Stormwater Design Challenges Hampton Downs Motorsport Park

Fraser Thomas were commissioned by GP Farms Ltd to prepare a Stormwater Management Plan for a new motorsport complex and associated Business Park covering some 90ha at Hampton Downs, North Waikato. This paper describes the stormwater management systems adopted for the complex and the issues experienced in implementing these systems in a unique and dynamic motorsport raceway environment.

A comprehensive Stormwater Management Plan was prepared in accordance with relevant guidelines which determined hydrological characteristics of the area encompassing the motorsport circuit and business park catchments and included detailed design of stormwater collection, conveyance, treatment, detention and monitoring measures for these catchments.

Effective stormwater treatment and detention was designed and implemented for both the motorsport and business catchments as appropriate to satisfy stormwater quantity, quality and channel protection requirements. A “treatment train” approach was adopted, involving the use of suitable devices for the removal of litter and hydrocarbons from runoff, swales for stormwater treatment and conveyance and downstream wetlands to provide contingency treatment and peak flow attenuation and to improve the flooding situation which occurs at times on the Flats below the site.

The motorsport complex is now operational, with an extension to the race track and completion of the business park planned for the near future.