The Santa Paula wastewater facility that experienced a chemical explosion last November remains closed and an investigation by the Ventura County District Attorney’s Office remains active.

But company officials say operational improvements have been made and the facility will host an open house event on March 18 with hopes to reopen soon.

On Nov. 18, a vacuum truck sucking up non-hazardous waste at Southern California Wastewater — formerly known as Santa Clara Wastewater — inadvertently sucked up a chemical known as sodium chlorite, causing a 1,000-gallon chemical spill and hazardous explosion that injured five people. Since then, the Santa Paula facility has been shut out of public pipelines by the city of Oxnard.

“There were high levels of radioactive elements so Oxnard shut the facility out of its pipelines,” said Ventura County Supervisor Kathy Long, who represents the area where SCWW is located. “So they can’t operate until that’s resolved.”

She said the company must receive clearance from the city of Oxnard, as well as clean up the explosion site, before it can start using the pipelines again. SCWW cleaned up the explosion site and disposed of waste from the incident in January, according to company officials.

And the company disputes the findings that led to it being shut out of the pipelines, as its environmental engineering consultant, Santa Barbara-based Haley Aldrich, has reviewed and substantiated company research that indicates initial testing failed to account for naturally occurring potassium levels. By not accounting for the potassium, some radioactive elements appeared to be out of balance when they actually weren’t, the company said.

“The notice of violation appeared to have been calculated wrongly in that it only tested for Gross Beta without speciating the sample to quantify and then deduct the natural potassium from the final calculation,” a report from SCWW said.

The report also said that naturally occurring potassium can be found in “every organic cell, all ocean water, and all human and animal waste” and that additional testing — performed with a formula accounting for this substance — found that SCWW waste is in compliance with state regulations and Environmental Protection Agency standards.

“Based on testing and analyses performed by independent laboratories specializing in this subject matter, it is their professional opinion that the required speciation, detection and re-evaluation protocols were not recognized by the city, which, if followed, would have shown that both the city of Oxnard and the SCWW facility had in fact been in full compliance with USEPA standards,” Rick Conrad, a company spokesman, said in an email.

County officials lifted an emergency declaration on SCWW last month, but Chris Stephens, resource management director for Ventura County, said the county needs “a clear description of [SCWW] operations” before the plant can reopen. Along with cleaning up the explosion site and sorting out its issue with the city of Oxnard, Stephens said this requires “ensuring, to our satisfaction, that controls are in place so this incident doesn’t happen again.”

An earlier investigation by ex-district attorney Michael Bradbury and experts hired by SCWW found that the explosion in November likely resulted from an accidental mixture of non-hazardous wastewater and sodium chlorite.

“The accident occurred when an employee inadvertently mixed non-hazardous domestic waste with a product identified as sodium chlorite, which is commonly used for hydrogen sulfide (H2S) treatment, in a vacuum tank truck,” Conrad wrote in an email. “The two materials reacted, pressurized, and subsequently caused an explosion.

Conrad said SCWW’s parent company — Green Compass — has made permanent changes to its operations to prevent another such incident from happening at SCWW or at Green Compass’ two other facilities.

“The sodium chlorite was in a clearly marked shipping container or ‘tote.’ To eliminate any possibility of confusion in the future, Green Compass will no longer accept non-hazardous waste contained in totes at any of its three facilities,” Conrad wrote. “The only totes to be delivered and handled at their facilities will be those containing products used in the treatment of non-hazardous waste materials.”

SCWW will host an open house event at its Santa Paula facility this month to invite public officials and other community members to view its operations. The event will feature walking tours hosted by management who will explain the facility’s processes, Conrad said.

“And of course, we will dispel any misrepresentations that have echoed or promoted relating to the circumstances leading up to that unique, first of its kind incident occurring at the facility on Nov. 18, 2014,” Conrad told the Business Times via email. “Our efforts to remediate the situation and address any remaining concerns, and finally, protocols that redefine industry standards will help to ensure that such a situation never happens again at any facility in the United States, much less Ventura County.”

For now, county officials are waiting for more information to reactivate SCWW’s land use permit and allow for reopening.  No date or time frame has been set so far.

“We have not received from them a description of their operation,” Stephens said. “Until we see their project description, we really don’t know when they can reopen.”

SCWW handles septic waste for about 90 percent of those Ventura County residents who aren’t connected to a sewer system. The company has not experienced any other accidental spills or explosions since it opened in 1960, according to Conrad.

“We hope that the regulatory agencies will soon give us the greenlight to once again provide these services, which we have been safely providing for more than 55 years,” he wrote in an email.