A gas leak blew away a section of this San Bruno neighborhood, killing 8 and destroying 38 homes. The NTSB wants to find out if anyone knew a gas line failure was imminent. (Photo courtesy Current.com)
Mammoth should exercise “diligence,” Heller says
Are aging gas pipelines actually ticking time bombs, waiting to explode and level entire neighborhoods? Could the same thing happen in Mammoth Lakes which happened in San Bruno, Calif. last fall? A line failure there caused an explosion, which killed eight people and destroyed 38 homes in a suburban subdivision. Since then, earlier this year, other explosions leading to fatalities have occurred in Pennsylvania — one in Allentown and another in Philadelphia.
The National Transportation Safety Board (NTSB), which has ultimate jurisdiction over the country’s gas pipeline infrastructure, began a rare three-day public hearing in Washington, D.C. this past week, holding discussions about general pipeline safety. The last time the NTSB held a pipeline safety hearing was in November 2000.
NTSB officials are still probing the failure of a section of San Bruno pipeline. The section that ruptured and set off a blast was 50 years old, and across the country, there are thousands more like it. Since 1990, federal officials have reported more than 2,800 “significant” gas pipeline accidents, which either didn’t result in fatalities or ended up as potential crises that were averted.
“There are 2.5 million miles of pipeline all over this country, and on average there’s a significant pipeline incident every other day,” Carl Weimer, Director for the Pipeline Safety Trust, told NPR. Pipeline Safety Trust is an advocacy group based in Bellingham, Wash.
The best way to detect a natural gas leak is to conduct a leak survey, which is done with various types of “gas sniffers” and surveys that can pinpoint where a leak is happening, both up to the outside wall of a structure and the service line leading into it. Propane is colorless, odorless, tasteless and non-toxic, but providers add a chemical that gives it a unique sulphur-like smell.
A local look
In our state, the California Public Utilities Commission (CPUC) is charged with inspecting the propane pipeline system to ensure compliance with federal safety rules.
Local providers and officials periodically survey delivery systems situated both above and below ground, but leaks can result from corrosion, snow, ice, equipment failures (particularly valves) and natural events, such as earthquakes. Any steel piping is protected by a system that is supposed to inhibit corrosion, but is monitored on a “routine basis” just to be on the safe side.
In a public awareness letter dated Jan. 30, Turner Propane officials said, “The greatest risk to underground pipelines is damage caused by excavation.”
Excavation could mean anything from general construction digging, to snow and ice removal. In the case of lines that are buried but close to the surface, punctures can occur from putting in snow stakes. “What are the odds of that happening? Not great, but it does happen,” said Mammoth Lakes Fire Protection District (MLFD) Division Chief and Fire Marshal Thom Heller.
MLFD and the Town of Mammoth provide oversight for the franchise line underground, and the Fire District is the oversight for the tanks and tank farms above ground. Heller said users are not required to hook up to the franchise line, but doing so where available does eliminate the tank being in the yard and addresses other potential issues, such as exposed meters and deliveries, etc.
Sheet: Is there any reason we should be as concerned as other parts of the country when it comes to our own gas network?
Heller: The franchise line here is relatively new. It’s a plastic line system, and doesn’t have the steel construction and seam issues that are found in other parts of the country. And we use propane, which is delivered at 14-15 pounds of pressure, whereas natural gas typically is at 350-400 pounds. Propane is heavier than air, as opposed to natural gas, which is lighter than air, which requires significantly more pressure to push it through the network.
(Heller pointed out that the San Bruno line was pressurized at about 396 pounds when the section failed.)
Other safety devices such as isolation valves are now required in Mammoth, and Heller said local providers are working with the district and the Town on getting them installed.
Heller said that the devastation may have been on a smaller scale, but between 1992 and 1994, two fatalities occurred and several homes were destroyed prior to revising Mammoth’s gas codes. Since then, Heller said lesser, but no less dangerous events have occurred. “Diligence is a constant for us if we choose to use propane,” he advised.
In the wake of the recent deadly pipeline blast and other serious leaks in Michigan and Illinois, the secrecy surrounding the nation’s 2.5-million-mile network of gas transmission lines is facing criticism. Before 9/11, there were no restrictions on who could look at maps of the nation’s gas pipelines. Since then, access to that data has been limited to industry, and local, state and federal officials. The fed has also asked utilities to remove from their websites maps of pipeline infrastructure, tens of thousands of miles of which go through densely populated areas.
Meanwhile, the MLFD and service providers issued the following reminders to all propane users. It’s required that everyone install propane detectors in any crawlspaces and lowest habitable places in any home or business. If you think a leak may be present, find your shutoff valve if at all possible. Don’t light matches or use any devices that may causes sparks, evacuate people and pets from the building and contact your propane service provide and the Mammoth Lakes Fire Department from a neighbor’s or other phone. Keep emergency numbers handy. Make sure that regulators and shut off valves on above ground tanks are clear of snow and ice.
Additional sources: Washington Independent, FOX News and National Public Radio.