The Douglas Dam Emergency Response and Rehabilitation

Hatton, Christopher N.; Gipson, Allen H.; Andrew, John W.; ,

The Douglas Dam Emergency Response and Rehabilitation

by Christopher N. Hatton, Woodward-Clyde Consultants, Denver, United States,
Allen H. Gipson, Jr., Woodward-Clyde Consultants, Denver, United States,
John W. Andrew, Woodward-Clyde Consultants, Denver, United States,

Document Type: Proceeding Paper

Part of: Geotechnical Practice in Dam Rehabilitation

Abstract:

Through the timely response of the Owner, the potential failure of Douglas Dam was averted, and lives and property downstream were protected. The economic losses created by loss of irrigation water from the reservoir and damage to an irrigation canal structure downstream were also prevented. The Owner, upon noting seepage, immediately contacted his Consulting Engineer and the State Engineer. With the consultant's assistance and the cooperation of the State Engineer, the Owner made temporary emergency repairs. The long-term repairs followed, including remediating a seep that developed in the dam near the outlet structure, and upgrading the capacity of the spillway as recommended by the Army Corps of Engineers. The Owner elected to remove and replace the embankment above the base of the outlet structure while leaving the outlet structure in place. The remedial measures also included constructing a soil-bentonite slurry wall along the upstream toe and replacing the embankment with a compacted fill. A chimney/blanket drain was installed in the downstream slope. The repair was designed such that the slurry wall or chimney/blanket drain could be extended in the future if needed. The source of seepage was identified during construction as a portion of an old outlet structure which was replaced but never completely removed. The following presents a history of the project and the actions taken to mitigate seepage in the embankment, both for the emergency response and long-term repairs made to the dam.

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