Sevier Bridge Dam
Sevier Bridge Reservoir is the largest privately owned reservoir in the State of Utah. Constructed by pioneer families in the early 1900s, this dam has a riveted steel plate upstream cutoff through the embankment that is embedded in a concrete foundation cutoff wall. Several features of the dam did not meet current State of Utah Dam Safety requirements, necessitating remedial measures. Our Phase I work involved, among other things, field and laboratory studies showing that a layer of liquefiable foundation sands underlaid the entire upstream slope of the dam. We recommended the following construction work be accomplished:
- Stabilizing an approximately 60- to 65-foot-wide stretch of reservoir sediments at the upstream dam toe.
- Constructing a 50-foot-wide upstream berm over the stabilized sediments and downstream dam toe.
Over a Saturday and Monday time period the Contractor placed 10 feet of stabilization berm materials using large mine trucks, resulting in slope failures across the entire embankment due to insufficient time for pore pressures in saturated foundation materials to equilibrate. We drilled several test holes in the effected area and installed vibrating wire piezometers in those test holes. Subsequent fill placement rates were allowed only at the rate that would maintain pore pressures at a level consistent with embankment stability.