2009-01-07_PERMIT FILE - C1981022 (10)

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The three primary fac[ors affecting soil availability and suitability aze previous site disturbance, • topographic and physical constraints on soil salvage, and soil depth and material limitations. Early mining disturbance did not incorporate soil recovery and salvage operations, with the result that available soil resources were lost or mixed with and contaminated by coally materials, coal refuse, and ash. Because of this, there is an inherent soil material shortage and surficial materials in several existing surface disturbance areas may be unsuitable or marginally suitable due to high coal and coal refuse content. Topographic and physical constraints which may Gmit soil recovery include steep sideslopes where safe equipment operations may not be feasible, naturally occurring aeeas of surface instability, extensive rocky outcrops, and soils with very high rock fragment content. Relatively thin soils on ridges and steep valley sideslopes and highly vaziable soil depths represent both a physical soil recovery and a soil suitability limitation since effective soil recovery while minimizing dilution with non-soil materials may be difficult. Additional soil suitability limitations include high rock fragment content and relatively extensive clay soils. Minor concerns with boron and selenium content were noted for isolated samples but should not generally affect overall soil suitability. Soll Recovery and Stockpiling As previously noted, soil recovery and stockpiling operations were implemented for all new mining- related disturbance after 1977. Because of soil depth variability, no reasonable documentation is available on average soil recovery depths, although general practice has involved recovery of ail operationally recoverable soils. Similarly, good documentation on soil recovery volumes is not available. At the time that soil recovery operations occurred for the Elk Creek Coal Handling Facilities and Stockpile expansion and West Valley Fill construction activities, documentation of soil • recovery volumes for the individual component sub-aeeas was not collected. Verifiable documentation is limited to a survey of the Elk Creek Soil Stockpile following completion of soil recovery operations. This survey indicated a stockpile volume of approximately 18,600 cubic yards. Contractor surveys and load counts for the North Elk Creek Soil Stockpile indicate a total volume of approximately 59,500 cubic yards, which includes [he volume moved from the Elk Creek Soil Stockpile. Subtracting the Elk Creek Soil Stockpile volume from the total yields a volume of approximately 40,900 cubic yards of soil material recovered from the Ells Creek Mine Surface Facilities Area. Total stockpile volume was confirmed by ground survey on completion of construction activities. Table 2.05-ES-Tl, Soil Recovery and Replacement Summary, presents soil recovery and replacemen[ information and estimates based on both verifiable documentation and other information. Breakouts by disturbance area are, in most cases, estimates based on the limited historical documentation available and conversations with mine personnel. Soil Re~acement Because of the overall soil material shortage, available stockpiled soil materials will be distributed to maximize revegetation benefits for the entire mine disturbance area. Because of the material movement distances involved, stockpiled soil resources for individual sa[ellite facilities have been or will be used in reclaiming the associated individual disturbance areas. OMI has committed to replace approximately S inches of soil material on those areas disturbed by construction of the Elk Creek Mine Surface Facilities and will replace the required 4 feet of suitable material on the West Valley Fill Coal Refuse Pile. The 4 feet of suitable material to be replaced on completed benches in the Wes[ • Valley Fill area will come from foundation preparation activities for each successive new fill bench. Remaining available stockpiled soil materials will be distributed as outlined by Table 2.05-ES-Tl, with the priority of placement of a minimum of 6 inches of soil or suitable substitute materials on historic disturbance areas that have been identified as marginally suitable or unsuitable. MR-67 2 Revised May 2003