Going Down the Drain

The Franklin Delano Roosevelt Campus of the Veterans Affairs Hudson Valley Health Care System is one of the largest community care programs for veterans. Located along the banks of the Hudson River in Montrose, N.Y., the hospital provides tertiary care in acute and chronic psychiatry, as well as inpatient and outpatient services, from 30 office buildings with graceful architecture and exterior brick veneers.

The drains from the roof gutters of these elegant buildings had reached the end of their useful life, yet there seemed to be no satisfactory replacement strategy. The 40- to 50-ft vertical drops of 3-in. cast-iron pipe were concealed within the walls of the buildings. They made a 90-degree transition to 4-in. horizontal pipe at basement crawlspaces in concrete slab on grade, leading rain water to the storm sewer system.

Replacing the drains from within the building would entail substantial demolition and interfere with the hospital’s sensitive operation. The other choice, simply bypassing the drains with exterior installations, would blemish the buildings’ aesthetic appeal.

Cured-in-place-pipe (CIPP) presented a perfect solution. Whispering Pines Development Corp. of Vails Gate, N.Y., was contracted to rehabilitate the existing gutter drainage system, with help from HammerHead Trenchless Technologies and its line of HydraLiner CIPP products.

What Is CIPP

As its name implies, CIPP technique constructs a new composite pipe within the existing pipe by means of a resin-impregnated felt or woven liner. It can be used for pipe of nearly any composition, including clay, PVC, ABS and cast iron. Typical applications include rehabilitation of sanitary sewers, storm sewers, process piping, electrical conduit and water and ventilation systems.

The CIPP rehabilitation at the VA hospital was managed in two stages of 13 buildings each. Runs for each building consisted of 20 to 22 cast iron drainpipes. Equipment and materials Whispering Pines and HammerHead agreed on for this job included two HammerHead Mini-Hydra CIPP lining inversion drums, four application nozzles, four 150-psi portable air tanks, Picote chain flails for cleaning the existing pipes, a Picote CIPP reinstatement system and more than 7,100 ft each of composite liner and calibration tubing, with epoxy resin and hardener.

The liner that the team chose was HammerHead’s 3-in. and 4-in. HH Flex Liner, whose characteristics were matched to this specific application. HH Flex Liner is designed for multiple bends with minimal wrinkling. Flex liner will also permit upsizing one step, seamlessly making the transition from 3-in. diameter pipe to 4-in. pipe.

The fabric of HH Flex Liner is able to step up to 4-in. horizontal pipe at a 90-degree turn and yet retain its integrity and stiffness to soundly bridge any irregularity, gap or split in the existing pipe without bulges or failures. And the felt’s material composition matched HammerHead’s specifications for installation pressures and curing temperatures for the resin and hardener used in this application.

Process

HammerHead sent CIPP specialist Cory Steckmann to serve as onsite consultant and trainer for the six Whispering Pines employees who would form a four-person installation crew as needed. Steckmann said the trainees were running lines on their own in short time on the first building.

First, the team opened an access into an existing vertical pipe at its elbow to the gutters inside the attic and then they cleaned the pipe of tuberculation with an electrically powered chain flail. Flailing was a remarkably quiet operation, Steckmann said, since the flails are sized for the pipe and “really just scour or grind rather than flail.” The only audible sound was a muted scraping within the office walls, which minimized any impact on hospital operations. Video camera inspections after cleaning verified installation readiness.

The crew cut felt tubing to length for the “wet out” process. The crew began wet out by clamping a liner at one end, then used a pump to create a vacuum within the liner. They poured resin in through the open end, sending it through adjustable rollers mounted on the wet out table to completely and uniformly impregnate every fiber of the liner.

When the wetout process was complete, the team rolled the liner on the reel of a specially designed “inversion drum.” They folded the end over the inversion drum’s nozzle like a cuff and clamped it in place. Once the nozzle was in place against the pipe opening, they charged the drum with compressed air. The pressure caused the liner to exit the drum inside-out into the existing pipe, unwinding itself from the reel as it went. This step, called the “inversion” process, unfolds the resin-impregnated side of the felt outward against the pipe’s interior surface.

After the inversion process, the crew disconnected the nozzle so it could wind an inflatable hose, called a calibration tube, onto the drum’s reel. The crew inverted the calibration tube into the liner that was just installed. Pressurizing the calibration tube to 10 psi pushed the liner uniformly against the pipe throughout its length. Other product combinations call for water or steam for this step, but air and ambient temperature were specified for this project.

John Leonette of Whispering Pines said using two drums made the inversion and calibration tube processes go faster. They could load one drum while the other was in use. By detaching the nozzle and attaching a portable air tank to maintain the tube at 10 psi, they freed up the drum for another run. They were able to complete four runs this way in a normal eight-hour shift.

Ambient cure time for this product combination was five hours. When the cure time was up, the crew removed the nozzle and pulled out the calibration tube. Then they verified the quality of the clean, joint-free installation with a video camera before reconnecting the pipe and returning it to service.

Invisible Installation

Leonette said the compact size of HammerHead’s Mini-Hydra Drums and the light weight of the CIPP consumables were a tremendous asset in this application. “We couldn’t tie up the front elevators. We basically stayed out of sight, using the back stairwells to gain access to the attic.”

While some of the attics offered adequate space to lay out the lengths of liner for measurement and wet out, not all did. In those cases, Leonette said, “We had to do the wet outs outside on the ground and then carry the loaded drums up several stories. And once in the attics, there were trusses and obstructions on the floor we had to navigate to get it all in place.”  

The crew performed wet out and inversion of four runs in a morning. It took only about an hour per 50-ft run to prep the pipe for lining, invert the lining and calibration tube and set up a portable air tank to maintain pressure throughout the cure time. In the afternoon the crew removed calibration tubes, video-inspected the installations and reconnected the four drainpipes.
The project was completed in December 2013.

Joe Bradfield is senior writer for Ellenbecker Communications, an international communications firm specializing in the drilling, mining, and construction industries.