PROJ01997

• Contract/PO #: FS0065FX
• Contractor Name: Greeley and Loveland Irrigation Company
• Contract Type: Loan
• Water District: 0
• County: Larimer
• Loan Projects - Doc Type: Feasibility Study

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EXECUTIVE SUMMARY

The findings of the feasibility study show that Alternative Five - Undetained Diversion to the
Boxelder Creek is the preferred ahernative. The estimated project cost is $3.2 Million.

Alternative Five - Undetained Diversion to Boxelder Creek proposes to construct a drainage
channel system beginning at Larimer County Road 66 and divert approximately 1270 cubic feet
per minute (cfs) to Boxelder Creek. Other attributes of this alternative are to reconfigure and
provide improvements for Boxelder Creek. Considered improvements are excavation to increase
the cross-section and conveyance of Box elder Creek; a bike trail along the creek; revegetation;
remapping the floodplain and bridge improvements.

The project begins at the Town of Wellington Northern comprehensive planning study boundary
and continues south for approximately 3.25 miles to bridge structure for Boxelder Creek, under
Interstate 25.

Other studied alternatives are:

1) No Action (Alternative One)
2) A detention volume and channel routed to Boxelder Creek (Alternative Two)
3) A diversion to the Windsor Canal (Alternative Three);and,
4) Reduced Flow Through Town (Alternative Four).

Alternative One is presented for comparative purposes and is not considered feasible because it
does not address removing the floodplain from within the Town's planning area

Alternative Two is similar in configuration to Alternative Five, the preferred alternative. However,
Alternative Two utilizes a sizable detention volume to reduce the size of the facilities needed to
convey water to Boxelder Creek. The large detention volume is not feasible due to cost
constraints oflocating and constructing the detention facility so it does not inundate residents and
land users north of Wellington.

Alternative Three utilizes a levee to detain water north of Larimer County Road 66. Then through
a controlled release, water is diverted through a pipe or open channel to a discharge point into the
Windsor Canal. This option was considered inferior because the floodplain is still with in the town
limits and the diverted flow is limited to less than 200 cfs, the available surcharge capacity of the
Windsor Canal. Furthermore the canal owners have stated their facilities shall not be used for
stormwater conveyance.

Alternative Four is considered infeasible for the following reasons. One, flow passing through
town is limited to approximately 140 cfs. Two, restricting the flow to 140 cfs drastically increases
the detention volume. Three, this option does not remove the floodplain from town.

A variety of quantifiable and non-quantifiable criteria were used to evaluate the alternatives.

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