Dangerous Business: Safe Hydroexcavation Requires An Understanding And Respect For All The Potential Risks

From: Cleaner Magazine
Written By: Doug Day

Gary Toothe has seen enough injuries and deaths in his years to realize that hydroexcavation involves much more than a water hose and vacuum. “There’s a huge void in training,” says the training manager for Federal Signal’s Environmental Products Group, who also spent decades in private business dealing with such equipment.

The most common mistake, he says, is sending an operator out alone. If something goes wrong, yelling for help is the only option. “There’s not much else you can do.”

Trenching and excavation violations are another common safety mistake, according to Toothe. “If you’re going more than 4 feet down, you’re covered by the OSHA standards,” he says. “You have to worry about benching or sloping, and you need shoring or a shield system if someone is getting into the hole.”

OSHA requires that a competent person be on site during such excavation, someone who knows how to classify soils and knows the requirements. “If there were a competent person on site, a lot of situations wouldn’t develop because people would know better,” Toothe says.

Adding water to the situation makes it more dangerous. He adds, “If you add too much water, you’re destabilizing that which you’re trying to create. You’re supposed to keep everything 2 feet back, but if you’re not benching or sloping, that 2 feet can easily give way.”

That’s why you should never stand within 2 feet of the hole. If you have to be that close, Toothe says you should use proper fall protection, such as tying off to the truck.

The risks of vacuum and high-pressure water injuries are recognized by most people, though they may not understand the level of risk. A typical hydroexcavator operates at around 3,000 psi. “That is certainly enough to damage the human body,” he says.

An operator must also understand how much pressure the underground utilities can take. “Part of the training I do is about determining what you’re trying to locate, what else may be in the area, and setting your pump pressure so you can’t possibly damage any utilities you’re trying to locate,” Toothe says.

Fiber optic cable can handle 1,500 psi even with direct contact. But at less than 3 inches, 2,000 psi can damage the cable. “That’s a lot of money if you take it out,” he warns. HDPE gas pipe can suffer damage at 2,000 psi. Even coated steel gas pipe can be damaged at the typical 3,000 psi.

The vacuum presents risks, as well. Toothe investigated an accident in which a man’s arm was caught in the hose up to the shoulder. “He was working by himself,” he recalls. “When they finally got him out, the vacuum had sucked all the muscles and ligaments from his upper arm into his lower arm below the elbow. Above the elbow was just bone and skin.”

While some people may consider safety a trade-off with efficiency, Toothe disagrees. “Hydroexcavation should be used primarily to loosen the material so the vacuum can pull the dirt out of the hole,” he stresses. “It is not meant to dissolve soil. That’s both inefficient and unsafe.”

In fact, he adds, safety devices can make you more efficient. “I can move more water at 1,500 psi than I can at 2,000. By selecting the right tip, the right pump and nozzle configuration, I can actually be more productive at the same time I’m being safe.”

While some companies provide training with a truck purchase, the responsibility lies with the employer. “There are certain things you can do and certain things you ought not do,” says Toothe. “Rather than learn them the hard way, let’s talk about it so you can come out of the blocks safely and efficiently.”

Applying Pressure: Customers must understand the equipment for hydraulic and vacuum excavation before putting it to work.

From: Grading & Excavating Contractor
Written By: Carol Brzozowski

Hydro- and vacuum excavating systems are becoming so much an increasing part of the construction site landscape these days that one manufacturer states it’s been the busiest year for his company to date, with the demand in some cases exceeding supply.

The driving factors: increasingly strict construction site regulations, the growth of oil and gas exploration in North America, and not truly knowing what lies underneath the ground despite line locating technology.

Vacuum excavation is a technology that uses water or air as the medium to loosen the soil surrounding buried utilities, points out Ben Schmitt, product manager for Vactor Manufacturing. A vacuum source will remove the soil into a debris body for offloading at a remote location or back into the excavation site. Since only water or air is being used to disrupt the ground, buried utilities are exposed without disruption or damage, he adds. “By using vacuum excavation as the preferred method of exposing utilities for repair, the user protects the asset from damage along with any other buried utility that may or may not be known to occupy the same general area,” Schmitt says. “Not knowing the exact location of other buried utilities is a leading cause of unintentional utility strikes.”

Schmitt explains that on most dedicated hydroexcavators available today, end users can choose either a fan system or a positive displacement (PD) blower as the vacuum source. Each has distinct advantages. A fan system “moves an incredible amount of air, excavating more rapidly than other systems,” he says. “It’s also easier to operate and maintain, and the unit’s overall weight is usually less. Also, fan units are generally less expensive than the PD versions. “A PD blower moves air over longer distances and generates higher amounts of vacuum, allowing for excavation at greater depths, but at slower speeds than fan units,” he adds. End users often have unique applications that lead to a preference for one type of vacuum system, so Vactor offers both PD and fan machines, says Schmitt. “In either the fan or PD configuration, a simplified airflow path design will maximize pickup and filtration effectiveness,” he says. “Additional features that improve the unit’s overall productivity include extendable or telescopic booms offering a wide range of rotation and mounted on the curb side, large-capacity water tanks and debris bodies, heavy-duty solid construction, heated pump and hose reel cabinets, convenient operator controls, and tool storage.”

Vactor’s typical customers are primarily municipalities, contractors, and utilities, as “non-destructive vacuum excavation is quickly gaining acceptance as a relatively safe, effective alternative to traditional excavation methods,” notes Schmitt. “We see a rapid growth in vacuum excavation,” Schmitt adds. “The method is increasingly becoming the preferred alternative to conventional excavation practices. The cost of strikes to buried utilities is a risk most construction companies, utilities, and cities are no longer willing to accept. As a result, there is a desire to seek alternative means. Vacuum excavation is true damage prevention.”