Rigonomics: Modern HDD Contractor Tools For Drilling Rock

By Jeff Griffin, Senior Editor | June 2011 Vol. 66 No. 6

Southern Diversified Technologies
Southern Diversified Technologies (SDT), Brookhaven, MS, specializes in telecommunications construction. The largest of its HDD units has 30,000-pounds of pullback.

“For rock, we use an air hammer and Railhead bit with diamond teeth,” said Jack Freeman, division manager of outside plant construction. “We don’t use mud motors.

“With the air hammer, not as much equipment is needed, and there is much less clean up than when a mud motor is used. Anything we can’t get through, we have subcontractors running 80,000 and 100,000-pound equipment who can bring in mud motors if necessary.”

Freeman said it is rare that the company crews run into unexpected rock.

“We’ve been drilling a long time and have worked in most areas of the country, and we know what to expect when we bid a job, so normally we are aware of rock,” Freeman said. “Engineers that plan projects do a good job identifying soil conditions and anticipating rock so we are very close on our estimates.”

Freeman said SDT crews always are prepared for rock, typically having air hammers and specialty air compressors ready.

One of the toughest rock jobs Freeman recalls was in Leeds in north central Alabama on a fiber optic project. Soil conditions included a granite mix and solid granite for 15 miles. “It was very slow going,” he said, “about 200 feet per day.”

SDT keeps from 18 to 25 drill rigs working most weeks, six are Vermeer and Universal company-owned machines with crews while the balance are subcontractors.

Woods Construction
Woods Construction, Colorado Springs, CO, operates 30,000 and 40,000-pound HDD units working mostly in rock in Colorado, Arizona, Missouri and Wyoming. Most projects are gas, but also includes some water, telecommunications and on-grade sewer installations, said Ed Libby, Woods president.

“We don’t do large-diameter installations,” said Libby, “but much of our work is in rock, and our approach has been to use Ditch Witch All Terrain equipment with dual-pipe mechanical counter bore drilling systems. In the conditions we work in, we believe this is a better choice than using machines with mud motors.”

For a new gas distribution system in Branson, MO, Woods Construction crews installed more than 100,000 feet of HDPE main line pipe with a diameter mix of two, four and six inches. Most services were 3/4, 1 1/4 and 2 inches.