Port Waikato stormwater resilience project
Port Waikato’s stormwater network was affected when Cyclone Gabrielle hit, with damage to existing infrastructure and issues arising because of several landslips.
After completing initial repairs, Council successfully put forward a request for funding to central government and was allocated $2.35m to invest in stormwater resilience for Port Waikato.
Our specialist waters team has assessed the current stormwater network and future demands for Port Waikato and has put together a list of projects that will improve its long-term effectiveness and resilience.
It is important that we prioritise the projects that will give greatest overall benefit. So, we have been working with the community to make sure we select the right areas to focus on.
Consultation
Feedback and discussions within the community to date have helped define a list of possible projects. We are working through your feedback to make sure we prioritise those projects to give the greatest possible benefit for Port Waikato.
We are establishing the cost of the identified priority projects, then we’ll know if there is money to do any of the other projects. At that point we will reconsider the slip and campground flooding projects.
What we plan to do
We worked with the community and specialist experts to list a number of potential areas for investment. Detailed modelling helped us evaluate the options in terms of factors such as the impact of each project on property, reduction of future flood risk, long-term community benefit, environmental issues such as water quality, cultural considerations and, of course, costs. With budget from the Government’s flood resilience fund able to cover 3 to 5 projects, further consultation with the community resulted in a prioritised shortlist, with some proposed work requiring further investigation.
Two of the projects are considered to be the cornerstone of the drainage system and it has been agreed that, for future stormwater work to be successful, these projects need to be completed first. Some projects need further investigation before they can be confirmed as included in the fund investment, if funds allow. Others will be held over for consideration as part of future stormwater development.
For the confirmed projects, consulting services have been procured to manage the design stage, with survey work, geotechnical assessment and landscaping design underway.
A: Landslide above Port Waikato Wharf Store & Post Centre
This blocked Tuakau Bridge Port Waikato Road and damaged buildings. The proposed works are on farmland to reduce risk of future re-occurrences. The works are predominately upper catchment planting but may also include reshaping of some gully sections. Subject to private landowner approvals.
Recommendation: Potential priority project with further investigation needed before it can be confirmed.
B: Landslide above Pats Culvert
This blocked Tuakau Bridge Port Waikato Road. The proposed works are on farmland to reduce risk of future re-occurrences. The works are predominately upper catchment planting but may also include reshaping of some gully sections. Subject to private landowner approvals.
Recommendation: Not included in this programme of work.
C, D and E: Pumpstation - Power resilience upgrade and capacity upgrade
Control systems and backup power upgrade to ensure the pump station continues to operate during power outages. Increase pump capacity from 90 litres/second to 240 litres/second. Improvements to discharge outlet to mitigate any scour risks due to increased discharge rate.
Recommendation: Confirmed as a priority project.
F: Main drain widening
Widening the main drain that feeds the stormwater pump station to increase flood storage. This will likely consist of widening to the west and including some re-shaping of the existing drain/removing any existing sediment build-up.
Recommendation: Was confirmed as a priority project. Further modelling work has determined that drain widening will not provide the benefits that were initially thought, therefore this work will not go-ahead.
G: Maunsell Road Bridge raising
Mitigation work to reduce flood levels in the upper urban area above the bridge by increasing the capacity under the Maunsell Road Bridge. Proposed works would raise the existing bridge deck. A new bridge is not being considered due to likely costs.
Recommendation: Not included in this programme of work.
H: Reduced flood risk at Oraeroa Marae
Mitigation work to reduce flood levels around the Ooraeroa Marae. Likely to include daylighting of the existing culvert (removal and installing open channel(s).
Recommendation: Confirmed as a priority project. Consenting and detailed design work is underway.
I: Reduced urban flood risk at Port Waikato Holiday Park and surrounding Urban area.
Work to reduce flood levels without directing additional stormwater into the swamp. This is likely to include installing pipes and a small pump station to convey stormwater to the main channel.
Recommendation: Potential priority project if funds available, with further investigation needed before it can be confirmed.
J: Reduced urban flood risk around Westside Road and Phillips Reserve
Work to reduce flood levels in 2 flood zones. This is likely to include installing pipes to convey stormwater to the main channel/upgrading existing open channels.
Recommendation: Hold for future consideration.
K: Reduced urban flood risk around Maunsell Road
Reinstatement of roadside/verge swales to improve stormwater conveyance (and reducing flooding) along the section of Maunsell Road close to the Sunset Beach Carpark (southern side of road).
Recommendation: Hold for future consideration.
For more information
If you have any questions or feedback, please feel free to contact Mark Curtis.