SANTA ANA, Cailf. — Fire officials said late Monday that the risk of a catastrophic blast from an overheated chemical container in a Garden Grove aerospace plant is now low enough that they believe it is safe to lift evacuation orders for more than half of the people who spent Memorial Day weekend out of their homes.

But officials also said the threat of a smaller blast or of a dangerous chemical leak remain, so they’re keeping roughly 35% of the original evacuation zone in effect.

An exact timeline for when everybody will be allowed to return hasn’t been established, but officials said it wouldn’t be until Tuesday at the earliest.

Orange County Health Officer Dr. Regina Chinsio-Kwong said if there is an explosion or leak at the GKN Aerospace plant, residents and those who haven’t heeded the evacuation order will be instructed to shelter in place.

The new evacuation zone will reach from Orangewood Avenue to the north, Dale Street to the east, Knott Street to the west and Garden Grove Boulevard to the south, Garden Grove Police Chief Amir El-Farra said. All on-ramps and exits of the 22 freeway will also remain open.

Officials who spoke at the Monday evening news conference urged residents whose homes remain in the evacuation zone to stay out of the area for their safety and the safety of first responders.

Residents also were told that there is no safety risk for people who are returning to their homes who were removed from the evacuation zone.

News about the new evacuation rules came hours after fire officials said the worst case scenario — a potential heat-induced explosion — has been averted. Orange County Fire Authority officials said Monday that a crack detected in the container has allowed the chemical to cool slightly, reversing a trend that they feared could lead to a “boiling liquid expanding vapor explosion,” or “BLEVE.” Such a blast could have sent chemical plumes into the air and extend its toxic reach.

“The crack is there,” Division Chief Craig Covey added. “We had identified it is there, and the tank has released its pressure.”

After days of often dire warnings by fire officials and experts, the announcement was the most optimistic update yet by those working to head off a potential disaster. A boiling liquid expanding vapor explosion, which would have likely caused massive damage and released a toxic chemical plume into the air, occurs when a sealed, pressurized container holding a liquid chemical ruptures.

“The threat of a BLEVE is off the table,” Interim Fire Chief of the Orange County Fire Authority TJ McGovern said. “That threat has been eliminated.”

The crisis is not fully averted, authorities cautioned. The possibility of a lesser explosion or a leak remains, and large-scale evacuations are still in place. But the worst possible outcome is not expected to occur.

The temperature inside the tank has also gone down, from at least 100 degrees to 93 degrees, the chief said. That is a key metric: At a high enough temperature, the chemical process was at risk of accelerating out of control, which could lead to a massive explosion. A smaller explosion or a leak from the crack, which is at the top of the tank, remain potential threats.

Addressing concerns from some in the community about the lack of regular updates on that internal tank temperature, Covey said authorities had been allowing the tank to “settle” during the warmer hours and sending crews in to check on it during the cooler overnight hours. Another check was slated to occur Monday evening.

“We were not doing tank temperature checks during the day when the sun was on it in the most extreme conditions for that tank to go in the wrong direction,” Covey said. “We were only doing tank temperature checks at night.”

Danger has not passed

That means that the worst-case scenario of mass damage to nearby homes and businesses, starkly illustrated in“blast zone” maps OCFA released days ago, is no longer one of the likely outcomes.

But it doesn’t mean the danger has fully passed.

A smaller explosion would still release chemicals and send debris from the plant flying, or a leak could release the chemicals from the tank. In either case, wind could disperse a chemical plume farther into the community.

With the dropping temperature and lowering pressure inside the tank, it is now more likely to leak than to explode, according to a Federal Emergency Management Agency brief.

That means the evacuation of roughly 50,000 residents in Garden Grove and nearby communities continues. Those evacuations have lasted for four days, through the holiday weekend.

At some point, when the threat of any explosion or leak is eliminated, the evacuation zones will be strategically reassessed, the chief said in a Monday morning interview following the video update. But there isn’t a time frame yet for when that will occur.

“When the evacuation zone decreases,” McGovern said, “repopulation occurs.”

Crafting a solution

When they first arrived at GKN Aerospace on Western Avenue on Thursday, fire crews were told by a project manager there was nothing they could do: A tank filled with 7,000 gallons of methyl methacrylate, a flammable, toxic and highly volatile chemical, was going to fail, either spilling and sending the chemicals pouring into a parking lot or exploding with a fireball that would send a plume of chemicals into the wind.

While fire officials publicly warned of the likelihood of an explosion or leak, they also began troubleshooting with a group of experts, including specialists with ties to Los Angeles, San Bernardino and Long Beach.

Gummed up valves and concerns that drilling into the tank may spark a reaction with the volatile chemicals seemed to rule out obvious solutions. But a continued water deluge of the tank appeared to keep an explosion or leak at bay, giving the experts time to craft potential out-of-the-box solutions.

The current goal is to keep lowering the temperature of the tank to 50 to 60 degrees to stabilize the situation and put some of those solutions the experts have been crafting into play.

Crews and chemical experts, at their own personal risk, have carried out the overnight operations to get a first-hand assessment of the compromised tank. That led to the discovery — overnight on Saturday — of the crack at the top of the tank.

They don’t know if it is a new crack or one that previously existed. Since it is at the top of the tank, the crack has not yet resulted in any chemicals leaking.

Once the water was directly hitting the tank, the temperature started to fall.

The chemical also appears to be solidifying, McGovern said. But that process seems to be happening from the outside in, so the current density of the center is unclear.

“We need to see the density inside,” the chief said. “It solidifies into a plastic form. We don’t know yet if all the substance has solidified.

“That’s what we believe is going on. That’s what the readings are showing,” he added. “At the end of the day — and I don’t mean today, but at the end of the day — if we open that tank up, (there’s) a big chance that it’s a big plastic pill.”

Air quality experts who have been tracking the atmosphere near the tank have not detected any contaminants so far. But the chief said that has made it challenging at times to impress upon people the reason for the evacuations. Unlike the smoke and flames of a wildfire, the danger of a failing chemical tank isn’t as obvious to the naked eye.

“There’s nothing in the air,” the chief said.

Even with the internal temperature of the tank appearing to be trending down, authorities said, it is still too risky to send crews in during the day. So they will again wait until Monday night to directly approach the tank.

In the event of a new crack that would allow chemicals to leak out, crews have set up a system of sand barriers to divert the flow and prevent the chemicals from entering storm drains or river channels.

In an “earliest, best case scenario,” changes to the evacuation orders still wouldn’t come until at least Tuesday, if not later, OCFA Capt. Nick Garton said.

A holiday away from home

For those forced out of their homes since Friday, Memorial Day was yet another uncertain day in a long-running evacuation.

Jacqueline Riegos, a 51-year-old Stanton resident, and her service dog, Jericho, were planning to spend the night at Kennedy High School. Riegos lives a little more than 2 miles from the GKN site, and she got a phone alert Thursday evening.

They evacuated, then were told they could go home — before being reevacuated Friday morning.

“A lot of us left with just what we had on,” she said.

Riegos has been sleeping in her car since then, but on Monday, she became worried about her dog getting heat stroke. She also struggled herself. She’s had three back surgeries and is recovering from a hip replacement, Riegos said. Initially, she avoided the shelters because she was worried they’d separate her from her dog, a rescue who is anxious.

Stella Nunez, 53, left her Anaheim apartment Thursday night with her dog, Reagan Messi. She stayed with her daughter Saturday night, but her daughter’s place is small, so she and Reagan spent last night at the Elks Lodge, which opened their doors to evacuees this weekend.

It’s been a hard and emotional week, Nunez said. She just got out of the hospital after a bout of anemia on Wednesday and was evacuated two days later.

But “they’re all angels,” she said of the Elks Lodge workers. Before today, she hadn’t laughed or smiled since Friday.

“Today, I smiled,” Nunez added.

Jackie Page, club manager of the Elks Lodge, said that while their facility is not an official evacuation shelter, they opened their doors this weekend for those with nowhere else to go. They were offering open RV spots, space for tents in their park and ballroom space for sleeping bags.

“We’re humans,” she said of the Elks lodge community. “We have the space. We have the capacity.”

Janet and Alyana, a mother and daughter who preferred to be identified by only their first names, evacuated from Stanton on Friday night. Both appeared bleary-eyed and weary on Monday, sitting on picnic tables outside the Kennedy High School shelter, where they ended up after sleeping in their car for two nights when other facilities they visited were full.

Most of the shelters that opened in the wake of the evacuations, in fact, remained at capacity early Monday, with authorities indicating that only a new Los Alamitos High School shelter and Golden West College were not full.

“It is what it is,” Janet said. “We’re alive.”

State of emergency

Gov. Gavin Newsom, meanwhile, declared a state of emergency on Saturday afternoon, opening the way for extra resources.

The White House, on the request of Newsom and other California leaders, also approved a federal emergency declaration to aid with the ongoing response at the aerospace company. That would include federal cost-sharing for a response that has already run up a hefty price tag not only for the efforts to address the compromised tank but also to evacuate and shelter so many people.

The White House, in a statement released Monday morning, said the administration is “engaged and monitoring the situation in Garden Grove.”

“The U.S. EPA has integrated with the local Unified Command composed of state and local agencies, and has enabled air monitoring at 20 locations around the area,” the White House said. “FEMA has deployed a Liaison Officer to coordinate with officials and has also deployed a team to the State Emergency Operation Center to support incident contingency planning. FEMA has also activated the Interagency Modeling and Atmospheric Assessment Center to provide plume modeling of airborne hazards, informing incident leadership and contingency planning.”

While bringing the crisis to a close has been the main focus, the owners of GKN Aerospace have already come under heavy criticism for the apparent failure of any emergency systems involving the chemical tank.

The United Kingdom company, a worldwide leading manufacturer of cockpit windows, jet canopies and aviation widows for civil and military aircraft, has been operating in Garden Grove for decades and employs more than 500 local workers. I t previously paid a nearly $1 million fine to settle numerous environmental violations. The company on Sunday released an apology in the midst of the chemical incident.

Orange County District Attorney Todd Spitzer has already announced his office is investigating the current failure of the chemical tank. Prosecutors on Sunday sent a letter to GKN Aerospace ordering the company not to destroy any documents or records pertaining to the business. They warned that destroying evidence in the midst of an active investigation would lead to criminal charges.

And at least half a dozen law firms also pledged to file lawsuits seeking class-action status on behalf of residents and businesses impacted by the evacuations.

The city of Garden Grove will hold a community meeting at 5:30 p.m. on Tuesday at the Community Meeting Center, 11300 Stanford Ave. Mayor Stephanie Klopfenstein said it will focus on the incident, the city’s response and the latest information available, and the community is invited to attend and ask questions. The City Council meeting previously scheduled for Tuesday has been canceled.

The City Council is also expected at the meeting to ratify the local emergency that City Manager Lisa Kim declared on Friday.

Garden Grove and Westminster school districts warned that students who attend schools remaining in the evacuation zones should be prepared to pivot to online learning on Tuesday if the evacuations continue and to watch for more information from their schools.

In the Westminster School District, Fryberger Elementary and Sequoia Elementary remain within the active evacuation zone and are not currently accessible, officials said.

In the Garden Grove Unified School District, the latest list of schools in the evacuation zone includes Alamitos Intermediate, Barker Elementary, Bryant Elementary, Bell Intermediate, Carver Early Childhood Education Center, Enders Elementary, Garden Park Elementary, Lawrence Elementary, Pacifica High School, Patton Elementary, Rancho Alamitos High School and Wakeham Elementary.

(Staff writers Tony Saavedra and Kaitlyn Schallhorn contributed to this report.)

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