Khandallah Pool redevelopment

Following the Council’s decision in May to proceed with a technical review of the options for seismic remediation and upgrade of Khandallah Pool, council officers are procuring an independent infrastructure engineering consultant from the All of Government (AoG) panel to assist.

Technical Advisory Group

To assist, the Council has set up an Advisory Group with three members from the Council and three members from the community.

Technical review

The work will be in two parts:

• Stage 1 – an independent cost estimate of the current scheme to renew Khandallah Pool (peer review)
• Stage 2 – an analysis of any possible alternate schemes that will meet the regulatory requirements and geotechnical assessment of the conditions of the site (options analysis); specifically, attempt to find an alternative and less expensive option that achieves the objective of extending the life of the pool while meeting regulatory and safety requirements.

The selected consultant will engage with the Advisory Group members about their knowledge and findings on the matter.

Technical review report

A report will be provided to the Council in early 2025 to determine the next steps.

On 15 February 2024, the Council’s Long-term Plan, Finance, and Performance Committee voted to include funding for a landscape (non-pool) option in Wellington’s Draft Long-term Plan 2024-34, for community consultation.

Council officers outlined in committee papers that the combination of high construction costs, significant site constraints, a reduced pool size, and low pool usage would contribute to a low value outcome for the level of investment required for a new Khandallah Pool.

View Council report from 15 February 2024 (pages 23-25) (35.7MB PDF)

February 2024 options update

The cost of $11.7m to rebuild the pool within the physical site constraints is now more expensive than when it was considered by the Council in 2022 ($8.05m). This estimated cost could result in a potential increase in ratepayer subsidy per swim from $25 per swim (in the 2022/23 year) to $60-$80 per swim.

The Council is therefore proposing to close the pool and landscape the site, including improving flood mitigation, and creating a new entranceway into Khandallah Park. This would be designed with accessibility in mind to support family and community gatherings and events. Work to date on the concept plan includes large flat grassed areas for play, picnics and events, a structure for small community events, and restoration of the stream. Current estimates to deliver this option are $4.5m. Annual operating costs are estimated at $0.34m.

Following the identification of significant site challenges (see June 2023 update), we’ve received a quantity surveyor report which gives updated cost estimates for two options for the site redevelopment - a new pool option and a landscape (non-pool) option. See the quantity surveyor report below.

A new pool would have to be smaller, due to identified site constraints.

We’ve used data-modelling to also estimate the annual operating costs for each option. This includes costs such as: staffing, utilities, maintenance, and depreciation.

The Community Reference Group for the project will discuss the two options with council officers at a November reference group meeting.

Estimates are:

• New pool option (25m x 7.5m in size) – $11.7 million plus annual $1.1 million operating costs (increased operating costs reflect the reduced capacity/income of a smaller pool and an extended season)
• Landscape (non-pool) option – $4.5 million plus annual $340,000 operating costs

The Council is working towards setting Wellington City’s budget for the next 10 years in our Long-term Plan 2024-34. The Khandallah Pool redevelopment project will be considered, alongside other council projects, as part of this planning and prioritisation process.

A Draft Long-term Plan will be shared and open for community feedback, before the final Long-term Plan 2024-34 is prepared and approved in June 2024. More information on this process is available on the Let's Talk website.

See the full Khandallah Pool Quantity Surveyor Report - Cost estimate (240KB PDF)

The findings of the Khandallah Pool site assessment report, completed in April 2023, identify significant challenges and costs associated with mitigating resilience and vulnerability (see the full report below).

Overcoming these challenges greatly reduces the useful available space for development of a new pool.

Rebuilding a similar pool on the same site won’t be viable due to site constraints, stream flooding mitigation requirements and slope instability risks associated with the adjacent hill.

A detailed options assessment will commence to explore what the relative merits, risks and costs are of the various options that the Council could now pursue given the new technical advice.

Technical investigations

We commissioned several technical reports to better understand the existing site conditions at Khandallah Pool.

The report, completed in April 2023, covered:

• topographical survey
• geotechnical investigation
• flood hazard investigation and modelling
• infrastructure review
• environmental analysis.

The most significant findings being due to the risk of flooding from the nearby Tyers Stream and slope instability of the adjacent hill. The site for any new pool would need to be reduced from the existing footprint and raised vertically by 1.8m to mitigate the flood risk.

In addition to this, investment is required to improve core infrastructure to support the build of any new pool. Specifically, installation of a dedicated transformer and installation of below ground attenuation tanks. The report also highlighted parking constraints due to the changes required at the site.

See the report and presentation:

Khandallah Pool Site Assessment Report June 2023 (20MB PDF)
Khandallah Pool Site Feasibility Presentation (2.5MB PDF)

In February 2022, Council discussed seven concepts of new investment for the future of the pool. This included: replacing the building, maintaining the current level of service, development within the existing pool tank, increasing the level of service by a full rebuild, creation of a splash pad, a potential commercial partnership for hot pools, and the creation of a landscape park.

After undertaking economic and environmental feasibility assessments, more detail was provided on three options:

• Option 1: maintain the status quo with the current level of service,
• Option 2: increase the level of service, or
• Option 3: change the type of service.

In February 2022, Council resolved to ‘increase the level of service’, which meant rebuilding the full structure (option 2), subject to further detailed design and community (place and interest) engagement.

To inform detailed design the following site research was undertaken: a topographical survey, geotechnical investigation, flood hazard investigation and modelling, and infrastructure review.

These works identified several physical restrictions and risks at the site which mean that either of option 1 (maintaining the status quo with the current level of service) or option 2 (increase the level of service) would require a rebuild of the pool structure.