Why did it take 16 hours to shut off the natural gas at the explosion site?
A – NorthWestern Energy employees at the scene worked with emergency responders to determine the appropriate strategy to shut off natural gas at the explosion site. It was determined that shutting down the zone and disrupting service to thousands of natural gas customers was not needed. Crews worked to shut off gas to the affected area by installing valves and stopper fittings on either side of the main. A third valve was needed after crews found that the gas wasn’t depressurizing as expected. In the chaos of the event, crews overlooked the presence of a connector between two gas mains in the area. While initially NorthWestern Energy spokespeople said the map didn’t show the connector, it actually was indicated on the map; however, it was overlooked in the initial response. This misread of the map resulted in the installation of a third valve, which took another four hours to install.
