2014-10-21_REVISION - M1988044 (5)

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TR-07 RECLAMATION PLAN REQUIREMENT 1: Backfilling must create a final surface that does not deviate more than 25 feet from the original surface elevation. The less deviation that can be created the better,but 25 feet is the maximum deviation allowed. REQUIREMENT 2: If the bottom of the mining pit is already less than 25 feet below the original surface then backfilling will include whatever overburden is available to return the final surface to an elevation as close to the original grade as possible or to be compatible with adjacent reclamation or natural topography.. Discussion: Although the pit depth, in this case, is within the specifications, it still needs to be backfilled to some extent with overburden. The reason for this is to create a suitable subsoil on top of which the soil will be placed. This is because the soil is not the only part of the growth medium that is important. The subsoil is also important. If the sand has been extracted then the underlying material may be something other than sand and if it is different it is most likely to be silty or clayey. It is also likely to be quite firm, making it difficult for roots to penetrate. Placement of topsoil on top of the pit bottom without first including at least a few feet of overburden would very likely result in poor revegetation or a revegetation failure because the material under the sand is not very likely to be suitable as a subsoil. REQUIREMENT 3: Backfilling will be done primarily with overburden,but other materials may also be used such as cleanings from sediment basins at the processing plant. If a variety of materials are used they will be mixed so as to avoid creating continuous layers of widely different materials under the surface. JR-07 Note: Experience since the original amendment has shown the use of sediment from the processing plant to be useful and effective.) Discussion: Backfilling with overburden, in most cases, will be sufficient to bring the elevation up to or higher than the 25 foot maximum depth requirement. One advantage of using only overburden is that it is very likely similar to what was originally at that location. Another advantage is that it is inexpensive to backfill using material that has been stored adjacent to the pit. But it is possible, in some situations where overburden was originally thin, that there will not be enough overburden to accomplish the full backfill depth. In that case, other materials can be brought to the site or"borrowed" from other locations where there is an excess of overburden. In the event the imported material differs in texture from the original overburden, thick, continuous layering of overburden and imported material should be avoided. Over time, these layers may create zones in the subsoil that hinder the growth of vegetation, especially if the imported material is fine and contains a good deal of clay sized particles. When different material is imported it should be blended with overburden or laid down in thin seams and then mixed with a dozer so no widespread layers are created. Coal Creek Sand Resource Amendment 3 (2005)- M-1988-044 Exhibit E Page 9