Bell Holing

Bell holing differs from potholing in that the excavation is typically larger and shaped to provide working clearance around a specific component of a buried utility. The hole is widened at the bottom to give workers room to access, inspect, or repair the target point, creating the characteristic bell shape that gives the technique its name.

This method is frequently used by pipeline operators and gas utilities to expose pipe joints for integrity inspections, cathodic protection testing, or leak repair. Bell holing with a hydrovac is far safer than using a backhoe or hand tools near pressurized pipelines, as the water jet is much less likely to damage steel, polyethylene, or PVC pipe when used at appropriate pressure settings. Too much pressure, or hot water near plastic pipe, can still cause damage.

Bell holes are commonly required during pipeline integrity management programs mandated by federal regulations such as 49 CFR Part 192 for gas pipelines and Part 195 for hazardous liquid pipelines. The non-destructive nature of hydrovac bell holing makes it the preferred method for exposing high-consequence pipeline segments.