How does it work?

In a nutshell  a bursting head is pulled or pushed through a pipe, breaking or splitting the old pipe as its replacement is pulled in. Taking a look inside the line with a drain camera makes both the estimating and the repair easier. There are various types of bursting equipment available. However, the typical plumbing contractor that needs to break up four to eight-inch lateral drains would use static (hydraulic) or pneumatic equipment. Some bursting heads include an expander that enlarges the size of the hole, allowing the contractor to upsize the drain or to run a water line beside the drain.

Static systems

Static systems can burst virtually any type of drain. A cone-shaped bursting head is pulled through the pipe with a hydraulic pulling assembly that the technician assembles in the pit. There are usually two pits, one at the house or, better yet, in the basement and another at the municipal connection. The plumber must also excavate any underground connections or divert the line. A gas-fueled hydraulic power unit or an excavator, skid-steer, backhoe, etc. with a hydraulic feed can supply power. Hydraulic cylinders operate a gripping mechanism that pulls a chain or cable attached to a bursting head through the existing pipe. Cables or chains for the smaller machines used in residential work typically pull up to 150 ft. Bursting heads come in numerous designs. Basically, they are cone shaped and may have a fin or fins to split the pipe. One model has cutting wheels that slit the pipe, reducing the required hydraulic pressure for a given pipe size. Some hydraulic pulling units can be converted to push a rod through to make a hole for water, gas or electrical lines. The Pipe-Genie unit, invented by Vancouver plumber Gerry Robinson, is used by a number of Canadian contractors. With our system, you can pull a water line and a sewer line in side by side. When you burst the old sewer line, you pull a sleeve in so that you can insert the water line beside the sewer line, said Robinson.

Pneumatic equipment

Pneumatic, as it name suggests, uses compressed air to hammer a bursting head through a pipe. A variable tension winch guides it from the other end. A small trailer-mounted compressor supplies air. A five-inch piercing tool requires a steady supply at about 125 cfm. Depending on the equipment the contractor chooses, a pneumatic system can be less expensive than a static system designed for the same pipe sizes. The major shortcoming of pneumatic equipment is that it doesnt work well for ductile iron or steel pipe, noted Mike Schwager, national product specialist for TT Technologies, Aurora, Illinois, a manufacturer of static and pneumatic systems. The pipe tends to gather on the front end of the pneumatic equipment and just be pushed out of the other end. The other problem is that the vibration can cause the soil to compact if it is wet.

Training and safety

This is powerful machinery and it is absolutely critical that the technician knows how to operate it and takes the appropriate safety precautions for working in a pit. Pit walls must be securely shored up to prevent cave-ins. One of the advantages of pipe-bursting is the relatively small hole that the plumber makes in the customers lawn. However, that hole must be big enough to allow working room around the equipment and a ladder must be in the hole at all times so that the operator can get out quickly if something goes wrong. The manufacturer provides training, typically in person or by video. More often than not I can walk them through the job on the phone, notes Robinson. Most plumbers are fairly mechanical, so they understand. If (a job) is something way out of the ordinary, I will come and train them. Luongo said it took his technicians a few jobs to get up to speed. He found the initial training process went a lot smoother after he put together a detailed checklist of tools required at the site and tasks to be completed. Rather than training all employees on pipe bursting, he trained one two-man crew that does all pipe bursting operations for the company. The skill of the operator does make a difference, he reported. The initial cost of pipe bursting equipment can be high. A professional quality pneumatic or hydraulic system can cost between $25,000 and $40,000, depending on the size of lines the contractor needs to burst. As a result, contractors that need an occasional pipe burst generally subcontract it out, reports Collini. But in Canadas cities drains are crumbling in older neighborhoods. Municipalities often share part of the cost where damage has been caused by roots from city trees. It can be a lucrative business.

On the job site

On a cool March day journeyman plumber Igor Vydysh and apprentice Andrew Chekamov  Mr. Rooter employees  are busy replacing a lateral drain outside a home in east Toronto. Its warm down in the pit. Above ground, a brisk cold wind blows. Its not unusual to find workers arguing over who gets to work underground, Vydysh laughs. There are two holes  both about 10 feet deep. One is next to the house and other is at the municipal connection in the street. The company just purchased a second pipe bursting unit. The new model is considerably more compact  the necessary hole is reduced from 3-1/2 by seven feet to three by five. The pulling unit frame is now two pieces instead of six. Vydysh has done over 40 pipe bursting jobs in the past 1-1/2 years. It is typically a two-man operation that can take up to three days  most of which is preparation. The actual pull takes about an hour. He typically uses PVC drain pipe to replace the existing drain. The length is limited by the size of the hole. He strings enough lengths on a chain to run the entire line. He chamfers the end of each connector with a grinder to make it slide through the earth easier. When the first five-foot length is pulled in, he stops the machine, releases the tension and then glues the connector and the next piece in place prior to resuming the pull. Its been a tough job. They are into their third day. They are looking forward to wrapping it up.