From the magazine

No need to borrow the neighbour’s vacuum

Truck-mounted vacuum excavation systems are popular among city sewer and water departments for the cleaning of sanitary and storm sewers. These units offer users a combination of high water pressure and a powerful vacuum force. They can clean sewer systems or excavate soil for potholing and small excavation projects in a safe, productive and nondestructive manner. However, many cities realise that once they have a unit, the other city departments begin borrowing the vacuum truck for projects.

“What we find is when a municipality buys their first vacuum, whether it’s a truck or trailer unit, everybody starts coming up with different ways to use it,” says President of McLaughlin, Dave Gasmovic.

“It might have been bought to just clean out water valve boxes, but soon the sewer department’s borrowing it to clean out catch basins and the electric department is borrowing it to expose electric lines.”

In most cases the city soon realizes it needs another unit. But they don’t need to spend up to $500,000 for a truck-mounted unit. Trailer-mounted vacuums are ideal for small- to medium-sized potholing, excavation and cleanup work.

“Municipalities should look at trailer units as a second unit, as it is more cost effective to mobilise a smaller unit than a big truck,” says Mr Gasmovic.

Versatility in a small package

Vacuum excavators are quite versatile, but a wide array of attachments can expand their applications. Different size reduction tools allow cleaning of smaller water valve boxes and catch basins.

An expanding application for vacuum excavators among municipalities is excavating post holes for road guard rails and traffic signs, as well as small excavation projects. Using a vacuum helps eliminate the chance of damaging an existing underground line and requires less labour and time than using an auger.

According to Mr Gasmovic, today’s trailer-mounted vacuum excavators are well suited for these applications because they are more portable compared to units in the past. Municipalities can choose a 455 litre unit that fits into the bed of a one-ton truck or trailer units up to 5,460 litres. These units also have the power to move displaced soil up to 62 metres from the source and only one person is required to operate the unit.

Truck-mounted systems provide more lift

Trailer-mounted vacuums have some limitations when compared to truck-mounted vacuum systems. The biggest limitation with trailer units is the size of hose in using. Most trailer vacuums provide about 381 mm of mercury lift. This will give you a solid water lift of 4.6 metres from the port without introducing air into the stream.

Secondly, the positive displacement blowers on trailer-mounted vacuums are typically smaller and provide 575 or 1,025 cubic feet per minute (cfm), compared to 3,000 cfm and up from some larger truck units.

Selecting the right unit

Mr Gasmovic recommends that a municipality consider the following before purchasing a vacuum excavator:

* What is the main application?
* What options do they want on it?
* Do they need dry as well as wet excavation?

Vacuum excavators come in all sizes and options, so it is important to select the unit that will best fit your intended use.

The heart of the system

Mr Gasmovic recommends that contractors pay special attention to the filtration system and select a system that will filter the spoil and avoid clogging. In addition, be sure to select a strong trailer frame that will support the weight of the unit and a full tank of spoil.

Trailer vacuums are a great complement to a truck vacuum and an ideal and affordable tool for smaller municipalities.

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