Inlet, outlet and energy dissipation design for stormwater treatment devices

Authored by Kim Buchanan, Caleb Clarke and Emily Voyde. Prepared for Auckland Council Technical Report TR2013/018.


Inlets and outlets of stormwater assets are used to provide a transition between the reticulation network, treatment devices and the receiving waters.

They are an integral part of the stormwater system and can affect whether the network is safe, whether treatment devices operate effectively, and whether erosion or other environmental problems occur. They also offer the space and opportunity to provide energy dissipation and mitigation measures to address high velocity stormwater flows, safety, or operational issues.

Many inlets and outlets are in reserves or other public spaces. Poor attention to critical design details can result in the area being unattractive, unsafe, underutilised, and unappealing. Poor design (or lack of design) also misses an opportunity for providing landscape or recreational elements.

This report provides information to supersede Chapter 13 and other sections of the former Auckland Regional Council Technical Publication 10 (TP10), Stormwater management devices: Design guidelines manual. Since TP10 was last revised there have been improvements in treatment technologies, a strong focus on low impact design, and more institutional and development community experience in designing appropriate treatment. This new report broadens the topic to include developing smooth inlet transitions and functional outlets for treatment devices and acknowledges that the stormwater network needs to integrate with the environment it sits in. It also acknowledges that a stormwater network is exactly that, a network of various reticulation, appurtenances, devices, and receiving streams that all need to work together optimally to achieve the goals of good stormwater management.

Jennifer Howe

Digital Content Manager