Trenchless Sewer Repair: Pipe Bursting and Lining

Pipe bursting

A bursting head is pulled through the old pipe, breaking it outward while a new continuous pipe is pulled in behind it. SPU notes it needs an access pit at the start and at the end, and that it’s useful when you want to minimize surface disturbance.

Bursting replaces the pipe rather than lining it, so it can upsize a line or fix one that is badly deteriorated, as long as the route is reasonably straight and there is room for the pits.

Source: SPU: Side sewer repair methods.

Cured-in-place pipe (CIPP) lining

A resin-saturated felt liner is inserted into the cleaned pipe, inflated to its shape, and cured until it hardens into a pipe within the pipe. SPU describes the result as a seamless length of pipe that can prevent roots from getting in and extend the side sewer’s life.

Lining works best on pipe that still holds its shape: cracks, root-prone joints, moderate exposed aggregate. Before lining, the pipe has to be cleaned, usually by hydro jetting, and roots cut out.

Source: SPU: Side sewer repair methods.

When trenchless isn’t the right call

• Sags. A liner follows the old pipe, so it keeps a belly that holds water. SPU grades a sag of 50% or more of the pipe diameter as severe.
• Collapsed or missing pipe. The liner needs something to form against; a collapse usually means a spot dig.
• Severe offsets. Badly offset joints may need excavation at that joint before a liner or burst can pass.
• Code changes needed. If the line needs a new route, a cleanout, or a different size to serve more units, that may change the method.

Source: SPU: Side sewer defects and issues.

Permits and inspection still apply

Trenchless work on a side sewer is repair work, so it needs an SPU side sewer permit. If the access pits or the work extend into the planting strip, sidewalk or street, an SDOT permit is required too. Seattle code reserves work in a public place for registered side sewer contractors. New sewer pipe longer than 10 feet must pass a pressure test (SPU how to apply; SDOT FAQ; SPU permits).

Hillsides, retaining walls and access

Much of Magnolia and Queen Anne sits on steep ground. The City's Environmentally Critical Areas maps include steep-slope and known landslide-prone areas in both neighborhoods. Those maps are advisory, but they're worth checking before planning pits or trenches on a sloped lot (SDCI ECA code). Smaller excavation footprints are one reason owners on sloped lots ask about trenchless options.

Before choosing a trenchless method

For any method, the decision should be based on a recent camera inspection with footage-marked defects. Get a copy of that video, as SPU recommends.

Bursting and lining each suit some lines and not others. We’ll walk through which options fit your pipe, and which permits apply, before anything is scheduled.

Where we offer trenchless sewer repair

• Magnolia: our home neighborhood (98199).
• Queen Anne: small pits instead of long trenches on terraced lots
• Interbay
• Ballard
• Fremont

Homeowner guides

• Seattle Side Sewer Permits: What Homeowners Need to Know: Ownership, permits, fees, inspections and contractor rules, all in one place.

Related services

• Side Sewer Repair & Replacement: Repair or replace the private sewer pipe from your house to the City main, permitted through SPU.
• Sewer Repair: Broken, sagging, root-filled or backed-up sewer lines, diagnosed on camera before any digging.
• Hydro Jetting: High-pressure water cleaning for grease, sludge and roots, and to prepare a pipe for lining.
• Sewer Camera Inspection: See inside your side sewer: roots, cracks, sags and offsets, and what the video and findings should show.

All plumbing and sewer services