Hydro-excavation - also called soft-dig, vacuum excavation, or hydrovac - is the non-destructive way to move dirt around utilities. High-pressure water breaks up soil, an industrial vacuum lifts the slurry into a debris tank, and the utility underneath is exposed without a scratch. In Austin's rock-shot clay and around the fiber, gas, and water mains that lattice every commercial site, it's often the only responsible way to dig. This guide walks through how the process actually works, when to spec it, and what to look for in a contractor.
How a vac truck actually works
A hydro-excavation truck has three working systems: a high-pressure water pump (typically 8–12 GPM at 2,000–4,000 PSI), a large-capacity blower generating 18–27 inches of mercury vacuum, and a debris tank sized between 8 and 16 cubic yards. The operator directs a hand-held wand that fractures soil with a fan-tip water jet while a co-located suction hose evacuates the slurry in real time. The tank collects everything; nothing is discharged on site. When the tank is full, the truck moves to an approved dump site and offloads.
Water vs. air excavation
Air-vacuum excavation exists - it uses compressed air instead of water - and has niche uses in cold-weather regions or around delicate landscaping. In Central Texas, water is almost always the better tool: our clay and caliche soils cut faster with water, and freezing isn't a real concern. Every job we run is hydro unless a spec explicitly calls for air.
Where hydro-excavation is the right call
- Daylighting a utility before boring, trenching, or setting a pole
- Potholing to verify depth and alignment of gas, water, fiber, or electric
- Exposing existing lines for tie-ins on commercial site work
- Slot trenching for irrigation, low-voltage, or landscape lighting
- Cleaning out valve boxes, meter pits, and manhole channels
- Excavating around tree roots without severing them
- Any dig inside the OSHA 24-inch tolerance zone of a known utility
Why it wins in Austin-area soil
Central Texas geology is unfriendly to mechanical excavation. The Blackland Prairie clay east of I-35 swells and cracks; the Edwards limestone west of it eats teeth off a backhoe bucket. Hydro cuts through both. On a fiber daylighting job in Cedar Park last year, a mechanical crew had spent half a day pecking at limestone before switching approaches - the vac truck exposed the target line in 40 minutes with zero damage to the adjacent gas main.
Cost model: what you're actually paying for
Hydro-excavation is billed by the hour, not the hole. Expect $250–$400/hr in the Austin market with a 4-hour minimum, plus dump fees for spoil disposal. That covers the truck, a two-person crew, water, fuel, and PPE. It does not cover permits, traffic control, or after-hours premiums. Compared to a mechanical dig it looks expensive on paper - until you price in a single utility strike, which averages north of $56,000 in direct costs before litigation.
What drives the hour count up
- Depth beyond 6 feet - every additional foot slows extraction
- Rock or heavily compacted caliche - cutting speed drops
- Restricted access - long hose runs cost suction efficiency
- Wet or saturated soil - tank fills faster with water than solids
- Distance to an approved dump site - offload cycles add up
Speccing a hydro-excavation job correctly
A clean scope of work saves everyone money. Include: (1) the exact locations and count of potholes, with station or GPS references; (2) target depth and expected utility type at each; (3) hole dimensions required by the receiving contractor (a boring crew typically wants a 24"x24" window); (4) whether backfill and compaction are in scope or handled by others; (5) site access hours and any traffic-control needs. Give the vac crew this in writing before mobilization and the job runs on rails.
What to look for in a hydrovac contractor
- Owner-operated or long-tenured crews - vac work rewards experience, not turnover
- Truck capacity matched to the job - a 12-yard tank on a small pothole job just means fewer dump runs
- Clear billing terms, including how travel and dump fees are handled
- Proof of insurance including underground utility damage coverage
- Willingness to coordinate with your 811 locate and any private locator on site
- Same-day scheduling capability for daylighting emergencies
Common misconceptions
"Hydro-excavation is only for utilities." It's the primary use, but crews also handle debris removal from wet wells, cleanouts on lift stations, and even landscape-sensitive tree work. "It's overkill for shallow work." Shallow work is where strikes happen - irrigation, low-voltage, and landscape lighting all live in the top 18 inches. "Any excavator can do it." A vac truck costs $400k+ and requires specific training; general excavation contractors sub it out for a reason.
Bottom line
If you're digging within arm's reach of a utility, on a commercial site, or in Central Texas rock, hydro-excavation isn't a luxury - it's the responsible default. Get a quote for your next potholing or daylighting job at (737) 618-0219 or through our online form, and we'll come out with the right truck for the scope.
Frequently asked questions about hydro-excavation
- How deep can hydro-excavation dig?
- Practically, our trucks pothole efficiently to about 15 feet. Beyond that, extraction slows as hose friction drops suction, and cost per foot climbs. For 15–30 foot work we bring extended boom equipment; below 30 feet, mechanical shafting is usually the better call.
- Is hydro-excavation safe around fiber and gas lines?
- Yes - that's exactly what it's designed for. A fan-tip water jet at the right pressure erodes soil without cutting cable jackets or pipe coatings. The Common Ground Alliance and every major utility owner recommend vacuum excavation as the preferred method inside the 24-inch tolerance zone around any known utility.
- Do I still need to call 811 before hydro-excavation?
- Always. 811 is a legal requirement and marks public-side utilities. Hydro-excavation is how you verify those marks and expose private-side utilities that 811 does not cover. The two are complements, not substitutes.
- How much does a typical potholing job cost in Austin?
- For 4–6 potholes at standard depths on an accessible site, plan on $1,500–$2,500 including dump fees. Larger scopes, deeper holes, or rock-heavy sites bill by the hour at $250–$400/hr with a 4-hour minimum.
- Can you dispose of the spoil, or do I need to handle that?
- We haul spoil to a permitted disposal site as part of standard scope. If the site has known contamination - hydrocarbon impact, heavy metals, anything requiring special handling - flag it before mobilization so we route to the correct facility and price accordingly.
- Do you work outside the Austin metro?
- Yes. We regularly run jobs inside a 100-mile radius including San Antonio, Waco, Killeen, and the Hill Country. Travel beyond ~40 miles from Cedar Park is quoted with a mobilization fee.
- How quickly can you get on site for a daylighting emergency?
- For active-site holds where a boring or excavation crew is waiting, we can typically mobilize same-day within the Austin metro if you call by mid-morning. Call (737) 618-0219 directly for anything time-critical rather than using the web form.