Non-Destructive Exposing of Buried Energized Lines

Mike McGarry

In the past few years, Hydrovacs and "daylighting" have gained industry acceptance by minimizing the challenges of exposing underground pipelines, fiber-optics, and utilities. "Daylighting" is a non-destructive process using pressurized water (hydro) and a vacuum system (vac) to remove soil cover, thereby allowing a visual observation of underground lines. Hydrovacs expose these facilities to daylight, thus the term "daylighting".

Pressurized water through a hand-held wand liquifies the soil cover while the resulting slurry, composed of water and earth, is sucked through a debris hose by a powerful vacuum system into a debris tank on a self-contained truck. The exposed lines can now be identified and/or repairs completed.

Alberta Occupational Health and Safety recognizes Hydrovacs as the only acceptable and safe alternative to hand exposing, and they can be up to ten times faster. Hydrovacs provide a cost-effective and safe excavating solution around energized lines. In hard-to-reach locations, some Hydrovacs can dig by remote access up to 400 feet away. Their precise excavations preserve landscaped property, minimize ground disturbance and greatly reduce backfill and restoration costs. Applications can include power pole holes, trenching and test holes. The most efficient Hydrovacs carry on-board heaters capable of heating the water to allow excavating in frozen earth to any depth of ground frost, thus eliminating the need for gound thawing.

In working for non-electrical utilities (gas, telephone, water/sewer, etc.) Hydrovacs expose energized lines on a daily basis. Water and electricity obviously do not mix and very specific safe-work procedures must be followed for Hydrovacs to expose these lines. Proactive Hydrovac procedures should be written in accordance with Compentent Persons training, electrical awareness training and trench safety.

Badger Daylighting's Safety Coordinator Mac MacIntyre has recently written Equal Potential Bonding Hydrovac procedures in cooperation with TransAlta's Electrical Training School to ensure safe work practices around energized lines. By assisting companies with the testing and writing of specific Hydrovac procedures, the safety of personnel is ensured and the risk of damages to buried lines is minimized.