More thorough manual checks of the Raglan Wastewater Treatment Plant software programming system are among efforts being made to prevent treated wastewater discharging into Raglan Harbour on the incoming tide.
There have been two incidents, over two separate 24-hour periods, of discharging treated wastewater on the incoming tide that breaches Waikato District Council’s consent with Waikato Regional Council. One on 11/12 October and one on 25/26 October.
Waikato District Mayor Jacqui Church is absolutely gutted that this has happened over the past couple of weeks.
“We are deeply disappointed to advise our community that treated wastewater was again discharged on the incoming tide at Raglan Harbour this week due to a technical fault at the treatment plant’” she says.
“Whaaingaroa (Raglan) Harbour is one of the jewels in our district’s crown.
“Our apologies go out to the local community and all harbour users, and we will keep everyone informed as our investigations continue.
“I am assured that our team and our partners at Watercare are deep diving into what the system failure was, how it has happened again and how additional safeguards for the system are being implemented.”
The fault on 25/26 October was a repeat of what happened two weeks ago when the same issue occurred on 12 October.
Usual practice is for treated wastewater to be discharged on the outgoing tide.
An error in the software programming caused the system to ‘glitch’ as it could not confirm the tide times.
The programming for the tide times was inverted. This meant the plant discharged on the inbound tide instead of the outbound tide.
There were no alarms because the programming believed it was discharging on the outgoing tide as normal.
The fault was picked up in Watercare’s validation process of the plant software. The fact that no alarms went off was a reason why it was only picked up on 24 hours after the fact.
Watercare believed this fault was resolved after the 12 October incident, but the same problem has occurred.
As a result, while further investigations are continuing, the system is being manually checked at the turn of every tide to ensure the trigger to discharge treated wastewater is at the correct time, which is on the outgoing tide.
Meanwhile Watercare is continuing to work on the software programming with the acknowledgement that more robust validation process of the software programming is required.
There is also work being done to install an additional alarm system.
Council’s consent with the regional council only allows for the discharge on the outgoing tide, unless there is a significant storm event.
Fortunately, the discharge was fully treated wastewater, the plant’s process to treat wastewater is working correctly.
The treatment plant accelerates natural processes that treats effluent so it can be returned to the environment. The plant and process breaks down organic matter, uses U.V disinfection to kill bugs and restores the oxygen content of treated water.
Nevertheless, as a precaution, signs have been put up at the harbour urging the community to avoid swimming and collecting shellfish for the next three days (until Sunday 29 October).
“Again, we apologise for this news. Rest assured this is a high priority focus for us and we will keep the community informed,” says Mayor Church.
