Plymouth residents were allowed to return to their homes Tuesday as liquefied natural gas continued to leak from a storage tank more than a day after a violent explosion shook the town.
Northwest Pipeline employees and fire crews were able to put out a large blaze early Tuesday that had burned since the blast, officials said.
The natural gas seeping from two holes in a 90-foot tank is not toxic and the chance of another explosion is slim, said Michele Swaner, spokeswoman for Williams Partners, the subsidiary that owns the plant.
"It's complicated, but the liquefied natural gas material is natural and dissipates into the air," she said. "It takes a special set of circumstances for it to ignite."
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Crews continued Tuesday to work to figure out how to stop the leaks before they can determine what caused the initial blast, possibly in a storage building.
Five people were hurt during Monday's incident, officials said. Four were treated and released from the Hermiston hospital. The fifth, a man, is being treated for burns to his hands and face at a Portland hospital.
Emergency responders told the Herald that residents need to be aware there is still a risk of an explosion, and chemicals from the plant could cause people to become sick.
"As long as the tank is punctured there is a danger," said Joe Lusignan of the Benton County Sheriff's Office. "If it is potentially given the right ignition source, the tank could blow up. And with that would be significant injuries."
However, officials from Williams Partners said residents in the rural community of about 300 people in south Benton County are not in danger.
Officials don't know how much liquefied natural gas is left in the tank, which was estimated to be holding 7 million gallons. It wasn't clear Tuesday how the incident could affect the supply of liquefied natural gas in the region.
The Washington Utilities and Transportation Commission and the Department of Labor & Industries are heading up the investigation.
L&I officials will make sure the plant was in compliance with safety regulations and a pipeline engineer from the UTC will investigate the cause of the fire and explosion. All Williams employees have been tested for drugs and alcohol, according to the utilities commission.
Local officials lifted the evacuation order Tuesday afternoon and opened all roads, except for a section of Christy Road next to the plant. Traffic on the Columbia River, a section of Highway 14 and train tracks in Plymouth were shut down for most of Monday but have since reopened.
The Burlington Northern Santa Fe rail line was reopened Tuesday afternoon after tracks were damaged during the explosion, said BNSF spokesman Gus Melonas.
Residents were warned that a dust-like substance called perlite from the tank's insulation was released into the air after the explosion. The nontoxic substance can irritate the skin or eyes, and shouldn't be inhaled.
Authorities will use infrared technology to scan areas around the track for safety because liquefied natural gas can be invisible, officials said.
Residents who returned to Plymouth on Monday evening to stay or collect belongings were asked to sign a waiver absolving local and state agencies of any liability, they said. Some residents decided to stay in Plymouth overnight Monday.
"I really wasn't afraid because from a scientific standpoint, it's nearly impossible for (liquefied natural gas) to explode," said Bill Scott, who slept at his house on Christy Road despite warnings to evacuate. "You can't imagine how many degrees you would have to add to get some kind of (fire) or explosion. Anyway, I thought it would be nice to get a shower and start out fresh in the morning."
The plant and a connecting pipeline were shut down immediately after the blast, which sent plumes of black smoke into the sky and shook houses. Officials believe there was only one explosion, possibly in a storage building. It could be heard as far as 20 miles away.
Up to 1,000 residents and agriculture workers were evacuated from a two-mile radius around the plant. The evacuation zone was reduced to one mile later in the night.
Authorities, firefighters and emergency personnel stayed the night and will be on scene at least through Wednesday.
"Some of us got to get a little sleep last night," said Capt. Devin Helland, Benton Fire District 1.
Many residents were happy to return to Plymouth on Tuesday and try to get back to their regular routines, they said. They were thankful for the quick actions taken by the first responders.
Many said they trusted Northwest Pipeline representatives and emergency personnel to decide when it was safe to return.
"They should have enough knowledge and know what's going on," said Doug Taylor, who lives on Third Street in Plymouth. "If it was going to blow it would have blown by now."