Pasadena’s Tetra Tech is Building a Dam to Replace One Built in 1840

Published : Thursday, February 15, 2018 | 6:08 PM

Tetra Tech, a Pasadena consulting and engineering services firm which posted record quarterly revenue of $760 million, up 14% year over year, on January 31, reported it has begun work on the East Reservoir Dam restoration project near Coventry, Ohio.

The $30 million project involves building an unusual and massive underground wall and soil cement block to protect the existing and aging embankment along Portage Lakes Drive, according to a report in the Akron Beacon Journal.

The levee prevents water from spilling toward Akron, Ohio.

The report said the project site is now filled with heavy duty equipment, such as chain link fences, bulldozers, diggers, cranes, giant cement mixers and 60-foot drilling booms, used by several contractors in the project being undertaken by the Ohio Department of Natural Resources, which owns the lake.

The original dam, built around 1840 to create a reservoir for the Ohio and Erie Canal, has outlived its lifespan and fails to meet modern safety standards. The work, the report said, is part of the state’s ongoing effort to repair old dams across Ohio, including several in the Portage Lakes.

The project, scheduled to have begun late last summer, was delayed while the Ohio Environmental Protection Agency and the U.S. Army Corps of Engineers were readying permits.

Tetra Tech is overseeing the design and has been working with the Ohio Department of Natural Resources as design consultant of the project for several years before the project started in December.

The project involves constructing a three-story, 30- to 40-foot wide soil cement block and an even deeper wall along the embankment and then covering it with grass, the Akron Beacon Journal report said. The block and wall will protect the existing levee, a fragile and porous sandy embankment with dirt and Portage Lakes Drive on top of it.

The block will be made up of side by side 8- to 9-foot in diameter soil cement cylinders. The cylinders are created in the ground using large augers that drill and mix the soil and cement at the same time; in effect, it will be a dam structure underground that nobody sees.

Pete Nix, a Tetra Tech engineer and program manager, told the Beacon Journal it’s the first time such a dam has been built.

“It’s cool,” he said. “I just love the fact that you can stand there at the road and look out at the lake and you have no idea that there’s $30 million underneath your feet.”

Data from the Ohio Department of Natural Resources show the East Reservoir Dam is a high-hazard, earthfill embankment located just south of Akron, Ohio. The project was constructed in the 1820’s as part of the feeder system for the Ohio and Erie Canal system. The dam is approximately 1,300 feet long, has a maximum height of 25 feet, and lake levels are controlled by two spillways, one uncontrolled 21-foot long weir and one with two 30-inch gates. Portage Lakes Drive runs along the top of the embankment and the crest width is 40 to 50 feet. The embankment was constructed using the natural fine sands at the site and the foundation soils consist of fine sands and silts.

The embankment failed during the 1913 flood and caused widespread damage into downtown Akron. The embankment was reconstructed, this time with a new spillway, in 1915.

 

 

 

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