Underground Utility Trenching & Hydrovac

Underground Utility Trenching, Hydrovac Daylighting & Septic Excavation

Everything a property depends on underground, from the water service and sewer to gas, power, fibre and an acreage septic system, arrives through a trench. We dig those trenches around Calgary to the depth each line needs, expose existing utilities by hand or hydrovac before a machine gets near them, and backfill so nothing settles or freezes later.

A steel trench box holds the walls of a narrow service trench, with a blue water pipe on a sand bed at the bottom.

What This Work Covers

This family of work splits by what goes in the ground and how deep it sits. Deep utility trenching carries water, sanitary and storm service lines, which in Calgary need at least 2.7 m (9 ft) of cover in clay and 3.3 m (11 ft) in gravel for water, 2.5 m for sanitary mains and 1.2 m for storm mains. Those depths bring trench boxes, dewatering, bedded pipe and tested backfill, plus a City connection in the right-of-way that must be installed by a utility indemnified contractor. Shallow utility trenching carries gas lines, electrical conduit, fibre and power feeds to garages, shops and backyard suites, at depths set by the utility and the installer who holds the permit.

Hydrovac daylighting is the non-destructive side of the category. Pressurized water loosens soil and a truck-mounted vacuum lifts it away, so a buried line can be uncovered and measured without a bucket touching it. It is how existing utilities are exposed inside the hand-expose zone, 1 m either side of the locate marks and 5 m for high-pressure pipelines, before either kind of trench crosses them. It also cuts slot trenches along proposed routes, digs test holes for piles and posts, keeps working in frozen ground, and sends its slurry to an approved waste facility.

Septic system and field excavation serves acreages that are not on piped sewer. Under the Alberta Private Sewage Systems Standard of Practice 2021, a certified installer designs the system and obtains the county permit, and we dig the soil test pits, tank holes, treatment field trenches and mound bases to that design. The four services share a discipline: locate first, expose what is buried, dig no deeper or wider than the job needs, protect anyone in the hole, and put the ground back in lifts that stay put. What changes is the depth, the regulator and the trade who installs what goes in the trench.

Trenching & Hydrovac Services

Inside a steel trench box, a green PVC sewer pipe rests on a bed of sand at the bottom of a deep trench.

Deep Utility Trenching (Water, Sewer & Storm)

Shored, bedded trenches for water, sanitary and storm service lines.

How it works

A narrow shallow trench runs across a backyard lawn from a house to a detached garage, with grey electrical conduit laid in the bottom.

Shallow Utility Trenching

Narrow trenches for gas, electrical conduit, fibre and suite power feeds.

How it works

A hydrovac hose reaches into a small neat hole in a boulevard while a worker in high-visibility coveralls loosens the soil with a water wand.

Hydrovac & Non-Destructive Daylighting

Non-destructive digging to expose buried lines before any machine gets close.

How it works

An excavator lowers a precast concrete septic tank on chains into a pit with sloped walls and a gravel floor on a foothills acreage.

Septic System & Field Excavation

Test pits, tank holes and treatment field trenches for acreage septic systems.

How it works

Choosing Between Them

Water, sewer or storm line: Choose deep utility trenching for planned service replacement or a new service connection. Calgary cover depths put these trenches well past the 1.5 m point where protection is required for workers in them, and they can go past 3 m, where protective structures must be engineer-designed. If the line is leaking or backing up right now, use emergency dig-outs instead.
Gas, power, fibre or a suite feed: Choose shallow utility trenching when an electrician, gas fitter or provider needs a narrow trench to a garage, shop, backyard suite or acreage building. Depth and bedding come from the installer, and every existing line crossed on the way is exposed first.
Finding or protecting what is already buried: Choose hydrovac daylighting when lines have to be seen before digging near them, when frozen clay makes hand exposure impractical, or when a small hole matters because of pavement, landscaping or a crowded sidewalk. It is often booked alongside one of the trenching services rather than instead of it.
An acreage with no sewer main: Choose septic system and field excavation when a parcel needs a new or replacement private sewage system. Hire the certified installer first; the design and the county permit come before the excavator. Parcels on communal piped wastewater need a service trench instead.

Why It Matters Around Calgary

Calgary’s climate is the reason these trenches are deep. The City reported frost reaching 2.4 m (8 ft) in the extreme winter of 2019, and its normal frost depth has been described as around 2 m, so water services are buried deeper than most people expect and backfill that goes in frozen, or too thick to compact, shows up as settlement in spring. Clay can stand well in a fresh cut and then fail without warning, which is why no one works in a deep trench without cut-back walls or a trench box. In Chestermere, the City of Chestermere also vets the excavation contractor through its Quick Trench programme, which begins automatically with a building permit application, so owners there should confirm a contractor’s standing with the City.

Beyond the city limits, the authority changes with the parcel. Acreages in Rocky View County’s Springbank and Bearspaw areas have historically relied on wells and septic fields, and their private lines, tanks and tile beds are invisible to the utility locate. Foothills County issues its own permits and inspects private sewage installations before backfill is complete, while Heritage Pointe, in the same county, is served by communal piped water and wastewater and needs service trenching rather than septic work. The digging methods do not change from one municipality to the next; the permit office, the inspector and the connection rules do.

Trenching & Hydrovac: Common Questions

Which underground utility jobs need a professional engineer involved?

Several, depending on depth and surroundings. Under Alberta’s OHS Code, temporary protective structures in excavations deeper than 3 m must be designed to a professional engineer’s specifications, and a building foundation that a trench may affect must be supported by an engineer-designed structure before digging begins. An engineer can also certify that ground is and will remain stable. Separately, the City of Calgary requires approved insulation where a water service cannot get its full cover depth, which is a design decision rather than a field call. Septic systems are designed by a certified installer.

Who is responsible for which part of the buried services on my property?

Utilities locate and maintain their own lines, and marking those is at no charge through Utility Safety Partners. Lines you or a previous owner installed, such as power to a garage, yard gas lines, irrigation, and water and sewer past the property-line shut-off valve, are yours and are not located by the utility. In Calgary, the owner is responsible for the service from the property line to the building plumbing, while connections in the City right-of-way are installed by a utility indemnified contractor.

Can hydrovac and trenching be booked as one job?

Often they should be. The usual sequence is locates first, hydrovac to expose each crossing inside its hand-expose zone, then the trench dug by machine with the crossings visible. Locates may be valid for up to 30 calendar days, or as stated on the locate report, so exposure, trenching, pipe or conduit installation, inspection and backfill are scheduled to finish inside that window where possible, and a locate refresh is requested if the job runs past it.

Other Excavation Services

Site Prep & Earthmoving

Foundations & Basements

Demolition & Removal

Drainage & Erosion Control

Commercial & Specialized

Talk to Us About Trenching & Hydrovac

Tell us about the site, what is there now and what is going in. We will recommend the scope that fits, including when a smaller job will do.

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