Coast Clear for Wellington: Seaview Wastewater Treatment Plant

SUEZ’s innovative design-build approach to a new wastewater treatment plant in New Zealand’s Hutt Valley has helped clean up the region’s coastline and marine ecosystem, and deliver efficient, reliable and cost-effective wastewater treatment.

The mission

Preserving the marine ecosystem

The Hutt Valley in the Wellington region of New Zealand’s North Island is renowned for its stunning coastline and pristine natural environment.

In the 1990s, Hutt City Council saw a need to improve and protect the region’s marine and coastal environs. The existing Wainuiomata Wastewater Treatment plant needed to be replaced, and Wainuiomata Valley’s wastewater redirected to a new plant through a pipeline connecting the two valleys.

The new plant needed to meet stringent effluent quality requirements to cleanse Wellington’s southern coast and reduce discharge to Wainuiomata River.

Seaview Wastewater Treatment Plant next to Wellington Harbour

Effective and sustainable wastewater treatment is helping keep Wellington’s southern coast beautiful and preserve its marine ecosystem.

Our answer

A design-build solution

In 1999, Hutt Valley Water Services – a subsidiary of SUEZ and OMI Beca – was awarded the contract to design, build, operate and maintain the new Seaview Wastewater Treatment Plant (WTP) for 20 years.

The team cultivated a deep understanding of the client’s needs before developing a range of smart solutions targeted at improving the coastal environment while minimising the plant’s impact on the local population. Integral to the plant is a thermal drying facility that treats and dries wastewater sludge into a pathogen-free pelletised product for horticultural use. A range of odour control features ensure a safe, healthy environment for workers and the community.

Commissioned in 2002, the plant can treat up to 53 million litres daily, servicing around 146,000 residents and a large number of local industries.

53 Million

Litres daily

is treated up to service 146,000 residents

Ready for anything

Wellington lies along an active seismic fault, with variable amounts of vertical movement causing uplift to the north-west. This meant that the plant’s design needed to incorporate seismic engineering requirements to enable it to operate under high-stress conditions.

The wastewater tanks developed for the plant are designed to remain intact during an earthquake, reducing the chance of wastewater spilling into the harbour and minimising operational disruptions.

The results

Enduring benefit

SUEZ’s smart solutions to Hutt City Council’s wastewater treatment challenges have delivered vast improvements to the region’s marine and coastal environment, and returned the water in the Wainuiomata River to its natural state.

With flexibility to upgrade the plant’s capacity by up to 50 per cent, the Seaview WTP is well prepared to handle future population growth.