Trenchless vs. dig-and-replace sewer repair: which is right?

What are the three ways to replace a sewer lateral?

There are three main methods, and each one has a job it does well.

Open excavation, also called dig-and-replace, is the traditional method. The crew digs a trench along the whole run of the old pipe, removes it, lays new PVC at the correct slope, and backfills. Everything gets seen and everything gets replaced.

Pipe lining, sometimes called cured-in-place pipe or CIPP, inserts a resin-soaked felt liner into the old pipe through an access point, inflates it, and cures it in place. The old pipe becomes a mold for a new, jointless pipe inside it.

Pipe bursting pulls a new pipe through the old one. A cone-shaped bursting head is winched through the old lateral, breaks it apart outward into the soil, and drags the new HDPE pipe in behind it. It needs a pit at each end but nothing in between.

Lining and bursting are the two trenchless options.

When does trenchless make sense?

Trenchless earns its keep when digging is the expensive or disruptive part of the job. That describes a lot of our service area.

• The lateral runs under a finished basement floor, a rear patio, mature trees, or a long stone-walled front yard.
• The line crosses under a busy street where a full trench would mean days of traffic control and a large paving restoration.
• The pipe is clay with root intrusion at the joints but is still round and in line. A liner seals every joint at once.
• The pipe is cracked in several places but the path is straight. Bursting replaces it with a new pipe at the same or larger size.
• The estimate is driven by the length and depth of the run, the number of access pits, what has to be restored on the surface, and the permits your municipality requires. Trenchless is not always less work, and it is not always the right answer. It is a tool, and the camera decides whether the tool fits.

When is trenchless not possible?

This is the part a lot of sales pitches skip. Both trenchless methods depend on the old pipe being usable as a path.

A liner cannot fix a belly. A belly is a sagging section that holds standing water. The liner follows the sag, so the low spot stays. A liner also cannot pass a collapsed section, a badly offset joint, or a crushed pipe, and it slightly reduces the inside diameter.

Pipe bursting struggles when the old pipe is too close to other utilities, when it is encased in concrete, when the soil is loose fill that will not hold the burst, or when the run has sharp bends. The bursting head has to travel in a fairly straight line.

Both methods also need the connections handled: the house side, the curb trap, and the tie-in at the main. In Philadelphia the curb trap often has to be excavated and replaced anyway, so a small dig at the curb is common even on a trenchless job. When any of these conditions show up on camera, open excavation is the right recommendation, and we will say so.

How do we decide which method fits your line?

Every sewer job we do starts with a camera inspection, and this decision is the reason why. We run the camera from the house to the main, record the footage, and note the pipe material, the depth, every joint, root mass, offset, and low spot, and the condition of the curb trap.

Then we look at what is above the pipe. A lateral under a plain lawn in Bensalem is a different job from one under a Fishtown sidewalk and street, or an Ardmore stone retaining wall.

From that we build options. Sometimes it is one option, because the pipe only qualifies for excavation. Often it is two or three: a spot repair now, a liner, or a full replacement, each with its trade-offs written down. No high-pressure sales. We give you options. If another company has already told you that you need a particular method, ask us for a free second opinion on qualifying larger projects.

What do permits and inspections look like for each method?

All three methods need permits. In Philadelphia, sewer work goes through L&I for the plumbing permit, and any sidewalk or street opening needs a Streets Department permit. Lining and bursting still require the plumbing permit and an inspection of the connections, even though the digging is smaller. In Lower Bucks, the township or BCWSA reviews the work and may require its own inspection of the lateral before backfill. Lower Merion Township does the same on the Main Line. Requirements differ by municipality and change over time, so confirm current rules.

We pull the permits, schedule the inspections, and handle the street and sidewalk restoration with our own underground crews, so you are not coordinating three contractors. Whichever method your line qualifies for, the next step is the same: request a camera inspection, watch the footage with us, and pick the option that fits your house and your budget.