FLOOD05940 - Laserfiche WebLink

Home Browse Search

6. Existing structure no. 10 is a 30-inch CMP crossing Bennett Avenue at C Street. Thi, structure is adequntelysized but should be cleunedand a grate installed on the inlet end of the pipe to eliminate future clogging. 7. Existing structure no. 8 is an IS-inch CMP crosslng Teller County One. Although this structure is adequately sized to convey the lO-year design storm runoff,f1ows exceeding the lO-year designslOrm runoff will not cross Teller County One at this location increasing the potential for flooding problems on downstream properties. It is rceommendcd that this struetufe be replaced with a 3(}"inch CMP with a minimum headwater of three feet. B. Thurlow Avenue Tributary The Thurlow Avenue draioageway collects runoff from a relatively small basin with minor develnpmcnt in the southerly portion of the city's corporate limits. Runoff from this basin is conveyed by a poorly developed channel to Cripple Creek at a point directly north of the city's wa.~tewater treatment racility. Several small culverts presently exist within the Thurlow Avenue drainage basin. These culverts primarily exist to convey flows through road crossings. Two improvements are presently recommended within this basin but as futun: development occurs, channel improvements and confinement of flood waters may be warranted. The rcconunended improvcmcnts are as follows. 1. Existing structure no. 29 (15-inch CMP witlJ 18 inches of headwater) is too small 10 cunvey even the 10-year design storm runoff. This culvert should he replaced with a 24-inch CMP with a minimum of 3 feet of headwater thus increasing culvert capacity 10 meet lhe lO-ycardesignstorm runoff condition. 2. Existing structure no. 31 (existing 24-inch CMP) is not capablc of conveying runoff from the 10-year design storm. Design storm runoff at this point is VI-5 32 CFS for the lO-year storm and 109 CFS for the }(~)-year storm. Although flooding potential at the present time is minimal, it is recommended that this structure be replaced with a structure capable of conveying runoff from the lOO-year de~;jgn storm due to the potential for development within this area. A 48-inch RCP culvert with a minimum of 5 feet of headwater should he installed at this location. The installation should include a headwall at each end of the culvert. c. Second Street Trihutary The Second Street tributary is comprised of three drainage basi~ which produce and convey runoff from the central portion of the city's corporate limits to Cripple Creek. The Second Street tributary is generally bounded on the north and south by the city's corporate limits, on the west by the alley between A Street and B Street and on me east by Third Street. Existing structures within this area include numerous culverl.\ at road crossings and a portion of the Bennett Avcnue storm sewer system. Numerous structures within the Seeond Street tributary are severely un dersizedand have created some of the most intense and frequcnt flooding problems within the city's corporate limits. This flooding occurs even though the actual design storm runoff in this tributary is relatively small compared to flows in Pony Gulch and Cripple Creek. Existing culverts used for road crossings in outlying areas appear, for the most part, 10 b<l adequate but as flows approach thcbusiness dist rict,undersizing of existing structures becomes acute a~ can bcscen by the frequent floodingwhieh occurs at the intCT!;ectionofSecond Street and BcnnettAvenuc. Somc of the recoIllmemlations for illlprovements within the Sceond Strcet tributary address replacemcnt of road crossing culverts in outlying areas. Thc majority of rccommendations revolve around installation of a storm sewer system within Bennet! Avenue and a storm sewer outfall line in Second Street from Eaton AVelJUe 10 Warren Avenne. The intent of this system is to imer<:Cpl as much runoff as possihle VI-6