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Southwest Gas executives claim record-keeping issue for piping with history of degradation caused two major gas leaks in the Valley

Southwest Gas executives told the Arizona Corporate Commission the M-8000 pipe was mislabeled and should have been replaced between 1999 and 2001.

PHOENIX — Southwest Gas executives faced an onslaught of questions from the Arizona Corporation Commission (ACC) on why Valley communities have experienced three major gas leaks in less than a year.

Timeline of incidents leading to the ACC hearing

In February, a ruptured gas line caused flames to erupt underneath the 7th Street Bridge over the Salt River between Broadway and the I-17. Six months later the bridge has reopened. 

Last month, the gas company found that a faulty pipe and human error lead to the Chandler Platinum Printing Company explosion. The blast sent four men to the hospital with serious burn injuries. 

Just weeks ago, at least 20 homes in a north Scottsdale neighborhood near McDowell Mountain Ranch Road and Paradise Lane were evacuated after reports of an underground gas leak. 

Executives told the commissioner the gas explosion in August at the Platinum Printing Company and leak in north Scottsdale were due to piping that should have been replaced between 1999 and 2001.

“The pipe in question was a 1-inch Driscopipe M-8000,” Luis Frisby, Vice President of Central Arizona Division for Southwest Gas told the commission members. 

What is Driscopipe M-8000 and why is it potentially an issue?

The small plastic piping is primarily made of nylon and in 2012, the Pipeline and Hazardous Safety Materials Administration (PHMSA) issued an advisory the model could degrade under high temperatures. 

Southwest Gas said it first became aware of the potential issues in 2005. Three years later they received they reported their first gas leak due to internal degradations. In 2010, executives said they understood there were issues with the pipe due to extreme heat environments. 

Mislabeled pipes led to records error

Although company executives knew of the potential issues and inspected for leaks, they told the commission the leaking pipes were labeled at M-8100 pipes which replaced the older models between 1999 and 2001. 

“We have discovered an error in the construction records misidentified the type of gas pipe used when facilities were extended to the commercial complex," said Frisby. "This information was then placed in our mapping system which labeled the pipe material as M-8100.”  

What is the company doing now to avoid others leaks and major incidents?

Executives told the commission they are now reviewing records for all piping between 1999 and 2001 in the high-temperature areas of greater Phoenix, Bullhead City and Yuma. 

“Southwest Gas transition to the M-8000 pipe material to the M-8100 during the 1999 to 2001 timeframe,” said Frisby. 

The company is now treating all plastic piping installed in those three years as M-8000 pipe. They are also conducting mobile patrols and educating customers on gas leaks. 

When Commissioner Sandra Kennedy asked the company CEO John Hester on the probability of another incident similar to Chandler occurring, he told her "essentially zero," due to only two or three leaks reported every year. 

What about the 7th Street Bridge leak and fire? 

Executives told the commission the gas leak had nothing to do with M-8000 piping and that an ongoing investigation so far has found tampering with the piping.

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