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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Realign Coal ridge Ditch Construction of the channel and bridge crossing will
require realignment of the Coalridge Ditch to a location immediately north of State
Highway 52. In conjunction with the realignment of the ditch, a side-channel weir
should be included in the improvements to divert potential stormwater captured by
the ditch into the major drainageway.

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3. Regional Detention Pond The existing detention ponds formed behind State
Highway 52 and the Coalridge Ditch should be preserved to reduce the downstream
flood peaks. This will require obtaining approximately 35 acres of land along with
the existing structures located immediately west of the major drainageway and
south of State Highway 52.

5.2.8 Godding Hollow Basin Reach G8: WCR 12

Improvements in Reach G8 focused on the alleviation of flooding problems at WCR 12 and
the construction of a regional detention facility on a tributary to the major drainageway. The
specific improvements to Reach G8 are presented below and also in Figure 5.9.

1. WCR ]2 Crossing. Replace the existing 3' CMP crossing of WCR 12 with a
bridge structure with a minimum opening of 5.5'H x 35'W. Transitions from the
existing channel to the bridge crossing are required along with placement of
stabilization measures to control the potential erosion in the vicinity of the crossing.
In conjunction with replacement of the crossing structure, approximately 300 feet
of roadway should be raised a maximum of 2 feet.

2. Regional Detention Pond To reduce the peak flows from a tributary to the major
drainageway, a regional detention pond is proposed north and west of the
intersection of WCR 11 and WCR 12. The proposed pond will incorporate a
storage volume of 76 acre-feet and will require obtaining 17 acres of land and the
construction of an outlet structure from the pond and a transition into the major
drainageway.

5.2.9 Godding Hollow Basin Reach G9: 1-25/WCR 10

Improvements in Reach G9 focused on the alleviation of potential flooding problems at
WCR IO along with the construction of regional detention facilities on both the major drainageway
and a tributary to the major drainageway. The specific improvements to Reach G9 are presented
below and also in Figure 5.10.

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5.24

September 8, 1999