Hydro excavation is a non-destructive digging method that uses pressurized water to break up soil and an industrial vacuum to pull the slurry into a sealed debris tank. Because only water touches the ground, it exposes buried gas, water, electric, and fiber lines without the strike risk of a backhoe bucket or auger. Based in North Salt Lake, Delta Hydro Excavation provides hydro excavation, potholing, daylighting, and slot trenching for contractors, municipalities, utilities, and engineers across Salt Lake, Davis, Utah, Summit, and Washington Counties. Every truck in the fleet carries 12 yards of debris capacity and digs at 3,000–4,000 PSI, operated by CDL holders with OSHA 30-trained supervisors and confined-space-trained crews. Delta is a UDOT Masterworks registered vendor.
What Is Hydro Excavation?
Hydro excavation, also called hydrovac, vacuum excavation, or soft digging, replaces the mechanical force of a bucket or auger with water and suction. The operator controls exactly where soil is removed, so the hole is only as wide and deep as the job needs. Three terms describe its most common uses:
- Potholing: a small test hole over a marked utility to confirm its exact depth, position, size, and material.
- Daylighting: exposing a longer run of a utility so crews can work around it or tie into it.
- Slot trenching: a narrow trench for conduit, pipe, or cable through ground crowded with existing lines.
How Does Hydro Excavation Work?
Three things happen at once on a hydrovac truck:
- Water cuts the soil. An operator directs a handheld wand that delivers water at 3,000–4,000 PSI. The jet liquefies soil into slurry. Near a utility, the operator keeps the nozzle moving and never holds the stream on the line itself.
- Vacuum lifts the slurry. A boom-mounted dig tube sits beside the wand and pulls water, soil, and small rock out of the hole as fast as it is cut.
- The tank contains the spoil. Slurry travels into a sealed 12-yard debris tank on the truck. Nothing is stockpiled on the ground.
The result is a clean-walled hole with the utility visible and intact, and a job site with no spoil pile to manage.
When Should You Use Hydro Excavation Instead of Mechanical Digging?
Use hydro excavation whenever the cost of hitting something outweighs the cost of digging slower:
- Any digging inside the 24-inch tolerance zone of a marked utility
- Potholing utility crossings before horizontal directional drilling or boring
- Verifying utility locations for subsurface utility engineering (Quality Level A)
- Slot trenching through congested utility corridors
- Sites an excavator cannot reach, such as alleys, backyards, building interiors, and plant floors
- Frozen ground, where mechanical frost breaking sends shock into nearby lines
- Pole, sign, pier, and bollard holes near existing utilities
- Exposing pipe for repairs, taps, tie-ins, and pipeline integrity digs
- Cleaning out valve boxes, vaults, and catch basins
Hydro excavation is not the right tool for mass excavation in open ground with no utilities. An excavator moves bulk dirt faster and cheaper. Most projects use both: hydrovac to find and expose what is buried, mechanical equipment for everything outside the tolerance zone.
What Equipment Is Used for Hydro Excavation?
A hydrovac truck carries the whole operation on one chassis.
| Component | What it does |
|---|---|
| Water tank and pump | Supplies clean water at 3,000–4,000 PSI |
| Dig wand and nozzle | Lets the operator aim and control the cutting stream |
| Vacuum system | Generates the airflow that lifts slurry out of the hole |
| Boom and dig tube | Positions the suction hose over the excavation |
| Debris tank | Holds 12 yards of slurry in a sealed body |
| Remote hose | Extends the dig point away from where the truck can park |
Every truck in Delta's fleet carries the same 12-yard capacity, so the equipment on your job does not depend on which truck is dispatched. Full specifications are on the Equipment page.
What Industries Use Hydro Excavation?
- Municipalities and public works: water and sewer repairs, valve and meter exposure, catch basin cleaning
- General contractors: potholing before foundations, trenching, and site utilities
- Utility companies: daylighting gas, electric, water, and telecom lines for repair and new service
- Civil engineers: test holes that turn approximate locates into surveyed positions
- Property managers: digging on occupied sites without tearing up landscaping or parking
- Pipeline operators: integrity digs and line exposure
What Does Hydro Excavation Look Like on a Job Site?
- Locate ticket. Hydro excavation is still excavation under Utah law, so a Blue Stakes of Utah 811 ticket is filed and the marks are in place before the truck arrives.
- Site walk and setup. The crew confirms the marks against the plans, sets traffic control if the work is in or near a roadway, and positions the truck.
- Cut and vacuum. The operator cuts with the wand while the dig tube removes slurry, working down until the utility is visible.
- Verify and document. Depth to top of pipe, size, material, and condition are measured and photographed. The location is marked for your surveyor or driller.
- Protect or restore. The hole is plated or barricaded for your crew, or backfilled to the specification in your permit.
- Haul off. Slurry leaves in the sealed tank for disposal at an approved site. It is never released to a storm drain.
A single pothole in workable soil often takes less than an hour. Crossings, deep utilities, cobble, and frozen ground take longer.
What Are the Safety Advantages of Hydro Excavation?
- Fewer utility strikes. Water moves soil away from a gas line or fiber conduit without the force that cuts or crushes it.
- Less trench entry. The operator works from the surface, which reduces the time anyone spends inside an excavation.
- Smaller openings. A pothole is far smaller than a backhoe pit, which means less traffic exposure and shorter lane closures.
- Contained spoil. No stockpiles, less dust, and no mud tracked onto the road.
- Trained crews. Delta's supervisors are OSHA 30 trained, crews are confined space trained, and operators hold commercial driver's licenses.
Utah-Specific Considerations
Blue Stakes and the 24-inch tolerance zone
Utah Code Title 54, Chapter 8a requires excavators to notify Blue Stakes of Utah 811 at least 48 business-day hours before digging. Once facilities are marked, the tolerance zone extends 24 inches on either side of the mark. Inside that zone, digging must be done with hand tools or methods designed to avoid damage. Blue Stakes names vacuum excavation as one of those methods, which makes hydrovac the practical way to work a tolerance zone at production speed.
Frost depth and winter digging
Salt Lake Valley jurisdictions use a design frost depth of 30 inches, and the figure increases with elevation in Summit County and other mountain jurisdictions. The St. George area is far shallower. This matters for two reasons. Water lines and footings are buried below frost depth, so a pothole for a water main goes deeper than one for a gas service or telecom line. And many dry utilities sit above the frost line, which means in January they are locked inside frozen ground. Breaking that frost with a hammer or ripper puts shock directly into the lines you are trying to protect. Water cuts frozen soil without that impact.
Soil conditions
Much of the Wasatch Front sits on sediments left by ancient Lake Bonneville. Valley floors are fine silt and clay, often with shallow groundwater. Clay cuts slower and makes heavy slurry, and groundwater adds volume, so trucks fill faster. The benches along the mountain front are sand, gravel, and cobble. These cut quickly, but walls can slough and cobbles larger than the dig tube have to be lifted out by hand. Washington County adds expansive clays and collapsible soils that react to water, so share your geotechnical report with the crew before work starts there.
UDOT right-of-way requirements
Any digging in a state highway right-of-way requires a UDOT encroachment permit under Utah Administrative Code R930-6 and R930-7. Each application must include a traffic control plan that conforms to the Utah MUTCD. Work cannot start until the permit is issued and UDOT authorizes it in writing, and the permit must be activated 24 hours before work begins. Equipment cannot be staged in the right-of-way until traffic control is in place, and restoration must meet UDOT's standard specifications. Delta Hydro Excavation is a UDOT Masterworks registered vendor.
Hydro Excavation FAQ
Is hydro excavation required near buried utilities in Utah?
Utah law requires hand tools or other non-damaging methods within 24 inches of a marked utility. Hydro excavation is not the only method allowed, but it is the one that meets the requirement at production speed. Many project owners specify it for work near gas, fiber, and high-voltage lines.
Do I still need a Blue Stakes ticket for hydro excavation?
Yes. Hydro excavation displaces soil, so it counts as excavation under Utah Code 54-8a. A Blue Stakes of Utah 811 ticket must be filed at least 48 business-day hours before work, and the marks must be in place before the hydrovac truck starts digging.
What is potholing?
Potholing is using hydro excavation to dig a small test hole directly over a marked utility to confirm its exact depth, position, size, and material. Locate marks show approximate horizontal position only. A pothole gives drillers, designers, and excavator operators a measured location before boring, trenching, or foundation work begins.
How much does hydro excavation cost in Utah?
Hydro excavation typically runs $200–$500 per hour in Utah, compared with $80–$180 per hour for a mechanical excavator. Most jobs carry a minimum mobilization charge. For work near utilities, total cost is often lower with hydrovac because it avoids strike repairs, shutdowns, and larger restoration areas.
Can hydro excavation be done in frozen ground?
Yes. Pressurized water cuts frozen soil without the impact of hammers or rippers, which makes hydro excavation the preferred winter method near buried utilities. Frozen ground takes longer to cut than thawed soil, so winter potholes should be scheduled with more time per hole.
What happens to the slurry after hydro excavation?
Slurry is vacuumed into the truck's sealed debris tank and hauled to an approved disposal site. It is not left on site or released to storm drains. Because the removed soil leaves as liquid, holes are backfilled with imported material that meets the project or permit specification.
How much material can one truck remove before dumping?
Every Delta Hydro Excavation truck has a 12-yard debris tank. That is enough for a full day of typical potholing or a substantial slot trench without leaving the site to dump. Clay, shallow groundwater, and large excavations fill the tank faster.
What is required to hydro excavate in a UDOT right-of-way?
Work in a state highway right-of-way needs a UDOT encroachment permit with an approved traffic control plan. The permit must be activated 24 hours before work starts, traffic control must be set before equipment is staged, and the site must be restored to UDOT specifications.
To schedule hydro excavation or request a quote, call (801) 435-3203 ext. 1501.