Under the Clean Water Act Phase II rules, the Environmental Protection Agency requires local governments to develop stormwater programs to manage the stormwater in their municipality. Large facilities, such as community colleges, must also develop and implement a stormwater management plan. In New Jersey, the state Department of Environmental Protection oversees how muncipalities manage their stormwater. The Stormwater Management rules (N.J.A.C. 7:8) specify stormwater management standards that are mandatory for new major development (www.njstormwater.org).
So just what is stormwater management?
The major goal of stormwater management is to increase absorption of rainwater by soil and vegetation, usually by reducing the speed of flow or by retaining the water in basins. This will reduce the amount of pollutants being carried off into storm sewers and streams, as well as reduce flooding. Increasing absorption by soil has the added benefit of helping to maintain ground water supplies, which are seriously depleted in many areas.
There are various methods and techniques to managing stormwater. Some methods are structural, such as the use of manufactured treatment devices, and others are non-structural. An example of a non-structural stormwater management technique is a bioretention basin/rain garden.
Bioretention basins are landscaped depressions or shallow basins used to slow and treat on-site stormwater runoff. Stormwater is directed to the basin and then percolates through the system where it is treated by a number of physical, chemical and biological processes. The slowed, cleaned water is allowed to infiltrate native soils or directed to nearby stormwater drains or receiving waters. Vegetation growing in the basin helps to remove nutrients such as nitrogen and phosphorus from stormwater, preventing them from entering creeks and rivers which flow to Barnegat Bay.
The bioretention basin/rain garden can be large-scale, capturing stormwater runoff from an entire residential development or shopping area, or it can be small-scale, such as a rain garden on an individual homeowner’s property. A biorention basin/rain garden is one example of what is known as a “Low Impact Development” (LID) stormwater management method.
What is Low Impact Development?
Low Impact Development (LID) is an innovative and ecologically-friendly approach to site development and stormwater management. Its basic principle is to mimic a site’s pre-development hydrology by using design techniques that infiltrate, filter, store, and detain stormwater close to its source. LID aims to minimize development impacts to land, water, and air.
Ocean County Department of Planning
Ocean County Soil Conservation District
New Hampshire Stormwater Center
US EPA Low Impact Development — videos, information resources, and design manuals about LID methods