FLOOD00927

• Designation Number: 216
• County: Logan
• Community: Sterling
• Stream Name: Sand Creek and Pawnee Creek Overflow
• Title: Floodplain Information and Drainage Plan - Sand Creek and Pawnee Creek Overflow
• Date: 5/1/1983
• Designation Date: 7/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

103

Hence, a new outfall is proposed which would intercept the North Third
Street Trunk line at the intersection of Sydney Avenue and Broadway
Street. Additional laterals would also be required.
The proposed outfall would be a 54.inch reinforced concrete pipe fro~
Sidney Avenue to the point of discharge in the South Platte River. The
exact location of this outfall would be determined by further study.

drains the Whitcomb Addition, three 18.inch lines Which drain the mobile
I1omepark,anda 12-inch line which intercepts flow on FranklinStr eet.
Major drainage improve~ents will be required to reduce flooding
in Service Area 7. Because it is a low. lying area. storm flows generated
in Service area 8 should be intercepted and diverted away from the
existing points of concentration. As seen in Plate 28, much of Area 7
is also inundated during 5-yearrecurrence interval flows in the
Pioneer Ditch.
If recommended lmprovements in Service Area 8 and Pioneer Ditch
were made, the drainage lateral would be adequate to convey local storm
flows to the Pioneer Ditch. However, the lateral should be cleared Of
brush. small trees, and other debris that presently lil'lit its capac ity.

102

Service Area No. 8
In order to provide adequate drainage and reduce flooding problem s
in service Area 7, major drainage improvements are recommended for this
service area. Additional storm sewer capacity would be installed to
coliect the excess storm runoff and convey ittoa 66-inchoutfall on
North Oi.lsion Avenu~ between Franklin St. and the point of di5charge
in Pioneer Ditch. Trunk 1ineswouldbe installed on Franklin Stand on
Pawnee Avenue as summarized in Table 15 . The recently constructed
30-inch pipe would be e~tended to the outfall at Franklin and Division
Avenue by means of 35-inch pipe. The new trunk lines would intercept
flows from laterals laidoutina north to south configuration. The
drainage improvements in Service Area 8 should be mJde only after the
Pioneer Ditch is upgraded ~~ di seussed subsequently in thi s report.

Service Area No.5.
If a new 54-inCh outfall Were constructed to serve Area 4, the
existing 42-inch outfall would provide much improved drainage in Service
Area ~Jo. 5. No II<Ij or cira i nage i mpro vements a re pro posed.

Service Area No.6
Service Area 6 is served by a 3D-inch corrugated metal pipe outfall
which discharges into the Pioneer Drainage Ditch at Highway 138. Another
24-inch pipe collects runoff from the Hagen School and Northeastern
Junior College North Campus Addition and discharges this water in the
PioneHOitch
Area5isnotsubjecttoseriOusfloodingfrcmthe?ioneerd1tch
during a 10-year runoff event. However, one limiting factor during larger
floods is the capacity of existing hignway anct railroad bridges. Recently
a new bridge was constructed and track elevations were raised at this
location. The higher ernbankment can be expected to increase backwater
flooding in Service ~rea 6. In 1968. flood waters overtopped the highway
and railroad tracks (see Figurei ). r\{M,with the tracks being
approximately 0.7 ft. higher, Overflows to the river cannot occur at
Highway 138 during floods of the magnitude experienced inlg6S.

Service Area ~o. 7
Area 7 is a lew-lying area and susceptible to flooding from essen-
ti ally th ree sources a~ "ell CW$:
1. Pioneer DitCh overflews.
2. 8ac~ater fro," the rloneer Ditch, and
3. ~ncontrolled stcr~ runoff rrcm Scrvicn AreJ G.
This area is ~erved by a drainage lateral w'Iieh recehes discharges
from a 27- inch outfa 11 en Oi v i ~ i on Avenue. il 2~ - inch outfa 11 ',,' hi ch