Property owners who experienced flooding in Ōtaki Beach during heavy rainfall will have celebrated the news of a new stormwater pump station for Ōtaki Beach.
This project began in late 2013 and finished in early 2017. It consisted of replacing old underground stormwater pipes with larger ones, and a new pumping station built on a Council-owned property to increase the capacity of the existing stormwater network.
The new pumping station discharges stormwater into the dune area opposite Marine Parade, substantially reducing the amount of stormwater that was discharged directly into the Waitohu Stream.
ABOUT THE PROJECT
This project featured a large catchment area of 52 hectares. The existing pipes were undersized in relation to today’s design standards, and most of them were at a very flat grade.
Additionally, Otaki Beach frequently flooded during heavy rainfall events flooding roads and residential properties.
WHAT THE PROJECT INVOLVED:
- Preparation of a resource consent application for the subdivision of 37 Moana Street to create a local purpose reserve and residential lot.
- Land Transfer survey.
- Arranging sufficient ground investigations to identify all significant service conflicts.
- Resource consent from GWRC.
- Arranging for sufficient topographical survey to undertake detailed design of upgrade.
- Detailed design of the upgrade including the pump station rising main, outlet works, pipe network upgrades, inlets and associated works.
- Consultation with affected parties including Iwi, GWRC.
- Detailed design report.
- Provision of an Engineers estimate.
- Preparation of a staging plan, allowing for the current approved KCDC budget.
- Preparation of NZS3910 based tender documentation.
- Tendering and tender evaluation based on open tender through the Tender Link website.
- Contract management to a CM4 level.
Cuttriss met with Iwi during the design process. Iwi wanted no final discharge to Waitohu Stream, no discharge direct to the sea and no pumped discharge to the foreshore to be hazardous.
The final solution was to discharge to beach dune areas with balancing pipes between disposal areas. This relies on a combination of soakage and storage. The storage area in dunes amounted to 7,300 m2. The storage volume in dunes was 3,900m3.
THE OUTCOME:
This project was put forward in the Contractors Federation Regional awards for a technically complex project – and won!
Practical Completion was issued on 09 January 2017, and a Defects Liability Certificate was issued on 09 January 2018. There have been no defects or problems with the pump station since gaining Practical Completion.
ABOUT CUTTRISS:
Celebrating 70 years in the industry, Cuttriss Consultants are leading experts in land surveying, civil engineering and resource management planning in New Zealand.
Working with a range of stakeholders, including; business owners, developers, local Councils, central government agencies and local Iwi, Cuttriss Consultants take pride in creating thoughtful, socially and environmentally conscious spaces.
At the forefront of significant projects including the Aotea and Waikanae North housing subdivisions, as well as the relocation of Saint Patrick’s/Our Lady of Kāpiti School Cuttriss is working to build mutually beneficial relationships with our local communities.
