Report Blames CenterPoint for 2010 Edina House Explosion

An investigation into a 2010 Edina house explosion places blame on a lengthy shutdown process and misidentified lines, among other issues, according to a Monday release from the Minnesota Department of Public Safety’s Office of Pipeline Safety.

TD&I Cable Maintenance hit a natural gas line while installing a telephone cable Feb. 23, 2010. That caused a release of natural gas underground, and emergency workers began evacuating the area. While the evacuation was still in progress, a home at 5000 Arden Ave. exploded.

Nobody was hurt, but people felt the blast from several blocks away.

The investigation concluded that natural gas went through the soil, under the frost cap, and into the Arden Avenue home—where an unknown ignition source caused it to explode.

TD&I Cable did call Gopher State One Call—which locates utilities for people who are digging—before crews began work, according to the report. But workers inadvertently hit the line because there were two natural gas pipelines close to one another in the area where they were digging.

One of the pipelines was an abandoned line that had not been marked in response to a Gopher State One Call ticket request. Workers found the first line but kept digging because they were unaware there was a second line nearby. As they continued excavating under the line, they hit the second, active line.

Crews alerted authorities after hitting the line, but CenterPoint Energy did not shut off the gas for more than eight hours after workers hit the line and more than six hours after the house exploded. Although it could have used its 50th Street emergency valves, the company’s valve spacing meant a gas cut-off would result in an outage for 266,000 customers.

Instead, CenterPoint opted to squeeze off the gas in the plastic pipelines and put a stopper in the main steel pipeline. In addition to the house that exploded, another house in the area filled with gas but did not explode.

The Office of Pipeline Safety initially fined CenterPoint $1 million based on “probable violations” arising from the company’s procedures and emergency response actions.

Since the explosion, CenterPoint has bought new equipment for handling pipeline emergency and reviewed the adequacy of its emergency valve spacing, including 78 new valves in 2012. It has also created new engineering standards for valve installation on new projects.

CenterPoint’s fine has since been reduced from $1 million to $50,000.