Design Development

Stormwater features such as constructed wetlands, green roofs, and bioswales can be designed as a site asset (aesthetic, habitat, etc.) and provide valuable amenities. Including these features can also increase property value.

Stormwater systems can range from bioswales to cisterns to green roof systems, and range greatly in cost and effectiveness depending on the application. Certain on-site stormwater treatment technologies can be costly but serve additional environmental purposes and may contribute to various other LEED credits related to open space and heat island effect. See ‘Related Credits.’ These strategies should be considered and designed for multiple purposes.

Porous pavement can be incorporated into many sites and climatic conditions. Proper design, installation, and maintenance is important. Work with an experienced contractor, and verify that porous paving will work with your site’s climate and soil conditions. For example, snowplowing, sanding, and salting can damage porous paving.

In urban areas and sites with little land, use a variety of features to achieve project goals. For example, green roofs and rainwater cisterns may be effective in these situations. Capturing rainwater for irrigation will reduce the amount of stormwater runoff leaving the site as well as outdoor potable water use. Reusing captured rainwater for toilet flushing will have similar effects, in addition to reducing potable water use indoors.

All design methods must consider the soil type and infiltration rates to show that soils are capable of treating the appropriate amount of rainfall.

Stormwater storage and biofiltration can be incorporated into landscape features and can also include educational elements for occupant and community benefits.

Soil type, planting medium and plant species must be considered for their capacity to promote infiltration.

Consider contouring the land to direct stormwater to planting beds to reduce irrigation needs of potable water in locations where stormwater capture and reuse is not allowed.

Treating captured stormwater to the quality standards required for this credit provides the potential for a clean water source for irrigation or toilet flushing, and a further reduction of the burden on municipal treatment facilities.

The stormwater design should reflect unique site features, attempt to minimize impacts on natural stormwater hydrology, and promote infiltration and treatment of stormwater runoff.