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Photo Credit: Dakota County Soil & Water Conservation District
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There are generally two forms of substantial impacts of post-construction runoff.
First, as runoff flows over areas altered by development, it picks up harmful sediment and chemicals such as oil and grease, pesticides, heavy metals, and nutrients (e.g., nitrogen and phosphorus). These pollutants often become suspended in runoff and are carried to receiving waters, such as lakes, ponds, and streams. Once deposited, these pollutants can enter the food chain through small aquatic life, eventually entering the tissues of fish and humans. Second, increased impervious surfaces interrupt the natural cycle of gradual percolation of water through vegetation and soil. Instead, water is collected from surfaces such as asphalt and concrete and routed to drainage systems where large volumes of runoff quickly flow to the nearest receiving water. The effects of this process include stream bank scouring and downstream flooding. Post-construction storm water management in new development and redevelopment needs pre-construction planning and budgeting. The goal: maintain good water quality conditions after an area has been developed. Studies have shown that it is much easier and more cost-effective to control pollution at its source rather than after it enters into an MS4. It is important to consider BMPs that may be needed for post-construction pollution control prior to the construction. Strategies include a combination of structural and non-structural BMPs appropriate for the community. Structural controls include use of storage, infiltration, and vegetative practices. Non-structural controls include planning and procedures and site-based local controls. Learn more about innovative ideas: Post-Construction Stormwater Management Best Management Practices Design and Specifications
If you have any questions / comments please contact: Pat Sauer, Iowa Association of Municipal Utilities (IAMU) 800-810-4268 or psauer@iamu.org |
