Technology: Trends in trenchless

If you’re looking around at the construction landscape and wondering where all the business has gone, maybe you need to look down – underground specifically, and trenchless even more so. While there is concern over the impact of the housing and mortgage crisis on residential site development, contractors specializing in trenchless construction methods are finding plenty of work.

Horizontal directional drilling, pipe bursting, ramming and auger boring are all growing thanks to the energy boom, aging infrastructure and environmental concerns. What makes the trenchless industry particularly intriguing is that the technology is still evolving. Manufacturers and contractors are continuing to develop new machines and methods to improve profits and productivity.

Energy infrastructure
With crude oil today fetching $140 a barrel, the North American energy development markets are booming.

Every oil or gas well drilled is surrounded by a network of small-diameter underground pipelines. Some of these can be installed with open-cut methods, but many drill sites today face surface obstacles to which HDD is the only practical solution.

There are also several interstate pipeline projects underway that will result in thousands of miles of large diameter underground pipelines. When complete, these projects will transport product from the oil sands areas of Canada and North Dakota and natural gas from big gas fields straddling Texas, Oklahoma, Arkansas and northern Louisiana.

“We’re seeing a tremendous number of pipelines being built,” says Richard Levings, senior product manager over trenchless product at Ditch Witch. “The energy industry is a long way from being able to meet demand.”

The energy development market is providing work for almost every size of HDD machine except for the smallest. Oil and gas drill site pipelines run the gamut from 6 to 8 inches to 12-, 14- and 16-inch pipes. “For the interstate pipelines, they’re talking about 48-inch-diameter pipes,” says Ed Savage, trenchless segment manager for Vermeer. Such a diversified market calls for everything from 24,000-pound machines (as measured in thrust or pullback torque) for the small stuff, to 1,000,000-pound directional drills for the big interstate jobs, he says.

Water and sewer
While new home construction and development has slowed to a crawl, the rehabilitation of existing water and sewer infrastructure continues to grow. This is an area where pipebursting is particularly well suited.

“Cities are becoming more comfortable with the pipebursting process,” says Eric Nicholson, director of global and key accounts, Hammerhead Mole. “The bigger challenge has been the pipe. The water and sewer side has been using ductile iron or PVC pipe for a long time and they’re a little reluctant to switch to the HDPE (high-density polyethylene) used in pipebursting applications. Open cut may still be the number one method, but pipebursting is definitely a growing trend,” he says.

Additionally, pipe ramming, particularly in the past 12 months, has taken off, Nicholson says. The primary applications here are putting in large diameter casings and culverts, much of it for storm sewers and drainage projects.

Although the growth in water and sewer rehabilitation is proceeding well enough now, most public utility officials say this area is ripe for huge gains. Over the next 20 years, the country will need to spend $151 billion to rebuild and maintain our underground drinking water infrastructure and $390 billion in construction investments to replace existing wastewater systems and build new ones, according to the Federal Environmental Protection Agency. For wastewater funding, the $390-billion figure represents three times what’s currently being spent.

The hitch in all this is getting somebody to pay for it. After the passage of the Clean Water Act in 1972, the federal government funded the lion’s share of this construction. But since 1980 federal funds for water infrastructure have been cut 70 percent. Since 2001 these funds have been cut an additional 50 percent.

The Bush administration has continued to call for budget cuts in the Drinking Water State Revolving Loan Fund (which works a lot like the Highway Trust Fund in providing matching grants to states). Democrats in the House, however, appear to be more favorably disposed to funding water infrastructure rebuilds. The House Transportation and Infrastructure Committee has asked the General Accounting Office to present it with a study on ways to fund U.S. water infrastructure needs and close the funding gaps that now exist. The report is due January 15, 2009.

The last mile
The Internet and telecom boom of the early part of this decade sparked a boom in long-distance installations of underground fiber optic lines. But when the dotcom/telecom bust hit and capital dried up there was a lot of fiber in the ground just short of its final destination. Now the push for “last mile” installations (to hook up individual homes and businesses to this cross-country network) has started back up and seems to be gaining momentum in select areas of the country.

According to the Fiber To The Home Council, the growth rate for fiber to the home has doubled in the past year. Fiber-to-the-home connections topped out at 2.91 million households as of April this year compared with 1.48 million connections in April 2007. Verizon is currently leading the charge in contracting for fiber-to-the-home work, having committed $20 billion to the effort.

“We’re not going to see any big booms in fiber to the home, but it’s going to be steady as funding is available,” Levings says. “People still want fiber to the home. But the telecoms have to be strategic about how they implement it.”

Properly equipped contractors have developed a highly efficient way to install fiber to the home using small HDD machines, or piercing tools in an application known as stitch boring. In stitch boring the contractor digs a series of small launch pits and threads them together with the pipe carrying the fiber lines from house to house and under lawns, driveways and sidewalks.

Power underground
In the past five years, ice storms, hurricanes, tornadoes and other natural disasters have wrecked many overhead electrical distribution networks. As a result, some developers and communities are looking to put their electrical service lines underground, Nicholson says.

According the Edison Electric Institute, nine out of 10 new subdivisions put their electrical distribution lines underground. The EEI cautions, however, that installation of electrical lines underground can cost up to $1 million a mile, as much as 10 times the cost of overhead installations.

In addition to new work, a lot of the first generation of power lines that were placed underground are reaching the end of their lifecycle and need replacing, Nicholson says. Although protected from falling trees and storms, underground power lines have an average lifecycle of 20 years, compared with 40 years for overhead lines, according to EEI.

Growing acceptance
One of the more interesting drivers of the trenchless construction industry doesn’t have anything to do with markets. It has to do with the increasing acceptance by municipalities and project owners of trenchless methods and technology.

“You used to have to fight with the engineers because they weren’t familiar with it,” Levings says. “But during the telecom boom of the late 1990s, a lot of utilities, engineers and inspectors got their first look at HDD and saw the benefits. Some of them saw the ugly side of it too, which was incompetent contractors. But those fell by the wayside and the companies that survived the bust are competent, responsible, professional contracting firms who have applied HDD in the right manner.”

Throughout much of this decade the industry has continued to develop and disseminate standards and best practices resulting in a better understanding of the process and a high acceptance rate among engineers and project owners. “Today, the cost of restoring ground torn up by open cut methods is no longer considered just another cost of doing business,” Levings says. “It’s too inefficient.”

The environmental angle also works in favor of trenchless applications says Rob Foster, marketing manager for American Augers. Open cut methods can sever up to 40 percent of the tree roots in an area. Communities and environmental groups won’t tolerate that kind of damage when HDD and other trenchless applications offer a solution, he says.

Better machines, evolving technology
Trenchless construction is still a relatively new field. Unlike most earthmoving applications, trenchless contractors and equipment manufacturers continue to innovate with new methods and technology to improve results, productivity and profitability.

One of the more recent developments is the use of pipe ramming to assist in HDD operations, sometimes called HDD-plus or HDD-assist. In cobble or loose rock, pipe casings can be hammered into the ground to get beyond the difficult conditions, followed by an HDD pilot bore and pullback using the pipe casing as a guide, Nicholson says. And when an HDD drill string gets stuck or becomes difficult to move underground, contractors will use a pipe ram to get the bore moving again or to free up the drill rods so the tooling can be retrieved.

The most common marriage of pipe ramming and HDD, however, is to assist the pullback operations on long or difficult runs. “If they have 800 feet of product pulled back on a 1,000-foot job, the goal is to pound on the product to complete the bore,” Nicholson says. “Or if they’re 200 feet into a 1,000-foot bore and having issues, they’ll attach the hammer so they can get the product out of the ground, change the mud mixture and try again.”

Five or six years ago hammers were used only on an emergency basis, Nicholson says. Today it’s common for a hammer to accompany a large drill rig to most jobs.

The science of mud mixing also continues to evolve, says Foster. Better and more accurately designed mud formulas can increase the efficiency of HDD pilot bores and back-reaming operations, allowing contractors to do the same level of work with less horsepower and fuel consumption. Most HDD manufacturers have responded to this increased interest in mud mixing by selling drills and mud mixing and cleanup systems as a package, he says.

Geothermal installations, the next big thing?
Although it’s not exactly mainstream technology yet, geothermal heating and cooling systems are garnering newfound attention as the price of energy continues to climb. And HDD, according to Richard Levings at Ditch Witch, is playing a key role in bringing the cost of geothermal installations down.

Geothermal systems pump a fluid through pipes installed 8- to 12-feet deep underground that run in giant loops anywhere from 250 to more than 1,000 feet in length. The fluid exploits the small difference between the underground and ambient air temperature to heat and cool a building. Geothermal systems are highly energy efficient, but in the past the cost of excavating these deep and lengthy trenches was prohibitive, and you needed an acre or more to install them.

With HDD the loops can be installed without disturbing the landscape and can even be put in with a vertical application in crowded conditions and small building lots. Because of high demand, the companies that make the geothermal equipment are begging for HDD contractors to install systems, Levings says.

To find out more about the geothermal industry, visit: