A Look at Hydro Excavation
Hydro excavation isn't the latest trenchless technology but it offers many benefits to trenchless construction.
While hydro excavation isn't the latest trenchless technology to be developed, today, it's time to take another look at its advantages and how its operation process works well with other trenchless technologies being undertaken in the same construction area.
A water jet that’s steered is an effective way of producing a tunnel that follows a project design path almost perfectly. Add suction to remove the slurry the water jet creates and you have the hydro excavation process. Although not the latest iteration in trenchless technology, hydro excavation uses these two proven systems to meet the needs of the trenchless contractor.
At first glance, hydro excavation resembles drinking a milkshake: the machine uses its water jet to create a slurry along the project’s design path, much like inserting a straw into the shake. It then sucks the slurry - like the milkshake that accumulates in the straw - out, leaving behind a perfect bore. It’s a system that merits serious attention.
Proven Technologies, Blended
The technology was first developed in Germany, by Reschwitzer Saugbagger Produktions GmbH, in 1993. Water jets are used for precise cutting of metals, stones and any material that must be cut and which can’t withstand the temperatures generated by the friction of other cutting methods. The water jet used in hydro excavation is no less precise, in part because it’s operator-steerable.
he hydro excavator’s water jet produces an intense stream of water, sometimes along with an abrasive, to cut a precise bore in the earth. When it does so, it produces a muddy or stony slurry (depending on the subterranean material) that must be removed from the bore. That’s where the vacuum function steps up: it uses a vacuum suction head - attached to or around the water jet nozzle - to suck the slurry from the bore almost as soon as it’s created, leaving a clean bore with good, compressed walls.
Hydro Excavation is Versatile
Horizontal directional drilling, boring and hydro excavation needn’t be mutually exclusive. Microtunneling is only one of the useful activities for hydro excavation. Operations where microtunneling occurs alongside other forms of trenchless construction, from boring for pipe installation or repair to large-scale tunneling, can be expedited by the precise nature (and resultant speed) of hydro excavation.
Hydro excavation is also safe: your personnel aren’t subjected to potential cave-ins or other injuries that might result from conventional horizontal drilling or boring operations, meaning a potential saving in Workman’s Compensation claims. Additionally, hydro excavation plays well alongside other types of drilling equipment and can remove itself quickly when no longer needed. (Learn about "Trenchless Operations Safety Do’s and Don’ts.")
This means that, whether you own your own hydro excavation nit or use a contractor’s equipment, its speed and precision make it a cost-effective addition to your operation.
Not Stuck in a Pothole
Hydro excavation can fulfill yet another role. Who hasn’t had to pay a geotechnical operator to go potholing by hand or by backhoe? One eats up money as the geotech’s personnel dig holes with shovels and buckets, the other risks include hitting and damaging the same underground facilities they’re potholing for.
The hydro excavator can dig more quickly and accurately that an entire geotechnical staff and do so with greater precision than a backhoe, meaning the final search for existing utilities will take much less time and be less fraught with every underground contractor’s nightmare, unnecessarily damaged pipes, cables or other utilities. (Read on in "The Science of Getting it Right: Locating Underground Utilities .")
The Bottom Line
You can contract it as a service or buy it. It’s quick and precise. It can work with the rest of your equipment or get out of the way. It’s safe and it’s a proven technology. Whether you choose to use hydro excavation to augment your existing inventory, it’s a technology that’s worth a serious look, if not for your current project, then almost certainly one down the road.
Written by Will Carpenter
A retired merchant seafarer, Will Carpenter sailed the world extensively before settling as far from the sea as possible. Now a technical writer, Will lives in the "hills and hollers" of Tennessee with two formerly feral cats.