Matapihi residents want a community meeting with the council about a wastewater overflow that saw approximately 80 cubic metres of sewerage enter the harbour.
Residents, including one who staunchly opposed the $107 million southern pipeline's passage through Matapihi, say they are disappointed and frustrated by Wednesday's spill.
Tauranga City Council has launched an investigation into the overflow and how to make sure it doesn't happen again.
The overflow happened 100 metres on the Matapihi side of the harbour-spanning wastewater pipeline about 3pm, the council said.
Director of city water Stephen Burton said contractors were doing routine maintenance on air valves along Matapihi Rd.
"Wastewater pipelines require air valves at various points to release gas associated with transport to treatment plants, which need to checked and maintained on a regular basis."
An air valve 100m above the Matapihi carpark was taken off for maintenance and normally an isolation valve would seal off the pipeline, Burton said.
However, he said this was not securely sealed even though contractors believed it to be closed and that the valve was in working order.
He said it was difficult to say precisely how much wastewater was spilt.
"It may have been approximately 200 cubic metres. Contractors were able to stop 120 cubic metres from entering the harbour by using sucker trucks as part of the response."
Burton said it took more than three hours to completely stop the overflow.
"The southern pipeline flow was immediately diverted to Chapel St when the overflow was notified. Sucker trucks were brought in to prevent as much flow as possible from entering the harbour while the isolation valve was manually closed."
He said the area from the overflow to the bottom of Matapihi Rd has been cleaned and disinfected, including the carpark, surrounding vegetation and accessway to the bridge.
"Warning signs have been placed on the foreshore and the waterfront steps along The Strand until water quality samples have been tested and show the water is safe."
Residents have alerted staff that at times shellfish have been collected so council staff will also be sampling shellfish if they can be found, Burton said.
Neighbouring residents were offered alternative accommodation for the night while the clean-up was under way, he said.
Burton said council staff were investigating what further protocols could be put in place to prevent similar incidents in future.
"It is likely more than one preventative measure will be added to ensure air valves are isolated prior to maintenance," he said.
Hayden Henry of Ngāi Tukairangi hapū said this kind of incident was what he and others in the Matapihi community feared when they fought the pipeline plan.
Henry said even if the leak was due to human error, it was "very disappointing" given the council's past assurances there were emergency response procedures in place.
"This matter requires a community meeting with council staff so we can express our disappointment and also hear what the council intends to do to better manage the whole process of the pipeline going forward," he said.
"There have been repercussions on the wider community which is also very disappointing,
and we need to make sure this does not reoccur".
Matapihi Residents and Ratepayers Association chairman Greg Milne agreed.
"It's very disappointing, frustrating, and obviously not an acceptable situation."
Milne said that was especially so after the council had previously assured residents the system was secure from this type of failure.
He said it appeared the overflow was the result of human error and he knew the people involved and the council staff would be very upset this has happened.
"I know there will be outrage among the Matapihi community, particularly those who were opposed to the southern pipeline through this land for this very reason."
Milne said a please-explain meeting would be sought with the council.
"I'm confident that the council will do everything they can to solve this problem and make sure this does not happen again."
Wednesday's incident is not the first overflow since the pipeline came online in October 2018 after 15 years of work.
In August 2019, an air valve by Te Kura o Matapihi became blocked with fat, causing a malfunction and an overflow.
"That overflow was the reason we are doing more regular inspections and maintenance on the air valves along Matapihi Rd," Burton said this week.
In response to Milne and Henry's comments, he said the council shared the community's sentiments.
"This has been disappointing and frustrating to all of us. We are in the process of organising a hui with the Matapihi community next week.
"We'll share what we know about what caused this, what measures have been put in place to prevent similar issues and provide opportunity for the community to talk to our team and ask further questions.
"It's also important to know that there is no problem with the pipeline itself, and all valves are in full working order."