2003-03-31_REVISION - M1979097 - Laserfiche WebLink

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LAFARGE NORTH AMERICA Land M Lafarge Front Range Aggregates est, Inc. Western U.s. Region 1800 North Taft Hill Rd., P. O. Box 2187, Ft. Collins, Co. 80522 Office: 970-407-3600 Fax: 970-407-3900 Web: www.lafargenorthamerica.com Construction Materials March 20, 2003 Mr. Tom Schreiner Division of Minerals & Geology 1313 Sherman St. Rm. 215 Denver, CO 80203 RECEfVED MAR 3.1 Zpp3 Dlvislen ~f Minerals an/ Dealody Re: East Rigden, Technical Revision No. TR-2, Permit No. 1979-097 ~/oss ~ ~~vitioh y e f~.: Tk-a Dear Mr. Schreiner, This letter is in response to your letter regarding Lafarge West's request for a TR at the site noted above. In 1999 there was a severe flood that broke over the bank at the location referred to in the TR as the Rigden Bridge. At the time of the event the entire area of the East Rigden pit, as well as a significant area beyond the site, was completely under water which caused concern to Lafarge, Flatirons Company, the City of Ft. Collins, the Boxelder Sanitation District, Larimer County, Colorado State University, the Railroad, as well as ditch companies and other landowners in the area. In response to the flood event the City of Ft. Collins commissioned a Poudre River Stability Study, which was eventually completed in June of 2001. In the interim, in March of 2000, the City of Ft. Collins and the engineer contracted for the Stability Study (Anderson Consulting Engineers) advised Lafarge that a weir should be built at the Rigden Bridge. Lafarge built the weir to the specifications determined by Anderson. It is our understanding that the design was intended [o control the elevation of waters entering the East Rigden Site in order to protect the Rigden Bridge as well as the overhead conveyor that had been installed to convey material from the Resource Recovery Site on the north side of the river. The construction was completed in April of 2000 and inspected and surveyed in June 2000 by Lafazge and the City of Ft. Collins. The weir remains in place as of this date and will be there throughout the life of the mining permit at East Rigden. Flooding has not occurred at the site since the weir was constructed, but it is expected to control river flows into the pit as it was designed to do. The TR was applied for as a result of a 2002 inspection by Erica Crosby of the DMG. She requested that we furnish information on the weir as it was not shown on the original reclamation plans. We furnished plans to the DMG shortly after the inspection and enclosed is Sheet 4 of those plans which show the weir in plan view. If you have further questions or comments please don't hesitate [o contact me. We appreciate your patience and the extension of time to complete this response.