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controlled underdrain under a portion of the fill and a gravity <br />sorted underdrain under the remainder of the fill. The proposed <br />underdrain will be extended to the head of the fill to meet the <br />requirements of Rule 4.09.2(2). It is important to note that in <br />the opinion of CTL/Thompson, the extension of the subdrain will <br />serve to meet a regulatory requirement, but will not provide for a <br />substantial improvement in mass stability. <br />Taking into consideration CTL/Thompson's site investigation, <br />proposed designs and construction plans with modifications <br />resulting from joint OSMRE/MLRD discussions and review, Colowyo <br />will commit to the following design and construction plan. <br />CONSTRUCTION PLAN <br />All available topsoil will be removed and either stockpiled <br />for later use or direct haul replaced to a reclaimed area. <br />CTL/Thompson could not confirm their prediction for the <br />existence of shallow bedrock at the toe of the fill because of snow <br />cover at the time of their inspection. This shallow bedrock will <br />be confirmed prior to construction of the fill. <br />Colowyo will construct a controlled underdrain in accordance <br />with the CTL/Thompson recommendations from the head to the toe of <br />the fill. The harder, available sandstones obtained from the <br />mining operation will be selectively handled and placed in at least <br />a 24 foot wide by 8 foot high configuration to serve as the <br />underdrain before covered by spoil material. The natural spoil <br />sorting which will occur by utilizing the thicker lifts recommended <br />by CTL/Thompson will be sufficient to protect the drain from <br />clogging. <br />CTL/Thompson also believes that it is desirable to create a <br />permeable fill to reduce the risk of developing free water levels <br />within the fill. Lift thicknesses up to 100 feet thick is <br />acceptable and will be utilized to construct the fill. This method <br />of spoil placement also enhances the construction of a free- <br />draining layer of spoil material at the base of the fill. <br />Experience at Colowyo provides evidence that the natural sorting <br />process which occurs while dumping in higher lifts is sufficient to <br />create this drain. Inspection and documentation of this natural <br />sorting is recommended and will be conducted by Colowyo. See the <br />Inspection Plan section for additional details. <br />RECLAMATION PLAN <br />The final configuration of the fill is designed to minimize <br />erosion. The final configuration takes into account a number of <br />the components of the Streeter Fill reclamation which have proven <br />successful. The final outslope will not exceed 3h:ly. Drainage <br />benches of at least a 12 foot width will be constructed at <br />approximately 100 foot vertical increments. These drainage benches <br />will direct surface runoff to the west into a permanent drainage <br />