Laserfiche WebLink
• Section 16 and East Pit data. <br />3. Postmining Land Use <br />It was determined during the inspection that the vegetation community appears to be progressing <br />toward one that will support the postmining land use (in terms of diversity, species composition, <br />presence of woody plants and noxious weeds) of Rangeland (PAP page 4.16-1). <br />4. Suspended Solids <br />Contributions of suspended solids to streamflows or runoff outside the permit azea were evaluated by <br />use of the Revised Universal Soil Loss Equation (RUBLE). The equation is A = R times K times LS <br />times C times P, where A =gross erosion per acre per year, R =erosivity of rainfall and runoff, K = <br />soil erodibility, LS = hillslope-length and gradient, C =cover management, and P =support practice: <br />A = (R)(K)(~)(C)(P)• <br />Four representative study blocks of approximately 20 acres in size were used to compare gross annual <br />erosion per acre in both the premising and postmining conditions. Values for parameter R were as <br />• previously approved in the PAP, and relate to rainfall intensities of the area. Values for parameter K <br />were based on values previously approved in the PAP, but were weighted to represent the four study <br />blocks for premising conditions, and represent a blend of topsoils for postmining conditions. LS <br />factors represented the topography of the study blocks for premising and postmining conditions. The <br />parameter C reflects the vegetative surveys conducted during July 2000 for the reference azea <br />(premising conditions) and the study blocks (postmining conditions). Values for the parameter P were <br />as previously approved in the PAP. Posturing values of P represent the furrows and roughness of <br />postmining surface treatments. Previously approved values of parameters or the base values for <br />weighted values may be found in the PAP Appendix 7 Section 13 page 4. <br />As demonstrated in the application, there is less erosion anticipated from the reclaimed areas than <br />from the same areas previous to mining. The following table presents the conclusions of the analysis. <br />Gross Erosion Per Acre Per Yeaz (four test azeas) <br /> East Pit A East Pit B East Pit C Section 16 <br />Pre-minis 0.0043 0.0076 0.0766 0.0466 <br />Reclaimed 0.0008 0.0016 0.0005 0.0019 <br />The Division accepts the premise that as the quantity of soil eroded from the reclaimed sites is less <br />than from the sites in their premising condition, the amount of suspended solids in the runoff is less <br />from the bond release areas in their reclaimed condition than from the bond release areas in their <br />C-81-019, SL-03,15 August 2001 <br />Page 8 of 10 Pages <br />