FLOOD06011 - Laserfiche WebLink

Home Browse Search

_.~ . . . ~'!o(jIlM.@, " - i o 0 Federal Emergency Management Agency Washington, D.C. 20472 AUG 2 3 2001 CERTIFIED MAIL RETURN RECEIPT REQUESTED IN REPLY REFER TO: Case No.: 01 -08-125R The Honorable Nancy Heil Mayor, City of Westminster 4800 West 92nd Avenue Westminster, CO 80031 Community: City of Westminster, CO Community No.: 080001 104 Dear Mayor Heil: This responds to a request that the Federal Emergency Management Agency (FEMA) comment on the effects that a proposed project would have on the effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS) report for Adams County, Colorado and Incorporated Areas (the effective FIRM and FIS report for your community), in accordance with Part 65 of the National Flood Insurance Program (NFIP) regulations. In a letter dated January 23,2001, Ms. Sheila Beissel, P.E., Senior Civil Engineer, Department of Community Development, City of Westminster, requested that FEMA evaluate the effects that the proposed McKay Lake project would have on the flood hazard information shown on the effective FIRM and FIS report. The proposed McKay Lake project will include: . Improvement of McKay Lake to convert it to a regional detention pond with a storage volume of 98 acre-feet during the flood having a I-percent chance of being equaled or exceeded in any given year (base flood). The improvement of McKay Lake will include placement of fill in the southern embankment; buttressing and raising the embankment along most of its length; construction of a service spillway with a dam crest elevation of 5245.8 feet; and installation of an approximately 60-foot-Iong, 30-inch-diameter, reinforced-concrete pipe culvert (RCP) as an outlet on the east embankment. . Relocation of the existing McKay Lake Drainageway through construction of an approximately 5,500-foot-Iong, grass-lined channel with five 3-foot drop structures, a IS-foot bottom width, and 4: I side slopes. The channelization of the relocated McKay Lake Drainageway will extend from the above-mentioned 30-inch-diameter RCP outlet to Interstate Highway 25 (I-25) along the southern side of the existing McKay Lake Drainageway. . Construction of a IS-foot by 4-foot reinforced-concrete box culvert (RCB) under the proposed Neighborhood Parkway, an 18-foot by 4-foot RCB under the proposed Access Road, a 20-foot by 5-foot RCB under Huron Street, and a 16-foot by 5-foot RCB at Bull Canal. The project also will include improvement of three 72-inch-diameter RCPs for the 1-25 crossings. The Special Flood Hazard Area (SFHA), the area that would be inundated by the base flood, for the subject reach is designated Zone A, where Base Flood Elevations have not been determined. This request also included an updated hydrologic analysis that incorporated improved data and methodology to reflect existing conditions along the McKay Lake watershed. All data required to complete our review of this request for a Conditional Letter of Map Revision (CLOMR) were submitted with letters from Mr. Stephen Brown, Kiowa Engineering Corporation, and Ms. Beissel.