Crossbore Inspection Program

The City of Palo Alto leads the utility industry with its proactive natural gas safety programs.
Starting in 2011, we added a new component to our program---checking privately-owned sewer lines 
to ensure that there are no natural gas lines accidentally crossbored through them.

 Crossbore Situation
Crossbore		  Correct Alignment
Correct alignment

The City of Palo Alto began the crossbore inspection program in July 2011. HydroMaxx LLC is the contractor performing the work. Churches and schools were inspected first and then work began in various downtown neighborhoods. Inspections are expected to continue in locations throughout the City until all sewer lines with possible crossbores have been checked.

Check out this short video recently created by the Mayor's Youth Video Corp to get some background on the crossbore issue and an update on how the City's inspection program is addressing it.

You do not need to take any action right now to arrange for an inspection.  The Hydromax trucks will get to every neighborhood over the course of the program. When they do, if they have any issues accessing your sewer line, they will contact you---typically by leaving a doorhanger asking you to call for an appointment.  Meanwhile, please remember the following:

      • If you have a clogged sewer line, ALWAYS call us first at (650) 329-2579 to have the line checked for a crossbore.
      • If you are planning on digging in your yard, check on where your utility lines are first by calling 811.
      • You can get additional crossbore information in our brochure.
      • If you, your family or your contractor smells natural gas, leave the area and then call 911.

Frequently Asked Questions

  • What is a crossbore? A crossbore exists when one utility line has been drilled or “bored” through a portion of another line. This situation typically happens during construction using “horizontal boring” practices. Our current safety program is focusing on crossbores involving natural gas service lines bored through larger sewer service lines.
  • What is horizontal boring? Instead of digging an open trench in order to install a new service, the pipeline is pulled through an underground tunnel. The tunnel is created using a piece of equipment that cuts through soil and rock. In the 1970s, the City began installing gas service lines on customers’ private property using horizontal boring. This eliminated the need to trench across properties to connect the gas meter at the house to the main gas lines in the street.
  • How can a gas line run through a sewer service line without the utility’s knowledge? Since the tunnel drilling equipment is designed to cut right through rock and other hard surfaces without stopping, it can easily pass through a sewer pipe without giving the operator any indication that this has happened.

What to expect when we're inspecting:

  • What is the City’s current inspection program?  The City has been checking sewers after new gas line installations since 2001 to make sure there were no crossbores. In 2011 we expanded that program to include inspecting for crossbores in sewer lines that were already in place. After inspecting high-occupancy structures, such as schools, churches, hospitals and public meeting places, the City began inspecting individual homes and businesses. There are over 18,000 sewer laterals in Palo Alto that were identified for inspection and many have access problems, so this has been a bigger job than originally anticipated. However, over one third of the inspections have been completed as of January 2013.
  • What is the City’s schedule of crossbore inspections? The City is targeting those areas where gas services have been installed using boring techniques. There are multiple Hydromax USA crews (the City's contractor) doing the inspections and areas often have to be revisited due to accessibility issues. So it is not possible to give an exact schedule of when the contractors will be in a given neighborhood.
  • Will I be notified when my property is inspected? The City's contractor (Hydromax USA) is required to deliver a 7-day advance notice letter to you before they enter your general neighborhood area for the first time. If they are still in your area after 4 weeks, a second notice letter is issued. Our contractor keeps track of all the notices delivered. These notices describe the inspection process and include contact information in case you have questions. However, because the contractor moves up and down the streets, and the time at each home is quite variable, there might be a several week spread between when you receive a notice and when the truck is in front of your particular property.
  • Do the City contractors carry ID? Yes, and you can ask to see it. We have recently been able to produce photo IDs for the contractors, but previously the ID had no photo. Some crew may not yet have their photo ID when you ask, in which case they can show you the City ID and their driver's license. You can and should feel free to call us here at the City if you are ever in doubt about a worker claiming to be a City contractor---that applies in all cases, not just for this crossbore program.
  • What happens if my sewer line can't be easily inspected? In those cases where there were problems accessing the sewer line, the contractor (Hydromax USA) hand delivers a doorhanger notifying the resident of the need to schedule an appointment for an onsite inspection.
  • Will the City pay for a private sewer inspection before the City inspects my private sewer line? The inspection of a private sewer by any person other than the City or its authorized contractors will be conducted at the expense of the private sewer owner.
  • Will the City inspect for crossbores other than sewer and gas? Yes. The City completed a video inspection of the storm water system; several years ago and existing crossbores were fixed. Two years ago the entire city-owned wastewater system was video inspected, and no crossbores were found. Now the City is focusing its attention on potential crossbores in customer sewer lines.

More crossbore background:

    • How many crossbores are in Palo Alto? For inspected gas lines installed since 2000, the City records show no crossbores exist. Further, there were no crossbores found in the sewer laterals serving any of the high-occupancy structures listed above. As for the other residential and commercial properties inspected thus far, approximately 21 gas-sewer crossbores have been identified and repaired. Because Palo Alto has been a national leader in adopting newer and safer construction standards, it likely has fewer crossbore situations than some other utilities. However, our attitude is that no crossbores are acceptable, so we have chosen to be proactive and check all relevant sewer pipes.
    • Are there crossbores involving other utilities? (electric, cable and water)? While other types of crossbores are possible, crossbores involving natural gas are of a greater safety concern. In the case of a sewer line, a crossbore could remain undetected until a clogged sewer is cleared, and the gas line that goes through the service is detected.
    • How many crossbores have resulted in fires or explosion in Palo Alto? None.
    • Is the City now inspecting every sewer line in Palo Alto? No. The City is inspecting only those sewer lines where there was no previous inspection and so an undetected crossbore could exist.
    • How will the City be changing installation and inspection practices in the future so that crossbores are eliminated? The City is conducting a citywide program to inspect laterals that may have been cross bored in the past. Construction and inspection practices to eliminate the possibility of gas line crossboring through a sewer line are already in place for future installations. Current construction practices require video verification of sewer lines after the new gas lines is installed before gas is introduced into these service lines.
    • Doesn’t the building inspection department have to approve the installation or replacement of gas lines to ensure that they are safe? No. Utility owned infrastructure is regulated by the U.S. Department of Transportation and gas infrastructure matters are not subject to local building codes.
    • Doesn’t the City require a permit to move a private sewer line? Yes, however, local building code requirements do not include submitting a final drawing of exactly where the sewer was installed. Also, the homeowner may make additional repairs or changes to the sewer line at a later time. For these reasons, the exact location of a private sewer line is still not known even if there was a permit for the line.
    • Will I see higher gas or wastewater rates as a result of this program? No, this program is funded through the Utilities Department's existing preventative maintenance program.
    • What will it cost to fix this problem? Council originally approved $3,800,000 to complete an inspection of sewer laterals. Since there are more laterals, and more complicated inspection situations, than originally anticipated, additional funding will be required before the program finishes in 2014.
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