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".\)~! :::J.~ J ~ -- 't: ~ " ~~"'1\1D S~{j; - Federal Emergency Management Agency Washington, D.C. 20472 RECEIVED MAR 2 9 2004 MAR 2 5 2004 CERTIFIED MAIL RETURN RECEIPT REQUESTED The Honorable James R. Sullivan Chairman, Douglas County Board of Commissioners 100 Third Street Castle Rock, CO 80104 IN REPLY REFER TO: OoIomdo Water ConseNatlon Board Case No.: 03-08-0425P (Formerly Case No. 01-08-058P) Community: Douglas County, CO Community No.: 080049 Panels Affected: 0285 C, 0295 C, 0303 C, and 0315C E~ective.~ate of J U l 2 9 2004 This RevlSlon: 102-I-A-C Dear Mr. Sullivan: This responds to a request that the Department of Homeland Security's Federal Emergency Management Agency (FEMA) revise the effective Flood Insurance Rate Map {FIRM} and Flood Insurance Study (FIS) report for your community in accordance with Part 65 of the National Flood Insurance Program (NFIP) regulations. In a letter dated November 6, 2000, Ms. Allison Rice, P.E., JR Engineering, requested that FEMA revise the FIRM and FIS report to show the effects of a new bridge across East Plwn Creek and culvert construction along Section 34 Tributary and Glade Gulch, all associated with the Bell Mountain Ranch residential development. In addition, this request included a hydraulic analysis to incorporate more detailed topographic information along East Plwn Creek from approximately 2,000 feet upstream to approximately_4,200.feet.upstream.of.the.confluenc_e with Section 34 Tribu~. This rc:guest also included revised hydrologic and hydraulic analyses for Section 34 Tributary from approximately 600 feet upstream to approximately 15,500 feet upstream of the confluence with East Plum Creek and for Glade Gulch from approximately 2,400 feet upstream to approximately 6,000 feet upstream of the confluence with East Plum Creek. The modifications along Section 34 TributaIy and Glade Gulch resulted in replacement of approximate Special Flood Hazard Areas (SFHAs), areas that would be inundated by the flood having a I-percent chance of being equaled or exceeded in any given year (base flood), designated Zone A, with no Base Flood Elevations (BFEs) determined, as shown on the effective FIRM panels, with SFHAs based on detailed analyses. This request follows up on a Conditional Letter of Map Revision issued on September 4, 1997. All data required to complete our review of this request were submitted with letters from Mr. Brad Robenstein, P.E., Engineering Division, Public Works Department, Douglas County; Mr. David L. Mallory, P .E., Project Engineer, Floodplain Management Program, Urban Drainage and Flood Control District; and Ms. Rice. Bell Mountain Parkway crosses East Plum Creek via a three-span, double-tee bridge approximately 2,800 feet upstream of the confluence with Section 34 Tributary. The installed culverts along Section 34 Tributary included a double-6-foot by ] O-foot reinforced-concrete box culvert (RCB) under the Glade Gulch Road crossing approximately 3,200 feet upstream of the confluence with East Plum Creek; a 6-foot by 12-foot RCB under Bell Mountain Drive approximately 9,000 feet upstream of Glade Gulch Road; and an 8-foot by 8-foot RCB under High Spring Road approximately 2,1 00 feet upstream of Bell Mountain Drive. The installed culverts along Glade Gulch included triple 96-inch-diameter corrugated-metal pipe culverts (CMPs) under the Mariposa Road crossing approximately 2,700 feet upstream of the confluence with East Plum Creek; quadruple 58-inch-diameter CMPs under the Lot 16 driveway approximately 530 feet upstream of Mariposa Road; and double 96-inch-diameter CMPs under the Young Circle crossing approximately 3,200 feet upstream of Mariposa Road.