Information and access to the site of a liquefied natural gas (LNG) storage tank explosion and fire in Washington state was restricted on Tuesday as company, state and federal representatives waited for an “all-clear” from facility operator Williams’ Northwest Pipeline Co.

The cause of the explosion, which occurred Monday morning at the two-tank LNG storage facility (see Daily GPI, March 31), was unknown a day after investigators began arriving at the site near Plymouth, WA, along the Columbia River. The fire had been extinguished by 2 a.m. Tuesday.

A Salt Lake City-based Williams spokesperson told NGI Tuesday that there was no no information on the possible cause of the incident in one of the two 1.2 Bcf-capacity storage tanks, and that the plant’s shutdown would have no impact on Northwest Pipeline’s 4,000-mile interstate gas pipeline network in the Pacific Northwest.

There were no immediate impacts on the regional gas pipeline grid due to the storage facility shutdown.

The Washington Utilities and Transportation Commission (WUTC) said its pipeline safety investigator, along with an accident coordinator from the U.S. Transportation Department’s Pipeline and Hazardous Materials Safety Administration (PHMSA), continued their work Tuesday, despite the fact that they could not get access to the facility.

“Williams personnel and local public safety authorities are working to establish safe access,” a WUTC spokesman said. The state regulators’ investigator, a pipeline engineer, said there were “ongoing safety concerns” preventing the inspectors’ access.

The Williams’ spokesperson said five workers initially were injured but only one person was transported to a Portland, OR, for hospital care. The other four workers were treated at the site and released. Residents in the area who had been evacuated were allowed to return to their homes Tuesday afternoon.