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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3.2,2 Tri-Town Basin

There are nine major road crossings of the major drainageway in the Tri- Town Basin, The
crossings consist of two timber/steel/concrete bridges, two reinforced concrete box culverts
(RCBs), four arched corrugated metal pipes (CMPs), and one circular CMP cluster. Table 3,2
summarizes the location, condition, and hydraulic capacity of each crossing structure. A brief
description of each road crossing is provided in the following paragraphs.
WC:R 24 Culvert The crossing at Weld County Road 24 is a 3'H x 5'W arch corrugated
metal pipe culvert. At this location, roadway overtopping occurs at a depth of approximately 3,5
feet from the invert of the culvert. The capacity of the culvert prior to overtopping is 60 cfs, The
lOG-year existing condition discharge in Tri- Town Drainageway at Weld County Road 24 is 3,820
cfs,

WCR 22 C:ulvert The crossing at Weld County Road 22 is also a 3'H x 5'W arch
corrugated metal pipe culvert. At this location, roadway overtopping occurs at a depth of
approximately 4.5 feet from the invert of the culvert. The capacity of the culvert prior to
overtopping is 80 cfs. The 100-year existing condition discharge in Tri-Town Drainageway at
Weld County Road 22 is 3,840 cfs.
WCR 20 Culvert The crossing at Weld County Road 20 is a 2.5'H x 3.5'W arch
corrugated metal pipe culvert. At this location, roadway overtopping occurs at a depth of
approximately 2,9 feet from the invert of the 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.
Milavec Lake Access Culvert This road crossing provides access from WCR 13 to
Milavec Lake: The crossing at Milavec Lake is a 4'H x 6'W arch corrugated metal pipe culvert.
At this location, roadway overtopping occurs at a depth of approximately 8,0 feet from the invert
of the culvert. The capacity of the culvert prior to overtopping is 190 cfs. The lOO-year existing
condition discharge in Tri-Town Drainageway at Milavec Lake Access Road is 3,450 cfs,
WC:R 18 BTidge, This steel and timber bridge incorporates an opening which is
approximately 17,5 feet wide and 6 feet in height. The depth of flow at which roadway
overtopping occurs is approximately 7.0 feet. The capacity of the bridge prior to overtopping the
roadway was calculated to be 750 cfs, The 100-year existing condition discharge in Tri-Area
Drainageway at WCR 18 is 3,450 cfs,
WC:R 13 Bridge This steel and concrete bridge incorporates an opening which is
approximately 50 feet wide and 6 feet in height. The depth of flow at which roadway overtopping
oc=s is approximately 8.8 feet. The capacity of the bridge prior to overtopping the roadway was

T:\OPENlCoweidOJlcoweldO/ In! rpt.wpd

3,9

September 8, 1999