Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/43082
Title: East Branch Dam, East Branch Clarion River, Elk County, Pennsylvania : Dam Safety Modification, Environmental Assessment
Authors: United States. Army. Corps of Engineers. Pittsburgh District.
Keywords: Dams
Clarion River (Pa.)
Dam safety
Environmental assessment
Environmental protection
Publisher: United States. Army. Corps of Engineers. Pittsburgh District.
Abstract: Preliminary dam safety studies completed during January 2008 revealed that East Branch Dam may have structural deficiencies that could cause it to fail unexpectedly. Because of confirmed and unconfirmed risk, the District—whose mission priority is public safety—decided in February 2008 to lower operating pool levels to make the dam safer, until further studies could be completed. The new maximum summer pool was lowered 20 feet (from elevation 1670 to 1650) to reduce the hydraulic head and seepage within the dam. The maximum winter pool was lowered 28 feet (from elevation 1651 to 1623). East Branch Dam is currently operating with reduced risk under this new operating schedule and will continue to provide flood risk reduction downstream. Periodic storage of floodwaters will not reduce dam safety. The impacts of the lowered pool were addressed in an environmental assessment (EA) prepared and circulated for agency and public review in the spring of 2009. This EA analyzes the impacts of the following five dam repair plan alternatives: NS1: Non-Structural, the “No Action” alternative; operate at reduced maximum summer pool (El.1650) and continue interim risk reduction measures, S3: Structural; full-depth cut-off wall, full length of embankment with grouting, S4: Structural; dam extension immediately downstream and fortification, S5: Structural; downstream concrete gravity structure positioned downstream, S6: Structural; removal of dam. 7. Based upon engineering and cost analysis, Plan S3 best achieves the desired level of safety for the least cost. Additionally, this plan will not cause any long-term significant adverse environmental or socio-economic impacts, either within the lake or downstream. The current interim operating pool and low-flow augmentation schedule will be maintained during construction. Thus, Plan S3 is the preferred plan.
Description: Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
URI: https://hdl.handle.net/11681/43082
Appears in Collections:Environmental Documents

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