Hamilton wastewater spill: City council convicted for discharge into environment

The blockage caused wastewater to overflow into the Delia Court stormwater system and then into Te Awa o Kaataapaki Stream which flows into the Waikato River. Photo / Belinda Feek

The Hamilton City Council (HCC) has been convicted of knowingly discharging wastewater into the environment over a period of nine days in October 2020.

It is estimated that over this period, 1,272,000 litres of wastewater were lost into the Te Awa O Katapaki Stream in Flagstaff which flows into the Waikato River. This is about half the volume of an Olympic-size swimming pool.

HCC has been fined $76,500 with the sentence imposed by District Court Judge Melinda Dickey last week.

The prosecution was initiated by the Waikato Regional Council, the environmental regulator for the Waikato region.

The wastewater spill was first noticed on October 6, 2020, by a consultant and staff member undertaking an audit and inspection on behalf of the Hamilton City Council.

Regional council compliance manager Patrick Lynch says HCC knew it was likely the contamination had been occurring for some time.

"Despite having that knowledge, through a series of communication failures within the city council, the discharge was not stopped until October 12," Lynch says.

The wastewater spill was caused by a pipe blockage in the Cumberland Drive wastewater pipe network due to a build-up of fats, rags, and other materials, most of which should not be put into the wastewater system.

The blockage led to wastewater overflow into the Delia Court stormwater system and then into Te Awa o Katapaki Stream.

HCC, which pleaded guilty to the charge, has apologised and undertaken system improvements. The council also participated in a restorative justice process to acknowledge the impact and effect the discharge had on tangata whenua and other river and stream users.

Hamilton's infrastructure operations general manager, Eeva-Liisa Wright, says: "No wastewater overflow to the environment is acceptable, and we are taking all steps to reduce the risk of similar events happening again."

The council says it wasn't able to escalate the issue earlier due to a breakdown in its reporting processes.

Lynch says the case was unfortunate since the city council maintained the very large wastewater network "very well from a regulatory and environmental perspective".

"However, in this instance, they have dropped the ball, resulting in avoidable discharges of large volumes of contaminant into a tributary of the Te Awa O Katapaki Stream in Flagstaff," Lynch says.

Hamilton City Council has been fined $76,500, with 90 per cent to be paid to WRC and 10 per cent to be paid to The Crown. Photo / Supplied

HCC has since identified areas for improvement to reduce the risk of blockages and overflows which include analysis of wastewater trends and community education.

The council is also ensuring that the point in the wastewater system from which excess wastewater can escape, so-called overflow points, are either remotely monitored and alarmed, or removed.

There are 24 overflow points in the city's wastewater system of which 15 have now been removed, including the one at Delia Court.

For four overflow points which are unable to be removed, HCC is trialling remote monitoring technology.

Wright says the Waikato River was an important part of the city's identity and a source of pride.

"We are a river city, and the Waikato River and its tributaries make our city special...They are important for local iwi and a taonga for all, deserving of our greatest respect and care," Wright says.

Lynch says the conviction was "a very clear reminder" to any company or council that manages large volumes of contaminant as part of their business.

"They must have fit-for-purpose infrastructure, manage that infrastructure well and ensure they take immediate steps to mitigate any discharges that occur into the environment."

Wastewater comprises used water from domestic and commercial premises and includes a range of potential contaminants. Sewage is a subset of wastewater that is contaminated with urine or faeces.

HCC has to pay 90 per cent of the fine to the regional council and the remaining 10 per cent to the Crown.

If you see, hear or smell something of concern in our waterways, the council says, please call 07 838 6699. Issues can also be reported using the Antenno app or by emailing info@hcc.govt.nz.