Trenchless professionals are collaborating to find a solution to utilitycross-bores — particularly those involving gas lines installed through sewerlaterals. As concerns mount about damage prevention, public safety andliability, a solution is in the works. That solution appears to be, well, acombination of solutions that will help prevent future incidents and approachhow to attack legacy cross-bores.
Trenchless professionals involved with engineering, contracting andmanufacturing have put their heads together to address cross-bores in aproactive yet sensitive way. Those cross-bore crusaders are working together,one-on-one and through organizations such as NASTT, Common Ground Alliance (CGA)and DCA.
Gas line-through-sewer lateral cross-bores have been identified as a prioritybecause of their surreptitious threat. Sewer laterals clog. Sometimes the clogis a result of a gas line cross-bore and sometimes not. A typical fix employs amechanical drain cleaning device designed to cut through roots and other debristo clear the stoppage. If that device pierces a gas line that was cross-boredthrough the sewer lateral, the result can be explosive and catastrophic.
All underground construction involving drilling faces a potential cross-bore,says Kevin Miller, president of Miller Pipeline, a gas utility contractor inIndiana. When any other utility is pierced during a gas line installation, theeffects are immediate.
“If you hit a water main, it breaks and you know it,” Miller says. “If youhit a gas main, it breaks and you know it. If you hit a telephone cable, peoplestart coming out of their houses and say ‘Hey, my phone quit working,’ andeverybody knows it.”
Sewer laterals are different.
Gas line installers who use trenchless methods often don’t know when they hita sewer lateral. Laterals are not pressurized so the damage is not readilyapparent when the lines are pierced. The sewer line usually can functionnormally afterward. The danger lies hidden like a mine along an otherwise saferoad.
The approach to solving cross-bores — elimination and prevention — thus farhas been education. Trenchless leaders have been mounting a sort of “get out thevote” campaign against cross-bores for the past five years. What started asreluctance about addressing the issue has transformed into acceptance thatsomething must be done.
The trenchless industry has been slow to act on cross-bores, but thatslowness is a result of spreading the message while remaining sensitive.Trenchless professionals say that they don’t want to run around like ChickenLittle with cross-bores because it could generate fear among customers and be adetriment to the industry.
Those who have been proactive about addressing cross-bores say that they haveto be proactive and sensitive at the same time.
That approach is important for sharing information about the issue whilemaintaining a reasonable discourse, says Dr. Samuel Ariaratnam, associateprofessor of construction and engineering at Arizona State University.
“People need to understand the ramifications of what the cross-bore issuesare and the other issues related to them,” Ariaratnam says. “We have to besensitive to the case that it has to be framed in such a way. We don’t want toall of a sudden have these big alarms going off that people point the finger attrenchless methods.”
Ariaratnam has worked with several groups that are facing cross-bores. Heteamed with NPL Construction Co. in Arizona to create an educational video aboutcross-bores starring the animated trenchless guru “Gopher Gus.” The video hasbeen presented to various stakeholders in the trenchless industry to help raiseawareness about cross-bores. Ariaratnam recently finished work on a riskmanagement software program, which he developed along with Jeffrey Sedillos, aformer energy industry professional. The software can be used to assess possiblehigh-risk areas for cross-bores. Ariaratnam also talks to his students aboutcross-bores.
The educational process is long term and ever-evolving, Miller says.Cooperation between trenchless groups can help minimize the risk of cross-bores,but he says that human error must be kept in mind.
“People are prone to make mistakes,” Miller says, “but I think the risk canbe greatly reduced to almost no risk at all if everybody does their part.”
Location, Location, Location
Pre-installation locating of existing utilities is an integral part ofsolving cross-bores. However, so many factors come into play that those locatesare often faulty. Poor existing pipeline records, inadequate technology,improper techniques and legislation regarding locating responsibilities varyingfrom state to state are just some of the causes for bad locates.
Federal regulations, such as GASB-34, have already mandated thatmunicipalities keep better inventory of underground infrastructure to qualifyfor capital improvement funding, prompting municipalities to remap pipelinesystems and keep more accurate records of infrastructure.
Some solutions to the technology issue are already in the works (see Part IIof “Facing Cross-Bores,” Trenchless Technology, November). Innovationssuch as ground penetrating radar and digital tomography are just some of theadvances that could be employed to create more accurate locating devices in thenear future.
Improper locating and marking techniques can be solved with better training.One improvement, Miller says, would be to include the entire sewer lateralthrough the property.
The biggest issue, Ariaratnam argues, is the legislation about locating.Legislation is often unclear about who is responsible for locating whatutilities. Sewer laterals by in large are omitted from most state locate laws.
“Legislation really needs to spell it out a lot clearer as to who theresponsible party should be,” Ariaratnam says. “In my opinion, it should be thesystem owner-operator.”
Sewer laterals are considered to be on private property, Ariaratnam says.That classification has caused confusion as to who owns those pipes and whoshould locate and mark them. Ariaratnam says the homeowner should be spared theresponsibility.
“The responsibility for marking and locating sewer laterals and facilitieslike that really lies in the hands of the people in the best position to locatethose,” Ariaratnam says. “That is really the owner-operator of the system or, inother words, the people who are generating the revenue from the sewer laterals.The private homeowner is just not equipped with the technology or the ability tolocate those.”
Legislation about locating varies between states, Ariaratnam says, and thatcreates even more confusion.
“If there was a little more uniformity in that, it would certainly help,”Ariaratnam says, “particularly when you have contractors that [operate] more atthe national level. They’re working in different states or multiple state areasand they have to deal with different legislations and that makes it moredifficult in terms of what their roles and responsibilities are. We need to haveclearer statutes on that.”
However, with no widely accepted responsible party for locating sewerlaterals, Ariaratnam says that the gas contractors are taking the brunt of theduties while most sewer owner-operators have avoided the cost burden.
Unfortunately, the quickest way to attack cross-bores might be that gasutilities and contractors shoulder the cost, Miller says, suggesting that gasutilities mandate that its contractors provide location and verificationservices for all projects.
“I don’t think we can wait around for laws to go into effect,” Miller says.“I think we should eliminate the risk out of the box right now and keep workingon the laws. Hopefully, there will be a point in time where the cost can betransitioned over to the sewer owners.”
Miller Pipeline instituted a policy to locate and verify sewer lateralsbefore and sometimes after the company installs a gas line. Miller uses cameraequipment and electronic sondes to locate sewer laterals from the building,through the yard to the sewer main. Although this policy does add equipment andlabor costs, Miller says it’s worth it.
“If you can directional drill a large project, then it’s cost-effective forthe gas company,” Miller says. “Rather than not being able to bore, if the gasutility goes ahead and pays for the service of having those sewer lateralslocated, it’s going to add several dollars per foot to the install, but it’sstill the most economical way to go.”
Liability Takes a Bite
Insurance liability is a major concern for contractors involved withtrenchless technology. When a utility is damaged, contractors feel the hit intheir billfold.
Insurers for underground construction are few and costs are high, Millersays. Minimizing the risk of cross-bores is one way that contractors can makethemselves a better customer to an insurance company, which in turn will lowerinsurance costs.
Cross-bores already are creating higher rates for trenchless contractors,Ariaratnam says, who describes the rate increase as a domino effect. “We have tostop it in front of the domino,” he says.
Practice Makes Perfect
Best practices and training can help contractors — and all stakeholders inthe industry — better prepare for cross-bores. Organizations such as CGA, DCAand NASTT have promoted these practices and programs to prevent damage andimprove risk management. Early next year, NASTT plans to introduce cross-borespecific best practices, the development of which has been part of its newlyformed Cross-Bore Committee.
Such educational measures are another way that the trenchless industry can bemore proactive about cross-bores, Ariaratnam says. Trenchless methods are aviable option and he wants to avoid any negative knee-jerk reaction byaddressing cross-bores in view of existing and future cross-bores.
Existing cross-bores first need recognition by the industry, particularlyplumbers, Ariaratnam says. When sewer laterals back up, it’s plumbers who areusually the first responders. They need to be more aware of the dangers of usinga mechanical drain cleaning device that could discover a gas line cross-bore inthe worst possible way.
Miller agrees, adding that before a plumber uses such a device that the gascompany or contractor be notified so that they can verify that the sewer lateralhas not been cross-bored. He also thinks that a safety plug could be installedon drain cleaning devices that could block gas from escaping back toward thehouse if a gas line were hit.
To address future cross-bores, Ariaratnam says that there needs to be moreresearch and development, better technologies for locating non-metallic pipe andcoordination between owners and contractors.
Putting best practices in place creates a road map for contractors to reducerisks and improve public safety, which Ariaratnam says is the ultimate goal insolving cross-bores.
Through a combination of tools, education, clearer legislation and soundconstruction practices and the coordination between all the stakeholders in thetrenchless industry, that goal can be met head on.
Bradley Kramer is assistant editor of Trenchless Technology.