SETTING THE STANDARD: UPDATING WAKA KOTAHI’S P46 STORMWATER MANAGEMENT STANDARD

S. Reed & B. Chester (Tonkin & Taylor Ltd), R. Jayaratne (Waka Kotahi NZTA).

1. Introduction

Stormwater management is a critical aspect of resilient highway design. Recent weather events around the country have highlighted the climate resilience challenge we face, which is only expected to escalate as the climate changes and risk increases over the coming decades. Most recently Waka Kotahi New Zealand Transport Agency's (Waka Kotahi) has begun works on recovery projects such as SH25a Taparahi Slip in the Coromandel, SH1 Brynderwyn Hills and the Transport Rebuild East Coast (TREC) project responding to Cyclone Gabrielle.

P46 Stormwater Management Standard (P46) is a contractual document providing the minimum standards for stormwater management on all Waka Kotahi projects. The role of P46 is to drive and enforce well-considered stormwater design and management practices to ensure road safety, climate and flood resilience and to contribute to Te ao Māori, environmental and sustainability outcomes.

The document was originally published in 2016. This abstract outlines the stormwater management challenges Waka Kotahi are facing, and how these challenges are addressed in the recently updated P46 document, which also incorporates industry feedback. A P46 Guidance Document has also been created to provide clarity on expected outcomes and processes to follow. 

The long abstract is below