C150208 Feasibility Study

• Contract/PO #: C150208
• Contractor Name: High Line Canal Company
• Contract Type: Loan
• Water District: 17
• County: Otero
• Loan Projects - Doc Type: Feasibility Study

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A ground survey for the project was conducted by B-F in March of 2005. Also, a
geologic/geotechnical field investigation was completed in late May 2005 under the
direction ofLEC, followed by geotechnical laboratory materials testing in June 2005.
The geotechnical firm of A. G. Wassenaar, Inc. of Denver, Colorado was used for
completing test drilling and soil sampling activities in the field and for the geotechnical
laboratory testing of selected soil samples collected during the field test drilling
investigation. The surveyed plan and profile views of the existing Smith Arroyo siphon
pipeline crossing, including the inlet and outlet structures, and portions of the upstream
and downstream canal bottom profiles, are shown on Plate 1. Pertinent geologic/
geotechnical information, based on the results of the ground investigation, is also
shown. Approximately 150 feet of the existing siphon pipeline is apparently installed
below claystone bedrock. Ground water levels are also shallow, and the pipeline is
submerged below ground water for much of its length.

Photographs of the existing High Line Canal system facilities and site conditions at the
Smith Arroyo siphon pipeline crossing are presented in Appendix C.

ALTERNATIVES EVALUATED

In February 2005, the High Line Canal Company requested Mr. Brice E. Boesch, P.E., of
B-F to perform a feasibility-level evaluation and design for replacing the existing
decades-old High Line Canal siphon pipeline at the Smith Arroyo crossing. As a
followup to this request, B-F and LEC evaluated several siphon replacement alternatives
and selected a preferred design alternative given the High Line Canal Company's
reported available but limited monetary funds for final engineering design and project
construction. Both B-F and LEC, along with Knudsen Engineering, Inc. of Morrison,
Colorado, the contracting agent for the project, formed a High Line Canal Siphon
Pipeline Design Team. The Design Team started initial feasibility-level engineering
studies shortly thereafter in March 2005. The Design Team also provided interim
estimated preliminary construction costs associated with replacing the existing High Line
Canal concrete-encased wood stave pipeline at the Smith Arroyo crossing.

A DO NOTHING ALTERNATIVE was never envisioned by the High Line Canal
Company because a possible failure of the existing siphon pipeline system, i.e., partial or
total collapse of the buried pipeline, could disruptthe delivery of needed irrigation water
to downstream users until effective system repairs could be made. Approximately two-
thirds (2/3) of the High Line Canal Company members farm downstream of the Smith
Arroyo siphon site. Based on providing 2/3 of the 501-cfs water right downstream, the
canal shareholders require a minimum flow of 334 cfs.

Based on preliminary input from Mr. Dan Henrichs, the High Line Canal Company
Project Superintendent, LEC completed an initial hydraulics evaluation of the existing
Smith Arroyo siphon pipeline system and a hydraulics equivalency evaluation of
alternative piping materials for eight proposed pipeline replacement alternatives, given
the hydraulic capacity of the existing wood stave pipeline system. In the feasibility-
level design evaluation and cost estimating tasks, the two major variables included the