2022-09-29_PERMIT FILE - C1980007 (2)

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West Elk Mine . If the ABP is positive, leachate from the sample would be basic; if negative, leachate would be acidic Any rock or earth material with an ABP of -5.0 tons of CaC03 equivalent per 1000 tons of material, representing a soil with a net potential deficiency of 5.0 tons of CaCOs equivalent per 1000 tons of material, is generally defined as a potentially toxic material (A.A. Sobek, W.A. Schuller, J.R. Freeman, and R.M. Smith, Field and Laboratory Methods Applicable to Overburdens and Minesoils, EPA=600/2-78-054). Table 64 summarizes some of the data in Exhibit 13. It shows weighted-average ABPB values calculated for samples taken from the strata enclosing the B, E, and F Seams. None of the overburden or floor strata for the B, E, or F Seams is potentially toxic, i.e., none has an ABP < -5.0 tons of CaC03 equivalent per 1000 tons of material. The weighted average of all strata has a positive ABP of +25.3, indicating that a substantial excess neutralizing potential exists in the enclosing strata. In addition, 109 other samples from strata adjacent to the B, E, and F Seams were analyzed for sulfur forms. Pyritic sulfur in these samples, ranged between 0.01 percent and 3.03 percent, with a mass-weighted average of 0.14 percent. These low values aze consistent with those used in the acid-base accounting and similazly indicate no acid producing potential. For a composite of these samples, a neutralization potential of only 4.4 tons of CaC03 equivalent per 1000 tons of material would be required to obtain an ABP equal to zero. The weighted average of all measwed neutralization potentials from similaz sample materials was 32.9 tons of CaCOs equivalent per 1000 tons of material, or about 7.5 times larger than necessary for complete neutralization of acid from pyritic sulfur. Using the value of 32.9 tons of CaC03 equivalent per 1000 tons of material, a calculated ABP for the 109 samples is +28.5, approximately the same as for the samples in Table 64. Therefore, the materials tested from the B, E, and F Seams show no potential for producing acid leachate. Assessment of Refuse Material Disposal Impacts on Groundwater Mining generates refuse consisting ]azgely of non-coal earth materials and low quality coal. The refuse is separated from the coal at the screening plant and rotary breaker or in the mine by two- cycle development mining techniques. The refuse is presently treated as coal processing waste. The refuse generated during this term of permit will be disposed in either the Lower Refuse Pile (LRP) (Exhibit 51), or the Refuse Pile Expansion (RPE) (Exhibit 70) or the Upper Refuse Pile (Exhibit 51} when it is constructed. These refuse piles were designed and shall be constructed in accordance with the performance standazds of Rule 4.10 of the CMLRB Regulations for Coal Mining, Coal Processing Waste Banks. Water levels monitored in wells GP-5 (MW-3), GP-1 (MW-5), GP-3 (MW-8) and GP-4 (MW-9) have remained dry or neazly dry. Only well MW-5 was found to contain enough water to permit collection of a sample for water quality analysis. Because of the low permeability of the colluvial soils and the lack of groundwater in the strata below the refuse pile, no impacts on groundwater are anticipated in subsequent years. In addition, water quality samples from wells and stream-gaging stations in the vicinity of the site of the pile aze being measwed as part of the on-going West Elk Mine hydrologic monitoring program. Water monitoring well SG-1, and water quality monitoring 2.05-191 RevisedJwie 2005 PRIG; Rev. March 2006; Rev. May 2006 PRI G