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2023)appear partially due to the influence of spoil spring discharges from the Seneca II <br /> Mine. Seneca Property, LLC predicts that lower Grassy Creek TDS will be 2177 mg/1 after <br /> addition of Yoast spoil springs. Thus, Seneca Property, LLC concludes that TDS in Grassy <br /> Creek will not increase as a result of Yoast Mine operations. <br /> Using Seneca Property LLC's assumptions about spoil spring development at the Yoast <br /> mine, and the existing baseline water quality data for lower Grassy Creek,the Division <br /> estimated the TDS of lower Grassy Creek after establishment of Yoast spoil springs will <br /> increase by approximately five percent. Because the quantity and quality of Grassy Creek <br /> water is marginal or unsuitable for use as domestic or irrigation water, this projected <br /> increase in salinity will not affect any uses of Grassy Creek water. The only current use of <br /> Grassy Creek water (livestock watering) will not be impaired by the projected increase in <br /> salinity. <br /> Sage Creek <br /> Life-of-mine plans for the Yoast Mine anticipated coal extraction within the Sage Creek <br /> watershed during the second and third permit terms. Preliminary estimates by Seneca <br /> Property indicated that TDS concentrations in Sage Creek downstream from Yoast spoil <br /> springs could increase from 641 to 2118 mg/1. <br /> With the submittal of PR1 in 1999, Seneca Property, LLC further evaluated the probable <br /> hydrologic consequences of Yoast mining operations in the Sage Creek watershed. This <br /> evaluation occurred prior to any mine-related disturbance in that watershed. <br /> Based on Seneca Property, LLC's evaluation, the Division finds that although the company <br /> has predicted that salinity levels in Sage Creek may exceed the Division's conductivity <br /> threshold of 1.0 mmho/cm, the effects to ranching/agricultural operations along Sage <br /> Creek are deemed to be insignificant. The Division finds that the coal mining operation <br /> would not interrupt, discontinue, or preclude farming on the potential alluvial valley floors <br /> that have been identified along Sage Creek, downstream from the mining operation. The <br /> Division's findings in regard to impacts to alluvial valley floors are presented in Section <br /> B-X of this document. <br /> IV. Topsoil <br /> Baseline soils information is found in Tab 9 of the permit application package. Mine soil <br /> reconstruction is discussed in Tab 21. <br /> All available, suitable topsoil was salvaged from areas disturbed by mining and either <br /> stored in a stockpile or immediately redistributed on regraded areas. Of the 16 topsoil <br /> piles excavated three topsoil stockpiles remain as permanent, with a total combined volume <br /> of 36.7 acre feet (2024 ARR). Stockpiles were seeded following construction and. The <br /> remaining stockpiles currently exhibit stable naturalized shrubs, grasses and in some <br /> instances trees and are marked with identification signs (2025 SL9 Inspection). <br /> Regraded pit areas were covered with an average of 1.8 feet, and a minimum of 1.0 foot, <br /> of topsoil. Areas where shrub or tree islands were to be established were covered with 0.5 <br /> feet of topsoil. The facilities areas, where subsoils were not disturbed, were covered with <br /> an average of 1.1 feet, and a minimum of 0.5 feet of topsoil. Replaced topsoil thickness <br /> 15 <br />