The City of Palo Alto is a utility industry leader in delivering a pro-active natural gas safety and inspection program. One area that was added to the program is checking sewer lines for crossbores, where one utility line is bored through another one. Sewer service lines in the City are being inspected with a television camera to ensure that there are no crossbored natural gas lines in privately owned sewer lines.
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The City of Palo Alto began the crossbore inspection program in July 2011. HydroMaxx LLC is the contractor performing the work. All churches and schools in the city were inspected first. By October 2011 work had begun in various downtown neighborhoods and will continue through 2012 and possibly early 2013, in locations throughout the City until all sewer lines with possible crossbores have been checked.
The following short video gives on overview of the crossbore issue and how the inspection program will address it:
Cross Bore Safety Video
You do not need to do anything right now. However, if you are going to clear a clog in your sewer service line, first call us at (650) 496-6995 to have the line checked for a crossbore.
As always, if you are planning on digging in your yard, check on where your utility lines are first by calling 811. If you, your family or your contractor smell natural gas, leave the area and then call 911. You can get additional information in our brochure here.
Frequently Asked Questions:
Answer: 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?
Answer: Instead of digging an open trench in order to install a new service, the pipeline is pulled through a tunnel that has been drilled underground. The tunnel is created using a piece of equipment that cuts through soil and rock. In the 1970s, the City of Palo Alto began installing gas service lines on customers’ private property using horizontal boring to eliminate 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?
Answer: Since the tunnel drilling equipment is designed to cut right through rock and other hard surfaces without stopping, it can pass through a sewer pipe without the equipment operator knowing it.
- Why is the City addressing the crossbore issue now?
Answer: The City has been checking new utility installations since 2001, and it is now expanding the existing program to inspect sewer lines in place.
- What is the City’s current inspection program?
Answer: The first locations that were video inspected include high occupancy structures, such as schools, churches, hospitals and public meeting places. These were completed in summer 2011. Other parts of town were inspected after these were completed.
- How many crossbores are in Palo Alto?
Answer: We are not aware of any existing crossbores in the system. For gas lines installed since 2000, the City has inspection records and no crossbores exist in those inspected lines. 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 even one crossbore is too many, so we have chosen to be proactive and check all relevant sewer pipes.
- Are there crossbores involving other utilities? (Electric, cable and water)
Answer: While it is 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.
- Will the City inspect for crossbores other than sewer and gas?
Answer: 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 lines.
- How many crossbores have resulted in fires or explosion in Palo Alto?
Answer: None.
- Will the City inspect every sewer line in Palo Alto?
Answer: No. The City is proposing to inspect only those sewer lines where a crossbore may exist.
- What is the City’s schedule of crossbore inspections?
Answer: The City is targeting those areas where gas services have been installed using boring techniques. The schedule will not be available until July 2011.
- Which sites (schools, churches) has the City inspected so far?
Answer: The City made the high occupancy structures such as schools, hospitals and other public meeting places its first priority.
- Does the City plan to inspect hospitals and nursing homes?
Answer: Yes, all these locations have been inspected.
- Will the City pay for a private sewer inspection before the City inspects my private sewer line?
Answer: 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.
- How will the City be changing installation and inspection practices in the future so that crossbores are eliminated?
Answer: The City is planning on 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?
Answer: 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?
Answer: 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?
Answer: No, this program is being funded through the Utilities Department’s existing preventative maintenance program.
- What will it cost to fix this problem?
Answer: City Council allocated $3,800,000 in July 2011 to complete an inspection of sewer laterals and repair any crossbores found.
- What will be the source of funds for this project?
Answer: The Utilities Department budgeted for this in Fiscal Year 2012’s budget, which began in July 2011.
