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<br />Colorado Water Conservation Board <br />Department of Natural Resources <br />721 Centennial Building <br />1 31 3 Sherman Street <br />Denver, Colorado 80203 <br />Phone, (303) 866.3441 <br />FAX, (3031866.4474 <br /> <br />STATE OF COLOAADO <br />~ <br />~ <br /> <br />r- ~.If <br /> <br />Roy Romer <br />Covernor <br /> <br />James S. Lochheild <br />Execuhve Director, DNR <br />OilriesC.lile, P.E. <br />Director, (WeB <br /> <br />February 5, 1998 <br /> <br />Mr. Jim Root, City Engineer <br />City of Arvada <br />8101 Ralston Road <br />Arvada, CO 80002 <br /> <br />Dear Mr. Root: <br /> <br />I am writing you concerning the submittal for a Letter of Map Revision (LOMR) for <br />Ralston Creek along the newly constructed extension of Ralston Road in Arvada. We <br />received a mailing dated January 26, 1998 regarding this project <br /> <br />The project involves the revision of FIRM panel # 6 from the City of Arvada's 1992 <br />Flood Insurance Study (FIS). The revisions being requested would alter the floodplain <br />and floodway delineations for Ralston Creek between 56'h Avenue at the downstream end <br />and Nolan Street at the upstream end. Through most of the project reach the floodplain <br />delineation would be substantially narrower than is currently shown in the FIS. Through <br />almost the entire project reach the 100-year flood elevations would be lower than shown <br />in the FIS. <br /> <br />Back!!:round <br />The Ralston Road project was a joint-purpose project designed to: 1) build a major <br />arterial road and 2) reduce flood hazards associated with Ralston Creek. For floodplain <br />purposes the project could be considered to be a channelization project From the new <br />intersection with Sheridan Boulevard at the downstream (east) end of the project, Ralston <br />Road is the new embankment along the northern edge of Ralston Creek, extending west- <br />northwest across the Burlington Northern Railroad to a point a little downstream of <br />Lamar Street East of Lamar Street it crosses the creek from the north side to the south <br />side. From that point Ralston Road now forms the southern embankment to Ralston <br />Creek through the intersection with Lamar Street, extending past Nolan Street. <br /> <br />In addition to the construction of the road, the.project included changes to Ralston Creek <br />itself. The channel was widened for a length of approximately 3300 feet In that <br />channel-widened reach the channel invert was substantially lowered, up to as much as 8 <br />feet lower than previous grades. Two new bridges (the replacement bridge for the <br />