Increasing Wellington’s resilience with Omārōrō Reservoir

The construction for the Omārōrō Reservoir began in 2020 and was one of the largest water infrastructure projects in the Wellington region. 

With only a few buried reservoirs across New Zealand, Omārōrō will play a key role in increasing the city’s resilience as it has doubled the water storage capacity for Wellington’s CBD and stores enough water to last around two days. 

The concrete structure is built to withstand a 1 in 5000-year earthquake, and serves 70,000 residents in central Wellington, Thorndon, Newtown, Mount Cook, Hataitai, Kilbirnie, Miramar, Strathmore and Seatoun, as well as Wellington Hospital.

This $70 million project was delivered on time and within the approved budget, with the reservoir put into service one year ahead of schedule, in December 2022. It was officially opened in February 2024.

This project was a joint venture led by Wellington Water, which manages the city’s drinking water, stormwater and wastewater, working with Wellington City Council and the Greater Wellington Regional Council. 

The reservoir was buried underground so as not to impact on the Town Belt and the greenery of Prince of Wales Park, in accordance with the Wellington Town Belt Act, to ensure this precious regional resource stays protected. 

A total of around 44,000 cubic metres of material was excavated, more than half of which was stored and used to bury and cover the reservoir site.

The area has now been landscaped to look like a normal park space, with plants such as young totara and northern rata, and the park is reopened for the public to enjoy.

Before the excavation, the priority was taking care of the native lizards and skinks. Special habitats were created near the site, with help from Department of Conservation, community volunteers, and students from Wellington High School.

Around 26 lizards were safely captured and relocated to their new habitats, allowing arborists to remove the large old pine trees and other vegetation.

Significant work went into protecting the local stream and surrounding environment, with erosion control systems and two sediment ponds. These collected runoff from the reservoir site during construction and the water collected in the ponds was used for dust control on site.

The project was recognised with two awards for its community engagement initiatives, including the Omārōrō Community Reference Group, a proactive forum for keeping the community informed and involved, and contractor HEB Construction's full-time community liaison representative, who was on hand to support the community and address any concerns for the entire three-year construction programme.