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n ~~ RAYE & ASSOCIATES 978 WELCH COURT • GOLDEN. COLORADO 80401 • 13031 988-4918 January 13, 1986 Mr. Jon C. Kubic WATER QUALITY CONTROL DIVISION ~~-&333 Colorado Department of Health ~ {.~~ -_ ' T ~ ' -l~ ~._~ 4210 East 11th Avenue i~`~~ ~~ Denver, Colorado 80220 r _---- __ -- dAN '1 ~ ~S2~ Re: "~kcastle Company-Grassy Gap Coal Mine COPS No. 0035653, Routt County ._ ~,~ ~„_.,~; WQCD. Pciir..l t ~~. V I ON Dear Mr.~Kubic: The Rockcastle Company received your letter dated December 19, 1985, and requests an amendment to CDPS No. 0035653 to add two point sources: Pond 5 and Pond 4 de- watering points. Both these point sources were added to comply with requirements of the Colorado Mined Land Reclamation Division (CMLRD). No discharge ponds were originally planned, but CMLRD regulations require that sediment ponds have self- dewatering devices so that a 10 year storm volume will always be available. Grassy Gap Coal Mine has temporarily ceased operations due to continued lack of market. However, both Pond 4 & 5 are maintained'in operational condition to col- lect runoff water. Pond 4 collects runoff from a partially reclaimed active pit and Pond 5 collects water from areas that are fully reclaimed, i.e., the area above Pond 5 has been backfilled, topsoiled, reseeded, and has two growing sea- sons of vegetation on it. The Rockcastle Company would refer to neither of these as "spoils spring" discharge, but as supernatant from sediment ponds. Water that contacts the open coal bed in the box cut at Pit 4 does not enter Pond 4. Since the box cut is lower than the pond, water that enters the active pit stays in the pit until it evaporates or seeps into the ground. CMLRD does not require any water treatment devices other than sediment control. Table 4 enclosed gives the runoff volumes that will accumulate in Ponds 4 & 5 during a 10 year 24 hour storm. The dewatering devices are designed to release collected runoff volumes in 24 hours. A drainage basin map is also enclosed showing the positions of Ponds 4 & 5. Upon final reclamation, Pond 5 will remain as a stock watering pond. The dewat- ering device will be plugged or removed. This is per the wishes of the landowner and approved by CMLRD. Pond 4 will be reclaimed by backfilling and returning the area to rangeland. We hope this information is sufficient to allow you to amend Permit No. CO-0035653. If you need additional information, please contact me at the number above. Very truly yours, '°!°-~ Tommy D. Raye Encl. cc: Bob Sherman