Stormwater Management: Peak Flow Attenuation System

This paper introduces a patented peak flow attenuation system that reduces a development’s peak runoff rates to pre-development levels.

The Resource Management Act 1991 (RMA) does not permit an adverse effect on the environment from the discharge of water-to-water. Current Low Impact Design (L.I.D.) methods for land development have been shown to achieve lower than expected levels of compliance with required standards.

Three case studies of Auckland subdivisions using L.I.D. demonstrated an average 11.3% reduction in peak discharge rate when compared to conventional subdivision. For the same case studies, the peak flow attenuation system model achieved a 100% reduction.

The peak flow attenuation system includes energy dissipation that reduces discharge velocity mitigating watercourse erosion and damage to riparian ecology. This system maximises the potential of any residential, commercial or industrial development while satisfying L.I.D. and RMA requirements. The attenuation system features low maintenance, a small footprint, enhanced environmental performance and significant financial benefit and should appeal to the wider engineering community.