The Aquacomb Response to Shrinking Permeable Surface Problem – an Innovative Solution

Stormwater attenuation is the mitigation of the adverse effects of urban development on flooding. Capturing post-development peak runoff so that it does not exceed the pre-development peak flow-rate is crucial to ensuring hydraulic neutrality. Hydraulic neutrality is achieved by providing a temporary storage for stormwater using different tank storage methodologies. Some of the traditional responses to collecting and detaining stormwater are fast becoming unfit due to the reduction of the size of residential sections. For instance, putting a big tank in an increasingly small backyard, if in fact there was a backyard at all, left no recreational space. Burying a large tank in the same spaces threw up the issues of when to excavate, with what machinery, and whether the tank would fit without displacing foundations. This paper provides a brief overview of stormwater attenuation regulations in New Zealand, and the growing limitations of traditional stormwater storage solutions. As a proffered solution for stormwater detention/retention, a fully engineered stormwater system consisting of interconnecting lightweight modular pods made from polyethylene is discussed. The applicability of this modular solution on a case by case bases for new developments in New Zealand are also highlighted.