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

I
I
II
I
I
I
I
I
II
I
I
I
I
I
I
I
I
I
I

. Where appropriate, undersized crossing structures along Godding Hollow and Tri-
Town should be improved and enlarged to meet existing drainage criteria. These
improvements will reduce backwater elevations and roadway overtopping.

· Open channels should be improved and enlarged to reduce channel overbank
flooding and mitigate potential channel erosion.

· Regional detention ponds should be constructed within each basin to limit the peak '
discharges within each drainageway. '

· On-site detention ponds should be constructed within the basin to limit the peak
discharges in the 'Godding Hollow and north of WCR 18 in Tri- Town Basin, as
well as the runoff from each subbasin, to the magnitude of the existing condition,
10-year and 100-year flood events. On-site detention ponds should be constructed
south ofWCR 18 in Tri-Town Basin to limit the peak discharges to the magnitude
of the existing condition, 2-year flood event.

. Maintain or replace the existing roadway and railroad embankment detention
ponds. The releases from these structures should be limited so as to maximize the
existing storage present at these locations.

· Construct spill structures, where appropriate, along the irrigation canalsiditches to
prevent flooding and redirect flows to the major outfall conveyance facilities or
major drainageways.

5.2 Description of Drainage Improvements

The improvements discussed in the previous section were initially evaluated and screened
for applicability'. A preferred list of improvements was identified and a comprehensive plan was
developed that would address flooding problems along the major drainageway within the Godding
Hollow and Tri-Towh Basins. In the paragraphs that follow, the preferred improvements are
discussed. Unless otherwise stated, these improvements assume that on-site detention is provided
to limit the releases for future developments in the Godding Hollow Basin and north of WCR 18
in the Tn-Town Basin to the 10-year and 100-year existing condition levels, and south ofWCR 18
in the Tri-Town Basin to the 2-year existing condition level.
The drainage improvement plans for each reach are referenced in Figure 5.1. Figures 5.2
to 5.11 present the plans associated with the improvements to the Godding Hollow Basin.
Improvements associated with the Tri- Town Basin are presented in Figures 5.12 to 5.17.

T:l0PENlCoweidOllc.oweidOI fn] rpt. wpd

5.3

September 8, 1999