Location and Description
Lake Alma is located in Vinton County, approximately 3 miles north of Wellston, and is part of Lake Alma State Park. The dam is an earthen embankment measuring 1,500 feet long and 16 feet high. The drainage area of the lake is 0.85 square miles and the lake has a normal pool surface area of 65 acres.
As a Class I high-hazard potential structure, a sudden failure of Lake Alma Dam likely would result in the structural collapse of at least one residence or one commercial or industrial business and probable loss of human life. (Hazard ratings refer to the consequences of dam failure, not the dam's condition.)
Click here for more about the Dam Risk Reduction Program.
Risk reduction efforts were completed in 2014.
During a probable maximum flood (PMF) simulation event, the dam was predicted to overtopped 2.0 feet, and required overtopping protection – prior to the risk reduction work that began in 2013 and was completed in 2014. The existing spillway outlet pipe, through the embankment, suffered from deterioration and joint separation of the pipe and was replaced.
While the ultimate rehabilitation of the dam included overtopping protection, the incremental improvement was to replace the existing spillway pipe outlet through the dam embankment. Other improvements at the park were included in the project to minimize disruption to the area and to save capital improvement costs. These included replacement of a deteriorated pedestrian bridge along the upstream face of the dam. The new pedestrian bridge is a single span pre-engineered bridge constructed of weathering steel with a hardwood deck.
Plans for the 30-inch HDPE outlet pipe were developed by Michael Baker, Jr., which included abandonment of the lake drain and a limestone riprap plunge pool to help trap sediment before entering Little Raccoon Creek. A new stop log system and trash rack on the upstream side were designed to allow for greater operational flexibility within the reservoir. The inoperable lake drain was replaced with a new system that has a self-priming set of valves and access boxes. Work was completed fall of 2014.
Long Term Plan
Routine inspections and maintenance of the dam will continue. An emergency action plan will be revised and shared with local emergency management officials once it is completed.
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