Restoration of Morris Sheppard Dam, A Buttress Dam

Morris Sheppard Dam impounds a 570,000 acre-foot lake on the Brazes River 75 miles west of Fort Worth, Texas. This concrete structure is a 190-foot high Ambursen flat-slab buttress dam with a crest length of 2,740 feet. The 13,000 square mile drainage area flowing into Possum Kingdom Lake is controlled at Morris Sheppard Dam by 9 roof-weir gates with a discharge capacity of 560,000 cfs. The dam is licensed to generate hydroelectric power by the Federal Energy Regulatory Commission. It also provides water for municipal, industrial and irrigation uses. The dam is owned and operated by the Brazos River Authority. During a routine five-year inspection, it was discovered that the dam had moved about 4.5 inches since it was complete in 1941 and was continuing to move. The foundation uplift pressures were as high as 65 percent of reservoir head. The dam was not capable of passing the probable maximum flood (PMF) as estimated on the basis of current criteria. The paper describes the physical features of the dam, the recommended corrective measures and an update of the investigative program leading to the relief of excess hydrostatic pressures and instrumenting of the dam’s buttresses and foundation.