Routing Roots

Almost every root-cutting job is different. Savvy contractors keep a variety of cutting tools on hand and know when to use them.

Every contractor runs into pipes plugged by invasive roots. It’s a problem that defies a one-size-fits-all approach, says David Bradford, product manager at Shamrock Pipe Tools Inc. of Baton Rouge, La.

“Anybody who says they’re a true expert in root removal is probably exaggerating, because each situation is unique,” says Bradford, whose company makes and distributes pipe-cleaning tools and products. “It’s amazing to see the diversity of root material that can infiltrate a standard 8-inch line in locations across the country.”

Regardless of the type of root, however, Bradford says the first order of business is to re-establish water flow as soon as possible. While root solvents may help to dissolve roots, and while chemical treatments discourage root growth as part of a longer-term maintenance strategy, the immediate task at hand often calls for mechanical cutting.

Saws and cutters

Bradford prefers saws and cutters as a first line of offense. A waterjet root cutter that drives a circular saw blade by hydraulic power is the most common tool used to combat roots. But choice of blade attachment is important. Bradford says some optimistic contractors use the maximum size blade in hopes of clearing the full diameter of the pipe.

“If you’ve got an 8-inch pipe and an 8-inch blade, you’d better hope you’ve got a pipe that’s true to diameter all the way along,” he says. “It’s better to select a blade that’s slightly smaller to get through the offsets and deflections you might find. When a guy pops open a manhole and sees that roots are present, you know that the pipe is broken somewhere along the line.”

Bradford recommends small-pipe hydraulic blade root cutters for 3- to 10-inch pipes and waterjet root cutters for 6- to 18-inch lines.

Re-establishing flow

In most cases, the quickest way to re-establish flow is to clear out the tenderest roots and remove the debris that has collected on them. In other cases, the first task is to clear enough roots to pass an inspection camera through the pipe.

“Engineers can be strange beasts,” he says. “It’s hard to convince some of them that a broken 100-year-old pipe running through a yard full of 100-year-old oak trees is really infiltrated with roots. They want to see pictures first.”

Bradford says simple tempered metal blades of alloy steel or carbon steel provide enough cutting power to get through the toughest root problems. Contractors can choose from flat blades that would lie perfectly flat if unwound, and concave blades that feature a slight indentation along the side. “I prefer a concave blade, because it offers a smaller surface wear against the side of the pipe wall,” he says.

Once the center of the pipe is clear of obstruction, a chain cutter – essentially a forward-facing set of blades with a length of chain swinging around its circumference – is a useful tool to clean off the pipe walls. “Let the blade cutter do the work of dealing with the initial blockage, and let the chain cutter scrape the pipes out,” Bradford says. “I like these a lot for cutting fine root hairs around the circumference of the pipe.”

A cable rooter, which uses metal cables to scrape the full diameter of the pipe in combination with a front cutter, can also be used to remove grease, scale, debris and roots from smaller-diameter cast iron and storm sewer pipes.

Slow and steady

While the temptation may be to force the cutter through the root blockage at top speed, Bradford recommends patience. “Get to the blockage at as low an angle as possible, with a slow and steady approach, and you’ll have the power to penetrate the root mass,” he says. “Use a lower rpm and let the tool do the cutting, without forcing it. Don’t be a cowboy.

“You don’t know what’s in that pipe, so if you progress too quickly at first, you may not be able to pull back out,” he notes. “Do manageable chunks of 20, 30 or 40 feet at a time. It’s a lot easier to move back and forth than to retrieve a tool that’s stuck 100 feet down.”

Waterjet nozzles alone can be used to flush out some grime and clear away roots in a pinch, but Bradford doesn’t recommend them as root cutters. “I can see where people use nozzles to remove some of the debris – anything from dirt, grease, oil and soap to cheap toilet paper – hanging onto the roots,” he says. “But I’m not convinced a nozzle can be used as an effective cutting tool.

“Some proponents of nozzle cutters look at me like I’m from the prehistoric age, but if you’re in a 15-inch line and using a nozzle, it loses impact almost immediately after the water enters the pipe.

“You could hit the root, clean the area a bit and perhaps pulverize the fiber, but the water pressure would just drive the root debris deeper into the pipe,” Bradford says. “When you try to retract the nozzle it will probably be buried in debris. Better to use the nozzle to clean away the grit that might cause premature wear on the blades and damage high-torque motors that can jam up with sand.”

While contractors might be forced to deal with a wide variety of problems related to root incursions, a disciplined approach and thoughtful selection of cutting tools can handle the toughest roots. Says Bradford: “It’s a combination of a little creativity and choosing the right tool for the job.”


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