Methods Vary, Safety Is Constant

By Curt Grandia | September 28, 2010

Working for the City of Omaha to install various types and sizes of pipe for a sanitary sewer outfall to the Old Lincoln Highway Interceptor, Roloff Construction Co., Inc., is using a combination of open trench, and tunneling to finish the $4.25-million project ahead of schedule.

No matter what the pipe or installation method, though, safety is a constant on the job.

The project, located north of West Dodge Street near the Old Lincoln Highway, includes more than 2,132 feet of jacked Hobas 36-inch pipe, 580 feet of 48-inch casings, 600 feet of 36-inch Hobas pipe, 3,000 feet of 36-inch Rinker concrete pipe, and 280 feet of 24-inch Rinker concrete pipe.

"We're using open trench for the Hobas and the concrete pipe, and we have jacking pipe and jacking casing with a carrier pipe inside the casing," said Project Superintendent Dwain Warriner. "We're self-performing all the open cut and we're preparing all the jacking pits and receiving pits. Horizontal Boring & Tunneling is doing this tunneling and boring."

Roloff Construction began the project in February and, as of late-April, had completed about 75 percent of the work in only about 40 percent of the working days.

For the open cut work, Roloff operators mainly use a Komatsu PC 400 with an "Add a Boot" boom extension that allowed deeper excavation, up to about 30 feet, for the Hobas pipe. "Our operator really likes that because he's able to pick up some pretty hefty loads," said Warriner. "It adds quite a bit more weight, but the 400 doesn't have any problem handling the extra weight and length.

"We can use it with our loading bucket or a cleanup bucket we have that's 8 feet wide. It moves a lot more dirt a lot quicker than a loader or a dozer, and the operator can use it to really make the site look good."

Other equipment on the job for Roloff includes a Komatsu PC 300 as a backup and for backfilling, a Komatsu WA 450 wheel loader, a Caterpillar 977 loader, and a John Deere 450 backhoe.

Boring was employed for crossing about 100 feet near an Omaha Public Power District high security fence. "The plan was to take that fence down and relocate it, but we decided to bore so they wouldn't have to move the fence and all the hardware, and that made working with them a lot better," Warriner said.

For the jacking and receiving pits used by Horizontal Boring & Tunneling for their tunneling rig, Roloff Construction's crew incorporated concrete floors into the trench boxes. "We did that to make everything watertight and to help give it extra support," said Warriner. "We used a temporary kicker until the concrete was in and that worked well for us. Then the biggest challenge for them was dealing with some unforeseen rock. They hit some glacial till and that rock slowed things down, but they do good work for us. It's always a pleasure to work with them because they are real team players."

Throughout the project, on the open cut work and on the jacking and receiving pits, Warriner said, safety was always the number one focus.

"Our main concern was doing what we needed to do to keep everyone and everything safe," he said. "We worked with United Rentals Trench Safety, and I think we rented 16 trench boxes of various sizes.

"It was easy to work with them because they had their engineer draw up the kinds of systems we needed. They engineered it for us and stood behind it so we didn't have to wonder or worry about it at all. And if we needed something, they were right here to help us."