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Neighborhood report

County's sewer line work to spare drivers

Rather than tear up State Road 60, the water department plans to tunnel under it to install pipes.

By S.I. ROSENBAUM
Published December 2, 2005

BRANDON - How do you put 11,000 feet of sewer pipe underneath one of the most congested stretches of road in Brandon - without creating traffic gridlock?

Well, instead of digging up the road, you could just dig a series of tunnels and thread the pipe through it.

It's a relatively new - and expensive - technique called "horizontal directional drilling," which engineer Tom Wilson likens to orthoscopic surgery.

The county water department is planning to use the technique on a multimillion-dollar sewer project along State Road 60 later this year.

The existing pipe under SR 60 is overloaded and in some places wearing out, Nicholas J. Houmis, a principal with the engineering firm Greeley and Hansen, said Tuesday night at a meeting at McLane Middle School.

"The original line in there was in place before the interstate. Before they widened 60, that pipe was in the ground," he said.

With all the development during the past 10 years, an expansion is sorely needed to carry all the sewage away from new houses and businesses, Houmis said.

Traditionally, installing sewer pipe means digging a trench the length of the pipe. But you can't just dig up a road like Brandon Boulevard.

"We're no longer rural. We're an urban area," Houmis said. "This is the least disruptive way of doing it."

Horizontal directional drilling was invented in the oil industry, Wilson said. Workers use special equipment, basically a rotating drill bit on the end of a very long, flexible pole, to drill into the ground at an angle. Then they level off and drill horizontally, tunneling through the earth.

To keep the tunnel from collapsing, it's constantly flooded with a special liquid clay from Wyoming, which is "the consistency of pancake mix."

The clay provides pressure to keep the tunnel open, and also helps with the next step: Once the drill comes out the other side, workers attach a larger head and drag it back out the other way, making the initial tunnel wider.

Then, the 24-inch plastic sewage pipe is threaded through the tunnel. Workers can thread about 1,500 feet of pipe at a time - that's about five football fields long.

Once the pipe is in place, running along SR 60 from Falkenburg Road to Limona, the water department will start to hook it up to the old pipe, creating a greater capacity for the flow of sewage.

The entire procedure is expensive, about twice the costs of putting in pipe the traditional way. It's also tricky, with a lot of room for mistakes.

"It's not going to be easy," Houmis said.

The county will put the project to bid in the coming month and hopes to complete it by the end of next year, he said.

Drivers on SR 60 will have to weave through some construction cones and a few lane closures. But engineers won't have to shut down the entire road to work underneath it.

- S.I. Rosenbaum can be reached at 661-2442 or at srosenbaum@sptimes.com

[Last modified December 1, 2005, 09:34:11]