PUBLIC SERVICE COMPANY OF COLORADO - TROUT LAKE DAM AND RESERVOIR
Trout Lake Dam and Reservoir is used as the forebay storage for the Ames hydroelectric generating station near Telluride, Colorado. W. W. Wheeler and Associates, Inc. performed safety inspections of the facilities under the requirements of the FERC dam safety regulations (Part 12D). As part of the dam safety assess-ment for FERC, Wheeler performed detailed hydrologic studies to determine the adequacy of the spillway to route extreme flood events. Through use of an incremen-tal damage assessment (IDA), Wheeler recommended an inflow design flood equivalent to 50 percent of the Probable Maximum event, reducing the spillway capacity requirements for the dam by more than 60 percent. The FERC and Colorado Division of Water Resources accepted the engineering in support of the lower value. It is our understanding that this was the first acceptance of the IDA concept by the FERC.
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Wheeler prepared engineering design plans and construction specifications for the rehabilitation of the spillway to accommodate the updated inflow design flood. The new spillway is a rock-lined channel, 120 feet in width. Wheeler was also responsible for the design of a new high-capacity toe drain installed along the down-stream toe of the embank-ment to control excessive rates of seepage without resulting in piping of the embankment soil materials. More recently, Wheeler provided the engineering design, including plans and specifications, to increase the embankment stability. The work included flattening the upstream slope of the dam and improving erosion protection with rock riprap and grouted riprap. Wheeler also provided contract administration and construction inspection services for the project. |