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C'YC'C-.Sediment Yield Deman.crrnrian Eckman Park Area 4/ <br />• As shown by the SEDCAD+ modeling results, the total sediment contributions calculated for representative areas <br />within Area 41 are equivalent to or less than comparable unmined areas with vegetative cover approximating that <br />of the approved Pastureland Reference Area. These results are derived using vegetative information provided <br />from the approved reference area for comparison and modeling surface roughness characteristics on the <br />reclamation as provided by contour furrows and seedbed preparation practices typically utilized on the reclaimed <br />areas. The time of concentration values presented for the post-mining areas represent the sum of the time of <br />concentration and travel times for the subwatershed exhibiting the longest hydraulic flow path within the modeled <br />watershed. The SEDCAD+ computer printouts are included in Appendix B. <br />3.2 FIELD INSPECTION SUMMARY <br />Field inspections of Eckman Park, Area 4l have been carried out through monthly DMG Coal Inspections, annual <br />Rill and Gully and Permanent Gully Surveys, and through summer vegetation sampling during 1998. Over that <br />time, thorough inspections of the areas have been completed. The reclaimed areas show no signs of significant <br />erosion. Contour furrows are still evident and continue to be stabilizing structures. <br />Several areas of down-cutting in excess of 12" have been noted on various drainages during the annual surveys. <br />These areas have been repaired as necessary and have remained stable. Rock rip rap, check structures, adequate <br />cover, and litter accumulation contribute to the stability of these structures. <br />Pond A in Eckman Park is a permanent sediment control structure. The overall watershed into Pond A is stable <br />with adequate vegetative cover to slow runoff flow velocities. All areas record an adequate litter component which <br />adds to the overall stability. <br />• [n conclusion, no significant or persistent erosional features are evidcnt within this area and the findings of the <br />field inspections are consistent with the results predicted by the SEDCAD+ modeling. <br /> <br />• is~wmnrironmm~nlleeAm~FunJrelarcaJl doc <br />