Directional drilling is a fast and efficient way to install underground pipe and conduit, but when a gas line is bored through a sewer lateral, disaster can ensue.

Cross bores — when a line bores through a sewer line — has been the cause of catastrophic events in the past. As a result, utilities, municipalities, contractors, and the trenchless industry are joining forces to ensure proper pre- and post-inspections are conducted and disaster is avoided.

“There are always more connections than what surface observation suggests,” says Jason Walborn, business development manager for Professional Pipe Services, or Pro Pipe, headquartered in Mission Viejo, California. “I have seen typical streets that have, for example, eight homes, eight clean-outs and eight green corresponding lateral marks from an 811 call. The reality, however, is that subsurface there are more like 10 sewer laterals. We are doing everything we can to coach facility owners on how to spatially map their subsurface infrastructure during routine maintenance to improve accuracy for 811 locate requests.”

Camera systems using lateral launch technology have made an incredible impact on finding those missing conditions. “We use state-of-the-art lateral launch cameras to locate potential cross bores in the laterals prior to the commencement of drilling,” Walborn says. “Cameras are launched from the main up each lateral to identify and record potential conflicts. The data, including GPS position and time stamp, are captured, recorded, and provided to the utility or system owner to address and/or proceed with the drilling. Equally important, however, is the process of post-drill inspection to confirm laterals have not been breached during the installation of the utility.”

While gas or communication lines are typically the utilities most of us think of when we hear the term cross bore, directional drilling of other utilities can negatively impact the integrity of laterals as well. Jerry Weimer of Jerry Weimer Consulting, formerly the wastewater collection supervisor for the city of Cincinnati, wrote the Cross Bore Prevention Detection Program for Cincinnati. He shared how waterlines, installed using directional drilling, compromised laterals during his employment for the city.

“Those waterlines hit just about every lateral,” Weimer says. “The city started getting calls. One house would back up, then the next, and so on — it was like a game of dominoes. Since the compromised pipes were waterlines, they were not part of the Cross Bore Prevention Program, as no real prevention, detection or standards were in place for installing this type of utility.”

The partnership between utility owners and municipalities is critical if cross-bore events are to be identified and addressed appropriately to keep our communities safe. Weimer also shared how the city of Cincinnati and Duke Energy came together to develop a comprehensive and mutually-beneficial cross-bore program. “It is rather uncommon for a city and utility to work so closely together on cross-bore prevention,” Weimer says. “In this case, both Duke Energy and the city recognized the importance of a comprehensive prevention program, so they shared the costs to get cross-bore inspection work done economically and responsibly. Since the city is under consent decree to televise a certain number of feet of pipe, it gets the assessment data needed while sharing the cost with Duke Energy. It’s a win-win for the city, the utility and the customers.”

NASSCO, whose mission is to set standards for the assessment, maintenance, and rehabilitation of underground infrastructure, identified the need to set standards for proper cross-bore prevention and detection. As a result, NASSCO recently introduced a cross-bore work group to address this topic. Specifically, the work group is developing protocol targeted to operators when cross bores are found during routine sewer inspection and cleaning.

“The worst thing that can happen is an operator runs across a cross bore and doesn’t do anything,” says Weimer, who also serves on NASSCO’s cross-bore work group along with Walborn.

“Our job is to get standard processes in place to support operators in identifying cross bores and provide the proper protocol to report them quickly to protect the public, the operator, the plumbers and the public,” Walborn says. “Awareness is the No. 1 objective of our work group.”

The standard assessment and cleaning of mainlines and lateral lines could also potentially uncover cross bores masked by roots. If a cross bore is hiding behind roots that have infiltrated the pipe and the roots are then cut, disaster could ensue.

“A significant benefit of a regular chemical root control maintenance program is the ability to kill the roots without cutting or damaging the pipe,” says Mike Hogan, president of Duke’s Root Control. “Our product, for example, which has a thick, shaving-cream consistency, is released from a manhole into the main, killing roots in the entire system. The foam compresses pipe surfaces, penetrates cracks, joints and the connecting sewers. Killing roots in laterals using chemical root control assists in identifying and revealing laterals compromised by cross bores without mistakenly cutting the roots away and breaking through a gas or other utility line.”

In addition to municipalities and utilities working closely together, the relationship between utilities and contractors is extremely important for the implementation of a successful cross-bore program.

Harley Peterson, a project manager with the SoCalGas Sewer Lateral Inspection Program, shares the importance of his relationship with contractors. “We work with a few contractors on our cross-bore program,” he says. “Pro Pipe is the largest contractor and does the majority of the work. We started working with them back in 2011, and the reason our relationship has been so successful is because of our mutual partnership and Pro Pipe’s willingness to adapt to our needs. Pro Pipe has their own fleet of camera trucks and crews, so we never need to wait to get out into the field. They also work with us to identify challenges and develop unique solutions. The result has been better quality data and a higher level of confidence that we are keeping homes and business protected.”

The most common question pertaining to cross-bore inspection and remediation is always who is responsible. The answer: When it comes to keeping our communities safe, we all are.