Author(s): E. J. Gemperline; Z. R. Matus; O. L. O’Donel
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Keywords: No Keywords
Abstract: Approximately two-thirds of the 460 m-Iong 20 m-high skimmer wall which protected the 417.5 MW Safe Harbor Hydroelectric Project fore bay from ice and debris overturned in January, 1996 following an upstream ice jam break-up. Extremely high Susquehanna River flows caused by the break-up and by prevailing meteorologic and hydrologic conditions, as well as large quantities of ice, caused a rapid 2.6 m increase in river water level. Videotapes ofthe event show that a surge ofwater and ice preceded the failure. The river water level rise was not irrunediately accompanied by a fore bay water level rise apparently resulting in unbalanced conditions and the greatest force experienced by the wall in its 66-year history. It is speculated that ice restricted the flow of water under the wall causing the fore bay to be unresponsive to the river water level rise. The importance of the wall to plant operation is well recognized as it had provided protection from numerous significant ice events as well as minimizing debris inflow into the forebay and related removal costs. A new skimmer wall is currently under construction. This paper describes how ice conditions were factored into design ofthe new skirruner wall and includes discussions of the ice regime in the area and the design criteria used.
Year: 1998