Turning Toward Trenchless

Horizontal directional drilling gains momentum for sewer and water installation as municipal managers learn the technology and begin to appreciate the advantages
Turning Toward Trenchless
Horizontal directional drilling is gaining favor for pipe replacement when examined in a “whole project” context that includes the costs of surface disruption and subsequent repair. (Photos courtesy of Vermeer Corp.)

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Municipalities have long embraced open-cut as the method of choice for installing water and sewer systems, but a growing number of officials are now abandoning the “we’ve always done it this way” mentality.

Leading the movement to challenge open-cut is horizontal directional drilling (HDD), an efficient and less disruptive approach that has significant advantages. The change has come as municipalities learn the benefits of trenchless technology and change their perceptions about its costs. As a result, they are adjusting the way they specify new projects and are updating their bidding processes.

“I think it had a lot to do with comfort level,” says Chad Van Soelen, trenchless segment business manager at Vermeer Corporation. “It’s often easy to become complacent when a system is in place and people are familiar with it. The other factor was a perception that HDD is more expensive than open-cut. Often neglected, however, is the cost for repairs and restoration on the surface. This should always be factored in to arrive at a realistic cost-per-foot calculation.”

HDD struggled in the mid-1990s, largely because of contractors who were inexperienced in bidding trenchless jobs. Since government customers must accept the lowest bid, many contractors underbid jobs, and then in the middle of the projects found themselves losing money. An irresponsible few simply cut their losses and walked away from the projects.

“On the flip side, the actions of those few prompted more overall due diligence among municipalities when reviewing bids and selecting contractors,” Van Soelen says. “It actually turned out to be a good thing for most installers. Project owners and municipalities now scrutinize bids more closely and are more receptive to looking at HDD as a viable option.”

 

Merits of methods

Chris Brown, president and CEO of Verdeterre Contracting in Canton, Mich., says both open-cut and HDD have their places. Founded in 1980 as an excavation and earth-moving company, Verdeterre recently expanded into HDD.

“We feel HDD is a better option for most water and sewer installations,” Brown says. “Our experience has been that HDD is a more efficient approach, but it depends on a variety of conditions. There are situations when open-cut will be a better choice, at least from a production rate standpoint. A lot depends on the job site, the surroundings, and number of surface area obstacles.”

Cost has always played a significant role in the decision to go with open-cut. While most HDD enthusiasts will admit that open-cut has the edge in a bidding war, Brown feels project owners often overlook the bigger picture.

“Perception is reality, and I think most city officials perceive open-cut as less expensive,” Brown says. “That obviously depends on factors like depth of installation. The shallower the installation, the greater the case for open-cut. But in areas where lines are being installed at greater depths, let’s say in excess of 8 to 10 feet, I think it will swing in the direction of HDD.”

 

HDD success story

Verdeterre Contracting recently completed an install where HDD was not the municipality’s first choice. The job was an upgrade to an aged waterline in a 40-year-old residential subdivision. The project was complicated, as the neighboring county and township were concerned about the costs to replace all the roads that would be damaged by open-cut replacement.

The project involved installing 32,000 feet of 8-inch TR Flex ductile iron water main as the replacement. Soil conditions — clay and silt — were of little concern, but Brown’s team lacked information about the sanitary sewers in the area. They had to rely on residents’ memories, along with repeated potholing, to zero in on exact service locations.

That proved inefficient, so Brown enlisted a subcontractor to inspect the line and all services with a camera. Equipped with a sonar device, the camera allowed the crew to detect the precise location of each service from above ground.

“The affected subdivision involved more than 500 homes,” Brown says. “We knew the location of the mainline, but few records existed for the individual off-line leads. It also involved connecting the new line to each home with 1-inch copper water service lines. Having to complete each of these individual service lines using open-cut would have been horribly disruptive and costly to repair.”

The municipality’s project engineer had a previous relationship with an HDD contractor and knew about the process, and that helped greatly, especially when it became necessary to alter the original drill plan. Brown used a D36x50 Series II Navigator HDD unit from Vermeer to install the ductile iron mainline.

“The original plan was based on the information available at the time, before we started the job,” Brown says. “You can imagine the number of modifications we had to make along the way, since the locations of so many of the service lines had not been identified. Occasionally, we also found an identified line that was deeper or shallower than specified, so we had to adjust vertically or horizontally.”

To complete the 1-inch service line connections, Brown used a combination of HDD and open-cut. For the longer runs, he used a Vermeer D7x11 Series II Navigator HDD to install service lines to 300 of the homes. The remaining 200 home connections were made using an open-cut approach due to the short distance from the mainline to the home.

“In this case, we ran the numbers, and the combination approach made the most sense,” says Brown. “Horizontal directional drilling on the longer runs required less time from an installation perspective and reduced restoration to the established lawns.”

 

Credible counsel

Most advocates of trenchless technology acknowledge that open cutting is viable in some situations. The point is to avoid the assumption that a backhoe is the solution to every water and sewer installation. The approach to use typically depends on variables such as the type of utility, the type of project (new or repair), the size of pipe to be installed, soil conditions, and the depth and length of the installation. Often, as in many large projects, a combination approach proves most efficient.

Municipalities with little experience in HDD may be well served to enlist a civil engineering firm that can provide an unbiased recommendation. HDD equipment manufacturers can also supply detailed information: They are experts at their business, and it would not be in their best interest to suggest an approach if the prospects for success were questionable.

“Our customers call on us all the time to provide insights and recommendations for installation projects,” Van Soelen says. “We have experts with years of experience in HDD and open-cut who are well qualified to identify the pros and potential stumbling blocks of each method for a specific job, whether it’s ground conditions, surface obstacles, local restrictions, confined access, you name it. If HDD is the best option, then, yes, we’ll recommend it. If not, we will suggest another approach.”

 

Bidding

HDD has led a number of municipalities to amend their bidding protocols. Assuming trenchless is feasible and cost-effective, city officials may even specify that HDD be used exclusively, although variations in state laws may make that difficult.

Murv Morehead, right-of-way coordinator in the City of Overland Park, Kan., says bids for the city’s utility installations are sometimes written with guidelines that outline expectations for project results, but do not specify what method the contractor must use.

“We reserve the right to encourage them to look at alternatives to open-cut, especially if digging up a street is involved,” Morehead says. “We can withhold the permit until we’re convinced that the contractor has done due diligence and has proved to us why there’s no method available other than open-cut.” Still other municipalities go so far as to word contracts to stipulate that a project must be “completed by a means other than open-cut,” but stop short of specifying the technique.

 

The green factor

Another factor moving municipalities toward HDD is air emissions, especially in non-attainment areas. “I think it’s really starting to play a huge part in looking at all these projects,” says Van Soelen. “The ability to prove the substantial reduction in emissions generated by HDD equipment compared to open-cut is a benefit. Generally, the carbon footprint of HDD can be up to 75 percent less than what you’ll have using open-cut, and municipal officials I’ve spoken with are delighted there is an option that addresses this issue.”

Brown feels the tide is beginning to turn more in favor of HDD. “It still isn’t a large number, but each year there are more municipalities looking at HDD as an option, especially with waterline replacements,” he says. “The more they learn about trenchless technology, the more their comfort level increases. It is a lot like much of everything we encounter in life.

“People tend to avoid situations they have little knowledge about and stick with what they know and what’s comfortable for them. As a contractor whose business was built primarily on open-cut, I know all too well the apprehension involved with opening up to HDD. But having done so, we are now able to inform more municipal officials about trenchless and promote more awareness of HDD.

“It isn’t always the best option, but HDD is certainly worthy of viable consideration for nearly all sewer and water installations.”



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