The Cheyenne Stage I pipeline is approximately 55 miles long and is
located in the Sierra Madre Mountains, Snowy Range, Laramie Plains and
Laramie Mountains. The Stage I pipeline system delivers 6,000 acre-feet
of water per year to Cheyenne. The project was constructed in about
1963 and consists of the following components:
- 7,000 feet of 30-inch diameter and 15,000 feet of 36-inch diameter
concrete pipeline located on the east and west side of the
continental divide near Hog Park Reservoir.
- 10,500 feet of 24-inch diameter and 47,000 feet of 33-inch
diameter concrete pipeline between Douglas Creek and Lake Owen
- 40 miles of 26-inch diameter steel pipeline between Lake Owen and
the Vedauwoo picnic area along a tributary to Crow Creek.
The Level II analysis, conducted in 1991 and 1992, found water conveyed
in the concrete pipeline has reacted with the aggregate causing severe
corrosion in most of the concrete pipeline. The condition of the
concrete segments of the Stage I pipeline was found to be worse than
originally anticipated. In addition, a lake (Sportsman Lake) has formed
over a portion of the steel pipeline crossing the Laramie Plains. The
lake is located in an area of corrosive soils and pH of the water is
extremely high. There was evidence that the cathodic protection on the
steel pipe was in need of improvements.
The City of Cheyenne Board has contracted with an engineering consulting
firm to provide design and construction management services. The
engineering firm, assisted by Cheyenne Board of Public Utilities staff,
has completed an electrical continuity survey to identify areas of the
Stage I pipeline that is inadequately protected from corrosion. High
resistant spans have been repaired by rebonding the joints to assure the
pipeline is cathodically protected.
The work associated with the 26-inch pipeline in the area of Sportman
Lake has been completed. (Item No. 3 above) In lieu of rerouting the
Stage I pipeline around Sportsman's Lake, the Cheyenne Board of Public
Utilities opted for the less expensive alternative associated with
draining the lake and rebonding the joints to assure the pipeline is
Repairs to the Little Snake River/Hog Park concrete pipeline have been
completed. (Item No. 1 above)
The design of the Douglas Creek to lake Owen phase (Item No. 2 above)
has been designed and will be awarded in March or April, 1996, pending
the availability of funds. The construction cost is higher than
anticipated due to a shortage of high density polyethylene (HDPC) pipe
that is used to line the existing concrete pipeline.
RECOMMENDED LEGISLATIVE ACTION:
The Commission recommends that the project appropriation be increased
from $12,500,000 to $15,500,000 or $3,000,000 for the rehabilitation
costs of the concrete pipeline between Lake Owen and Rob Roy Reservoir.
The financing plan would remain as a 50% grant and a 50% loan with an
interest rate of 4% and a term of 40 years.