The rehabilitation and replacement of sewer service laterals has always been a difficult, expensive and time-consuming job. They are usually located directly beneath someone’s yard, a business entryway or a sidewalk; all of which makes open cutting the least attractive lateral rehab option from the resident’s point of view. Moreover, most laterals continue on into some type of street or roadway where open cutting is even less popular among motorists and public safety officials.A trenchless rehab option is almost always preferable in those situations. However, the nature of most laterals precludes many trenchless options. For example, bringing in a 4-ton directional drill, with a crew of six, to replace a 30-ft., 4-in. sewer lateral is not only clumsy it’s inefficient. The small diameter of most laterals makes slip lining difficult and undesirable since the objective is often to increase capacity, not decrease it. CIPP lining works well for larger diameter pipes but can be questionable for smaller diameters and rather expensive. Pipe bursting may offer a solution to the lateral replacement dilemma. One utility contractor in Jacksonville, Fl is already seeing bursting’s benefits after its first bursting job. Callaway Contracting, Inc. is a licensed general and utility contractor specializing in sanitary sewer, water and storm drain rehabilitation and replacement. According to company President Patrick Callaway, pipe bursting has interested him for quite sometime. He said, “Several years back the city of Jacksonville was considering letting a storm drain replacement job as pipe bursting. I worked with Eddie Ward at TT Technologies to put a package together. The job never really came to be, however I knew that the opportunities were there. At that time I envisioned bursting large diameter pipes, not laterals.”The explosion in lateral pipe bursting has come about recently for several key reasons. Inherently the method is well suited for lateral replacement. It provides a trenchless option for lateral replacement that utilizes the existing line 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.According to Pipe Bursting Specialist Eddie Ward from trenchless equipment manufacturer TT Technologies, Aurora, IL, the acceptance of lateral pipe bursting has been a long time coming. 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. Also, for a long time, the thought in equipment manufacturing was the bigger the better. Not true anymore. Compact and highly portable winches and bursting tools are pouring into the marketplace.”Another reason for the rise in lateral bursting is what in many ways helped pipe bursting establish a foot hold in the sewer industry in North America in the first place–Inflow and Infiltration.
Pipe Bursting History Lesson
Pipe bursting was developed in Europe in the early 1980s to replace the aging gas and water infrastructure. The concept is simple. A pneumatic tool, similar to a piercing tool, is guided through a deteriorating line by a winch. As the tool travels through the line its percussive action breaks apart the existing pipe and displaces the fragments into the surrounding soil. As that happens, the new pipe, usually High Density Polyethylene is pulled in behind it. While the concept and practice is still the same, the growth and development of pipe bursting in the United States and North America has been much different. During the mid- to late-1980s, some pipe bursting work was done on the East Coast, but it was Houston, Texas, that became the epicenter for pipe bursting in the U.S. and North America. Houston took an aggressive stance toward improving its sanitary sewer infrastructure. In many ways, they have led the way for pipe bursting in this country.Coastal regions, areas that receive significant rainfall and areas with high water tables, like Jacksonville, FL, suffer the worst problems with Inflow and Infiltration. Not coincidentally, these are the pockets around the United States and North America where pipe bursting first took hold.Clean Water Act standards regarding treatment facility discharge levels have been a big motivating factor as well. During the ‘70s and ‘80s, billions of dollars worth of water treatment plants were built to solve discharge problems. It was soon realized that despite this additional capacity, the plants were still filling up with water they were unable to treat. Callaway said, “I’ve had people in other cities tell me that they’ve rehabilitated the sewer mains through lining or bursting, but they’re still handling all this extra wastewater. When they go back and look, they figure out that they didn’t do anything with the services and that’s where a lot of the I&I is coming from.”In the ‘90s, civil engineers began looking upstream to solve their treatment problems. Ward said, “They started by replacing big diameter, then small diameter mains. Now they’re starting to work their way back to the house. There are great opportunities for skilled contractors like Callaway. You can see why the demand for lateral bursting equipment is growing. One of the most efficient methods to replace and upsize these lines is pipe bursting.”
Entry Level Bursting
What once was considered a very difficult pipe bursting application, lateral replacement, has now become one the easiest ways to get into pipe bursting. Callaway said, “Our first bursting job only consisted of a few services. Even after spending a few days learning the process and how to use the equipment, will still spent a majority of the job doing the things we needed to do no matter what method we were using. These services were fairly deep and required a good amount of prep work. Even so, it still went faster than an open cut job.”For the company’s first pipe bursting project, Callaway selected a small job with just six laterals. The services were located 8 to 9 feet deep and average 30 feet in length. The 4-inch VCP lines needed to be replaced with 6-inch HDPE. For equipment, Callaway chose lateral bursting gear from TT Technologies. The selection included a 3 3/4-in. diameter pneumatic Grundocrack PCG 95 with a 7-in. front expander and a specially designed lateral bursting winch. Ward said, “We’re talking about equipment that’s extremely portable, but doesn’t compromise on pneumatic bursting power. The entire system weighs less than 600 pounds and that includes the tool, winch, expander, hoses, lubricator, everything. It can be easily transported in most pick-up trucks.”
On The Job
Working in Jacksonville, the Callaway crew often contends with water issues and difficult soil conditions. This job was no exception. Callaway said, “We get into a lot of ground water and sand. We get into some clay too. For this job we had to de-water which is not unusual. We were able to handle this one with rock beds and surface pumps.”While prep work consumed a majority of the job, bursting went very quickly. Callaway said, “The hardest part of the work is already what we do, the locating, the digging and putting pieces together. The easy part is pipe bursting.” Bursting times averaged 12 to 15 minutes. After each burst, the crew tied the service into the existing main using a saddle-T with steel clamps.
Bursting Into The Future
With the successful completion of its first bursting project, Callaway sees great potential ahead. A much larger 200 lateral replacement job is already underway. Callaway said, “We’re excited about it [pipe bursting]. The crews are excited about it. They feel like they’re doing something new; it’s not just digging dirt. We intend to grow with it.”
by Jim Schill
Pumper/Cleaner, September 2000