Officials at Crosby's Arkema chemical plant were warned that the facility was at risk for flooding a year before Hurricane Harvey's deluge resulted in a chemical fire at the plant.

But facility employees, with the exception of a manager who retired in early 2017, "appeared to be unaware of this information," an inquiry by the U.S. Chemical Safety and Hazard Investigation Board found.

The board concluded that Arkema, a French multinational company that manufactures chemicals used to create plastic products, was not prepared for the 6 feet of water that wiped out the facility's power and backup generators. With the power out and cooling systems failing, volatile organic peroxides exploded multiple times over the course of a week, producing towering pillars of fire and thick plumes of black smoke.

The board — an independent federal agency that investigates industrial chemical accidents — released a 154-page report Thursday morning detailing findings and recommendations to the company, to Harris County and to industry leaders. Those recommendations include developing better policies for determining risks from extreme weather events, such as flooding, and protecting first responders from releases of hazardous chemicals.

Also Thursday, Harris County District Attorney Kim Ogg said evidence would be presented to a grand jury "in coming weeks" as part of the county's lawsuit against the company.

Now Playing:

The chemical safety board can offer recommendations and guidance, but it can not fine or punish a company based on its findings.

Janet Smith, Arkema spokeswoman, said in a statement that the company was pleased with the board's investigation because it "accurately depicts the unforeseeable nature of the situation Arkema faced during Hurricane Harvey."

But board members determined that the company's emergency response plan was insufficient, confirming a Houston Chronicle report in November.

However, in her statement, Smith said, the report "shows that Arkema had multiple policies and safeguards in place to address the risks associated with hurricanes, that Arkema followed those policies, and that our employees went to extraordinary lengths, under difficult conditions, to maintain safety at our site."

Board officials said Thursday that Arkema is being proactive in its efforts to understand the facility's flooding risks and take steps to make sure an incident such as this doesn't happen again.

"Arkema wasn't prepared, but they were not alone," Vanessa Allen Sutherland, the board's chairwoman, said at a Thursday news conference. "The most valuable lesson here is that facilities should plan and plan again. Don't be lulled into a false sense of security by thinking it can't happen here."

Insufficient systems

As Harvey bore down on Southeast Texas and the National Hurricane Center warned of potentially "catastrophic" or "life-threatening" flooding, the company's plans for protecting its product were simple: keep the chemicals cold on-site. If they grew too hot, they would explode.

Arkema had multiple freezer buildings, six backup generators, and, as a last resort, refrigerated trucks. But the company didn't consider flooding a "credible risk," the report states, confirming previous reporting by the Chronicle.

Officials thought this despite a 2016 report from its insurer, Factory Mutual Insurance Co. (FM Global), stating that the facility was at risk for flooding and parts of it sat in both the 100-year and 500-year flood plains, the report states. FM Global was not Arkema's insurer during Hurricane Harvey.

The board found that Arkema was relying on longtime employee memory of flooding levels. The company's Crosby facility has a 40-year history of flooding, but employees could not remember a time when the plant received more than two-feet of water.

"A lot of people there had been there for 20, 30, 40 years and seen predictive rainfalls of similar amounts and they thought, with what was predicted, they'd be fine," said Mark Wingard, the board's lead investigator.

That method, he added, is insufficient.

"Companies should develop systems to retain key incident summary information that better document facility risks based on historical external events," the report states. "These external events, such as flooding, have a low probability of occurrence but can threaten severe health and safety consequences."

Along with an inadequate emergency response plan, the board's report confirms other aspects of the facility's failures reported by the Chronicle in November: The company's power transformers and backup generators were not high enough off the ground, and it had a tank of an extremely dangerous chemical, isobutylene, located about 40 yards from six refrigerated trailers loaded with organic peroxides that had been relocated during the storm.

Board members recommended in their report that Arkema develop a policy requiring any facility that manufactures organic peroxides or processes a significant amount of highly hazardous chemicals to periodically determine if they're at risk for extreme weather events like hurricanes or floods.

It also recommended that the Crosby facility, specifically, decrease its flood risk to "as low as reasonably practicable."

Since Harvey, Arkema has commissioned a site elevation survey and a hydrological study to better understand hurricane-related flooding.

Officials with the board said Thursday other chemical companies might also have inadequate emergency preparedness plans. While the board couldn't say just how many companies have inadequate plans, it stressed that Texas companies along the Gulf Coast that work with hazardous materials should be on alert.

"Given that experts predict that extreme weather events are likely to increase in number and severity, the chemical industry must be prepared for the worst-case scenarios," Sutherland said. "We cannot stop the storms, but by working together we can mitigate the damage and avoid future catastrophic events."

The board recommends that the Center for Chemical Process Safety, a New York-based nonprofit, develop guidance to help companies determine their risks from all types of extreme weather events, including hurricanes and flooding.

Exposure to chemicals

Just days after Harvey made landfall Aug. 25, a ride out crew at Arkema's Crosby facility transported 300,000 pounds of organic peroxides to nine refrigerated trailers. More than 2,000 containers had to be transported by hand in the dark, according to a simulation video created by the board.

But when those trailers began to fail, the ride out crew was evacuated and officials set up a 1.5-mile evacuation zone in anticipation of trailer explosions. Those explosions began Aug. 31.

Parts of Highway 90, which runs along the southern end of the plant and cut through the middle of the evacuation zone, were kept open to traffic too long, the report stated. At least 21 people were exposed to "decomposition products and smoke from the burning refrigerated trailer and organic peroxides."

For that reason, the board recommended Harris County do several things to ensure ensure emergency personnel are not harmed by hazardous chemical releases. The suggestions include updating protocols, revising training material, and providing adequate protective equipment for first responders.

Several first responders are suing Arkema saying they were sickened while responding to the fires and chemical releases at the scene. Hundreds of local residents are also suing the company for damages.

Local residents have said they were kept in the dark about what they may have been exposed to during and after the explosions.

Any long-term health effects that might arise from the release of the chemicals are unknown to the board.

"CSB is not a public health organization, so we can't do our own independent evaluation," board member Kristen Kulinowski said Thursday, adding that the board summarized the results of the EPA air monitoring data.

The Environmental Protection Agency and the Texas Commission on Environmental Quality also are investigating the incident, though their results have not yet been released.

Alex Stuckey covers science and the environment for the Houston Chronicle. You can reach her at alex.stuckey@chron.com or Twitter.com/alexdstuckey.