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i IIIIIIIIIIIIIIII111 ~ Sl ~ E=AGLEGYPSUM April 10, 1996 Mr. Bob Elderkin Bureau of Land Management Glenwood Springs Resource Area Office P.O. Box 1009 Glenwood Springs, Co. 81602 Dear Bob: As follow up to our inspection of the Eagle-Gypsum Mme lower stockpile area last week, I am submitting a proposed plan to help mitigate the effects of stormwater runoff in that area and also to repair erosion damage that has already ocaured along the mine hauh•oad. The mitigation plan is illustrated on the attached Exhibit "A" with the basics of the plan summarized in Parts "A", `B", and "C" Part "A" consists of extending the fill slope on the lower end (approx. 400') of the mine haulroad to a 3:1 ratio with waste rock fill material from the active mine. The fill slope will then be top soiled, slashed and seeded .The revegitated slope should help to contain sedimentation in that azea and also improve the visual impact of the lower portion of the mine haulroad. Part `B" includes repair oferosion cuts by using gypsiferous fill material on the north side of the mine haulroad where it crosses Trail Gulch. In repairing the cuts, we will also attempt to reduce the angle of the existing fill slope as much as possible by extending the toe of the fill with the gypsiferous material. Extension ofthe tce ofthe fill wiU be limited because we need to avoid burying the inlet to the culvert and also avoid rerouting the existing drainage channel in the bottom of the gulch. The haulroad is wide enough in this partiwlar area to cut the top of the slope back to the south and further reduce the slope angle. The resultant slope will probably still be too steep to hold top soil but we will slash and seed the gypsiferous slope in an attempt to stabilize it with at least some extent of vegetation. We have seen success in revegitating areas where indigenous gypsiferous material is the only growth medium available so there is a good chance that we will see some revegitation and stabilization on this slope. Part "C" consists of raising the elevation and resloping the mine haulroad so that runoff water will flow into the existing settling pond on the north side the road. This will help to divert water into the settling pond before it reaches the fill slope addressed in Part "B". The haulroad width directly west of the settling pond will also be reduced by extending a vegitated fill slope to the edge of the road, creating a dam that diverts water to the settling pond. The settling pond and the sediment control dam (illustrated in Exhibit "A") are currently in need of annual maintenance and repair so we will incorporate this work into the additional mitigation measures proposed in this letter. 740 Hwy 6 • P O Bo+ 900 • Gypsum, Cola.aAa 81637 19701 5249700