Lake Oneida Dam

In 2008, Schnabel began providing dam engineering services to the Pennsylvania American Water Company for the rehabilitation design of this 31-foot-high embankment dam. Located in Butler County, Pennsylvania, the dam and reservoir are operated as a water supply facility.

The preliminary phase of the project consisted of a topographic survey, file review, subsurface exploration and instrumentation program, geotechnical evaluation, and permitting, and the development of conceptual design alternatives which focused primarily on upgrading spillway capacity. Hydrologic and hydraulic analyses were performed to evaluate various spillway alternatives that could safely pass the Probable Maximum Flood. The alternative selected involved armoring the embankment with roller compacted concrete and replacing the existing spillway with a concrete box-inlet drop spillway, chute, and Saint Anthony Falls stilling basin.

Additional project features included the replacement of the existing pedestrian bridge, relocation of the existing electrical and instrumentation services, relocation of the existing blowoff conduit, and road modifications.

Since the impoundment was a fully operational water supply reservoir, construction required significant control/diversion of water to facilitate the removal of the existing spillway and construction of the new spillway. To accommodate this, Schnabel developed a sequenced spillway demolition/control of water plan, which included conceptual designs of braced and cantilevered sheet pile cofferdams and a diversion channel. The project was completed in November 2013.