Palo Alto Institutes Pro-Active Plan To Locate, Correct Crossbores

April 2012, Vol. 67 No. 4

As crossbores continue to cause concern and controversy across the United States, the city of Palo Alto, CA, is taking a pro-active approach to find gas lines that have penetrated sewer laterals during installation by horizontal directional drilling (HDD), and to correct the problem before a costly and dangerous accident can occur.

In July 2011, Palo Alto initiated a program to make closed-circuit television inspections of every sewer lateral in the city where HDD gas installations have been made near a lateral. A separate program ensures that a new crossbore is immediately discovered -- the city requires inspection of a lateral after a gas line has been installed by directional drilling in proximity of the lateral to confirm no crossbore has occurred or to correct it if one is discovered.

Inspections of laterals serving schools, hospitals and other public buildings actually began last spring before the crossbore program was approved, said Greg Scoby, engineering manager, Palo Alto Water, Gas, and Wastewater Utilities Department. Inspection of residential laterals followed. Contractor HydroMax USA is making the inspections.

By the first week of March 2012, approximately 4,000 laterals had been inspected, said Scoby.

“Four gas crossbores have been found to date and repaired upon discovery,” Scoby said. “Seven additional non-gas crossbores were also found. All were telecommunications conduit.”

At the present rate of inspections, Scoby estimated all laterals with potential of containing gas crossbores will be inspected and any crossbores found corrected by December 2012.

City-owned utilities

Palo Alto’s program to eliminate crossbores is simplified by the fact the city is one of the few municipalities in the country that owns and operates basic utility services, including water, wastewater, electric and natural gas distribution, and dark fiber optic cable infrastructure. With sewer laterals and gas distribution operated by the same entity, communication between water and gas personnel is improved, simplifying the task for finding and correcting crossbores.

Many cities have been sharply criticized for avoiding responsibility for crossbores by taking the position that sewer laterals are the responsibility of property owners. Palo Alto has a different perspective.

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