Fast-Tracking Force Main Rehab

Fort Lauderdale emergency project uses innovative technology to rehab miles of sewers in just nine months.

Fast-Tracking Force Main Rehab

An entry pit on Murphy Pipeline Contractors’ Fort Lauderdale, Florida, project shows a DD-440T directional drill and P-600 mud pumps from American Augers. Murphy installed 8,600 feet of new pipe on the project, using primarily directional drilling. (Photos courtesy of Murphy Pipeline Contractors)

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Faced with a public works emergency caused by a series of disastrous breaks in aging, ductile iron sewer force mains — including one line that handles about a third of the city’s sewage — officials in Fort Lauderdale, Florida, found themselves in crisis mode in mid-2017.

To resolve the burgeoning problem, which at one point had inundated some residential neighborhoods with more than a foot of sewage, the city hired Murphy Pipeline Contractors in Jacksonville to use trenchless technology to rehab a little more than 4 miles of sewer force mains.

City officials opted for trenchless technology because speed was of the essence in the wake of more than 20 million gallons of raw sewage leaks during the previous several years. The leaks were especially troublesome because of Fort Lauderdale’s location amid intracoastal waterways and other environmentally sensitive marine areas.

The nearly $15 million project centered on two different rehab technologies. The first involved installing approximately 8,600 linear feet of new 30-inch force mains via horizontal directional drilling. The second included rehabilitating another 11,500 linear feet of existing 30-inch force mains with an innovative new technology called compression-fit lining, which uses HDPE pipe.

“This was a true emergency in every sense of the word,” says Richard Crow, director of engineering and special projects for Murphy Pipeline Contractors. “On a scale of one to 10, it was an 11. It made the national news, with whole neighborhoods submerged in sewage. There was a dire need for repairs.”

It also hit the city hard financially. After city officials closed off the broken segments of force main, they had to hire contractors to pump wastewater out of lift stations. The contractors then transported the waste to manholes farther downstream, where it was discharged for treatment. At one point during 2017, the city spent nearly $12 million for pumping in just five months. (The cost was exacerbated by heavy rain from Hurricane Irma, which caused sewer overflows.)

Navigating obstacles

The project, which was designed by engineering consultant Chen Moore and Associates, posed numerous challenges. First of all, there was pressure to fast-track the project and complete the bulk of it in six months, from August 2017 through January 2018.

“We had three days to submit a bid,” Crow notes. “There was no time for feasibility studies or analysis. We had to design and build almost immediately.”

Murphy Pipeline Contractors also had to contend with several contaminated sites; sensitive adjacent intracoastal ecosystems; and dense commercial and entertainment districts where rights-of-way were limited and businesses couldn’t afford major disruptions. The company also had to deal with a thicket of permitting agencies — nine all told, including the Army Corps of Engineers and the Florida Department of Environmental Protection.

Moreover, there was a little snag called Hurricane Irma, which pummeled Florida with high winds and rain in early September. Crews also had to work around concerts and other large special events that had been booked a long time ago and couldn’t be canceled. “We worked a lot at night,” Crow says. “We wanted to avoid disturbing communities or places of business as much as possible.”

At the peak of the nine-month-long project, which concluded in May 2018, Murphy Pipeline Contractors had about 60 employees working on its various phases. “It was a massive operation,” Crow says. “To help us out, some of our clients (with less time-sensitive projects) let us work on their jobs later on. It was really great to see the mutual respect they gave us — they were very accommodating.”

Under pressure

To avoid complete disruption to business operations and potential accompanying financial losses, opencut replacement of the force mains wasn’t an option. “It would have been challenging, costly and very slow going,” Crow says. “Plus, the water tables here are very high, so there’s a lot of wet, nasty soil.”

But Murphy Pipeline Contractors had a perfect alternative technology: compression pipe-lining with HDPE pipe. The company’s owner, Andy Mayer, brought the technology — popular in Europe for decades — to the U.S. from England in 1999, the year he established Murphy Pipeline Contractors.

Here’s how compression pipe-lining works: Using powerful winches, workers pull long runs of HDPE pipe through custom-made steel dies and into the host pipe; the dies are slightly smaller in diameter than the host pipe.

As the pipe passes through the die under extremely high force — anywhere from 70 to nearly 100 tons of pressure, depending on the length of the pull — it gets compressed to a smaller diameter than the host pipe. Crews can pull up to 5,000 feet of pipe at one time. When the pull is complete, the line from the winch is removed.

Now no longer under pressure, the pipe slowly expands back to its original diameter and tightly conforms to the interior of the host pipe, typically within 48 hours. This forms an inner liner that should last about 100 years. The pipe can remain under tension for a couple of days; after that, contractors run the risk of the pipe hardening in its smaller-diameter configuration. After the new pipe passes a pressure test, it’s good to go online, Crow explains.

The actual pipe-pulling doesn’t take that long; on a good day, a crew can complete, say, a 2,000-foot-long pull in about 10 hours. So why did the project take nine months to complete? Because crews first have to dig access pits at the points of entry and exit (small pulls require 40-foot-long-by-8-foot-wide pits and longer pulls require 80-foot-long-by-8-foot-wide pits, with depths that vary by project).

Workers also have to inspect the lines to see if any obstructions exist, clean the lines to remove any debris and obstructions, send a “proving pig” through to ensure the pipe is ready for lining and so forth, Crow says.

“It also took awhile just to get materials,” he adds. “We pulled in our crews quickly, but that doesn’t mean materials are on the shelves, ready to go. It’s not like 30-inch plug valves and 30-inch HDPE pipe is just sitting on shelves in a store.”

Setting up

Compression-lining technology was used on about 65% of the 22,000 feet of force mains. DBE Utility Services used horizontal directional drilling to replace another 30%, and the rest of the repairs required opencut work.

“Some of the directional drilling also involved installing interconnects to cross-connect some of the force mains,” he explains. That way, the city could stop pumping the lift stations by diverting wastewater from the bad sections of pipe to the new pipes.

DBE Utility Services used a DD-440T directional drill and P-600 mud pumps from American Augers on the site. To fuse the pipe together, crews used McElroy fusion machines. Excavation equipment from Hitachi was also on site.

The project was broken down into four phases, the first three of which started concurrently.

1. Rehab several sections of force main — 3,200 linear feet in all — with compression lining and install 700 feet of new force main under the Tarpon River via horizontal directional drilling. (Six bore pits required.)

2. Install 1,500 linear feet of new pipe with horizontal directional drilling. (Two bore pits required.)

3. Install 6,400 linear feet of new pipe with horizontal directional drilling. (Three bore pits required.)

4. Rehab three segments of force main — a total of 8,300 linear feet — using compression lining. (Six access pits required.)

“We couldn’t start phase four until the first three were completed,” Crow says.

Collaborative effort

The project started in August 2017 and finished in May 2018. Along the way, the Murphy Pipeline Contractors team had to continually react on the fly to new situations and obstacles — pretty much what they expected, given there was so little time for analysis and planning, Crow says.

“Some of the locations were quite challenging due to unsuitable soils,” he explains. “In other areas, the original fittings didn’t work. We were working so fast that we didn’t have an understanding of what was in ground until we actually started working.

“In phase two, we did some excavating and saw things wouldn’t work as planned,” he continues. “Keep in mind we were working with only aerials and as-built drawings. We took on a lot of risk because most times we didn’t know what was in front of us. We had a game plan, but we had to pivot a little bit each day in order to keep moving forward.

“Sometimes we’d just roll out (as-built) plans on the tailgate of a pick-up truck and figure things out with city engineers,” he notes. “It was a total collaborative effort to find solutions. That was the best part of the project.”

It helped that Murphy Pipeline Contractors also has hundreds of miles of compression lining under its belt. The company has worked all over the U.S. and even internationally in Mexico, South Korea, Saudi Arabia and other countries.

“We’re definitely a niche contractor,” Crow says. “There’s only two other companies in the world that do compression-fit technology.”

Crow hopes that the success of the Fort Lauderdale project will help other communities buy into the compression-lining technology and HDPE pipe as a trenchless rehab solution, especially since it demonstrated what can be accomplished in terms of minimal disruption to residents, businesses and vulnerable ecosystems.

“This shows that HDPE pipe is a good long-term solution for clients that need to solve problems caused by corrosion and cyclical fatigue in ductile and cast iron pipes,” he says. “It also demonstrates what can be achieved on an emergency basis when installing HDPE pipe with trenchless methods and qualified contractors.” F


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