A New Era for Stormwater Management - NZS 4404:2010

The revised NZ Standard NZS4404:2010 “Land Development and Subdivision Infrastructure” now includes formal provision for Low Impact Design (LID) for stormwater, stormwater treatment and requires climate change impacts to be taken into account.

LID and the need to consider climate change impacts into stormwater design brings new responsibilities and accountabilities for all involved with stormwater management. Important questions include what is current best practice and what are the preferred sustainable solutions for robust, outcomes in this age of increasing uncertainty, and pressure for acceptance of “non-proven” alternative solutions?

The paper focuses on the changes to NZS4404 Section 4 “Stormwater”. The associated implications of these changes, the need for much earlier consultation by developers on stormwater management options and an even greater need for integrated catchment management planning along with the consequential implications for managing stormwater infrastructure in the long term are considered.

While some local guidance on LID is available in New Zealand, best practice national guidelines for LID stormwater alternatives, climate change adaptation design procedures have yet to be developed. The need for more enabling concepts for low impact design in planning documents, for NZS4404 to be supported by sound design guidelines and improved coordination between the planning, design and implementation phases of land development is discussed.