May 23 (Reuters) - Firefighters trying to prevent an explosion in a tank of hazardous chemicals in Southern California found overnight that the failing tank was heating up internally despite efforts to cool it, the incident commander said on Saturday.
Evacuation orders remained in place for an area covering tens of thousands of people in the Garden Grove suburb of Los Angeles.
California Governor Gavin Newsom declared a state of emergency for Orange County and his office pleaded for residents to follow
evacuation orders.
Craig Covey, division chief of the Orange County Fire Authority, said crews had gone back into the danger zone in Garden Grove overnight after drone readings on Friday suggested water sprayed on the tanks was helping stabilize the situation.
But those drone readings measured the outside of the vessel, not the chemical inside, Covey said in a video update posted on social media on Saturday morning. When crews reached the tank's gauge, they found the internal temperature was 90 degrees Fahrenheit (32 degrees Celsius), up from 77 degrees (25 C) when responders had pulled back.
The temperature was increasing by about one degree an hour, he said. "That's the bad news," Covey said.
Officials have warned since Friday that the tank, which contains methyl methacrylate, a flammable chemical used in plastics and manufacturing, could rupture and spill up to 7,000 gallons (26,500 liters) of toxic material or explode and endanger nearby tanks.
On Saturday, Covey said firefighters were exploring whether a heavy flow of cooling water might slow the curing process inside the tank enough to reduce pressure and prevent an explosion.
"Letting this thing just fail and blow up is unacceptable to us," Covey said. "Our goal is to find something and not allow that to happen."
The incident began on Thursday at the GKN Aerospace facility in Garden Grove, a city of about 172,000 people roughly 30 miles (50 km) south of Los Angeles. The site specializes in the manufacturing and testing of windows and canopies for commercial and military aircraft according to its website.
GKN said it is working with "all relevant experts" to solve the problem.
"We sincerely apologize for the significant disruption to the many local residents and businesses who have had to be evacuated," a GKN spokesperson said in a statement on Saturday.
Officials expanded evacuation orders on Friday after the risk of explosion increased. About 15% of people in the zone covered by the evacuation order are refusing to leave, Garden Grove Police Chief Amir El-Farra said, according to the Orange County Register.
Covey said crews shifted from a "defensive" stance to an "offensive" operation overnight with help from chemists from the manufacturer's emergency response team. The goal was to neutralize a nearby 15,000-gallon tank and reduce its explosive potential if the smaller tank failed.
"We did put people in harm's way last night," Covey said.
Officials have opened evacuation shelters in Garden Grove and the nearby cities of Anaheim and Cypress.
Health officials have said they were concerned that vapor from the chemical could cause severe respiratory problems with prolonged exposure. Air-quality monitors had not detected vapor as of the latest health update cited by officials.
"You are safe as long as you are out of the zone that was determined to be an evacuation zone," Dr. Regina Chinsio-Kwong of the Orange County Health Care Agency said on Friday.
Covey said crews were also preparing for a possible spill by looking for ways to dike, dam and divert the liquid into a holding area at the commercial site, rather than allow it to reach storm drains, river channels or the ocean.
"We are not giving up," Covey said.
(Reporting by Rodrigo Campos in New York, additional reporting by Dan Catchpole; Editing by Sergio Non and David Gregorio)
