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<br />. . <br /> <br />, <br /> <br />l <br /> <br />2-'1U <br />~\.l );.\0 ~ <br />Federal Emergency Management Agency ",Q~\~ <br />Washington, D.C. 20472 <br /> <br />.- <br /> <br /> <br />CERTIFIED MAIL <br />RETURN RECEIPT REQUESTED <br /> <br />IN REPLY REFER TO: <br />Case No. : 95.;oS'-OS2P <br /> <br />The Honorable Robert A. Christensen <br />Chairperson, Douglas County Commissioners <br />101 3rd Street <br />Castle Rock, Colorado 80104 <br /> <br />Community: Douglas County. Colorado <br />Community No.: 080049 <br />Panel Affected: 0301 C <br />Effective Date of <br />This Revision: MAR 2 0 1995 <br /> <br />102-D-A <br /> <br />Dear Mr. Christensen: <br /> <br />This is in response to a request for a revision to the effective Flood Insurance Study (FIS) and National <br />Flood Insurance Program (NFIP) map for your community. Specifically, this responds to a letter dated <br />March 6. 1995, from Mr. Steven A. Butherus, P.E., KLH Engineering Group Greeley, Inc., regarding <br />the effective FIS report and Flood Insurance Rate Map (FIRM) for the unincorporated areas of Douglas <br />County, Colorado. With his letter, Mr. Butherus provided additional informati<m in support of a <br />December 15, 1994, request for a Letter of Map Revision (LOMR) submitted by Mr. Daniel W. Bare <br />II, P.E., Engineer III, Town of Castle Rock. Mr. Bare requested that we revise the effective FIRM for <br />the Town of Castle Rock, Colorado, to show the effects of the Oman Road bridge replacement and <br />associated channelization along the Unnamed Tributary to Sellers Gulch. The channel improvements <br />extend from approximately 300 feet downstream tl) approximately 250 feet upstream of the bridge_ In <br />a letter dated December 2, 1994, Mr. Fred Koch, P.E., County Engineer, Douglas County Department <br />of Public Works, Engineering Division, requested that we revise the FIRM for Douglas County based on <br />the information submitted by the Town of Castle Rock. <br /> <br />All data required to complete our review of this request were submitted with Mr. Bare's December 15 <br />letter and with letters dated February 8 and March 6, 1995, from Mr. Butherus. <br /> <br />We have complettd our review of the submitted data and the flood data shown on the effective FIRM, <br />and have revised the FIRM to modify the elevations and floodplain and floodway boundary delineations <br />of a flood having a I-percent probability of being equaled or exceeded in any given year (base flood) <br />along the Unnamed Tributary to Sellers Gulch from just upstream of Lake Gulch Road to approximately <br />650 feet upstream of Oman Road. The Special Flood Hazard Area (SFHA) and floodway widths have <br />decreased a maximum of 150 feet along the revised reach, and the base (l00-year) flood elevations (BFEs) <br />have decreased a maximum of 3 feet. The SFHA and floodway are contained within dk; aforementioned <br />channelized portion. At the upstream limit of the revision, the BFE has increased 0.2 foot, as compared <br />to the effective FIS report and FIRM. This increase is the result of including an additional cross section <br />upstream of the channelization and not the result of the bridge replacement and channelization project, <br />as demonstrated by a HEC-2 hydraulic computer model of pre-project conditions that was submitted by <br />Mr. Butherus. As compared to the pre-project conditions, the BFEs have decreased along the entire <br />revised reach. The channel length along the revised reach has decreased approximately 50 feet as a result <br />of the channelization. <br />