Released On: October 21, 2004
The Association of State Dam Safety Officials presented its Rehabilitation Project of the Year award to Reclamation and Hayward Baker, Inc., for the innovative use of technology, creativity, and economy in the rehabilitation of Wickiup Dam. ASDSO presented the award during its annual conference in Phoenix, Arizona, on September 28.
Wickiup Dam is a earthfill structure built between 1939 and 1949, about 40 miles southwest of Bend, Oregon. The dam impounds about 200,000 acre-feet and is operated by the North Unit Irrigation District. The structure was considered to be below acceptable seismic safety standards and in need of rehabilitation.
"Reclamation investigated the dam's potential deficiencies associated with seismic failure modes for several years," said Reclamation Regional Director Bill McDonald, "and this award is the result of the public and private sectors working together to improve the safety of Wickiup Dam."
Reclamation conducted two comprehensive risk analyses which indicated that the likelihood of failure in a significant earthquake was unacceptably high and that the potential loss of life was significant.
In 1999, a multi-disciplinary team identified structural modification alternatives and decided on jet grouting as having major advantages to offering the best possible fix with minimal impact to the reservoir or surrounding area.
Reclamation proceeded with final design following a successful test on jet grouting by Hayward Baker, Inc., in December 1999. The test served to evaluate the effectiveness of jet grouting on the unusual foundation soils comprised of volcanic ash and silts. In order to design the jet grout treatment zones, a computer program was used to evaluate deformation patterns. Ten earthquake ground motions were evaluated at five different cross sections within the area to determine the geometry of treatment.
Attention to ensuring environmentally friendly aspects of the construction process included:
* Relocating a population of Oregon spotted frogs to newly constructed ponds approximately one mile downstream of the dam
* Protecting bald eagle habitat by limiting construction noise, and constructing eagle perches along the crest of the dam.
* Converting a large borrow area to a large open water body that provides new habitat for many local species of animals and waterfowl.
"The use of jet grouting was an innovative approach to solving the structural concerns at Wickiup Dam," said Larry Wolf, Reclamation Safety of Dams program manager. "This method eliminated the need for reservoir restrictions, and it saved millions over the estimated cost of the removal and replacement alternative. This was one of the largest jet grouting jobs of its kind, and will provide significant benefits to the water users, local population, and the area surrounding the dam for years to come."
DOI | Recreation.gov | USA.gov
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