Enhanced Natural Systems (ENS) Stormwater Management Design

Reydarjfordur, Iceland

Roux Associates was commissioned to design an enhanced natural stormwater treatment system for a 200-acre aluminum smelter site to be constructed in Reydarfjordur, Iceland. The project objectives included capture and treatment of smelter-related contaminants in stormwater runoff and passive, cost-effective remediation to meet required standards.

Pre-design elements of the project included an evaluation of the site water budget, usage of green space, site topography, native vegetation and site soils. Extensive geotechnical and chemical analyses were performed as part of a column testing program to characterize site soils and design an appropriate engineered soil profile for treatment and infiltration of stormwater at the site. The engineering design included retention and treatment of an average flow of 1,500 gpm in a 6.4-acre constructed treatment wetland (CTW) system. The CTW system design generally included a sediment forebay, a series of high marsh/low marsh areas, a micropool and extensive network of piping, swales and weirs for conveyance. The design also included planting with select species appropriate for the hydrology of the CTW system and to maximize TSS removal. The treatment system is currently under construction.