Rainsmart Tank Module system supersedes traditional gravel and pipe based systems by far. The system provides a void space ratio of over 95% compared to 30% in typical gravel and pipe based systems. Consequently, the Rainsmart system offers a smaller footprint for the same storage volume, significantly saving the amount of excavation, soil transport, importing clean aggregate and thus reducing earthworks related installation costs, and causes minimum site disruption, and doesn’t have any traditional problems of clogging associated with gravel and slotted pipe based systems, making it an Ideal Product for Bio-Swales.

Bioretention swales or Bio-Swales commonly known as, provide both stormwater treatment and conveyance functions. Ellipse Tank Modules are installed at the base of a swale wrapped in geotextile, and designed to convey stormwater as part of a minor and/ or major drainage system. The swale component provides pretreatment of stormwater to remove coarse to medium sediments and dissolved pollutants while the bioretention system removes finer particulates removal and provides oxygenation of stormwater.

Bioretention swales provide flow retardation for frequent storm events and are particularly efficient at removing nutrients. Bioretention swales also act to disconnect impervious areas from downstream waterways and provide protection from frequent storm events by reducing flow velocities compared with piped systems.

In some circumstances Bioretention swales can also be used as ‘infiltration’ systems in permeable and semi permeable soils to reduce peak runoff. The primary intent of Bio-Swales is to treat and store stormwater for possible reuse by wrapping the system in an impermeable liner, however, where the in-situ soils allow and there is a particular design intention to recharge local groundwater and reduce peak flow via Infiltration the swale can be wrapped in Geotextile and used as a infiltration system.

A key hydraulic design consideration for bioretention swales is the delivery of stormwater runoff from the swale onto the surface of a bioretention filter media. Flow must not scour the bioretention surface and needs to be uniformly distributed over the full surface area of the filter media. In steeper areas, check dams may be required along the swale to reduce flow velocities discharged onto the bioretention filter media.

Grassed (turf) bioretention swales can be used in residential areas where a continuous bioretention trench approach is used. The preferred vegetation for the bioretention component of bioretention swales is therefore sedges and tufted grasses (with potential occasional tree plantings) that do not require mowing

Bioretention swales may be located within parkland areas, easements, carparks or along roadway corridors within footpaths or centre medians.