Stormwater Design

Stormwater Design

Eliot Sinclair are frequently engaged to carry out the design of stormwater management systems for projects ranging from a single lot to a large sub-division of several hundred lots.

Whilst the scale of the development may vary, the requirements of the stormwater management system are generally the same. The dual purposes of stormwater management are to treat and attenuate the discharge from a developed site to match the pre-development conditions as closely as is practicable.

Assessing the site conditions including on-site invasive testing is crucial to selecting the appropriate stormwater management system. A site underlain by free-draining gravels with deep groundwater may be suited to a treatment train including dry basins with discharge to ground via soakage, where as deep layers of poorly drained silts combined with seasonally high groundwater may require treatment and attenuation via wet ponds and wetlands with disposal to surface water.

The engineers at Eliot Sinclair are experienced in designing stormwater management systems for these varying site conditions that meet the requirements of both the District and Regional Councils, and in obtaining consent for those systems from both. Typically, designing a stormwater management system will require hydraulic analysis of the catchment in some form. At Eliot Sinclair we are confident at performing this analysis using either hand calculations or proprietary modelling coupled to our land development software, depending on the complexity of the project.

As well as the designing and consenting, the team at Eliot Sinclair also produce specifications and documentation for tendering, and are able to provide supervision during construction as well as post construction testing to ensure that the stormwater management system performs as required by the design or consent.


Eliot Sinclair would be happy to put their knowledge of stormwater management to use for you on your next project.