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999 STATE OF- COLOR4D0 RIC ~anRn U. L41A`A. Govc'^m DEPARTMENT OF NATURAL RESOURCES U. Monte Pascoe, Ezecu[ive Director b1INED LAND RECLAl1~1ATION 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 TeI. (303) 866-3567 David C. Shelton Director M E M O R A N D U M TO: Dave Shelton & Joe Zalkind FROM: Jerry Zimpfer DATE: May 17, 1982 RE: Preliminary comments following a reconnaissance inspection of the Colony Oil Shale Project, May 6, 1982. She following includes some preliminary observations and comments resulting from ~ _-' my May 9th, 1982 site visitation with Jim McArdle, Jim Pendleton and Roy Cox. My thinking on these problems is very preliminary. Detail solutions can be worked out after the company makes its proposals for reclamation. Issues that should - be discussed with the company include: 1) The existing sediment ponds on the Middle Fork of Parachute Creek were sized for a limited watershed area on the assumption that two major dams (bliddle Fork and Davis Gulch) would be constructed upstream. At the present time, Neither dam has been constructed. Without these dams, the sediment ponds are grossly undersized and should be reconstructed. The sediment ponds will - - require periodic inspection and maintenance. 2) If the Middle Fork dam is not constructed, some provision must_ be made to route surface flow across the mine bench. The current system of piping flow through the mine bench and releasing it to a concrete flume down the face of the fill would require periodic maintenance. It is not a final reclamation solution. It may be appropriate to replace this system with a surface diversion channel as described in the permit application. 3) Activities in the plateau area and Davis Gulch are a major disturbance which is, at present, in a highly erosive configuration. The area needs to be graded, topsoiled, and revegetated to reduce the current excessive erosion rates. The Davis Gulch dam should be constructed both to trap sediment from above, and to protect the downstream haul road fill from extreme runoff events. (This may not require the PF1F structure currently planned, but the modified - design would have to be judge adequate.) 4) The existing disturbance is crisscrossed by numerous roads. Unnecessary minor roads should be removed and the area reclaimed. For those roads that must be left, a road drainage system should be completed including ditches, culverts, riprap outfalls, etc. Provisions for periodic maintenance would be necessary.