PROJC01820 ‎(2)‎

• Contract/PO #: C150189
• Contractor Name: Larimer and Weld Irrigation Company, The
• Contract Type: Loan
• Water District: 2
• County: Weld
• Loan Projects - Doc Type: Feasibility Study

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The retaining walls on the conveyance flume are falling in and will have to undergo significant
repaired if the structure is not replaced. The drop structure concrete and the outlet are deteriorated
due to erosion of the concrete and lack of energy control.

ALTERNATIVES

Three alternatives have been considered for the structures covered in the NEEDS Section. They
include: (1) Do nothing; (2) Repair existing structures; or (3) Replace all structures with new
concrete structures. An assessment of each alternative follows.

Alternative # 1

One course of action considered was the DO NOTHING AL TERNA TIVE. This option is not
viable for the system to continue to operate and is only valid if the irrigated land is to be taken out
of production and the water stock liquidated. The portions of the system that have not been
repaired are at an age (in excess of 100 years) and level of deterioration that they are becoming
very difficult to operate. Replacement or repair of these structures must be pursued if the ditch
company is to continue making water deliveries.

The option to "do nothing" does not mean spending no money on the system. The Company has
been operating under the "do nothing" option for many years and the structures are at or beyond
their effective life. The loss of effective use of the Lake Lee Dam and the Big Windsor Inlet
would have severe consequences for the ditch company and its water users. A major problem at
the Lake Lee Dam would at the minimum make the ditch difficult to operate as this structure
control the ditch flows in combination with Lake Lee which acts as an equalizer. At the worst,
a failure at the Lake Lee Dam would potentially cause a washout of the ditch which would cause
downstream damage and stop all water deliveries throughout the system. Loss of use of the Big
Windsor Inlet would jeopardize the storage of water in this reservoir as this is the only way the
reservoir can be filled. Failure of this structure would curtail ditch deliveries until a temporary
repair could be initiated. Our best guess is the system would be down at least a week with a
failure. The Finley Check is not critical to the overall operation of the system and loss of this
check could be overcome. However, use of the Finley check can not be maintained without
significant repair to the structure and its foundation.

Alternative #2

The second alternative explored was to repair the three structures. To repair the Lake Lee Dam
and the Big Windsor Inlet would require some demolition and replacement of existing concrete
that has deteriorated. Both Lake Lee Dam and Finley Check may require some treatment of the
foundation to repair the undermining and retard it from developing further. All the structures need
energy management to retard further erosion of the base slabs and the channel downstream of the
structures. The base slab for Lake Lee Dam and the Big Windsor Inlet would need to be repaired
by covering with a new concrete slab. The conveyance flume at Big Windsor would have to be

Larimer & Weld Feasibility Study
Lake Lee & Big Windsor - 03.043

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