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• Run-off from the uphill reclaimed area around portal sites will be collected in Ditch #1 <br />and drained to Pond B through Ditch #3 and #4. Ditch #5 and #6, downhill from the <br />original topsoil piles #3, #4 and #6, will pass run-off from the north-eastern portion of <br />the disturbed area to Pond B. Ditch #7 and a row straw bales or other sediment control <br />will contain run-off from the area north of Ditch #6 which encompasses approximately <br />one acre. <br />Run-off from the area originally occupied by topsoil pile #4, near the entrance to the <br />mine site, will be contained by a newly constructed earthen berm as well as a sediment <br />control structure such as a silt fence or straw bale dam. Run-off from the western <br />portion of SAE -2, which will not drain to the berm discussed above, will be collected in <br />a ditch on the south side of the main access road. An alternate sediment control <br />structure such as straw bales or a silt fence will be maintained in the ditch near the <br />entrance to the property so run-off is filter prior to leavinq the site. <br />Exhibit 4.7-1 shows and discusses the run-off control from the Portal #1 area. As <br />discussed in the exhibit, in order to keep the erosion and potential tractive forces as low <br />as possible, a registered professional engineer recommended the channel be <br />constructed in a wide and flat configuration. It was calculated the channel should be <br />a minimum of 15 feet wide and 0.35 feet deep. As constructed (see Exhibit 4.7-1) the <br />width of the channel is 22.5 feet wide and 32 inches deep in the upper portion. The <br />• stable channel will re-route potential surface flows at non-erosive velocities away from <br />the reclaimed area around the portal. Approximately 100 feet below the reclaimed <br />area, the channel will return the flows to one of the original drainage swales. <br />A vegetation study performed during October 2000 documents vegetation at the mine site <br />has flourished since 1994. The Phase II Bond Release, Revegetation Success Sampling, <br />located in Appendix 3.6-5 demonstrates the vegetation at the Coal Ridge No. 1 Mine <br />passed all applicable comparisons in accordance with Rule 3.03, Release of Performance <br />Bonds, as well as those of the promulgated Vegetation Guidelines , April 18, 1995. <br />The sagebrush grassland community was compared to a reference area located east of the <br />reclaimed mine site. The reclaimed sagebrush grassland community attained at least 90% <br />of the reference area's plant cover and passed the species diversity test. The irrigated <br />hayland attained 90% of the 3,000 pounds per acre production standard even though the <br />area had been grazed during the year. <br />A supplemental study (page 4-58vi) of the irrigated hayland and the adjacent irrigated <br />hayland field was performed on June 2, 2001. Both fields had in excess of 99% ground <br />cover. <br />Phase II bond release requires a soil loss comparison to determine if untreated drainage <br />from the reclaimed Coal Ridge No. 1 Mine sagebrush grassland community is contributing <br />suspended solids to streamflow or runoff outside the permit area in excess of premining <br />levels. The study presented on pages 4-58ii - 58iv demonstrates that untreated drainage <br />is from the reclaimed area will contribute the same amount or fewer suspended solids to <br />NCIG - Coal Ridge No. 1 4-58 06/18/01 <br />