When locating utilities under a street, there’s the hard way, and there’s the easy way.
The hard way of potholing for a horizontal directional drilling job is to saw cut and then dig with an excavator.
The easy way is known as core drilling. A crew uses a vacuum excavator equipped with a core drill to open a small hole, usually around 8 inches, to spot a utility. That smaller hole is less disruptive than saw cutting and results in lowers amounts of spoils, backfill and restoration costs.
Laclede Gas Company, the largest natural gas distribution utility in Missouri with about 625,000 customers, takes the easier, more efficient route.
“Using a vacuum excavator and core drill saves quite a bit on cost,” says Laclede’s Ray Hill.
He offers an example. With core drilling, the only pavement being disturbed is what’s drilled, usually 6, 8 or 12 inches in diameter. After removing the core, the crew vacuums down and finds the utility. They then haul away the spoils, backfill the hole and usually patch it with the same piece of concrete they removed.
With the break-and-dig method, a crew must replace at least a 4-by-4-foot slab if it’s a sidewalk and possibly a 15-by-15-foot slab if it’s a street, according to Hill. All of that material has to be trucked out, and then the larger surface area must be repaired.
Laclede has Vermeer vacuum excavators by McLaughlin. The vacs feature a McLaughlin core drill attachment that uses the vac’s hydraulic pump to power the saw, eliminating the need for a separate power source. Furthermore, the crew does not need to anchor the base of the core drill into the pavement because of a patented design in which the vac’s suction pressure keeps the base securely in place.
Jeff Wage, vice president at McLaughlin, says the core drill market is rapidly gaining momentum as awareness of the technology increases and as space becomes more constricted in urban settings both below ground and above.
Contractors also like that it’s a more cost-effective approach than saw cutting.
“Your excavation quantity, your haul-off quantity, your backfill quantity, your compaction quantity and your asphalt quantity is all significantly less with vacuum excavation and core drilling than it would be with a saw cut and open excavate method,” Wage says. “Core drilling with Vacuum excavation also reduces the amount of time of road closures and traffic disruptions and provides a superior and smaller reinstatement of the road surface when compared to excavation and patch methods.”
For more information about McLaughlin products, visit www.mclaughlinunderground.com or call (864) 277-5870. Check out the company on Facebook at www.facebook.com/mclunderground.