April 2010, Vol. 22, No.4

Safety Corner

Safety In and Out of the Trenches

John W. Bannen

Beginning in the late 1980s, in situ pipeline and manhole rehabilitation technology had developed rapidly, advancing through the growing use of cured-in-place pipe, sliplining, and hydroexcavation techniques. Along with these technologies came a new term of art, “trenchless technology,” which refers to underground excavation work performed without the need for continuous open trenches.

As trenchless technology grew, the consensus was that these methods provided a greater degree of safety by removing the workers from the trench. Instead, machines are allowed to perform the hazardous below-ground-level tasks. These benefits are on top of trenchless technology’s driving force: saving costs in underground operations in congested city rights-of-way and easements.

Even with reducing the numbers of workers present and exposed to hazards, job site safety and hazard recognition remain the focal points of trenchless safety. Workers are expected to be proficient and safe in the operation of the equipment. However, overall job site safety also must be addressed. Employers must continue to address all hazards within a location, such as traffic control, high noise levels from equipment, and traditional trench safety.

Often pot-holing and small excavations must be made to verify the exact location of underground utilities and that new lines are a safe distance away. Even though these excavations often are too small to enable a person to enter the excavation, employers still need to ensure that the provisions of the U.S. Occupational Safety and Health Administration construction standards for excavations (29 CFR 1926, Subpart P) are met.

Know Before You Dig          

With trenchless technologies, the exact location of other utility lines is a critical component to hazard awareness for workers onsite.

Under current laws, all states are required to have a “one-call” system for utility notification and location of underground utilities before beginning underground work. The laws apply equally to trenchless technologies and traditional trench and excavation work. Information on individual states’ call numbers and general “miss utility” information can be obtained at www.call811.com, a Web site created and maintained by the Common Ground Alliance (Alexandria, Va.).

Because of the high hazards due to possible contact with energized electrical lines or the fire and explosion hazard of contact with underground gas, oil, or fuel lines, companies performing this type of work should have effective pipeline damage prevention programs.

The U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) offers guidance for these types of programs. On Oct. 29, 2009, PHMSA issued an advance notice of proposed rulemaking (74 FR 55797) for a regulation to increase the enforcement and criteria for damage prevention laws. Current evaluation by PHMSA has concluded that the one-call system in place is not effective.

Strong Safety

However, within the trenchless technology industry, manufacturers and the companies that perform this type of work in the wastewater industry have developed safe work-performance standards through consensus. To date, there has been minimal regulatory guidance for these activities. It has been the effort of the trenchless technology industry and the strong safety ethic of the companies using this technology that have been the driving force to keep workers safe.


John W. Bannen is the Western Region health and safety advisor in the Gilbert, Ariz., office of Severn Trent Services (Fort Washington, Pa.). 


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