Utility locates and digging safely for a sewer replacement in Alberta

01 /What has to happen before anyone digs for a sewer in Alberta?

Someone has to request utility locates through Utility Safety Partners, wait for the marks, and find the private lines those marks will not show. Utility Safety Partners (USP) runs Alberta's Click Before You Dig service. Its homeowner guidance asks for a request at least three full working days before you start, made online or by phone at 1-800-242-3447.

Alberta's Occupational Health and Safety Code puts the same idea into law for employers. Under Part 32, s.447, before ground is disturbed the employer must contact the owners of buried facilities, have the facilities marked, and not dig until they are marked. A sewer contractor who arrives with an excavator and no locate ticket is breaking that rule.

Municipal pages repeat the timing with local detail. Airdrie's locates page, as checked September 2026, asks residents to request locates from USP at least three business days before disturbing the ground and allows requests up to 14 days ahead. City water, sewer, storm and fibre lines are registered with USP, so they are marked; privately installed lines are not.

02 /What do the locate marks actually tell you?

They tell you roughly where a registered line runs, not how deep it is. USP says marks give an approximate location, and that any line within 1 m of either side of the marks must be exposed by hand before machine digging continues. For high-pressure pipelines that hand-expose zone widens to 5 m.

Because the depth is unknown, a mark crossing your sewer route is a signal to slow down. Crews expose the crossing with shovels or a hydrovac, then work around the uncovered line. Budget time for that; it is one reason mobilisation and locates carry a typical quoted range of $500–$2,000.

03 /Why is my own sewer line not marked?

Because it is customer-owned and therefore not registered with USP. USP lists water and sewer service lines, sprinklers and lines between buildings among the facilities it does not mark, and advises hiring a private locator. That catches many homeowners out: the pipe being replaced, and often the water service in the same trench corridor, are exactly the lines a sewer crew most needs to know about.

The water service and the sanitary sewer often leave the house near each other and run toward the street. Hitting the water service during a sewer dig turns a planned job into an emergency. A private locate before excavation, and hand exposure where the lines are expected to be close, is the protection.

04 /How is a private sewer lateral located?

Usually with the same camera that recorded the defects. A small transmitter called a sonde sits behind the camera head. As the camera moves down the pipe, a technician on the surface uses a receiver to find the signal, marks the spot, and reads an estimated depth. Repeating that every few metres traces the route and the depth profile of the lateral.

1. Start at a known cleanout

   Note which cleanout was used, because every distance on the video is measured from it.

2. Mark the defects

   Stop the camera at each significant defect and mark the surface above it with paint or a flag.

3. Record depth estimates

   Write the receiver's depth reading beside each mark; treat it as an estimate, especially near metal or other lines.

4. Measure to fixed points

   Tape each mark to the foundation corner or another permanent feature so it survives rain and mowing.

5. Keep the video and the marks together

   The contractor pricing the dig needs both, and so does the permit reviewer.

A sonde locate also shows where the failure sits relative to the property line, which decides who pays and which approvals apply. The camera evidence page explains what a useful recording includes.

05 /Which Alberta OHS rules apply once digging starts?

Four sections of the OHS Code, Part 32, shape a residential sewer excavation. They are written for employers and workers, which covers any contractor on your property.

06 /Who pays if a buried line is damaged during the dig?

Generally the party doing the excavation. Airdrie's locates page says damage to buried utilities is the excavating party's responsibility, as checked September 2026. That is why the contract should name the excavating party and confirm that party requested the locates, holds the ticket and carries insurance for the work.

If you are doing some digging yourself, you may be that party. The homeowner DIY guide covers what that means for permits, trench safety and the city connection.

07 /What should a contractor show you before digging?

Ask to see these before the excavator starts. A professional crew will have them ready.

• The USP locate ticket number, date and expiry, and photos of the marks.
• The private locate result for the sewer lateral and water service, with depth estimates.
• The plumbing permit number and, where applicable, the city approval for the connection (for example Red Deer Engineering Services or the Okotoks CAO).
• The trench protection plan: cut-back slopes or a trench box, and where spoil will sit at least 1 m from the edge.
• Where hand or hydrovac exposure will happen at each marked crossing.
• Who to call and what to do if a line is struck.

The Alberta City Sewer Rules Finder lists each municipality's approval body alongside the Alberta-wide locate and trench rules. The cost factors guide explains how those rules show up in a price. When your plan is ready, send it through the request form.

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