Traditional vs. trenchless sewer replacement: which is right for you?

01 /What is the difference between traditional and trenchless replacement?

Traditional replacement, also called open-cut or excavation, exposes the sewer along its length in a trench, takes the old pipe out and lays new pipe on prepared bedding at a set grade before backfilling. Trenchless replacement leaves the ground over most of the line undisturbed and works through the existing pipe from a cleanout or a small number of pits.

Two trenchless families matter for a house sewer. Cured-in-place pipe (CIPP) lining pulls or inverts a resin-saturated tube into the old pipe and cures it into a new pipe inside the old one. Pipe bursting pulls a cone-shaped head through the old pipe, breaking it outward, while a new pipe, usually fused HDPE, follows in the same pass. Both follow the old route; neither can straighten a belly on its own.

For the national method theory behind each technique, SewerReplacement.ca covers the methods in depth. This page stays with the Alberta decision.

02 /Traditional and trenchless compared side by side

The last row is where comparisons usually go wrong. A trenchless quote that leaves out two pits under interlocking pavers, or an open-cut quote that says "restore to rough grade" when you have a finished yard, is not comparable to its competitor. Put both on the same checklist before comparing totals.

03 /Which defects point to which method?

The defect decides the method, and the method has to fix the worst defect on the run, not the average one. EPCOR's guidance for Edmonton homeowners, as checked September 2026, states it plainly: sags can only be fixed by removing the affected pipe and regrading the trench bottom, small cracks may be tolerated if they are not wide enough to let backfill into the pipe, and replacing a collapsed portion is the only viable option.

The Replacement Readiness Check applies this logic to your camera findings and returns the direction the evidence points, without prices.

04 /When is open-cut replacement the right call?

• The line has collapsed, or a section is missing or crushed.
• The grade is wrong: a sag holds water, or the pipe runs too flat to carry solids.
• The pipe needs relocating, for example around a new addition or away from a foundation.
• The connection at the main or at the house needs rebuilding, not just reinstating.
• The yard is being dug anyway for landscaping, a water service or foundation work.
• The existing material or the offsets make lining or bursting impractical.

Open cut is also the method that gives you the most to inspect: the pipe, bedding and connections are in plain view before the trench is covered. The open-cut replacement page walks through that process.

05 /When does trenchless work fit?

• The pipe still holds its shape and grade, with cracks, open joints or roots rather than collapses or bellies.
• A driveway, garage slab, deck or mature tree sits over the line.
• Access for a liner or bursting pits is practical at both ends.
• Branch connections can be reinstated or reconnected, and the contractor explains how.
• The selected system is supported by the camera evidence and the written scope.

Lining keeps the old pipe as a host and slightly reduces the inside diameter; bursting destroys the old pipe and can keep or increase the size. The trenchless lining eligibility page covers what makes a pipe a candidate.

06 /What do the methods cost in Alberta?

Typical quoted ranges for a 15–25 m residential run are below. The totals move most with depth, hard surfaces over the line, the number of access pits and the city-side connection.

The pricing page breaks these down by line item and explains what drives each one.

07 /What Alberta conditions change the choice?

• Frost. Frozen ground is slow and costly to dig; winter excavation usually needs frost removal or ground thawing before the trench can open. Trenchless work still needs pits, and the contractor should explain how cure or fusion is handled in the cold.
• Clay soils. Much of Alberta sits on clay that is heavy to excavate, holds water, and shrinks and swells with moisture. That affects trench stability, compaction of backfill, and how much settlement a finished trench shows.
• Depth and trench safety. Alberta's OHS Code requires protection for workers in excavations deeper than 1.5 m, by cutting back walls, a temporary protective structure, or both. Cut-back walls make the dig wider at the top, which raises restoration.
• Seasonal restoration. Sod, concrete and asphalt are hard to place properly in deep winter, so a winter open cut may leave final restoration until spring. Get that written into the scope.
• Mature trees. Boulevard and backyard trees in older Calgary and Edmonton neighbourhoods can sit right over the line; a trench cuts roots, while pits can often be placed clear of the root zone.

08 /A worked Alberta decision example

This is an illustrative example, not a real job. An Edmonton bungalow has an 18 m sewer from the basement cleanout to the property line. A recorded camera run with a locate finds roots at three joints under the driveway between 3 m and 9 m, a sag holding water from 11 m to 14 m under the front lawn, and a minor offset at 17 m, close to the property line.

1. Find the worst defect

   The sag. EPCOR says a sag can only be fixed by removing the pipe and regrading, so lining the whole run would leave the belly in place.

2. Check ownership

   EPCOR is responsible from the property line to the main. The offset at 17 m needs its position measured against the property line before anyone prices it.

3. Build the options

   Option A: open-cut the full 18 m, including the driveway. Option B: excavate and regrade the 3 m sag in the lawn, then line the driveway section from the cleanout, reinstating the joints the roots used.

4. Price both on one checklist

   Option A falls in the hard-surface open-cut range because of the driveway. Option B combines a moderate-depth excavated repair ($5,000–$9,000) with lining of roughly 10 m, plus locates, permit and post-work video.

5. Decide on the full scope

   Compare restoration, the permit holder, schedule and post-work video, then choose. Option B keeps the driveway; Option A gives a single new pipe end to end.

Your own findings will differ. Run the Alberta City Sewer Rules Finder for your municipality's ownership split and permit body before pricing.

09 /Questions to ask every contractor

1. Is my pipe a candidate for trenchless work, and which finding on my video decides that?
2. How will you correct any sag or collapse, and where exactly will you dig?
3. What is the total cost, including access pits, restoration and the city-side connection if needed?
4. How long will each method take, and what could delay it in winter?
5. Which permit is needed, and who applies for it?
6. Will I get a recorded camera run after the work, and a sketch of what was installed?
7. What warranty applies to each method, in writing?

Alberta's plumbing codes page notes that contractors may require a Restricted Certificate of Competency "R" for sewer and water services, so ask which certification the crew holds. When you have two written scopes, send them with your video through the request form.

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