Pipe Bursting

How bursting works

A pit is opened at each end of the run: one where the new pipe goes in, one where the pulling rig sits. A cable or rod string is threaded through the old pipe from the rig to the insertion pit and attached to a conical steel bursting head, and behind the head, a continuous length of high-density polyethylene pipe, butt-fused on site into one jointless piece. The rig pulls. The head splits the old clay, cast iron, concrete, Orangeburg or plastic outward into the surrounding soil, and the new pipe follows it in along exactly the same path. Pneumatic heads hammer their way through brittle pipe; static heads pull through anything, including steel and ductile iron with a cutting blade fitted. When the head reaches the rig, the new pipe is connected at both ends, the pits are closed, and the old pipe is gone, in fragments, in the ground around the new one.

What bursting fixes that lining cannot

Lining copies the host pipe. Bursting replaces it, and that single difference decides when each is used. A section crushed under a driveway, a joint stepped sideways beyond what a liner can bridge, a pipe deformed by Orangeburg's slow collapse or a cast iron line rusted through and separated can none of them be lined, because the tube cannot pass or the finished liner would narrow at the defect. A bursting head goes through all of them. Bursting is also the method for upsizing: the head can be larger than the old pipe, and a four-inch lateral comes out six, a six-inch main comes out eight, along the same route, without a trench. That matters on a building that has grown or a main that was undersized from the day it went in.

What bursting will not fix

Bursting follows the old alignment, so a pipe with a belly or a reverse grade comes out a new pipe with the same belly; correcting grade means an open cut, at least through the bad section. A pipe encased in concrete, laid in a bundle with gas or electric service, or passing close under another utility cannot be burst safely, because the fragments and the displacement have to go somewhere. Very shallow pipe under a thin slab or pavement can heave the surface. And bursting needs the two pits, which in a tight urban lot or a busy street may be the hardest part of the job to permit. The camera survey, a utility locate and a look at the surface decide whether bursting is on the table.

Where it is used most

• Residential laterals that have collapsed, been crushed or gone oval, especially Orangeburg and failed cast iron
• Deep laterals in frost country, where the alternative is a ten-foot shored trench down the length of a yard
• Lines under slabs, driveways, mature trees and hardscape that a trench would destroy
• Private mains under apartment complexes and HOA streets that need a larger diameter
• Municipal mains that have lost structural integrity or capacity, burst from manhole to manhole with bypass pumping
• Water services and mains, where the same method pulls new HDPE or fused PVC through the old line

A bursting day

A residential burst usually takes one to two days. Day one: the camera run and locate, the utility marks, the two pits opened by hand or with a small excavator, the HDPE fused on site into one piece and laid out, the head and rods threaded through. The pull itself, on a typical lateral, takes under an hour. Then the new pipe is connected at the house and at the main, pressure or video tested, and the utility inspection is called. Day two, if needed, closes the pits and restores the surface. The pits are the only disturbance: one a few feet square at the foundation or the cleanout, one at the property line or the main.

What you end up with

Fused HDPE is one continuous pipe with no joints along its length, flexible enough to tolerate ground movement that would crack clay or concrete, and rated by its manufacturers for a service life of a century. It is what most utilities now specify for new sewer services, which means a burst lateral is, from the utility's point of view, simply a new lateral, inspected and connected like any other. Installer warranties on bursting are typically comparable to those on lining; the written warranty governs.

What drives the price

Bursting costs more per foot than lining, because of the pits, the rig and the fused pipe, and far less than open-cut on anything deep, paved or landscaped. Length, depth, the diameter of the new pipe, the ground, what the two pits have to go through and what the utility requires at the connection set the number. It is scoped from camera footage, a locate and a look at the surface, never from a phone call.

Getting the right method

Most lines that need bursting were first quoted for lining by somebody who did not run a camera, and most lines quoted for bursting could have been lined for less. The footage decides. Your state page explains what is likely in the ground where you are and whether a verified installer is listed; if none is, the national line finds one for you.

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