Post-construction storm water management is necessary because runoff from developed areas can impair local streams and rivers if not properly managed. Two general types of impacts can occur. First, runoff can carry pollutants such as oil and grease, pesticides, heavy metals, and nutrients and convey them to nearby streams.
The second post-construction impact occurs as a result of increased storm water runoff volume and rates caused by an increase in impervious (hard or paved) surfaces. The added impervious area reduces the amount of rain water that soaks into the ground, and speeds the flow of the water toward a storm drain or open channel. This can result both in localized and downstream flooding, as well as stream bank erosion, if management practices aren’t put in place to address the added volume and increased flow.
Structural management practices, such as retention ponds, filter strips, and bioretention basins (rain gardens) can be put in to give storm water runoff a chance to slow down and soak in. Non-structural management practices can include buffer strip and riparian zone preservation, minimization of disturbance and imperviousness, and maximization of open space.
Ohio EPA developed and maintains the Rainwater and Land Development Manual which defines Ohio’s standards and specifications for stormwater practices implemented during land development. Below are links to specific chapters that address post-construction management practices.
