Updated Tue, Mar 4, 2014 10:52 am
Although a project to repair Dow Lake Dam near Athens is getting under way, it won’t bring the dam into compliance with minimum design flood standards, according to the Ohio Department of Natural Resources.
A separate project will be needed to accomplish that, said spokesman John Wisse.
As The Athens Messenger reported Sunday, a $2.9 million repair project on the dam is starting this month and is slated to be completed in September. Wisse said that project is the most that could be budgeted at this point.
Wisse said a timetable has not been established for doing a second project to bring the dam into compliance with flood standards. Design plans for that work have not been done.
Essentially, the dam needs to be capable of adequately retaining and releasing water in a 100-year flood event, Wisse said. A 100-year flood is a flood event that has a one percent chance of happening in any given year.
One concern, for example, is that the current spillway trash rack might allow trash in such a flood event to enter and possibly clog the spillway, he said.
Wisse said an inspection in 2012 found several issues that will be addressed in the current project, including stabilizing the dam embankment, replacing the toe drain with a new drain system and adding riprap to the upstream side of the dam. He said an operations and maintenance manual and an emergency action plan are also being developed.
Dow Lake Dam is a "Class I" dam, meaning that if it failed there would be probable loss of life. Within that classification, there are risk categories of low, moderate, high and very high. As reported in Sunday’s article, Dow Lake dam was recently changed from moderate to high, although Wisse said there is no immediate threat to the public.
The current project calls for adding about 78,700 cubic yards of material to the dam — widening it at the top, and correcting what Wisse has described as a “slumping situation” on the downstream face of the dam embankment.
The dam was built in 1959, and over the past two years temporary repairs have been made due to slides that were observed on the dam, according to ODNR.