Glossary
Hydrovac & Vacuum Truck Glossary
Clear definitions of the hydro excavation and vacuum truck terms you will run into when renting equipment or planning a job.
- 811
- 811 is the free North American call-before-you-dig phone number that notifies utility owners to mark buried lines before excavation; contacting 811 is a legally required first step before digging, including hydro excavation.
- Air Excavation
- Air excavation is a form of vacuum excavation that uses a compressed-air lance instead of water to break up soil, keeping spoils dry so they can be backfilled and avoiding the slurry produced by hydro excavation.
- Boom
- The boom is the movable arm on a hydrovac or vacuum truck that positions and supports the large vacuum hose over the dig site, letting operators reach into excavations and rotate the suction tube precisely.
- Call Before You Dig
- Call before you dig is the safety practice of notifying utility locators (via 811 in the US) before any excavation so buried lines are marked, preventing dangerous and costly utility strikes.
- Catch Basin
- A catch basin is a curbside or in-ground stormwater inlet with a sediment sump that traps debris before runoff enters the sewer; vacuum and combo trucks clean out the accumulated sludge and spoils.
- CFM (Cubic Feet per Minute)
- CFM (cubic feet per minute) measures the airflow a vacuum truck's blower moves, indicating how strongly and how far it can suction slurry, sludge, or debris; higher CFM generally means faster material pickup and longer hose reach.
- Combination (Combo) Truck
- A combination (combo) truck is a vacuum truck that pairs a high-pressure water jetting system with a powerful vacuum, used mainly to clean and clear sewers, catch basins, and wet wells and to recover the debris.
- Cyclone Separator
- A cyclone separator is a filtration component on many vacuum trucks that spins incoming air to fling out solids and moisture before they reach the blower, protecting the pump and improving suction efficiency.
- Daylighting
- Daylighting is the practice of digging until buried utilities or structures are exposed to open air (daylight), typically with hydro excavation so pipes and cables are uncovered without being struck or damaged.
- Debris Body
- The debris body is the sealed onboard tank of a vacuum or hydrovac truck that collects the spoils, slurry, sludge, or liquid removed during vacuum excavation or cleaning, holding it until offloading.
- Dig Tube / Wand
- The dig tube is the large vacuum hose that suctions slurry into the debris body, while the wand is the handheld high-pressure water lance the operator uses to cut soil; together they perform hydro excavation.
- Frost / Frozen Ground Digging
- Frost or frozen ground digging is hydro excavation in cold conditions using heated high-pressure water to thaw and cut frozen soil, letting crews dig safely through frost that would stop mechanical equipment.
- GPM (Gallons per Minute)
- GPM (gallons per minute) measures the water flow of a hydrovac's pressure system; combined with PSI it determines how effectively the wand cuts soil during hydro excavation.
- Hydro Excavation
- Hydro excavation is a non-destructive digging method that uses pressurized water to break up soil and a powerful vacuum to remove the resulting slurry, safely exposing buried utilities and creating precise excavations.
- Hydrovac
- Hydrovac is short for hydro excavation, a digging method (and the truck or trailer that performs it) that uses pressurized water to loosen soil and a vacuum to remove it, exposing utilities without damage.
- Hydrovac Trailer
- A hydrovac trailer is a trailer-mounted hydro excavation unit that provides pressurized water and vacuum digging capability, offering a more compact and towable alternative to a full hydrovac truck.
- Hydrovac Truck
- A hydrovac truck is a vacuum truck equipped with a high-pressure water system and boom that performs hydro excavation, breaking soil with water and vacuuming the slurry into an onboard debris tank.
- Non-Destructive Digging
- Non-destructive digging (NDD) is any excavation method that exposes buried utilities without mechanical cutting tools, most commonly hydro or air vacuum excavation, greatly reducing the risk of line strikes.
- Offloading
- Offloading is emptying a vacuum or hydrovac truck's debris body at an approved disposal or dewatering site; it interrupts digging when the tank fills, so debris capacity affects how much work is done per cycle.
- Pipeline Exposure
- Pipeline exposure is using hydro excavation to safely uncover a buried pipeline for inspection, repair, tie-in, or integrity assessment without damaging the coating or the pipe itself.
- Positive Displacement (PD) Blower
- A positive displacement (PD) blower is a high-vacuum air pump used on vacuum and hydrovac trucks that produces strong lift for deep digging and long hose runs, moving air by trapping and displacing fixed volumes.
- Potholing
- Potholing is digging a small, precise test hole to expose and verify the location and depth of an underground utility, commonly performed with hydro excavation to avoid damaging the line.
- PSI (Pounds per Square Inch)
- PSI (pounds per square inch) measures the water pressure a hydrovac produces; higher PSI concentrates the cutting force of the wand, letting it break hard, compacted, or frozen soil during hydro excavation.
- Sewer Jetting
- Sewer jetting is using high-pressure water through a hose and nozzle to blast away grease, roots, and debris inside sewer and storm lines; combination trucks jet the line and vacuum the loosened material back out.
- Slot Trenching
- Slot trenching is digging a narrow, precise trench with hydro excavation, commonly used to install conduit, expose long runs of utility, or create clean utility corridors with minimal surface disruption.
- Sludge
- Sludge is the thick, semi-solid mixture of solids and liquid removed from sewers, wet wells, catch basins, tanks, and industrial processes; vacuum and combo trucks suction it into the debris body for disposal.
- Slurry
- Slurry is the fluid mixture of water and excavated soil produced during hydro excavation; the vacuum draws this slurry from the dig site into the truck's debris body for transport and disposal.
- Spoils
- Spoils are the soil, mud, and debris excavated from a dig site; in hydro excavation the spoils mix with water to form a slurry that is vacuumed into the truck's debris body for disposal.
- Tremie Tube
- A tremie tube is a pipe lowered into an excavation or borehole to place backfill, grout, or concrete from the bottom up, ensuring even fill without voids after hydro excavation or utility work.
- Utility Locating
- Utility locating is the process of detecting and marking the position of buried utilities using electromagnetic and ground-penetrating tools, then verifying them physically by potholing or daylighting with hydro excavation.
- Vacuum Excavation
- Vacuum excavation is non-destructive digging that removes loosened soil with a powerful vacuum, using either high-pressure water (hydro excavation) or compressed air (air excavation) to break up the ground first.
- Vacuum Truck
- A vacuum truck is a tank-mounted truck that uses a powerful blower to suction liquids, sludge, slurry, or dry material into an onboard tank for transport and disposal, with or without high-pressure water cutting.
- Water Recycling System
- A water recycling system filters and reuses recovered water on a hydrovac or combination truck, extending runtime between refills by turning captured slurry or jetting water back into usable supply.
- Water Table
- The water table is the underground level below which the soil is saturated with groundwater; digging below it fills excavations with water and can produce thinner slurry and extra offloading during hydro excavation.
- Wet Well
- A wet well is the underground chamber in a pump or lift station that collects wastewater or stormwater before it is pumped onward; vacuum and combo trucks pump out accumulated sludge and grit for maintenance.
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