Squeezing in Stormwater

Often achieving low impact stormwater outcomes for a new development can be a difficult task, especially when modifying an existing site. This was the case in 2012 for the Hawke’s Bay Airport Business Park where the site has a very flat topography, shallow groundwater affected by tides and the receiving environment is a sensitive Department of Conservation (DOC) natural wetland. The site is less than 1m above sea level but was previously estuary prior to the 1931 earthquake that lifted the land significantly.

Providing stormwater collection, conveyance and treatment with minimal fall available limited the options for a gravity system and created significant constraints for the Business Park design. A design that integrated the Business Park buildings, car parking, roading, and landscaping with the stormwater conveyance and treatment systems was required.

A series of wide open planted stormwater channels provide soakage to groundwater along with conveyance to banded bathymetric wetlands to achieve a low impact system. The outcome is a cost-effective system that provides function and improves overall site amenity.

This paper describes the objectives, site constraints, tight timeframes, options considered, stormwater solution designed and constructed and the lessons learnt for the new Business Park and existing Airport landside development.