Nearly a century of heavy stormwater flow had eroded the drainage system at the historic federal building and U.S. District Courthouse in Sioux City, Iowa. The cost of replacement wasn’t feasible, so operations staff needed another solution.

Roof water runoff from the building is directed by a drainpipe network to enclosed-wall risers. Each precipitation event for the past 90 years has delivered the equivalent of a half city block’s rainfall down the pipes in a 70-foot freefall. While scale and rust had taken their toll on the entire drainage system, one of the risers tasked with redirecting each torrent to the city’s storm sewer system had finally worn through at its lower 90-degree fitting. It required urgent repair to prevent interior water damage from the coming season’s spring rains.   

Had it been just an old building, one remedy might have been to open the walls, replace the pipes and restore the walls. But this three-story Depression-era landmark is listed in the National Register of Historic Places. Building-restoration costs eliminated full replacement as an option.

Sioux City’s Morningside Plumbing had been contracted for a number of projects in the building over the years, including drainpipe repairs, so the contractor knew just how critical its condition was becoming. Owner Mark Corbin recommended lining the pipes, which would provide a long-term solution.

Court of appeal

A Sioux City newspaper’s coverage of the building’s 1933 dedication headlined it, “Uncle Sam’s Gift to the City.” Created to serve as the Sioux City U.S. Courthouse and post office, it was designed to inspire public confidence during the most severe economic downturn the industrialized world has ever known. Its bold, powerful exterior is created from light gray limestone and ashlar masonry atop a 5-foot-high granite base. Its fortress-like façade protects its blend of stripped classical and art deco styles.

In 1984, the U.S. General Services Administration (GSA) acquired the building from the U.S. Postal Service, which needed more room. The building currently houses federal courts as well as offices for several federal agencies.

Erik Peterson, a GSA facilities operation specialist, needed to limit costly restoration: “Just to get at the first 15 feet of pipe would have consumed a third of the total project funding in demolition and repaving of a 20-inch hole in the wall to access it.”

Peterson was familiar with CIPP. “I knew of its use for things like lining sewers, of course,” he says. “But I’d never heard of it used for lining pipes that collect rainwater from a roof.”

Corbin told Peterson how CIPP was used to upgrade the enclosed-wall drainage systems of a 30-building VA hospital campus in Montrose, New York. The Sioux City federal building was a similar candidate ideal for CIPP. Morningside Plumbing would just need a week free of winter weather conditions and precipitation. Working from the roof would have no impact on the building’s exterior or interior walls.

HammerHead lateral product representative Cory Steckmann, who had been at the VA hospital job, and lateral application technician Joe Walsh would be on site in person to provide Morningside Plumbing with manufacturer support for this project. Peterson confidently recommended the plan to the building manager.

Supporting evidence

Steckmann pointed out several major advantages of CIPP rehabilitation, which would form a new pipe within the old and provide a higher flow rate than when the original pipe was new.

CIPP lining smoothes over pipe wall irregularities, holes and cracks with its nonstick surface, right through pipe bends and fittings. Product offerings include a flexible felt liner that will make seamless upsize transitions of one step, such as 4-inch to 6-inch.

The installed liner’s 4-millimeter thickness equates to about a 6 percent reduction in the actual interior diameter of an 8-inch pipe. However, the smoother surface of CIPP improves flow and virtually eliminates the potential for future impediments to flow.

Since the liner does not rust, scale or otherwise corrode, the useful life of a CIPP-rehabilitated pipe exceeds that of pipe materials such as ductile iron and galvanized steel, and can be used to rehabilitate pipes of most any other composition.

Pretrial

Morningside Plumbing inspected the interior of the pipe runs after they were jetted clean and capped off to prevent contamination while the crew waited for a stretch of conducive weather.

Peterson says five or six of the threaded joints had holes in them. Areas where galvanization and metal had been removed to thread the pipe during the 1932 installation were more vulnerable to corrosion than other points in a run. The biggest was the same hole that had made the project urgent: a 3/4- by 2-inch-wide gap in a 90-degree fixture at the bottom of the riser.

Prior to lining through the fittings, Morningside Plumbing’s factory-trained installers applied PipePatch point repair kits from Source One Environmental. Although CIPP typically bridges small holes and fractures without distortion, PipePatch eliminates any potential for bulging during the pressurized setup and cure time.
A 3- by 5-foot section of the roof was removed to form a temporary access with a wood curb and metal cap.

In the boiler room at ground level, the crew removed 3 to 4 feet of the 8-inch riser, replacing it with 8-inch PVC pipe and a clean-out.

Proceedings

Morningside Plumbing owns its own HammerHead HydraLiner equipment, including a Super Hydra Inversion Drum and standard Hydra Inversion Drum and wet-out table. They used a crane to hoist these to the rooftop along with a boiler, felt liner, epoxy resin and hardener.

The four-person crew treated three 20-foot runs and one 50-foot run of 6-inch drainpipe first, completing two runs a day. These four drains connect the rooftop grates to a common 100-foot run of 8-inch pipe sloping at 1/4 inch per foot.

Each drain was first uncapped and re-inspected. The crew cut a felt liner to length and ran it through the wet-out table. The wet-out table allowed for precise and consistent distribution of the epoxy resin.

The crew wound the wet-out liner into the Super Hydra Inversion Drum, leaving the end extending outside the drum as they sealed it up. The end was folded and clamped over the inversion nozzle. Placing the nozzle in the drainpipe opening and charging the drum with air pressure to approximately 6 psi forced the lining to invert itself inside the pipe. As the lining spooled out of the drum, its inner resin-impregnated side turned inside out, uniformly mating with the clean pipe surface as it progressed.

The inversion drum was then spooled with a calibration tube, a tubular bladder cut to the same length as the liner. The calibration tube was immediately inverted inside the installed liner.

Unlike an open-ended liner, a calibration tube is sealed. This allows it to hold air, water or steam after the tube’s inversion. Inflating the tube with air, water or steam presses the liner uniformly against the pipe, ensuring a good bond between the pipe and liner and smooth interior surface.

The calibration tube was inverted with a recirculation hose inside that reached nearly to the end of the tube to allow continuous hot water circulation to maintain a uniform 160 degrees throughout the cure period. In this case, Morningside Plumbing left the tube in place overnight, though cure rates for thermally activated installations can be as short as one hour.

Part of the reason for leaving them to cure overnight was an unexpected change in the weather. Temperatures dropped below freezing. Brisk winds at rooftop level created brutal wind chills. Corbin would not have started the project in these conditions, but work was already underway. “The cold probably slowed our pace a little, but as long as the equipment didn’t freeze up on us, we could keep working.”

The 100-foot run of 8-inch common drainpipe was accessed from the space beneath the roof. Each CIPP-treated wye where 6-inch pipe joined the 8-inch pipe had to be trimmed and smoothed before inverting the 8-inch liner. After inversion and curing, the intersections between 6-inch and 8-inch CIPP were cut open, trimmed and smoothed using Picote reinstatement and cleaning equipment.

The 8-inch common pipe emptied into an 8-inch enclosed-wall riser descending three stories to the boiler room, angling 70 degrees side-to-side over the run. At the boiler room, the riser turned 90 degrees away from the building through a final 6-foot galvanized lateral, which attached to clay sewer pipe leading to a manhole in the alley. The CIPP project terminated at the end of the galvanized pipe, since other roof drains fed into the clay pipe beyond this transition point.

Once the riser CIPP had cured, all treated pipes were inspected, reconnected and returned to service.

Results

Peterson’s main objective had been to get the most urgent problems fixed, with as much additional replacement as funding would allow in this first drainpipe remediation project. Morningside Plumbing, however, accomplished more repairs within the project budget than would otherwise have been attempted­ — finishing two days ahead of schedule in spite of uncooperative weather.

Other than a crane that occupied a couple of parking spaces in the alley while hoisting their equipment to and from the roof, daily activities continued unimpeded and undisturbed throughout the CIPP operation.

The remaining roof drains may be a future lining project. For right now, Peterson wants to share the news of this technique’s benefits with his colleagues in other GSA buildings, who may be facing similar issues. “I think our takeaway here is CIPP’s versatility. We need to be aware of just how many other ways we can use it.”