As featured at ConstructionEquipmentGuide.com, The Beaver Excavating Company completed its second year of work on the $77 million Columbus Upground Reservoir in 2012 in Richwood, Ohio — the largest upground reservoir under construction in the United States.

“We’re using more than 100 pieces of heavy earthmoving equipment and have 180 Beaver personnel on site on the largest single-volume earthwork project in the company’s 60-year history,” said Beaver Senior Project Manager Steve Roberts.

It’s the longest dam in Ohio and the largest reservoir project in the nation, and perhaps the world, that features a geo-synthetic liner system comprised of an 18 in. (45.7 cm) layer of compacted clay, covered with a polypropylene geomembrane, a cushion geo-textile and then finally an 18 in. layer of protective cover soil, according to Roberts.

“The geo-synthetic liner was added because of the site’s potential for sinkholes due to the area’s Karst geology,” he added. “The underlying limestone bedrock has the potential of being eroded by water creating the possibility of underground openings and caverns.”

The project was awarded to Beaver by the city of Columbus and is the first of three planned upground reservoir projects recommended in the Columbus Department of Public Utilities’ Water Beyond 2000 Feasibility Study.

Work on the three-year project began in January 2011. When completed in October 2013, it will cover 850 acres (344 ha) and hold more than 9 billion gal. of water. Thus far 8.5 million cu. yds. (6.5 million cu m) of earthworks and 600 acres (243 ha) geo-composite liner system have been installed.

The work began with the reservoir dam — 5 mi. in length, 45-ft. (13.7 m) high — which surrounds the entire project. It also involved the removal of a 5-mi. (8 km) area of topsoil, 56,000 ft. (17,068.8 m) of existing agricultural field tile, constructing 10 mi. (16 km) of 15-ft. (4.6 m) deep by 20-ft. (6.1 m) wide cutoff trenches to prevent area field drainage and ground water from compromising the reservoir walls, and a dewatering system installed prior to construction to lower the areas artesian conditions.

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