Trenchless Sewer Replacement: Bursting, Lining, or Dig

When a camera inspection shows a sewer lateral that has reached the end, the traditional fix is a trench from the house to the street, a new pipe laid in it, and a yard, driveway or sidewalk to put back afterwards. That is still sometimes the right answer. But for a lot of the failed laterals we see in Garland, Rowlett, Mesquite and East Dallas, one of two trenchless methods does the job from a pit at each end.

Pipe bursting

A steel cable is threaded through the old pipe from a pit at one end to a pit at the other. A cone-shaped bursting head is pulled through behind it, fracturing the old pipe outward into the surrounding soil, and a new high-density polyethylene pipe is pulled in directly behind the head. The result is a continuous, jointless pipe of the same or slightly larger diameter along the original path.

Bursting works on clay, cast iron, Orangeburg and PVC lines. It handles a pipe that is badly cracked, offset at the joints or root-choked, because the old pipe does not need to be intact; it just needs to be a path. It needs access pits at each end and at any point where the line changes direction sharply. It is not a good fit if the line runs very close to other buried utilities, since the fracturing displaces soil, and it cannot follow a tight bend.

Cured-in-place lining

A flexible liner saturated with resin is pulled or inverted into the existing pipe, inflated against the pipe wall, and cured with hot water, steam or UV light into a hard new pipe inside the old one. The old pipe becomes a form. The finished liner is smooth, jointless and slightly smaller in diameter than the original.

Lining suits a pipe that is structurally mostly there but leaking at joints, scaled, or invaded by roots at several points. It can be done from a single access point, sometimes from the cleanout. It is not appropriate where the pipe has collapsed, has a significant belly, or has an offset large enough that the liner cannot pass. A belly lined is still a belly; the liner follows the pipe's shape exactly.

When digging is still the right call

• A belly. In expansive clay, a section of pipe that has settled below grade holds water and solids. Neither trenchless method changes the grade of the pipe. The low section has to be dug up and re-laid to a proper fall.
• A collapsed section that no cable or liner can pass.
• Multiple branch connections along the run. A liner blocks them until each is reinstated, and bursting can disturb them.
• A short, shallow run in open lawn. Sometimes a trench is simply the cheapest and cleanest option.
• Under-slab drains. Pipe bursting is not typically done beneath a foundation; those sections are tunnelled or spot repaired.

What a Garland lateral usually looks like

Much of Garland's housing dates from the 1950s through the 1970s, and the original laterals are cast iron under the slab and clay tile from the foundation to the street. Clay joints every few feet are where roots enter, and after sixty years of clay soil movement the joints are often offset. A line like that, with root intrusion at many joints but no collapse, is a good bursting candidate: the new pipe has no joints for roots to find. The same house with a settled section under the driveway needs that section dug regardless.

Permits, tie-ins and the city side

Sewer replacement is permitted work in every municipality we serve, and the connection to the city main typically has to be inspected. The portion of the lateral in the right-of-way is handled differently by different cities; some require a licensed contractor to do it under their own permit, some take responsibility for it themselves. We sort that out as part of the job so you are not caught between two sets of rules.

Family-owned in Rockwall, licensed and insured, with Garland and Dallas County on our daily routes. TX Master Plumber TXM11693. (469) 338-5533.