ANTIOCH (BCN) - Chemicals that were released into a pool recirculation system, despite the fact that water had stopped flowing, created dangerous levels of toxins that sickened 34 children at a water park in Antioch last month, according to a report released Wednesday.
The report said it's unclear whether the incident, which impacted just one of the park's five pools, occurred as a result of a recirculation system malfunction or as a result of human error.
But Nancy Kaiser, the city's director of Parks and Recreation, which operates the water park, said there are no conclusive findings in the report and denied that there was any evidence of human error.
Contra Costa Health Services' hazardous materials and environmental health departments both investigated the June 18 incident at the Antioch Water Park, located at 4701 Lone Tree Way, according to health services officials.
The environmental health report concluded that two events occurred which led to 34 children receiving treatment for possible chlorine exposure. First, a pump used to recirculate water stopped working at 10:40 p.m. the night of June 17, according to the report.
While the pump was inoperable, a chemical controller device released chemicals into the recirculation system despite the fact that water had stopped flowing, causing higher than normal concentrations of chemicals, the report said.
Those chemicals were released into the pool when the water pump was turned back on around 2:20 p.m. on June 18, the report said.
State law requires that water recirculation pumps are working properly when people are in the pool, environmental health director Dr. Marilyn Underwood said.
Kaiser said employees at the park checked the water pump at 10:30 a.m. on June 18 and saw that it was working properly. She acknowledged that the data in the report contradicts her statement but said, "We have a differing account of the information."
"There is no evidence of human error," Kaiser said. "That information is still inconclusive and there is no definitive or obvious reason why the chemical system malfunctioned."
But Underwood said there is evidence that someone turned on the manual override for the chemical controller at 8:35 a.m. on June 18, which she said should not have happened.
There were also text alerts that were sent out to employees at the park when the pump stopped working the night of June 17, hazardous materials assistant director Matt Kaufmann said.
But, Kaufmann and Underwood said their report did not look at which employees received which alert messages and they said it's unclear whether any employees received the specific warning from June 17, when the water pump stopped working.
The Parks and Recreation Department replaced the chemical controller, Kaiser said, adding that the new controller is now undergoing testing before it becomes operational.
The environmental health department is requiring the city evaluate the water park's systems and ensure that it is operating per approved plans and manufacturer specifications.
In addition, Kaiser said her staff is also reviewing all county, state and federal regulations to ensure that the city is complying with the most up-to-date policies and procedures.
The environmental health department is scheduled to review the city's compliance with the device manufacturer's specifications and state regulations on July 13, according to the report.
By July 15, the city must send the environmental health department its written policies and procedures and provide staff training on cleaning, recording and monitoring the chemical controller, programming the controller to alert staff of irregular activity, developing a logging system to simultaneously record the water recirculation pump flow and the chemical controller flow and establish criteria for overriding automated systems.
On June 18, 34 children swimming in the Sports Pool at the water park reported symptoms including vomiting, trouble breathing, burning skin and eye and throat irritation, according to the report. Of those, 17 were treated on site and 17 were transported to hospitals for urgent care, the report said.
The chemicals released into the pool, sodium hypochlorite and muriatic acid, are safe in a fully functioning recirculation system but can be toxic if the recirculation system fails, health services officials said.
Kaiser said she expects the city will meet all of the county's requirements by the July 15 deadline and the pool will reopen to the public by July 18. The park's four other pools reopened on June 20.
The Antioch Water Park is in its 20th season and its operating systems were most recently upgraded during the 2012-2013 winter, Kaiser said.