Staff knew about pool mishap
A potentially ‘‘catastrophic’’ postlockdown chlorine botch-up at Hamilton’s Waterworld pools led to three staff members and a swimmer suffering acute injuries when they inhaled the poisonous gas.
Details of the incident were revealed in a Hamilton City Council document that has – temporarily at least – been made secret.
The revelations in the safety and wellness report were sitting for all to see in the agenda of the council’s strategic risk and assurance committee meeting on Friday – before it was promptly yanked from view — not long before the meeting began.
The report was later discussed and received in the publicexcluded section of the meeting, but not before the sudden need for secrecy was queried by councillor Dave Macpherson.
In response, chief executive Richard Briggs said he had removed the report because it contained confidential information about staff members. A redacted version of the report, excluding the delicate information, would be published on the council’s website sometime after.
As of yesterday this had not yet happened.
The report analyses what happened after excessive chlorine was pumped into a Waterworld pool in April during the lockdown, when someone tried to fix the issue by adding hydrogen peroxide prior to the facility re-opening to the public.
This resulted in three staff members and one member of the public reporting acute injuries as a consequence of the chlorine gas emanating from the 50-metre pool.
All four were reported to have fully recovered about three days later.
The report makes no mention of whether any form of disciplinary action was taken, or if there were any other consequences for the staff members involved.
At the time of the incident, community general manager Lance Vervoort said about $3000 worth of additional chlorine had been added.
The facility’s re-opening in midMay had to be delayed due to the incident, and the 50m and dive pools were fully drained and further cleaned in July, when the entire facility was again closed for an electrical upgrade to take place.
An internal operational review indicated the chlorine dosing pump was switched to manual on April 25, which meant it continually dosed chlorine at the maximum capacity of the pump.
The situation remained undetected for four days.
The review found the software system readings could not be relied on as, due to the very high chlorine dose, the sensor had been corrupted.
During the four days there were no recorded instances of the responsible staff entering the pool complex – although they may have been getting in and out via an entrance that was not being monitored.
A graph showed on April 25 chlorine levels rose from 0.6 ppm at 9am to 10 ppm at 10am and remained at this level until 9am on April 28, when the readings rose from 10 ppm at 9am to 15 ppm at 10am.
The safety review found it was possible for the chlorine levels to have risen as such and the overdosing of chlorine ‘‘did not occur in a linear fashion’’.
This meant there was no single manual event that lead to the over chlorination of the 50-metre pool.
Staff on duty at the time did not undertake any water tests, even though water testing is used to validate the system readings.
A water sample correctly taken any time after April 25 would have revealed the high chlorine levels.
At 10 ppm normally the pool would be closed.
Subsequent attempts by staff members responsible for the complex during lockdown to correct the chlorine levels with hydrogen peroxide ‘‘increased the risk of a catastrophic event’’.
These attempts indicated that some staff knew of the high levels of chlorine. However, they did not discuss this with other staff members present.