Sewer pipe bursting in Denver

What sewer pipe bursting is

Sewer pipe bursting in Denver replaces a buried sewer without digging along its route. A cone-shaped bursting head, slightly larger than the old pipe, is pulled through the existing line from one pit to another. As it advances it fractures the old pipe and pushes the fragments outward into the surrounding soil, and a new pipe attached to the back of the head follows it into the space the fragments left behind. When the head reaches the receiving pit, a continuous new pipe occupies the old alignment and nothing above the line between the pits has been disturbed.

The new pipe is almost always high-density polyethylene, fused into a single length on the surface before the pull. Fused HDPE has no joints for roots to enter or for soil to work into, and it is flexible enough to be drawn through the mild curves a residential sewer usually has.

Pneumatic and static heads

• Pneumatic bursting uses a percussive head driven by compressed air, hammering forward like a horizontal jackhammer while a winch holds tension on the cable. It works well on brittle pipe such as clay and concrete.
• Static bursting uses no hammer. A hydraulic pulling rig in the receiving pit draws a chain of rods, or a heavy cable, through the pipe and pulls the head steadily by force alone. Static heads carry blades that split cast iron, ductile iron and steel, which a pneumatic head cannot reliably fracture.

Most residential work today is static, because the rig is compact, the pull is controlled, and it handles the mixed materials often found in one older line.

When bursting is chosen over lining

A cured-in-place liner needs a host pipe to form itself against. When the host pipe has failed as a shape, the liner has nothing to follow, and that is where bursting takes over. The camera survey usually points to one of three conditions.

• Collapse or crushing. A section that has caved in, flattened or lost its crown cannot pass a liner and would not support one. The bursting head simply breaks through what remains.
• Undersized pipe. A line that has never had enough capacity, or that serves more fixtures than it was laid for, can be replaced with a larger pipe. A liner slightly reduces the inside diameter; bursting can increase it.
• Badly offset or separated joints. A joint that has dropped more than a small fraction of the pipe diameter forms a step the liner would either bridge with a void behind it or fail to negotiate. Bursting removes the step altogether.

A description of how pipe bursting and lining compare sets out the boundary between the two methods in more detail, but the short version is that lining is chosen whenever the pipe holds its shape and bursting whenever it does not.

The pits at each end

Bursting needs access at both ends of the run: an insertion pit where the fused HDPE and head enter, and a receiving pit where the pulling rig sits and the head emerges. Each is a small, shored excavation, typically a few feet square and as deep as the pipe. On a residential lateral the pits often land at the house connection and at the property line or the main tap, so the disturbed ground is two patches rather than a trench. Where an existing cleanout or manhole can serve as one end, only one pit is dug. After the pull, the new pipe is connected at each pit with transition fittings and the pits are backfilled and compacted.

Depth and what sits above the pits matter more than the length between them. A pit in a driveway adds saw-cutting and restoration to that one spot, still far less than a trench the full length.

Bursting and lining on the same job in Denver

The two methods are not competitors so much as tools for different parts of the same line. It is common in older neighborhoods in Denver for a camera survey to show one collapsed or crushed section and a long remaining run that is cracked and root-damaged but still round. The efficient answer is to burst or excavate the failed section and line the rest, rather than bursting everything or trying to line through a defect the liner cannot bridge. The bursting pit at the boundary between the two sections becomes the access point for the liner, and the new HDPE and the cured liner are joined at that point with a transition that the post-lining video records. Contractors offering trenchless sewer replacement by pipe bursting in Denver normally carry both capabilities, and the survey, not a preference for one method, should decide how the line is divided.

What to expect from the work

Bursting is quick once the pits are open. A residential run is usually pulled in an hour or two, with the day spent on pit excavation, fusing the pipe, setting the rig and making connections. Utilities near the line are located before the pull, because the fragments are pushed outward into the soil. Sewer service is interrupted for the working day. Afterward a camera run confirms the new pipe is continuous and the connections are tight, and the owner should receive that video. verified CIPP installers serving Denver identifies installers who document both their bursting and their lining work, which is what to look for when the survey suggests a job needs both.

Common questions in Denver