by Kathy Danforth / Published Sept 2015
Age tends to have the same effect on both buildings and bodies: problems develop in parts that were formerly ignored entirely and taken for granted. The 5700 Mariner South, an eight-story condominium built in 1975, found that their main sewer drains were demanding attention, but they were pleasantly surprised to find a cured-in-place-pipelining (CIPP) solution.
“We’d had expensive losses from a couple of failures,” reports Cliff Somers, board president at the time of the project. “The cast iron pipes had rusted and, in some cases, had worn all the way through and even shattered. Strangely, all the pipes had been coated with foam and, in some places, only the foam had prevented leaking.
“When we started this repair process, we didn’t know pipelining was even possible,” Somers recalls. “It would have cost millions of dollars to physically replace the pipes, besides the fact that tearing out all those pipes would have been agonizing and would have taken forever. Lining the pipes cost less than $600,000.”
“Pipelining technology was developed for municipal sewer mains and has been around for 30 years,” says Jeremy Bowman with US Pipelining, the company that performed the Mariner project. “In the United States, the original patents were up in 1997, so people jumped on board. The process involves manufacturing a felt tube that is slightly smaller than the inner diameter of the host pipe,” according to Bowman. “One side of the felt tube has a PVC coating. The tube is cut to length and impregnated with resin so you’ve created a pipe within a pipe that is a structural repair.
“The liner does not restrict flow,” Bowman notes. “It has minimal thickness; for a four-inch pipe the lining may be three millimeters thick when finished. The larger the pipe, the thicker the liner will need to be. Because we’re lining over joints in the original piping—typically cast iron or clay—the flow is increased because there’s essentially a more slippery surface, or increased coefficient of flow.
“The 5700 Mariner had a very challenging job of lining the vertical pipes and the main line at the bottom leaving the building,” Bowman relates. “We often see deterioration of these cast iron vertical stacks in high rises near sea water. The theory is that the flow from sinks, toilets, and tubs down the open stack draws in salty air, and we all know what happens to anything metal at the beach! We had televised these pipes and had seen longitudinal cracks as large as five feet by half an inch.”
To perform the project, access is gained from the roof. “The equipment is not that big and is fairly mobile, so we can typically transport it to the roof easily,” says Bowman. “First, we thoroughly clean the pipe using a mechanical auger and sewer jet, though we do not usually use a chemical treatment.”
In this building, Somers recalls, it turned out that there were a number of curves and twists in the pipes that had to be replaced with straight piping before proceeding. “Unfortunately, the worst of those went through my unit, and it was literally in a corkscrew. We never could figure why on earth the original contractor would have done that. But the odds are, in most older buildings that are not commercial, the plumbing won’t be shown on any plans that are left, or there will be roots and obstructions that nobody knows about.”
With a clean, straight run to work with, the resin is added to the felt liner. “Once the resin is absorbed, we roll it into an inverter and shoot the liner straight down with air pressure,” Bowman explains. “It’s inverting down the pipe, so the resin we put inside is now outside the tube and up against the host pipe. When the felt is in place, we shoot a calibration tube down the center of the tube. It’s basically like a balloon that we blow up to squeeze the liner against the pipe. For more than two hours the resin migrates to breaks and cracks and joints and heats to about 200 F from an exothermic reaction. Our resins were developed to cure in about two hours because we’ve done a lot of work at Disney World and that was critical for their projects. The typical cure time for the epoxy often used in small drains is eight hours.”
“The liner stops at the inner diameter, so no matter how big a crack is, it doesn’t weaken the new liner,” according to Bowman. “We’ve lined pipes where there virtually is no pipe; all we need is a conduit to get from point A to point B. This is a structural fix and forms a new pipe. If the host pipe disintegrates into nothing, if the right materials are used, the liner remains. Once the liner is cured, we remove that bladder and send a robotic microcutter to open up the connections tying in to each floor,” Bowman relates.
“We’re one of the few companies that use industrial-grade resin for smaller jobs,” adds Bowman. “We use this for a 2-inch pipe up to a 120-inch municipal pipe, so the same guys who have worked on an 80-inch or larger pipe will be working on a smaller roof job or a job under the slab. Epoxy is typically used by many contractors for smaller jobs, but the resin we’ve developed cures much stronger and faster. The life expectancy for the liner is up to 50 years as long as harsh chemicals aren’t used.”
Somers reports that for their community, getting the right material was the most important factor in contractor selection. “We did our research and concluded this resin was better than the epoxy, so we would have a better chance of long-term success. We didn’t want to do this again! Of course, we checked references also, and this method was not outrageously more expensive than the lowest bid.
“The project took about six weeks and went quite well,” Somers recalls. “We have almost 50 sewer drains, which are divided into six areas controlled by cutoff valves. The residents had water shutdowns when a drain in their section was being worked on, but only during the day.”
“We also lined the underground pipe that carries effluent out of the building,” says Bowman. “Because it’s horizontal and larger, we have techniques to line the pipe while it is in use so the water does not have to be shut off. We are able to do the branch lines to toilets, showers, and sinks, but in this case, we didn’t.”
“We are also able to coat potable lines and smaller pipes,” Bowman adds. “We may use two technologies for some jobs and use different coatings on smaller pipes. We also developed an additive for a pleasant aroma, which covers any odor from the product and dissipates quickly. With underground pipes you don’t get an odor, but when lining a vertical pipe, the odor may escape.”
For communities with a pipe replacement issue, Bowman recommends thorough investigation of the options and the contractors. “Typically, pipelining is half the price, a fraction of the time, and lasts three times as long as physically replacing the pipe. For any contractor, check how long they’ve been in business and compare their materials. Anybody can put up a fancy website; the proof is in the references from a client who was in a situation similar to yours. Vertical pipe work is very different from horizontal and is much more difficult. Just as in any industry, there are good materials and bad; good contractors and not so good. Our company services industries all over the country, so there’s not much we haven’t seen.”
Somers advises, “Check what kind of pipes you have, and if they’re cast iron, you better watch out. Every five to ten years you should run a camera through and clean with a power wash, which we didn’t know. But if you have this problem, you should have it fixed. This solved our pipe failure problem without spending millions of dollars, so we are satisfied!”