Completed Projects

Major upgrades to the water treatment plants in Patearoa and Ranfurly were completed end of 2025 and beginning of 2026.

These critical improvements are part of planned infrastructure upgrades that have been in development since 2021, aiming to address ongoing issues with protozoa treatment.

The $4.2 million budget allocated in Council's 2024 Annual Plan and 2025 Long-term Plan allows for the treatment upgrade and necessary supporting works.

Why the upgrades were needed

The upgrades included the installation of protozoa barriers at both facilities, to ensure compliance with New Zealand Drinking Water Quality Assurance requirements (as required under the Water Services Regulation 2022, which came into effect in November 2022) and provide more reliable, safe drinking water. The water source for both towns is prone to high turbidity, particularly after heavy rainfall, which can compromise water treatment effectiveness and require boil water notices to protect public health.

What was installed

After evaluating all options, including building entirely new treatment plants (which would have cost approximately $15 million for Patearoa and $21 million for Ranfurly), Council opted for cartridge filter and ultraviolet (UV) protozoa barriers as the most cost-effective solution.

The upgrades included the installation of cartridge filtration and ultraviolet (UV) protozoa barriers at both facilities. UV treatment uses ultraviolet light to neutralise harmful microorganisms, including protozoa, without the use of chemicals. When combined with filtration during high turbidity events, this system significantly improves treatment reliability and compliance with drinking water standards.

What this means for residents

Residents can expect a significant reduction in the likelihood and frequency of boil water notices. While the improvements will greatly enhance the safety and reliability of the drinking water supply, severe weather events may still require occasional precautionary boil water notices.

We are excited to share the completion of one of our wastewater infrastructure projects in October 2024! Here’s what you need to know:

Scope Completion:

• The initial contract scope has been successfully completed and reinstated.

Additional Work:

• We allocated additional scope for replacing the mains on Knowles Crescent.
• Approximately 260 meters of mains has been replaced across four sections in Knowles Crescent.

We applaud South Roads for their outstanding work and timely completion of work on this crucial project.

Thank you for your patience and support as we enhance Ranfurly’s wastewater infrastructure! 💙

For more information see Improvements to Ranfurly’s wastewater resiliency begin - Central Otago District Council (codc.govt.nz)

We’re thrilled to announce the successful completion of a crucial project in our water infrastructure in November 2024. Here’s the scoop:

Project Overview:

• Our wastewater pump station sites have undergone upgrades.
• The addition of generators ensures that during power outages, these sites are no longer vulnerable to emergency overflows into nearby rivers and lakes.

Upgraded Pump Stations:

• Alpha Street
• Melmore Terrace
• Wrightson’s (Opposite Linger & Die Reserve)
• Bridge Hill

Next time you drive past these locations, take a moment to appreciate the enhanced resilience of our wastewater system!

Completed! This contract was awarded to SiteCare Ltd and was completed in June 2024.

The two wastewater ponds at Roxburgh underwent desludging with a dredge, and the extracted sludge was subsequently pumped into geo bags on the site.

Desludging of the ponds is an important maintenance activity for waste stabilisation ponds, as sludge accumulation reduces treatment capacity and can result in an increase in odour emissions.

A pyramid of geo bags has been established at the treatment plant site. These bags will remain in place for about 12 months or until they achieve the necessary level of dry solids, after which they will be disposed of.

Background information

Originally consulted on with the community in the 2018 Long-term Plan, the Lake Dunstan Water Supply project is getting close to going live at the end of May 2023. The $16.1 million upgrade to the water supplies of both Alexandra and Clyde reflect our focus on the health and wellbeing of our communities.

The project scope included the expansion of the Clyde bore field and the construction of a membrane treatment plant and water storage tanks now complete.

You might be aware of the benefit this upgrade will provide by reducing the lime in Alexandra’s water, but you may have questions about the membrane treatment. The membrane treatment provides an additional level of treatment, along with chlorination. The upgrade in treatment process will ensure we continue to provide safe drinking water to the community, and we meet our responsibilities against the New Zealand Drinking Water Standards.

A new reticulated wastewater system will replace Clyde's existing system which relies on septic tanks and disposal fields. The upgraded system will meet environmental and resource consent requirements, significantly improving the quality of Clyde's urban wastewater discharges.

Importantly, it will provide the Clyde community with an environmentally safe wastewater system that will bring significant environmental, health and well-being benefits for decades to come.

The project is being completed in three stages spanning. The first stage has now been completed, while two further stages which cover the remainder of the town have not got a scheduled date yet.

Stage one included installing a wastewater pipeline, a pump station and the new reticulated wastewater system for central Clyde.

The image below, provide an overview of the recent work involved in this project.

Progress through May 2023

The Clyde Main Wastewater Pump Station was fully commissioned on 13 December 2022.

This $3.4 million project is a key component of the Clyde wastewater reticulation system. Clyde’s wastewater will be gravity feed from the township through two smaller pump stations before reaching this main pump station off Sunderland Street adjacent to the Clyde dog park. This pump station will then transport the waste through to Alexandra for treatment.

This project provides infrastructure to support growth and will contribute to improved water quality in the Clutha Mata-au.

Progress through October

Through the last week in October and early November the commissioning of the Clyde main wastewater pump station is being carried out.

The commissioning is a multi-stage process that systematically works through each process within the pump station to ensure correct operation before the go live date.

The commissioning included the installation and testing of the two pumps into the well. The pumps, at 55kw each, will work one at a time to pump the wastewater from Clyde to Alexandra at 69 litres per second. The well is 8m deep and 3m wide and will control the flow of wastewater from Clyde through the pipeline to the Alexandra wastewater treatment plant.

Other processes being tested through this phase of the project include the odour controlling chemical dosing unit, instrumentation and telemetry, connection with the Alexandra pump stations, the generator, valve operation, the operation of the emergency storage tanks, and the priming of the 8km wastewater pipeline from Clyde to Alexandra

The completion of the commissioning will allow for the final connections to be made to the properties and stage one of the wastewater system to go live.

The completion of the renewal of the Clyde Falling Main through April and May was an important achievement.

Funded by the Central Government Water Stimulus package, the $1,050,000 project, replaced the existing gravity-pressured water main, a critical piece of infrastructure for the Clyde water network. The falling main supplies water from the reservoir, at the top of the hill, down to water mains at Sunderland Street.

The original falling main, constructed in 1987, was identified as having several issues that presented a risk to a resilient water supply in Clyde. The pipe material was identified as having poor seismic resilience and due to the steep terrain, effective maintenance and repair on the aging pipe was difficult.

This work will ensure that we continue to provide safe and reliable water to Clyde.

To create efficiencies across projects, three other pipelines were installed in conjunction with the falling main upgrade. Two pipes from the Lake Dunstan Water Supply and one from the Clyde Wastewater Reticulation project. We’ve invested our ratepayers' money effectively at the right time to ensure a positive outcome for the community.

CODC and its contractors have been busy with the replacement of the 100-year-old watermain along Centennial Ave in Alexandra.

This pre-emptive work occurred prior to the pavement renewal planned by Waka Kotahi later this year.

Work involves installing new stormwater drainage pipelines from standalone drainage sumps and soak pits to the existing reticulated network, thus improving stormwater drainage during high rainfall events.

As part of your Council's commitment to reduce the environmental impacts from urban wastewater discharges, we are upgrading two wastewater pump stations in Alexandra. The first in the Linger and Die Reserve adjacent to Walton and Rivers Streets, with upgrades to the Dunorling Street station to follow.

Both projects include the connection of the Clyde wastewater reticulation system to the Alexandra treatment plant and increase the emergency storage capacity of each station. The emergency storage ensures that we have storage capacity within the stations during any unplanned outages.

Progress through October

At the Wrightsons Pump Station, which is in the Linger and Die Reserve, the Fulton Hogan team has installed the underground tanks and completed the welding and electrical work.

This was then backfilled and reinstated, the grass will be seeded in the upcoming warmer months.

The commissioning of the Clyde main pump station is closely linked with the Wrightsons Pump Station. Ensuring the two assets are synced with each other is an important step.

The storage tanks for the Dunorling Street pump station upgrade have been ordered with delivery expected in early 2023.

Ensuring the protection of the flood bank and the restoration of the local area is an important part of all our projects. We gratefully thank the community and local residents for their understanding throughout this important project.

The drying bed area of the Alexandra Wastewater Treatment Plant was particularly vulnerable to erosion from a naturally occurring stormwater flow path that flows through the length of the treatment plant site, especially at risk during high rainfall events.

This project involved ensuring the protection of the walls from erosion around the plant’s drying bed area and clarifier.

Stage 1 commenced in early 2022 and Stage 2 continued in July 2023 with the construction of the rock erosion protection walls. This was a continuation of the Stage 1 work already completed past the clarifier (an essential step in a wastewater treatment process involving removing suspended solids through gravity settling, thus providing a clarified liquid effluent).

Following issues with the stormwater pipes negatively impacting private properties in Hawkdun Place, Alexandra, work is almost complete on remedying the stormwater systems in this area.

This has included undertaking CCTV footage of the existing pipeline, the installation of new sumps and pipework, and the installation of a surface mounted kerb along the uphill side of the road.

Following road resurfacing, the plant and equipment was disestablished and the project formally completed on 30th June 2023.

As you are all are hopefully aware, the new rising main pipe has been installed in Cromwell so we can get more water for all the growth Cromwell has now and in the future!

This project was completed in August 2024. This is a two-stage project, check out the project heading “Cromwell Water Treatment Upgrade” above for updates on stage two!

See the map below for where the pipe was installed.

Kudos to HEB Construction! We commend HEB Construction and all their local subcontractors for their excellent work and timely completion of work on this vital project.

Thank you for your patience and support as we enhance Cromwell’s water infrastructure! 💙

The Central Otago District Council (CODC) is actively upgrading Alexandra’s water network. By replacing ageing pipes, we are improving the reliability, pressure, and sustainability of the town's water supply, ensuring our infrastructure is resilient for decades to come.

A $2.7 million budget has been allocated to replace these critical water mains, and the delivery contract has been awarded to HEB Construction.

Priority Areas & Construction Status

Bridge Hill

• The Infrastructure: The concrete-lined steel rising and falling main is a critical pipeline linking Bridge Hill to Alexandra’s wider water network. This nearly 100-year-old infrastructure traverses challenging terrain—with sections laid above ground—dating back to when the Aronui Dam supplied the town’s water.
• Why it was prioritised: Following a significant burst in 2015 and a minor break in 2021, engineering assessments determined the main was nearing the end of its useful life.
• Current Status:Complete. Construction work for the Bridge Hill sector is now fully finalised.

Enterprise Street

• The Infrastructure: This pipeline serves as the main water source for Dunstan High School, Terrace Primary School, and local early childcare facilities.
• Why it was prioritized: The 70-year-old pipeline had been degraded by Alexandra’s softer water supply from Lake Dunstan, which previously caused issues like discoloured water for local schools and residents.
• Current Status:Complete. The renewal project along Enterprise Street successfully broke ground on July 22 and wrapped up ahead of schedule in early October 2025.