Seaton Valley Stream Upgrade: Case Study of Implementing a Channel Upgrade on Multiple Private Properties

The Seaton Valley Stream is the main watercourse draining the hills behind Mapua and Ruby Bay, across coastal flats beside the Mapua township to the Waimea inlet. The lower section of the stream is approximately 2.5km long and crosses multiple private properties with a number of culverts and driveways over the stream. It is also associated with some challenging drainage easements dating back to 1917, which afforded rights to the upstream property owners over the downstream section of drain in private property.

Our presentation will outline the key challenges and solutions in implementing the stormwater upgrade including:

• The consultation process with the multiple private property owners and the strategies to gain acceptance from the property owners.
• The lessons learned from the consenting process in a sensitive coastal environment.
• How to integrate the hydraulic design with landowner and consent constraints.
• How the infrastructure engineers and the policy planners worked in parallel to achieve the above.