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Walden Coal Company contracted with Mountain River Associates (MRA) to define the <br />soil loss regime at the site and recommend alternative sediment control. Field <br />measurements were made on soil structure, soil permeability, organic matter content and <br />particle size analysis to empirically determine the soil erodibility constant on reclaimed <br />and undisturbed soils. These tests resulted in a significantly lower soil erodibility <br />constant of 0.12, as opposed to the SCS published value of 0.32. The Division accepted <br />the values derived from field tests because they were site-specific, in comparison with the <br />generalized published values. A correlation matrix was performed on the five factors <br />making up the universal soil loss equation, and length and grade appeared to be the <br />predominant factors contributing to soil loss at the site. Therefore, MRA recommended <br />that slope lengths be limited to two hundred feet by terrace benches, and that slope shapes <br />minimize convex areas and channelized flow. Walden Coal Company prepared apost- <br />mining topography map based on those recommendations and proposed to construct <br />discontinuous, ten (l0) foot wide benches along the contour with a 2 - 4% inslope. <br />The effectiveness of this treatment system is monitored by annual surveys of vegetative <br />cover and rill and gully development. These are submitted to the Division no later than <br />January 30 of every yeaz. Areas where the vegetative cover is less than 20% will be <br />subject to mitigation based on Division approval. Gullies greater than twelve inches deep <br />will be stabilized with rock, hay bales, erosion mats or, silt fences and reseeded. No <br />mitigation has been necessary for several years. <br />The operation is in compliance with the requirements of this Section. <br />B. Groundwater <br />Information on groundwater can be found in Section I, Water Information; Appendices A <br />and I; and Plate 1, Water Elevation Control Map in the application. A detailed <br />description of the groundwater resources and the impacts of mining on groundwater can <br />be found in Section Dt of this document, titled "Probable Hydrologic Consequences of <br />Mining and Cumulative Hydrologic Impacts Study". <br />C. Surface and Groundwater Monitoring <br />The applicant will conduct monitoring of groundwater in a manner approved by the <br />Division. The groundwater monitoring plan is as follows: (4.05.13(1)). <br />The Walden Coal Company originally installed nine monitoring wells in the alluvium of <br />Mann Draw. These wells were used to measure fluctuation in alluvial water levels along <br />three stream transects. These transects were located above, below and in the middle of <br />the area which could be impacted by the Bourg Mine. Only two wells remain. One of the <br />Bourg Strip Mine. C-81-021 18 August 4, ]998 <br />