Stormwater carries pollutants off land. Pollutants come from:
- Cars leaving petroleum residues and metals on roadways
- Fertilizers, herbicides and pesticides applied to lawns, golf courses and farmlands
- Land clearing
- Broken sewer lines and leaking septic tanks
- Animal wastes: pets, livestock, and wildlife
What We Can Do: Innovative Stormwater Treatment
Types of Stormwater Treatment
Three general approaches are used to prevent, reduce and eliminate polluted stormwater runoff and hence constitute acceptable measures for Phase II activities.
- Structural best management practices (BMPs) replicate the original water flow patterns, or hydrology, of the undeveloped land. This maximizes infiltration of stormwater so natural processes can remove pollutants. Examples are constructed wetlands, filter strips, grassy swales, and rain gardens.
- Use of nonstructural BMPs. Examples include environmental education and preservation of pervious surfaces through establishment of riparian buffers. Others include using lawn chemicals efficiently, fixing and maintaining septic tanks, and picking up pet wastes.
- Better Site Design focuses on alternatives to traditional construction practices. Examples include reducing the amount of impervious surface in a development by installing narrower roads, using cluster development layouts or pervious concrete.
Continued monitoring for compliance and effectiveness is required to ensure the ultimate success of all three approaches.
Constructed Wetlands: Ivy Glen
Original Stormwater Detention Pond
In South Carolina, holding ponds are used to prevent flooding from stormwater runoff. The are not designed for water quality control and are not very attractive.
Building a Constructed Wetland: A Multi-Pond System
Adding constructed wetlands to these ponds could improve water quality, while giving a nicer appearance and maintaining flood control.
We retrofitted an existing stormwater detention pond sited at Ivy Glen, a planned unit development in Conway, SC. Our retrofit converted the largest of five detention ponds from a shallow non-vegetated dry pond into an extended detention, multiple pond system.
Pollution Removal by Constructed Wetlands
After a storm, the constructed wetlands removes 98% of contaminant bacteria. Removal of other pollutants was in the range of 50%.
Permanent educational signs are posted at the site and are used to educate developers, property owners, and municipal officials.