Seeing a trencher able to reach an 80-foot depth and mix in place soil, bentonite and cement can be unique for anyone, even other contractors.
Officials in Tyler, Texas, got to see that equipment firsthand in 2014 as DeWind One-Pass Trenching, based in Holland, Michigan, helped repair a dam and spillway along Lake Tyler. Gracon Construction was the general contractor; DeWind was a specialty subcontractor.
“The dam was leaking and there were homes on the backside of the dam,” DeWind co-owner Becky DeWind says. “Officials were scared it was going to have a blowout.”
Greg Morgan, managing director of utilities and public works for the City of Tyler, said that the dam was inspected in 2010, at which time boils were discovered, meaning water was coming up through the dam and transporting soil.
The boils weren’t leaking or bubbling up a large amount of water, but if not addressed they had the potential to create a structural problem with the dam. The city went ahead with the $8.3 million project. Years of design and analysis took place and a notice to proceed was issued in May 2014.
“They put out a bid for it, but you could not open excavate,” DeWind says. “It had to be in situ mixing, so there were only two or three contractors that bid on it. The engineers were very intrigued with our trenching technology and they hired us to do the job.”
Part of the project was to fill in some voids that were under the spillway so that construction could begin on a portion of the wall in front of the spillway. A barrier wall was not originally constructed with the lake. Instead, a collection system was designed to collect seepage from the base of the dam and discharge it into a nearby creek.
DeWind, on the project for a month and a half, filled in the voids under the spillway and created the barrier wall. The project was completed in December 2014.
“The job went in flawlessly,” DeWind says. “The Army Corps of Engineers came out to watch for a day, and the leak stopped as they were there and we were passing by. Everyone was happy. It was just a great day. That one put us on the map for more work with the Corps of Engineers.”
Seepage will still occur out of the lake even with the barrier wall, Morgan says, but water won’t migrate through the dam, which is what could cause a structural problem.
