Lateral Rehab & Replacement Goes Trenchless: Lateral Pipe Bursting
In the past, the rehabilitation and replacement of sewer service laterals was perceived as difficult, expensive and intrusive. With lateral lines running underneath yards, business entryways, sidewalks, etc. open cut trenching is usually the least attractive lateral rehab option. Most laterals continue on into some type of street or roadway where trenching is even less popular among motorists and public safety officials.
And that is just part of the lateral replacement issue. According to Collins Orton, Trenchless Equipment Specialist, TT Technologies, Aurora, Ill., the lateral problem is being addressed at all levels. He said, “According to the EPA over half of the sewer systems nationwide are beyond the mid-way point in their life expectancy. Seventy percent of utilities throughout the country are already experiencing some problems associated with inflow and infiltration. With laterals typically making up half of those systems, it’s not hard to determine where attention needs to be focused.”
Many municipalities are now offering lateral replacement programs that limit or even eliminate the homeowners fiscal responsibility for replacing the lateral, an indication of the seriousness of the I&I problem in some areas. But lateral replacement is not just a municipal/residential issue. Companies, corporations, factories, restaurants, etc. all face the problems caused by failing lateral service lines whether they are sewer related or not.
While every lateral replacement situation poses its own unique challenges, a trenchless rehab option is almost always preferable in those situations. However, many trenchless options are not applicable to lateral replacement. Pipe bursting offers a viable solution to the lateral replacement challenges. The following case studies highlight the various circumstances contractors find themselves in when replacing lateral.
Case Study #1: Carpet Outlet Store; San Diego, CA
The tenant at this particular mall was new to the property and had just established a retail carpet and tile store. The existing lateral sewer line for the location had failed via corrosion and age causing exfiltration of water into the surrounding ground soil whenever the bathrooms were used. The property management company provided the tenant with an outdoor portable bathroom until a solution to the problem could be found. With grand opening pending, the tenant was anxious to get rid of the portable bathroom, not only for themselves, but for their customers as well.
According to Underground Solutions sales and operations Manager Dave Munson, San Diego, CA, everyone was concerned about fixing the issue. He said, “Because of the failure in the cast iron lateral, the line regularly was stopping up and causing over flow situations in the building’s bathrooms. The property management firm was desperate for a means to replace the line without digging up the floor of the new carpet and tile store. The portable bathroom situation certainly wasn’t the answer for a retail outlet trying to impress customers.”
The project consisted of replacing an existing 4-inch cast iron lateral that ran from the bathroom area of the tenants building outside to an existing clean out. The lateral was approximately 120 linear feet and had a 45-degree bend about halfway through the run. For the project Munson chose the Grundotugger lateral pipe bursting system from TT Technologies, Aurora, Ill.
Munson said the Underground Solutions crew prepared a “precisely carved” launch pit inside the store and an exit pit outside of the building using a vacuum excavation system. Once prepared, the crew fused together the necessary 4-inch High Density Polyethylene pipe (HDPE) and connected the bursting head and expander. The tugger unit was positioned in the exit pit. Once the winch line was in place the bursting proceeded without incident. The entire burst took a little over one hour.
Munson said, “The fact that the lateral ran underneath a retail store and was considered a dire emergency by the client really made this project unique. The property management firm was under the gun to solve the problem. The solution was very effective. Combining state-of-the-art equipment in the vacuum excavation rig and theGrundotugger proved key to doing a fast, clean, precise and safe job.”
The Continued Growth Of Lateral Pipe Bursting
According Orton, the acceptance of lateral pipe bursting has taken quite a bit of effort. He said, “We have been bursting laterals for years, but because of bursting’s association with large diameter pipes, contractors that specialized in small diameter work never considered it. There was also a bigger is better mentality in the industry among equipment manufacturers. But, as the industry has now broadened it vision to include laterals, the manufacturing community has responded with high powered, highly portable lateral bursting equipment.”
Orton also noted that improvements in lateral bursting equipment have made the method accessible to everyone from specialty to general contractors. Orton said, “The new lateral bursting equipment is very portable, but doesn’t compromise on power. It’s also easy to use. Both static and pneumatic lateral bursting systems can be easily transported in most pick-up trucks. They only require a minimal crew compliment to operate. And they really get the job done well. With the big push for lateral replacement, the timing of some of this equipment couldn’t be better.”
Case Study # 2: Residential Lateral Replacement; Ventura, CA
What once was considered a very difficult pipe bursting application, lateral replacement has now become one of the easiest ways to get into pipe bursting. West Coast Plumbing, Ventura, CA recently made the leap into lateral pipe bursting on what could be considered a textbook lateral replacement.
For their first burst, West Coast Plumbing President Doug Ingram utilized theGrundotugger static system. The project consisted of bursting and replacing a 4-inch residential sewer lateral with 4-inch HDPE. The existing 40-foot VCP line was suffering from sever tree root intrusion and had been a reoccurring problem for the residents.
TT Technologies Pipe Bursting specialist Paul Rogers was on hand to provide the West Coast crew with technical support during their first burst. He said, “The crew did a great job. They caught on to everything very quickly and the job went very smoothly.”
The West Coast crew began operations by excavating launch and exit pits at either end of the lateral. Crews then rodded the decaying line and pulled the winch cable in place. The Grundotugger unit was placed in the exit pit, while the new HDPE was fused and positioned at the launch pit. Crews then focused on attaching the expander to the fused pipe and connecting the entire configuration to the winch line. Once connected, bursting was ready to begin. Thirty minutes later the new HDPE was in place and the crew began connecting the new lateral to the house and mainline.
Lateral Bursting Benefits
Pipe bursting is well suited for lateral replacement. It is capable of replacing relatively small diameter pipe and allows for increase or upsize of the original host pipe diameter. That fact alone is extremely valuable on jobs where lines are being replaced because of capacity issues.
The method is trenchless, which is of particular significance in a lateral replacement situation. Lateral replacement can be a sensitive issue on a municipal level because laterals are most often considered a private, residential issue. Convincing or mandating that a private homeowner replace their sewer lateral is difficult enough. Offering them a trenchless option that can mitigate damage to trees, driveways, sidewalks and landscaping can help soften the blow. In the urban setting when there is little right-of-way and a lot of concrete and asphalt, trenchless lateral pipe bursting can have a tremendous impact by limiting cost and disruption.
Case Study # 3: Grease Lateral Line, Hotel Restaurant; San Jose, CA
Sometimes it’s not yards or landscaping that worry contractors replacing laterals, it’s alleyways and sidewalks. Recently utility contractor James J. Viso Engineering, Santa Clara, CA took on a difficult lateral replacement at a hotel/restaurant in downtown San Jose. According to Viso Vice President, Joe Viso, tight working conditions made the project rather challenging. He said, “This project was downtown. There is no frontage; the hotel is on the sidewalk. The 4-inch cast iron line came out of the back of the hotel, from the restaurant, ran approximately 40 feet to a grease interceptor, then ran back under the hotel and to a main located in the front of the hotel in the street.”
Viso was contracted to replace the section of lateral that ran from the grease interceptor back to the hotel, the “downstream” section, with 4-inch HDPE. That 40-foot section of cast iron pipe was in very bad shape. According to Viso, attempts at video taping the line were hampered by its poor condition. It was completely collapsed in several locations.
The Viso crew excavated a launch pit next to the grease interceptor and an exit pit next to the hotel. Space was very tight. The launch pit measured approximately six feet long by a foot wide and the exit measured feet four feet by four feet. The pits needed to be constructed to minimal dimensions to accommodate the hotel’s above ground mechanical equipment and below ground utilities.
In addition to the host pipe condition and a cramped working area, Viso had to contend with poor soil conditions. He said, “The soil was very soft and unstable. When we first started, it just sucked the tugger in. What we decided to do was take some two inch steel pipe and drive it into the ground to brace the tugger. The ground was so soft we drove in about eight or ten feet of pipe with no problem. I thought there was no way it would hold, but it did and we were able to burst without problems.”
Lateral Replacement Future
All of the contractors involved with the aforementioned projects are aware of the potential that lateral replacement represents. According to Orton, the market is just beginning to develop. He said, “We’re seeing the very start of a lateral replacement frenzy. Failing laterals always need to be replaced, but with I&I mandates coming down, the pressure is on in many areas to rectify the problems. As main lines get replaced, laterals are soon to follow. There ”
Special thanks to the following individuals for contributing to this article:
Dave Munson, Sales and Operations Manager, Underground Solutions, Inc., San Diego, CA
Doug Ingram, President, West Coast Plumbing, Ventura, CA
Joe Viso, Vice President, James J. Viso Engineering, Santa Clara, CA
Collins Orton, Trenchless Specialist, TT Technologies, Aurora, Ill.
by Jim Schill