Holding the Fort

A cured-in-place lining system helps workers fix leaking drain lines while preserving the historic character of a Florida landmark
Holding the Fort

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The V-roof on the barracks of Fort Zachary Taylor Historic State Park in Key West, Fla., directed rain into seven deteriorated cast-iron drainpipes. Water running through cracks and breaches in the 5-inch lines kept the massive masonry rubble walls damp and caused structural problems. As the 166-year-old piping disintegrated, it spalled and expanded, causing the masonry to fall off.

The park brought in David Salay, design engineer for Bender and Associates Architects in Key West, to rehabilitate the pipe without cutting into or demolishing the walls. Salay researched trenchless options on the Internet, then specified cured-in-place pipe. Engineered Lining Systems, a Jacksonville company with a specialty in cured-in-place pipe and structure restoration, won the bid.

Although the total lining project was only 140 feet, maintaining the fort’s historical integrity brought multiple challenges, as did the need to minimize the impact on visitors to the site. Coordination between ELS production manager James Macko, assistant park manager Jayne Blatherwick, and Salay led to a successful project.


Preliminary work

The team worked out the logistics in a preconstruction meeting. The challenges were equipment storage, construction footprint, public safety and historical preservation.

“Our staging area, which was barricaded by cones with safety rails, took up a small part of the barracks entrance,” says Macko. “At the end of the day, all the equipment went back into our locked 20-foot MaxTrailer (MaxLiner USA).” A telescopic boom lift and air compressor stayed inside the barricade.

To interfere as little as possible with tourists visiting the fort, the ELS crew inspected the drains from the roof during the day. They brought their own generator for the Plumber’s Mate portable inspection system from Ratech Electronics. Besides using the digital footage counter on the camera to take measurements, Macko added indicating marks on the reel, then measured them with a tape measure to confirm distances.

The bottom six feet of each drain line was exposed in a niche where the end of the pipe turned into a trough made of what appeared to be another pipe with the crown cut off. In all but one case, the trough fed into the cistern. “Each time we televised a line, the camera bullheaded into the trough and stopped,” says Macko. “We had to reach in at the junction and pull the head around the bend.”

At some point, the park had replaced the bottom turn on one pipe with a 90-degree fitting, but raised it three feet. During heavy rains, water shot over the cistern and landed with such velocity that it was eroding the floor. Blatherwick asked what ELS could do to alleviate the situation. The crew added a second 90-degree elbow directed down into the cistern. When the time came, it was lined with the rest of the pipe.

The inspections revealed that the piping had minor scale and tuberculation, and two runs made a 90-degree bend in the walls. Due to the condition of the drains, the team agreed that aggressive cleaning would cause them to crumble. They settled on a low-pressure rinse from a garden hose.


Under pressure

Inflation of the liners was critical, as one extra pound of pressure could rupture the host pipe. “We chose 5-inch MaxFeltLiners from MaxLiner USA and supplied by PrimeLine Products,” says Macko. “The system enabled us to keep our construction footprint small, as we needed only a 185 cfm air compressor rather than a boiler truck, and we could accurately and immediately regulate the pressure.”

The system also used a 33-pound MaxLinerGun to invert the liner and calibration tube, as a standard drum inversion machine would be too cumbersome on the roof.

The first 20-foot liner was shot during the day. The metal roof became a solar oven for workers and shortened 60-minute ambient cure time by half. The noise of the equipment also distracted visitors and park staff.

Blatherwick then allowed the ELS crew to work on-site after hours. “This was a big advantage, because we could use 30-minute resins that sped up the curing process, and our activities, which often went on until midnight, weren’t a nuisance,” says Macko.

After cutting a calibration tube and liner to length, workers wetted out the felt liner using a hand-crank calibration roller. “We don’t like electric wet-out rollers because they can be cumbersome and we can’t control the wet-out as accurately,” says Macko.

Both materials were transported in 5-gallon pails to the lift. Then Asa Whitehead elevated the boom 15 feet into the V-slot in the roof. Mikal Biegner loaded the liner into the gun three to five feet at a time, and Whitehead monitored and controlled the pressure at 25 to 30 psi.


Low pressure

“We kept the inversion pressure as low as possible, and had Jody Wright watching at the niche to make sure that the cast-iron pipe wasn’t separating from the wall or over-expanding,” says Macko. “He also wiped up any resin that seeped through the cracks so it didn’t create an eyesore for visitors. The only time they can see the liner is where the pipe turns into the trough.”

Loading and shooting of the calibration tube followed the same step-by-step process. Biegner then closed a valve that sealed the air bladder and inflated it to 8 psi using a Kobalt air compressor.

“Everything we did on this job was critical,” says Macko. “Maintaining the exterior condition of the drains helps to reflect the age of the fort. If the lining process destroyed that, we would have failed in half our mission. The possibility weighed heavily on our minds the whole time.” Since the work was completed, all leaks have stopped, and the walls have begun to dry out.


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