HighThe hydro excavator water lance delivers water at pressures ranging from 2,000 to 5,000 PSI (140-350 bar), which is sufficient to penetrate human skin, muscle, and underlying tissues in milliseconds. Injection injuries occur when the high-pressure water stream contacts any part of the body, most commonly hands and fingers when operators handle the lance nozzle or when the lance kicks back unexpectedly. At these pressures, water can penetrate skin through even small openings such as existing cuts or between fingers, injecting deeply into tissue planes. The water carries soil particles, bacteria, and other contaminants into the wound, creating massive contamination in addition to tissue destruction. The injury mechanism involves both mechanical tearing of tissues from the pressure and hydraulic dissection where water forces apart tissue planes. Externally, the injury may appear as a small puncture wound that seems minor, but internal damage extends far beyond what is visible. Affected tissues swell rapidly as water and contaminants spread through fascial planes. Without immediate surgical debridement (within 2-6 hours), infection becomes inevitable, leading to necrosis (tissue death), compartment syndrome (pressure buildup that cuts off blood supply), and often requiring amputation of affected digits or limbs. Delayed presentation for medical treatment significantly worsens outcomes. Risk increases when operating in awkward positions, when fatigued, when the lance unexpectedly encounters hard objects causing kickback, or when wearing gloves that reduce tactile sensitivity and dexterity.
HighTrailer-mounted hydro excavators incorporate extensive hydraulic systems powering the vacuum blower, water pump, and control mechanisms, with hydraulic pressures typically ranging from 2,000-4,000 PSI. Hydraulic hoses conveying this high-pressure fluid are subject to fatigue from pressure cycling, abrasion from contact with rough surfaces, UV degradation from sunlight exposure, and mechanical damage from being driven over or struck by equipment. When a hydraulic hose fails under pressure, the sudden release of stored energy causes the hose to whip violently in unpredictable directions at high speed. The whipping hose can strike workers causing severe lacerations from the hose end fittings (which are steel and extremely heavy), fractures from impact force, or fatal head injuries if the hose strikes the head or neck. Additionally, the escaping hydraulic fluid sprays at high pressure, creating injection injury risks similar to high-pressure water, with hydraulic oil penetrating skin and underlying tissues. Hydraulic fluid injection injuries are particularly dangerous as the oil is not sterile and causes severe inflammatory reactions and tissue necrosis. The whipping hose can also rupture fuel lines, damage electrical systems, or strike other hydraulic or water hoses, creating cascading failures. Risk increases as hoses age and accumulate fatigue cycles, when hoses are routed across sharp edges or pinch points, or when equipment is operated beyond design specifications.
HighDespite the non-destructive nature of hydro excavation, utility strikes can still occur when service location information is inaccurate, when operators deviate from marked service positions, when unmarked or abandoned services are present, or when water pressure exceeds safe levels for exposed services. High-pressure water can damage protective coatings on pipes and cables, progressively degrade insulation on electrical cables with repeated exposure, or dislodge connections on gas or water services. Striking a high-voltage electrical cable with the metal water lance creates a direct path for electricity to flow through the lance to the operator, causing electrocution. Even if the lance is non-conductive, water is an excellent conductor and can complete the electrical circuit. Contact with high-pressure gas mains can rupture the pipe, releasing flammable gas that may ignite explosively. Telecommunications cable damage disrupts essential services including emergency communications. Water main strikes flood excavations and adjacent properties, undermine pavement, and can wash away excavation support. Additionally, some underground services (particularly older electrical conduits or cable joints) may be at depths different from those shown on plans, creating unexpected encounters. The risk increases when working in congested utility corridors where multiple services are present in close proximity, when service plans are outdated or inaccurate, or when working rapidly without careful progressive exposure and verification.
MediumTrailer-mounted hydro excavators become inherently unstable during operation as water is consumed from storage tanks (shifting the center of gravity as weight decreases) while excavated spoil accumulates in the debris tank (adding weight at a different location on the trailer). Additionally, the trailer must be positioned on various ground surfaces ranging from stable pavement to soft soil, gravel shoulders, or sloped terrain. If the trailer is not adequately supported on outriggers or stands, or if outriggers are deployed on soft ground that settles under load, the trailer can shift, lean, or in extreme cases, tip over. Equipment movement during operation can cause the water lance or vacuum hose to shift position in the excavation, potentially contacting underground services. A tipping trailer can pin workers underneath, sever hydraulic or water lines causing secondary hazards, or if the debris tank ruptures, release hundreds of litres of contaminated slurry. The vacuum hose running from the excavation to the trailer creates a tether that can pull on the trailer if the hose becomes snagged or if workers apply excessive force. Operating on sloped surfaces without proper blocking exacerbates instability. The tow vehicle connection point becomes a pivot point if the trailer settles unevenly.
MediumOperating trailer-mounted hydro excavators requires extensive manual handling of heavy equipment including vacuum hoses (100-150mm diameter, typically 6-10 metres long, weighing 40-80 kg when empty and significantly more when filled with spoil), water lances and high-pressure hoses, outrigger components, and hose reels. Workers must lift, carry, drag, and position these items multiple times per excavation location. The vacuum hose in particular presents significant manual handling risk as it is bulky, inflexible, and becomes progressively heavier as spoil accumulates inside. Workers often adopt awkward postures when positioning the hose into excavations, extending over trench edges, or maneuvering in confined spaces. Repetitive bending, twisting, and reaching while handling heavy loads causes acute back injuries including muscle strains, ligament sprains, and disc herniations. Shoulder and neck injuries occur from lifting hoses overhead or supporting them in elevated positions. Chronic musculoskeletal disorders develop from cumulative exposure to these tasks over time. The risk increases in hot weather when workers fatigue more rapidly, when working alone without assistance, when hoses become clogged with debris increasing weight, or when working on uneven ground that requires awkward postures to maintain balance.
