In St. Paul MN in 2010, a plumber called to unclog a sewer line at a home struck a gas line that had been installed through a sewer lateral to the house almost two decades earlier. A young woman lost her home in this tragic accident.
As a direct result of this incident, the Minnesota Office of Pipeline Safety mandated its gas utilities inspect sewer laterals for all future trenchless excavation installations. The order also mandated inspection of all laterals installed in a trenchless manner prior to the 2010 explosion.
These pre-construction sewer lateral inspections are designed to detect potentially dangerous cross bores by marking location and depth of all existing and abandoned sewer lines. Sophisticated automated cameras outfitted with sondes transmitting their location data probe the depths of sewer mains as a locator tech follows its progress from street level, communicating with the camera operator in their truck. A lateral launch camera is extended from the primary camera where the locator above ground detects the laterals’ locations off the sewer main.
Once laterals are verified as clear of any cross bores or other debris, the collected depths and location information are passed along to the utility contractor conducting the planned trenchless excavation.
Throughout the video, we present (via special guest Eric Bergstrom of HBK Engineering) how sewer inspections fit within the framework of SUE – Subsurface Utility Engineering. With each level of SUE, more accuracy is achieved in the locating process.
Mike Parilac, owner of Planet Underground and Staking University helps explain the theory behind how locating equipment provides accurate location and depth information as sewer lines are inspected.
From The Roundtable 2017, Blood Hound’s Tracy Pursell comments on the potential benefits for dollars invested in SUE and the increasing move by facility owners to require inspections of laterals to homes as part of cross bore prevention. Pipe View’s Tony Barger is also part of the discussion.
One common thread among all the inspection team is the great pride they take in safeguarding workers and the public.