Suck it up - Cold weather vacuum excavation is a thing

Vacuum excavation can work in cold weather.
Andrew Snook
May 16, 2019
By Andrew Snook
Boiler and heater options on vacuum excavators make it possible to use them even in permafrost. The one change to make in cold conditions is to anti-freeze the water tank.
Boiler and heater options on vacuum excavators make it possible to use them even in permafrost. The one change to make in cold conditions is to anti-freeze the water tank.
In Canada it is often said there are two seasons: winter and construction. These days it’s hard to differentiate between the two in many places across the country.

In many of our most populated cities, the demand for faster and broader telecommunications services continues to grow, as does the need for constant road improvements and new commercial and residential construction.

As the weather dips below freezing and the ground starts to wreak havoc on traditional excavation equipment, the opportunity for rental houses to take advantage of the vacuum excavation market grows.

For cold weather applications, Chapman Hancock, product manager for vacuum excavation at Ditch Witch, says  there are ground thawing solutions that make vacuum excavators more efficient, such as a heater or boiler package.

“You’ve got a boiler on either the trailer or the truck and it’s heating the water as it goes through the system about 115 to 150 degrees. That allows it to be a little more efficient. Depending on the ground conditions, once you get through that permafrost, the heater still helps with productivity and efficiency gains as you get in there,” he explains, adding that one example of a good application of this technology is for working in clay. “It helps break up clay so you can dig faster, whereas sometimes when you’re using just ambient water temperature on clay it’ll still dig, but just a little bit slower. So by flipping on that heater, whether you’re in cold weather or not, it helps productivity go up.”

Active in the Great White North
The most common applications where vacuum excavators are extremely active in Canada are typically for fibre-optic cable and other telecommunications installations (especially in the Greater Toronto Area) and for oil field applications.

“Right now, it seems the bigger market segment in Canada driving some of that vacuum excavation is fibre installation,” Hancock says. “You’ve got to be able to go out there – whether you’re trenching it in or boring it in – in daylight or expose each utility as you’re crossing it or paralleling it. That way you know the existing infrastructure wasn’t damaged when you’re putting in the new telecom.”

It is not unusual for telecommunications and oil field applications to swap the number-one and number-two spots for most common applications for vacuum excavators, depending on how oil is faring in the Canadian market.

“Those two are the ones that kind of go back and forth,” Hancock says. “Oil field application is typically your pipeline, rig washing and cleaning, mud disposal for oil fields. But also when you think of pipeline installation, when you have an existing pipeline you’re trying to repair or tie into, you have to create a big bellhouse, which is just a big hole stepped back to expose the valve or the pipe that you’re trying to repair or tie into. Some vacuum excavators can go in there and dig down effectively and safely so you don’t have any opportunity to damage that existing line with the vacuum excavator.”

Vacuum excavators are also commonly used for infrastructure applications related to water and sewer for new residential and commercial construction and during coring applications for road construction projects. “You take a core out of the road and then you need a vacuum excavator to go dig down, expose the line, tie into it, repair it – whatever the job may be –and then fill it back in,” Hancock explains.

Maintenance tips in cold weather
To keep vacuum excavators running smoothly in the colder months, perform the routine maintenance you would do on any normal day including dumping your debris tank, cleaning it out, and making sure your filters are clean, Hancock says.

“Most vacuum excavators have washable filters, so there’s a cyclonic filter that filters all of the heavier stuff out and we have a finer debris filter,” he says. “That finer debris material is something we want to make sure that we’ve cleaned out and we’ve washed it. It’s always a good idea to have at least two of those. I recommend three or four, so that way when you’re performing your job, you’ve got a dry clean filter ready to go in if you’re in a finer material or something starts clogging your debris filter.”

Dumping your fresh water tanks is especially important in cold weather applications.

“When you drain the fresh water tanks you want to anti-freeze the system,” Hancock says. “By anti-freezing the system we’re putting an environmentally friendly anti-freeze through the water pump and through the system so nothing freezes, and you’re able to go and start performing the same job you did yesterday, even though the temperature might be -40C. As far as cold weather applications go, that really is the biggest one. We want to make sure we’re draining our water tanks and anti-freezing the unit.”

Year-round machines
Although vacuum excavators can be very handy for a variety of cold weather applications for infrastructure projects, fibre installations and oil field work, the jobs these machines perform are mostly required year-round, making a strong argument for rental houses to stock them 365 days a year.

“Whether it’s summertime or not, you still need to go and perform the same jobs, so there’s absolutely a reason for rental yards to stock this equipment year-round,” Hancock says.

Since this type of equipment will perform differently depending on soil conditions, Hancock recommends users leverage their local  dealer network for helpful information.

“Not only for service and maintenance and selling of equipment, but they’re also the experts for that region,” Hancock explains. “So as you’re going to start a new job, or as you’re new into an area, or even if you’re in an area where something isn’t working right, go back to that local dealer for ground conditions, recommendations on how to use it and different techniques. The local dealer will be able to provide all that information.”

Safe exposure
One of the key benefits of using vacuum excavation – sometimes referred to as “soft excavation” – is that it very significantly reduces the possibility of damaging a utility when exposing it.

“Essentially we can go down and expose the utility with pressured water and a vacuum, sucking the spoils out, and you’re able to down and expose a line without damaging it,” Hancock says. “There’s a lot of regulations out there as far as tolerance zones on where you can use an excavator and where you can’t use an excavator. Vacuum excavation really is the best means for the safest excavation for exposing utilities. That way you’re going down and you’re not damaging a gas line or breaking a water line. You’re able to expose it cleanly, wash off the area and see the utility.”

In extreme cold conditions, the utility isn’t the only thing that risks being damaged.

“Permafrost and frozen ground can be very hard on your traditional equipment, whether it’s a drill, a trencher or an excavator. Sometimes that can be as hard as a rock, depending on the temperatures outside and how long the temperature has been at that level,” Hancock says. “But hydro excavation allows you to get in there, especially with the heater package or the boiler package, and expose and dig a utility without damaging other equipment. There are instances where hydro excavators are the first on the jobsite. They’ll go out there, they’ll trench down into the permafrost until they’ve reached the point where the permafrost stops. They’ll create however a big of a hole the excavator needs to get in there and perform the rest of the work. Vacuum excavation has very good use for permafrost areas or frozen ground so you can get in there and remove the permafrost safely without damaging equipment.”

New technologies and trends
While the use of vacuum excavators for a variety of applications has increased over the past five to 10 years, one regular issue that has come up over the years is that the units can run out of their supplies of fresh water. To combat this problem, Ditch Witch has designed new nozzle technologies.

“We’ve found that rotating nozzles are best for exposing utilities because you don’t have a single-point spray, the water is always oscillating so you’re never focused on one area,” Hancock says. “We’re also able to nozzle it down and use about 50 per cent less water and still be able to outperform older nozzles… which means you’re able to stay on site longer without having to go get more water – which is downtime – and by using less water you are filling up less volume in your debris tank.”

Filling up a debris tank less often allows the user to stay on site longer, and reduce the number of trips taken off site to empty the tank.

“A trip to the dump, or wherever your dump site is, can be half a day in some cases,” Hancock says. “Two hours is probably a typical round-trip dump. That’s two hours out of your day that you’re not able to continue to perform. Staying on site longer really helps complete jobs faster.”

Another relatively recent change in trends for vacuum excavators, fuelled largely by increased demand for fibre installations, is the need for quieter operation at jobsites.

“No one wants to be getting off work and going home to enjoy a nice evening with the family, then have this very loud piece of equipment outside working,” Hancock says. “We’ve decreased the sound of our overall units to a point where somebody inside would hardly hear it.”

In many residential areas, allowable operating times for heavy equipment are based on regulations related to the decibels that a machine puts out.

“So by getting underneath those decibels we’re able to allow our guys to work longer hours,” Hancock says.

With the combination of quiet operation, reducing the possibility of damaging existing utilities, and a reduction on the wear and tear of traditional excavation equipment in cold weather applications, vacuum excavators are set up to provide a solid option to construction contractors and telecommunications service providers for many years to come.

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