Healing Hands

A contractor executes cured-in-place pipe repair in the radiology department and physical therapy area of a Florida hospital without disturbing patient care
Healing Hands

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Two or three times per week, sewage backed up into the emergency room, radiology department, and cafeteria of the Martin Memorial Hospital in Stuart, Fla. Despite constant jetting by the maintenance contractor, stoppages continued in the 6-inch cast-iron sanitary sewer servicing the north side of the building.

While the hospital maintenance staff searched for solutions, a plumber tried unsuccessfully to rod the line. Other plumbers trying to inspect the 400-foot-long pipe through a 4-inch cleanout in the emergency room reported massive trenching and much of the invert missing. Three plumbers declined to try rehabilitating the line.

Open-cutting to replace the pipe would cost millions of dollars and take eight to 10 months. Then officials found David Shortz, project manager for Engineered Lining Systems (ELS) in Jacksonville, Fla. For a fraction of the cost of open-cutting, his crew restored the pipe with felt cured-in-place liners in five weeks.

Site preparation

A massive breakwater separates the hospital from the St. Lucie River. Because the building is almost below sea level, dewatering pumps keep it dry during high tides, downpours, or hurricanes.

Six ELS technicians inspected and mapped the line using a push camera with self-leveling head from Ratech Electronics. It sent back images of debris hanging on trenched areas and rough sections, causing huge blockages.

The 5-foot-deep pipe rose 12 inches as it traveled 220 feet from the cleanout to an area under nuclear medicine, turned 90 degrees, and ran 180 feet to an area under physical therapy. It then connected to a 12-inch cast-iron main flowing to the hospital’s 30-foot-deep, 20,000-gallon lift station, which discharged to the city’s lift station.

“Our first logistical challenge was keeping the hospital running at capacity,” says Shortz. “That involved bypassing the entire sanitary system for the north side without shutting down surgical scrub sinks, bathrooms, and the cafeteria.”

The second challenge was dirt and infection control. Following hospital guidelines, workers laid sticky mats on either side of doorways and enclosed work areas to remove contaminants from the soles of their shoes. They also erected plastic enclosures around doors.

“Our air filtration units ran constantly,” says Shortz. “While saw-cutting the 6-inch-thick concrete floors, we wet the dust to a workable slurry, then vacuumed it.” The men cut two 6-foot-square penetrations, one in nuclear medicine at the 90-degree elbow and the other in physical therapy where the pipe joined the 12-inch main.

Bypass systems

Hospital maintenance relocated the nuclear medicine laboratory during the project. ELS workers excavated with picks and shovels to the pipe, then well-pointed the areas, started electric diaphragm dewatering pumps, and set up the bypass system.

After plugging the sewer line, the men reversed the flow of the grease interceptors and diverted sewage to them. Waste was pumped to a city lift station 300 feet away. Flows from scrub sinks, bathrooms, and a cafeteria were diverted through a hose running 160 feet to a manhole.

“Our biggest concern while dewatering was the weather,” says Shortz. “Summer in Florida means storms and lightning. Any one could knock out the electricity with devastating results.”

Shortz was concerned that the groundwater pressure was high enough to buckle or collapse ambient-cured liners as they formed to the host pipe. Therefore, he chose the MaxFeltLiner system (MaxLiner USA) with Hot Kick, a mobile diesel-fueled boiler that would counteract the groundwater’s cooling effect.

ELS workers also rerouted condensate from the hospital’s air-handling units to keep it from flowing back into the pipe and the liner epoxy from curing.

Cocked and ready

ELS worked at night. One crew parked a GapVax MC 1510 combination truck outside, then dragged in hoses to clean the lines while another crew televised the work. “Our main concern in jetting was collapsing the pipe and removing more of the bedding,” says Shortz. “Fortunately, the occlusion was soft and the 220-foot line cleaned quickly.”

A third crew prepared the liners in a nearby service tunnel. As they brought the resin-impregnated liner through the calibration rollers, they folded the felt back and forth inside a large plastic stock tank filled with ice and water. This retarded the epoxy’s chemical reaction as they wheeled the tank 200 feet to nuclear medicine and loaded the liner into the inversion machine.

“Because we were shooting into a hole, we wanted the gun as close to the pipe as possible,” says Shortz. “So the men built a carrier system that spanned the excavation and pointed the gun downward.”

The inversion machine installed the liner a few feet at a time. Working it required two men topside to feed the liner into the gun and handle the controls, and another in the hole to align the liner with the pipe and start it rolling.

“It’s a step process,” says Shortz. “After pushing in three to four feet of liner, the men close a valve that seals the air bladder. Then they pressurize the gun to 7 psi to force that section up the pipe. Once all the liner is inverted halfway, they pressurize it to 14 psi, and that pushes the remainder to the end.”

The inversion took 10 minutes. A lay-flat tube pulled in with the liner connected to the input and output fittings on the boiler. After filling the liner with water and pressurizing it to 14 psi, the men started the boiler, located outside the building.

“By monitoring input and output temperatures, the crew gauged what the liner was doing,” says Shortz. “The normal cure time is two hours, but we cured it for seven to eliminate any chance of something going wrong.” The men reinstated 12 laterals using proprietary tools.

Fun starts here

Years of pouring x-ray film-developing chemicals down the 180-foot pipe had left it with major cracks, trenching, and missing sections. As the crew began cleaning, they encountered heavy groundwater infiltration. As the water flowed past the rehabilitated upstream pipe, it washed in the surrounding mud and sand.

“This section was in such bad shape that jetting it could have created enough voids under the hospital floor to collapse it,” says Shortz. “We estimated three or four days to clean the line, but it took seven because we worked so slowly.”

Once the pipe was cleaned, one-third of its invert was missing, enough for the liner to shoot out a void or snag on a jagged edge. To prevent that, the men pulled back a 1/4-inch cable, fitted a nose cone over a plastic pre-liner from MaxLiner, duct-taped the cone to the cable, and winched the pre-liner into the penetration in nuclear medicine.

“The pre-liner served as a sleeve and guided the felt liner as we inverted it,” says Shortz. “Heating the felt fused the plastic liner to it. In both runs, resins from the liner migrated and sealed any spaces between it and the host pipe.”

With the pipe rehabilitated, I&I flooded the penetrations faster than the dewatering pumps could keep up. The crew added more pumps before they could reinstate the four laterals and complete the job. “It’s amazing what they did and how much money they saved the hospital,” says Shortz. “The client was very happy.”


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