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IV. OBSERVATIONS AND FINDINGS <br />Phase I Bond Release <br />Removal ofstructures and regrading. The Division verified during regular monthly inspections, and <br />during the bond release inspection, that as required in the reclamation plan the permittee has <br />removed the conveyor belt structures, the lower tipple facility, and grizzly pad. The ground surface <br />has been adequately regraded where the structures were removed. No accumulations of coal fines <br />were found in the conveyor corridor. The fill area along the uppermost conveyor appeazs to have <br />been adequately reshaped, and water bars are in place along the length of the conveyor corridor. <br />Regrading throughout the bond release area restored the land surface to the approved postmining <br />topography. Slopes throughout the bond release azea appear stable. <br />Sediment yie/d. The premining sediment yield of the bond release area is unknown because the azea <br />was disturbed prior to the enactment of the Surface Mining Control and Reclamation Act (SMCRA). <br />The bond release application relies on a comparison of pre-disturbance and postmining sediment <br />yield using theoretical calculations of soil loss rates. This comparison was originally submitted in <br />Technical Revision 41 for demonstrating the Tipple ponds aze no longer needed for sediment control. <br />These ponds aze a short distance downslope from the bond release area. In the comparison, the pre- <br />disturbance soil loss rate is calculated using the Universal Soil Loss Equation (USLE). This <br />calculation already existed in the permit application as part of the Tipple pond design. The <br />postmining soil loss rate is calculated using the Revised Universal Soil Loss Equation (RUBLE). <br />Only the "C" factor is varied between the two calculations; all other variables aze held constant. The <br />pre-disturbance calculation uses baseline vegetation cover values from before enactment of SMCRA. <br />The postmining calculation uses vegetative cover data for the disturbed area collected in 1999, 2000, <br />and 2001. The resulting calculation indicates the postmining soil loss rate is 55% of the pre- <br />redisturbance rate. The variables used in the calculations appear reasonable for making the <br />comparison. The comparison, therefore, appears technically valid. A chief cause of soil loss is <br />transport of solids in suspension; therefore, the compazison indicates the untreated drainage, <br />currently, does not contribute more suspended solids than just prior to enactment of SMCRA. As a <br />further check, the Division independently calculated postmining soil loss for the disturbed azea using <br />the RUBLE, as follows: 30R X 030K X 3.53~s X 0.085c X O.SOP = 1.4 tons/acre/year. This is a <br />modest soil loss rate for steep-sloped rangeland in northwest Colorado. <br />Based on the foregoing observations, the Division finds that the bond release area meets the <br />requirements for Phase I bond release. <br />Phase II Bond Release <br />Topsoil replacement. As explained in the preceding discussion of Bond Release Criteria, the <br />conveyor was apre-SMCRA structure. Topsoil was left in place beneath and next to the conveyor. <br />As observed during the Division's regulaz monthly inspections and during the bond release <br />inspection, this topsoil supports vegetative growth along the conveyor corridor. There were no <br />topsoil replacement requirements for the Goat Trail road because it is a pre-SMCRA, permanent <br />feature, and the lower facilities pad area because it is approved as a permanent gravel pad. <br />8 <br />