What Is Hydrovac Excavation? Applications, Process, and Ontario Requirements

Key Takeaways

• Hydrovac excavation uses high-pressure water to break up soil and an industrial vacuum to remove it into a truck-mounted debris tank. No mechanical equipment contacts the ground.

• It is the standard excavation method for scopes where buried infrastructure is present and mechanical digging would create unacceptable damage risk.

• Applications include slot trenching, curb-stop repair, frozen ground excavation, personnel maintenance access holes, drill fluid removal, and contaminated soil haulage.

• In Ontario, transporting contaminated soil requires Ministry of Environment certification. CC Underground's hydrovac teams hold this certification. Not all contractors do.

• CC Underground's hydrovac units are equipped with high-rail gear for work in railway corridors. Standard hydrovac trucks cannot access rail environments.

• Hydrovac is not suited to every scope. Large-volume bulk earthworks on open sites with no buried utilities are faster and more cost-effective with conventional equipment.

Hydrovac excavation is a non-destructive excavation method that uses high-pressure water to break up and liquefy soil while simultaneously removing it with an industrial vacuum into a truck-mounted debris tank. No mechanical equipment contacts the ground during the process.

That is what makes it the standard method for excavating around buried utilities, tree roots, or sensitive surfaces where conventional equipment carries unacceptable damage risk. It is used across utility installation, municipal infrastructure, environmental remediation, and rail corridor work throughout Ontario.

Understanding what hydrovac is, how the process works, and what to look for in a contractor before work begins is what this guide covers.

How Hydrovac Excavation Works

Two systems operate simultaneously.

A high-pressure water system directs a pressurized stream into the ground, breaking up and liquefying the soil. As the soil turns to slurry, an industrial vacuum draws it up into the debris tank mounted on the hydrovac truck. The excavation footprint is limited to exactly what the scope requires. Adjacent soil structure, tree roots, and buried infrastructure beyond the excavation zone remain undisturbed.

The process is fundamentally different from mechanical excavation. A bucket or blade penetrates the ground with force and without precision. Hydrovac uses no mechanical cutting edges, no impact, and no blind penetration into ground where utilities of unknown depth may be present.

Surface locate marks from Ontario One Call provide horizontal utility position only. They do not confirm depth. That is why hydrovac is the preferred method for excavation near buried services. It removes material precisely without the strike risk that mechanical equipment carries.

CC Underground operates a fleet of hydrovac trucks and flusher trucks. Scopes requiring flushing alongside excavation are handled in house without bringing in additional contractors.

Who Uses Hydrovac Excavation in Ontario

Hydrovac is standard practice across several contractor and municipal disciplines in Ontario.

Utility contractors use it for slot trenching, curb-stop access, and utility daylighting. General contractors use it for drill fluid cleanup on horizontal directional drilling projects and for site preparation in congested corridors where mechanical equipment would cause surface and utility damage. Municipal crews rely on it for maintenance access, frozen ground work, and contaminated material removal where Ministry of Environment requirements around soil haulage apply. Rail infrastructure teams require it for corridor maintenance where standard equipment is excluded by track access restrictions.

Hydrovac Applications:

• Slot Trenching -Hydrovac units excavate clean, narrow trenches for conduit, cable, and pipe installation. The water jet is controlled and directional. Only the soil in the trench line is removed. Surrounding pavement, soil structure, and adjacent utilities are not disturbed. On utility corridor work where multiple buried services exist at varying depths in close proximity, that level of precision is a project requirement, not a preference.

• Curb-Stop Repair - Accessing a curb stop for repair or maintenance requires excavating a small, precisely defined area without disturbing surrounding pavement or adjacent infrastructure. Mechanical equipment cannot reliably achieve this on an active municipal right of way. Hydrovac units expose the curb stop accurately and leave the surrounding area undamaged.

• Frozen Ground Excavation - Hydrovac operations continue through Ontario winters. Units use heated water to break through ice and frozen soil, allowing excavation without waiting for ground thaw. Emergency utility repairs, scheduled municipal maintenance, and infrastructure work do not stop in January. Hydrovac means they do not have to.

• Mechanical equipment in frozen ground is slower, less controllable, and more likely to cause incidental damage to adjacent services. Heated hydrovac is the practical method for Ontario projects that need to proceed regardless of season.

• Personnel Maintenance Access Holes - Creating access points for maintenance crews in confined, congested, or environmentally sensitive locations requires precision that mechanical equipment cannot provide. Hydrovac units excavate exactly where access is needed. There is no overexcavation and no unnecessary ground disturbance.

• Drill Fluid Removal and Spill Cleanup - On horizontal directional drilling projects, bentonite drilling fluid is pumped through the drill string throughout the bore process. If drilling fluid migrates to the surface or a spill occurs on site, hydrovac units vacuum the material directly into the debris tank for containment and disposal. This is standard practice on HDD projects in Ontario. Hydrovac and HDD teams regularly work the same job sites for this reason.

• Contaminated Soil Removal - When excavation involves contaminated material, the slurry must be contained throughout the process. Hydrovac handles this by drawing material directly into the debris tank. It does not sit exposed on the ground at any point during removal. In Ontario, transporting contaminated soil from an excavation site requires Ministry of Environment certification. CC Underground's hydrovac support teams hold this certification. Not all hydrovac contractors operating in Ontario do. On any project where contaminated material is a possibility, confirm this certification with the contractor before mobilization.

• Rail Industry Work - Operating hydrovac equipment in and around active rail corridors requires trucks equipped with high-rail gear. This modification allows the truck to travel directly on railway tracks. Standard hydrovac trucks cannot access rail environments. CC Underground's hydrovac units are equipped with high-rail gear, enabling excavation support in railway corridors where access is restricted to rail-capable equipment only.

Hydrovac vs. Traditional Excavation

On open sites with no buried infrastructure and no surface constraints, mechanical excavation is fast and cost-effective. The comparison changes when buried utilities are present.

Traditional excavation uses buckets, blades, and digger teeth that penetrate the ground with force. Surface locate marks indicate approximate horizontal utility position. They do not confirm depth. Services installed at different periods cross at different levels. Mechanical equipment operating in a congested utility corridor carries real strike risk regardless of what the locates show.

Striking a gas main, water main, or electrical conduit with mechanical equipment causes damage that is expensive to repair, disruptive to surrounding services, and in some circumstances dangerous. Hydrovac removes the mechanical strike risk entirely. For any scope where buried utilities are present, where surface disturbance must be minimized, or where environmental compliance around contaminated material applies, hydrovac is the appropriate method.

When Hydrovac Is Not the Right Method

Large-volume bulk earthworks, site grading, deep basement excavation, and mass soil removal on open sites with no buried infrastructure do not benefit from hydrovac precision. These scopes are faster and more cost-effective with conventional mechanical equipment. Specifying hydrovac where it is not required adds cost without adding value.

Hydrovac is the right method when precision around buried utilities, non-mechanical contact with sensitive surfaces, Ministry of Environment compliance around contaminated material, frozen ground operability, or access to rail-restricted environments are genuine requirements of the scope.

What to Confirm Before Putting a Hydrovac Contractor on Site

Most guides on hydrovac stop at explaining what it is. For Ontario projects, here is what to confirm before work begins.

Ministry of Environment certification for contaminated soil haulage. If there is any possibility of contaminated material on the project, confirm this certification before mobilization. It is a provincial regulatory requirement and not universally held.

High-rail capability. If the scope is in or adjacent to a rail corridor, confirm the contractor's equipment is high-rail equipped. Standard hydrovac trucks cannot access railway environments regardless of operator experience.

Heated water systems for frozen ground. Not all hydrovac units are set up for winter operation. On Ontario projects scheduled through winter months, confirm the unit has a heated water system before ground conditions make it urgent.

In-house flusher truck availability. On combined scopes requiring flushing alongside excavation, confirm whether the contractor has flusher trucks in their fleet or will need to subcontract. In-house capability simplifies scheduling and accountability on the project.

Talk to CC Underground About Your Hydrovac Requirements

CC Underground has been providing hydrovac excavating services across Ontario for over 37 years. Ministry of Environment certified for contaminated soil haulage. High-rail equipped for railway corridor work.

Serving Barrie, Orillia, Simcoe County, Muskoka, Collingwood, and surrounding Ontario regions.

Call (705) 327-2751 or visit ccunderground.ca to request a quote.

Frequently Asked Questions

Q1. What is hydrovac excavation?

Hydrovac excavation uses high-pressure water to break up soil and an industrial vacuum to remove it into a debris tank on the truck. No mechanical equipment contacts the ground, which makes it safe to use around buried utilities, tree roots, and sensitive surfaces.

Q2. What is the difference between hydrovac and traditional excavation?

Hydrovac uses water and vacuum only with no mechanical ground contact. Traditional excavation uses metal equipment that can strike buried utilities. On sites with existing underground services, that difference matters.

Q3. Can hydrovac be used in frozen ground in Ontario?

Yes. Hydrovac units use heated water to break through frozen soil and ice. Work continues through Ontario winters without waiting for ground thaw.

Q4. What is slot trenching?

Slot trenching is excavating a narrow, precise trench for conduit, cable, or pipe using a hydrovac unit. Only the trench line is disturbed. Surrounding pavement and buried services remain intact.

Q5. Is Ministry of Environment certification required for contaminated soil haulage in Ontario?

Yes, it is a provincial regulatory requirement. CC Underground's hydrovac teams hold this certification. Confirm it with any contractor before contaminated material work begins.

Q6. What is high-rail gear?

High-rail gear allows a hydrovac truck to travel on railway tracks. Without it, the truck cannot access active rail corridors. CC Underground's hydrovac units are high-rail equipped.

Q7. What is drill fluid removal?

When bentonite drilling fluid surfaces or spills on an HDD project, hydrovac units vacuum it directly into the debris tank. This contains the material on site and supports environmental compliance.

Q8. When is hydrovac not the right method?

When there are no buried utilities to protect and the scope is large-volume bulk earthworks. Conventional excavation is faster and cheaper on open sites with no surface or utility constraints.