19 October 2021
Media: Rotorua Daily Post
Topic: Wastewater overflow
Enquiry
I’m inquiring about the public health warning for Lake Rotorua after the wastewater overflow.
Please find my questions below:
Could you please provide an estimate of the volume of wastewater that overflowed? How much of it reached the lake?
The statement said: Initial inspections have found a major fault in the on-site computer that controls the pump station.
Do you have any more information on this since the statement was posted?
How long will it be until you know what caused this and is there any risk or concern in the meantime that it could happen again? If so, how have you mitigated that risk?
Is that pump station out of action until you’ve figured out what caused the fault?
My deadline is 5pm, please.
Further comments:
I'm running the below comments by you for a right of response regarding the same story.
"this issue should not be minimised."
"We would expect greater transparency and more timely reporting... because these are our lakes."
Response
Please see information below in response to your questions. There is no comment in response to those [comments] that you’ve provided but thanks for checking.
From 3 Waters Services Manager Eric Cawte:
Could you please provide an estimate of the volume of wastewater that overflowed? How much of it reached the lake?
There is no way to definitively say how much wastewater actually made it into the lake however, we estimate it could be up to 20 cubic metres.
The statement said: Initial inspections have found a major fault in the on-site computer that controls the pump station.
Do you have any more information on this since the statement was posted?
The fault has been identified as a loss of programming code from the memory of the Programmed Logic Controller. We are trying to ascertain if the loss of programming code was related to a power cut in the area yesterday during which a generator was used to supply power. The mains power was restored around the time that the pump station is believed to have stopped operating.
How long will it be until you know what caused this and is there any risk or concern in the meantime that it could happen again? If so, how have you mitigated that risk?
Investigations will continue over the next few days. The Programmable Logic Controller at this station has been re-programmed and has been operating satisfactorily, and a level sensor for the backup alarm system has been replaced with a new one as a precaution.
Where possible the network has backup systems, including monitoring alarms and secondary pumps, and the system continues to be improved as technology and engineering practices evolve. However, there are more than 80 wastewater pump stations across the district and there is always a risk that there could be a fault or damage that causes issues with the network.
Is that pump station out of action until you’ve figured out what caused the fault?
The pump station was manually restarted and has been operating as normal since 7.30pm last night