The company is using a Vermeer MTR12 microtrencher attachment on a project in and around Scottsdale, AZ. (See “Microtrencher Speeds Fiber Installation”.) Kwigs Bowen, area manager of Team Fishel’s office in Chandler, AZ, compares the advantages of microtrenching to the advent of rocksawing a couple decades ago.
“Back in the 1980s, [they] used rocksaws all over the country to install cable TV services,” he says. “Microtrenching is kind of like a mini-rocksaw, because we are cutting a small trench with the microtrencher cutter wheel, then installing a small duct product and putting a microfiber cable in that product.
“Microtrenching helps reduce initial capital costs of the construction, and we can roll it out very quickly,” he continues. “Production has been faster than traditional construction, so we can provide the service at a lower cost and with less disruption.”
“Installation costs of cutting the trench are quite low compared with other methods,” agrees Proctor. “The largest variable is restoration cost, and is job dependent. Restoration methods vary from re-using the spoils from the trench and capping with cold patch, to partially filling the trench with flowable grout and sealing with an overlay.”
While restoration is still a factor, it is significantly less so compared to other methods. “If you use a traditional rock wheel or trenching system, you’re going to create a lot more damage to the infrastructure,” says Kuyers. “It’s going to be a lot slower process and a lot more restoration.”
Another advantage of microtrenching is the ability to cut above utilities in most cases. “That way, you don’t have to pothole every utility crossing that you run into,” Kuyers comments. “That saves an inordinate amount of time in cutting a patch out, using a vacuum to expose the utility and then backfilling it — and then you have the potential for a pothole.”
That said, he advises, “Even though microtrenching cuts above the normal depth of utilities, we recommend that contractors work with One Call and ensure all of the utilities are identified. This will help save time and money in the long run in case a line was not placed at the correct depth.”
Slim Lines Trenching Ltd has seen the benefits of cutting a narrower, shallower trench on a recent project in George Town in the Cayman Islands, located roughly 500 miles south of Miami in the Caribbean. Working at night, the company installed approximately 17,000 ft. of telecommunications conduit in just four months using a Ditch Witch RT45 with MT12 attachment and an FX60 vacuum excavator. (See “Small Start Brings Big Results”.)
“We did two cuts on this project. One was 3/4 in. wide and 12 in. deep, and that was about 13,000 ft.,” says Richard Corbin. The second cut, measuring .95 in. wide by 12 in. deep, made up the remainder of the footage, allowing for two conduits to be placed side by side for increased capacity.
“One of the reasons 12 in. was chosen — not only by the infrastructure contractor, but the telecom and the National Roads Authority here — is that all other utilities are deeper than 12 in.,” he explains. “So crossings were not as much of an issue. There was reduced risk of interfering with or even severing any of the existing utilities.”
It also provided maximum coverage for the conduit being installed. “It gave the telecom piece of mind that they had adequate coverage,” says Corbin. “The conduit that we installed is 4 in. tall, so we ended up with 8 in. of cover. Any major road work that takes place normally would be only 4 to 6 in. deep.”
A narrower, shallow trench meant restoration, using EZ Street cold patch, was completed quickly, with minimal disruption to the surrounding community. Oftentimes, local business owners weren’t even aware the installation had taken place. “I had business associates and friends of mine say, ‘When are you coming down in front of our building?’ and I would say, ‘Well, we did that a week ago or two weeks ago,’” notes Corbin. “They just didn’t notice.”