2008-07-18_PERMIT FILE - M2008006

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Mr. Garv DeWitt RF. SerFer Pit July 3, 2008 Page 3 of 4 must be approved by the Division of Reclamation Mining and Safety prior to installation. Considering a combined overburden and gravel thickness of 12.5 feet, as stated on page 3, and using the acres of the reservoir and the capacity shown on page 7, there will only be approximately 1.5 feet of bank above the water level of the reservoir. We request that the portion of the reservoir paralleling SH 392, and the NW and NE corners be protected with rip rap to help preclude wave action erosion on the banks. We also request that the setback be increased to a minimum of 50 feet along the CDOT ROW. A wave run-up calculation was performed to estimate the wave crest for varying wind speeds. Denver data from the National Climatic Data Center reports that the prevailing wind direction is from the north in gusts up to 62 mph with mean wind speeds of 9-10 mph. As a result, it is likely that wind driven wave erosion will occur primarily along the southern embankments. The wave run-up calculation estimated wave peaks of 2.0 ft. for 100 MPH winds. Future Right of Way and setbacks place the limit of mining approximately 60 feet from Highway 392. Wave run-up calculations determined that rip-rap is not necessary for the embankment slopes. ® Page 11 states that the site is within the Cache La Poudre River 100 year flood plain, and all work will conform to Larimer County Flood Hazard Regulations. People from Larimer County and Windsor indicated that Windsor Flood Regulations would be followed. Could this be clarified and could the applicants - - plan-for-complying-be-made availablefor- review? -We-are-again-concerned about potential negative impacts on SH 392. As of the date of this response, a floodplain permit application is being prepared for submission. Mining will not commence prior to the approval of the floodplain permit. A copy of the floodplain permit application is included as an attachment to this letter. There is a sizeable (15'+ wide and 10'+ deep) ditch along the north edge of the pit area. Much of this ditch is in the setback area. What are the plans for this ditch, will it be abandoned, mined, backfilled, left as is? How does the flood plan and drainage plan address this ditch? This ditch starts at least a mile north, appears to run along the west side of the Kyger Gravel Pit, through a pipe under Highway 392, continues through the affected area, and drains into the Poudre River. Will disturbing this ditch divert flood water onto CDOT ROW? This ditch is visible on the maps, but is unlabeled and we could find no mention of how it would be handled. At least a portion, if not all, of the ditch was man made.