FLOOD01374

• Designation Number: 521
• County: Weld
• Community: Erie, Firestone, Dacono
• Stream Name: Tri-town drainageway, Godding Hollow Basin
• Title: South Weld I-25 Corridor Master Drainage Plan
• Date: 9/8/1999
• Prepared For: Weld County
• Prepared By: Anderson Consulting Engineers, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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4.6.5 Tri-Town Rasin: Summarv of Existing Drainage Problems

Similar to the Godding Hollow Basin, storm water runoff typically exceeds the capacity
of the natural channel during the 100-year storm event. The limits of flooding were identified in
a floodplain analysis of the Tri- Town Drainageway shown on the currently effective Federal
Emergency Management Agency (FEMA) flood insurance rate maps. The regulatory floodplain
information is also provided on Sheet 1 in this report. Flooding along the Tri- Town Drainageway
has been exacerbated where road crossings exist. A brief summary of the major problem areas
noted during this master planning effort is presented in the following paragraphs. This summary
is limited, however, to those locations along the major drainageway of the Tri-Town Basin.
, WCR 24 Culvert Tbe capacity of the culvert prior to overtopping is 60 cfs. The 100~year
existing condition discharge in Tri-Town Drainageway at Weld County Road 24 is 3,820 cfs.
Flows will spread out east and west along the road before overtopping. An improved crossing
structure could reduce the localized flooding problems at this location.
WCR 22 Culvert. The capacity of the culvert prior to overtopping is 80 cfs. The lOO-year
existing condition discharge in Tri-Town Drainageway at Weld County Road 22 is 3,840 cfs.
Flows will spread out east and west along the road before overtopping. An improved crossing
structure could reduce the localized flooding problems at this location.
WCR 20 Culvert The capacity of the culvert prior to overtopping is 40 cfs. The 100-year
existing condition discharge in Tri-Town Drainageway at Weld County Road 20 is 3,840 cfs.
Flows will spread out east and west along the road before overtopping. An improved crossing
structure could reduce the localized flooding problems at this location.
Milavec I.a ke Access Culvert. The capacity of the culvert prior to overtopping is 190' cfs.
The lOO-year existing condition discharge in Tri-Town Drainageway at MiJavec Lake Access Road
is 3,450 cfs. Flows will spread out east and west along the access road before overtopping. An
improved crossing structure could reduce the localized flooding problems at this location.
WCR 18 Bridge The capacity of the bridge prior to overtopping the roadway was
calculated to be 750 cfs. The lOO-year existing condition discharge in Tri-Area Drainageway at
WCR 18 is 3,450 cfs. Flows will spread out east and west along the road before overtopping.
An improved crossing structure could reduce the localized flooding problems at this location.
WCR 13 Bridge. The capacity of the bridge prior to overtopping the roadway was
calculated to be 1,500 cfs. The 100-year existing condition discharge in Tri-Area Drainageway ,
at WCR 13 is 2,590 cfs. Flows will head north along the road before overtopping at the
intersection ofWCR 18 and WCR 13. An improved crossing structure could reduce the localized
flooding problems at this,location.

T:\OPENlCoweldD/lcoweldDlfnl rpt..wpd

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September 8, 1999