PRINCIPLE NO. 5 Use Vegetated Open Channels
Where density, topography, soils, and slope permit, vegetated open channels should be used in the street right-of-way to convey and treat stormwater runoff.
Notes:
Curb and gutter systems are required for many jurisdictions, particularly in medium to high density residential projects and sometimes even in low density residential projects. While curb and gutters allow the quick transport of stormwater, it does not provide treatment of the stormwater which is often polluted from vehicle emissions, pet waste, lawn runoff, etc.
Open vegetated channels remove pollutants on site by allowing infiltration and filtering to occur, unlike curb and gutter systems which move water with virtually no treatment. Engineering techniques have advanced the roadside ditches of the past which suffered from erosion, standing water and break up of the road edge. Grass channels and dry swales are two such alternatives and with proper installation under the right site conditions, they are excellent methods for treating stormwater on site. In addition, open vegetated channels can be less expensive than curb and gutter system.