US-based Nicholson Construction has been awarded a contract to upgrade the Portage Lakes East Reservoir Dam in Ohio to bring the structure up to Federal Emergency Management Agency (Fema) safety standards.
Nicholson will use deep soil mixing to create a cut off wall and gravity foundation to remove Fema’s high hazard classification of the 1840s-built dam.
“Nicholson has a long and very successful track record of rehabilitating dams using multiple technique,” said Nicholson president Steve Scherer.
The 1.2m thick cut off wall will extend the length of the dam and reach depths of up to 16m to remove the seepage risk. Behind the wall, Nicholson will construct a 9m to 12m wide black gravity section.
“This block will hold the dam in place, so it can stand independently in the unlikely event that the sand embankment washes away,” said Nicholson project manager Ryan Streets.
This rehabilitation is part of the Ohio Department of Natural Resources’ push to improve the safety of the state’s aging dams. Construction on the East Reservoir Dam is expected to end in June 2018, and the improved dam will have a lifespan of up to 100 years.