Threat of smaller blast or leak from malfunctioning chemical tank remains.

Ton Tran high-fives one of his two sons as they carry bags into their home Monday evening after days of being evacuated from their neighborhood in Cypress due to a malfunctioning chemical tank in nearby Garden Grove. Jeff Antenore - staff photographer

Orange County Fire Authority division Chief Craig Covey updates the media and public about the threat remaining from a malfunctioning chemical tank in Garden Grove on Monday evening during a news conference at the incident command post at the Los Alamitos Race Track. Jeff Antenore Staff photographer.

By SEAN EMERY, RACHEL FOBAR, SYDNEY BARRAGAN, TODD HARMONSON AND BRIAN ROKOS | STAFF WRITERS

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 it is safe to lift evacuation orders for more than half of the area residents who spent Memorial Day weekend out of their homes.

But fire and county health officials also said the threat of a smaller blast or of a dangerous chemical leak remains, so they're keeping roughly 35% of the original evacuation zone in effect.

An exact timeline forwhen everybody will be allowed to return hasn't been established, but officials said it wouldn't be until today 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.

"I want to reassure everyone who is outside of the new evacuation zone that when you go home, you can feel safe," Chinsio-Kwong said. "There was no contamination, there were no fumes, no vapors that came from this incident. There was no leak."

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.

"I know this may be frustrating," El-Farra said of those still under evacuation orders. "Please understand that we're doing this for your own safety."

Though the evacuation has been in place since Friday, little has transpired in the affected neighborhoods. El-Farra said police arrested one person on suspicion of looting and six others on suspicion of prowling.

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

News about the new evacuation rules came hours after fire officials said the worst-case scenario - a potential heat-induced explosion involving the chemical methyl methacrylate, sometimes known as MMA- has been averted.

Orange County Fire Authority officials said Monday 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.

The temperature inside the tank has also gone down, from at least 100 degrees to 93 degrees, officials said. Earlier, officials said they feared a temperature of over 100 degrees might spark an explosion.

"The threat of a BLEVE is off the table," OCFA interim fire Chief TJ McGovern said. "That threat has been eliminated."

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.

Such an event could have posed a health emergency.

MMA causes everything from respiratory problems and dizziness to nausea for people who are exposed, and it can cause more harm for people who are allergic to the chemical. Products with MMA have been banned in nail salons and other public settings because workers exposed to it have developed respiratory problems.

Though the worst-case scenario has been dodged, authorities cautioned that the crisis isn't over. A smaller explosion, or a leak, still could put MMA into the air. A leak could result in the chemical, which is heavier than air, to hug the ground and possibly spill into the storm drain system and eventually flow into the ocean. A small explosion could send the chemical higher, where it would be moved by prevailing winds.

"There were 6,500 gallons in this tank, but we feel that a lot of that is cured already," said OCFA division Chief Craig Covey, indicating the chemical has thickened, or gelled, as it has cooled and is less likely to spread into the air.

McGovern said, bluntly, that the crisis hasn't passed.

"We still have work to do.... We still have to mitigate a fire and very small explosion concern and also a spill potential."

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.

"For a first responder to hear that there's no options is unacceptable," McGovern said in a phone interview early Monday. "We knewwe had to come up with options, solutions. That's what we do."

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.

"We developed a think tank," McGovern said. "These gentlemen got into a room and started developing options. That was a success. These are unprecedented issues."

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.

The crews went back in Sunday night, McGovern said, and confirmed the crack was releasing pressure.

Then, the chief said, they began removing some of the outside skin of the tank and the insulation around it. Those layers were keeping the temperature inside the tank high, despite the cooling water that crews were spraying on it.

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

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 evacuated again Friday morning. "A lot of us leftwithjustwhatwe 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 Monday, 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 andAlyana, 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."

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

On Monday, 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 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 (the Federal Emergency Management Agency) 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. It 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.

Spitzer has opened a hotline for receiving tips on the chemical tank crisis at 714-347-8714. Anyone with information can also email prosecutors at tipster@ocdistrictattorney.g

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. today 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 today 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.

Though area school districts have scrambled during the crisis, by late Monday, just three Garden Grove Unified School District campuses remain in the modified evacuation zone: Alamitos Intermediate, Lawrence Elementary and Wakeham Elementary.

Nine Garden Grove Unified schools are no longer affected and will reopen normally today, Garden Grove district officials said in an online post.

District officials had warned previously that students who attend schools remaining in the evacuation zones should be prepared to pivot to online learning today if the evacuations continue and to watch for more information from their schools.

All Westminster School District campuses have been cleared from the evacuation zone and will return to normal operations today.

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

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