 feet above the B-Seam. Map 37 depicts these springs. The probable implications to springs caused by subsidence vary between colluvia]/alluvial springs and bedrock springs. Colluvial and alluvial springs are much more likely to be impacted by surface cracks than bedrock springs aze, while bedrock springs aze much more likely to be impacted by the . fractures extending upwazd from the mining azea than alluvial and colluvial springs. These impacts aze discussed in the context of the schematic cross-section provided in Figure 20. Figure 20 depicts 2.05-160 Nmember 1004 PRt 1