With a nickname like “Silicon Hills,” it’s no surprise that the fiber market in Austin, Texas, is thriving. Gearing up for a fiber install project in Austin often means navigating a puzzle of difficult ground conditions, the section of rock tooling and an underground crowded with existing utilities. These factors have caused project engineers to take a step back from the popular horizontal directional drilling (HDD) method and explore alternative installation methods.
For a recent fiber project in Austin, a contractor opted for the quick and efficient method of microtrenching. His crew was able to install 9 to 13 feet of 1-inch fiber conduit per minute using this often-overlooked technique. Microtrenching is the cutting of a narrow, shallow trench, typically on the side of an asphalt road. Many contractors selecting microtrenching for the first time might not realize what a key role a vacuum excavator plays in the process.
Tag-teaming the job
For this particular job in Austin, the contractor put three Vermeer ECO50-800 vacuum excavators to work along with a Vermeer microtrencher attachment and a 10-man crew. The goal was to install 1000 feet+ of fiber that day: The crew cut a 1200-foot-long trench by lunchtime.
To maximize productivity on the jobsite, two of the McLaughlin vacuum excavators worked in shifts to collect the spoil left by the microtrencher rather than allowing it to fall back into the trench. A microtrenching application requires a vacuum excavator with a high CFM — usually over 1,000 CFM — and a 4-inch hose. As the microtrencher steadily digs a 1.75-inch wide by 10-inch deep trench, the vacuum is creating enough CFM to collect the spoil, moving at roughly 160 miles per hour. When one vac was filled to the point where it needed to travel to the dumping site, the other was waiting to take its place.
Innovative misting ring
One of the most important pieces of equipment on this job is also one of the smallest. The device, called a misting ring, moistens spoil collected by the vacuum just enough that it knocks the material out of the airstream, preventing it from reaching the second stage of filtration. The light mist is not creating a sloppy, unmanageable slurry but rather light, fluffy material that can often be reused on the jobsite as backfill. At the very least, spoil that passes through a misting ring is easier to manage using loaders and backhoes at the dumping site — an important quality on microtrenching jobs where vacs may need to be emptied every hour.
“On this project, the misting ring allowed the spoil to be captured during the first stage in filtration,” says Jeff Wage, vice president at McLaughlin. “This was very important to the contractor’s productivity because it kept the vac’s cyclones empty and prevented the vacuum from clogging and causing downtime.”
Once cut, the fiber conduit is installed in the narrow trench is backfilled with 6” of slurry concrete grout. Meanwhile, the last of the three McLaughlin vacs was used to hydro-excavate 10×10-inch excavations in the road where the fiber conduit was run under the curb and gutter into easement between the sidewalk and street where it is terminated in “flowerpots” or junctions boxes. When a homeowner subscribes, fiber will be run to the premise and delivered to the homes in the development. By opting for microtrenching, the contractor was able to reduce costs and complete the project on time despite challenging and crowded underground conditions.
Interested in a similar equipment setup for your next fiber install project? Call your local Vermeer dealer or visit mclaughlinunderground.com for more information.