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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3.2 Major Road Crossings

3,2,1 Godding Hollow Basin

There are eleven major road crossings, one railroad crossing, and three canal crossings on
the major drainageway of Godding Hollow. The crossings consist of three timber/steel bridges,
four reinforced concrete box culverts (RCB) , six arched corrugated metal pipes (CMP) , one
circular CMP, and one concrete flume. The capacity of each crossing was calculated using the
D,S, Army Corps of Engineers' HEC-2 Water Surface Profile program and/or the Federal
Highway Administration's HY-8 Culvert Analysis program. Table 3,1 summarizes the location,
condition, and hydraulic capacity of each crossing structure, A brief description of each road
crossing is provided in the following paragraphs,
WCR 26 Culvert The crossing at Weld County Road 26 consists of a 3'H x 8SW
reinforced concrete box culvert. At this location, roadway overtopping occurs at a depth of
approximately 4.2 feet from the invert of the culvert, The capacity of the culvert prior to
overtopping is 210 cfs. The 100-year existing condition discharge in Godding Hollow at Weld
County Road 26 is 7,000 cfs,
I.ast Chance Ditch Flume, Low flows generated within the Godding Hollow Basin cross
over the Last Chance Ditch in a concrete flume. Large flow events will be out of bank prior to
reaching this location and will spill into and out of the Last Chance Ditch east and west of this
crossing, The capacity of the existing flume crossing is estimated to be 370 cfs.
WCR 24 Culvert The crossing at Weld County Road 24 is a 6'H x 8'W arch corrugated
metal pipe culvert. At this location, roadway overtopping occurs at a depth of approximately 6.4
feet from the invert of the culvert, The capacity of the culvert prior to overtopping is 240 cfs.
The lOO-year existing condition discharge in Godding Hollow at Weld County Road 24 is 4,490
cfs,

WCR 22 Culvert The crossing at Weld County Road 22 is also a 6'H x 8'W arch
corrugated metal pipe culvert. At this location, roadway overtopping occurs at a depth of
approximately 7.7 feet from the invert of the culvert. The capacity of the culvert prior to
overtopping is 300 cfs. The 100-year existing condition discharge in Godding Hollow at Weld
County Road 22 is 4,510 cfs,
Godding Ditch Bridge/Flume, At this location the Godding Ditch is conveyed over
Godding Hollow in a steel flume. This bridge incorporates an opening which is approximately
60 feet wide and 10 feet in height, The depth of flow at which the canal embankment overtopping
occurs is approximately 11.3 feet. The capacity of the bridge prior to overtopping the canal

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3.6

September 8, 1999