Many counties and townships in the Eastern United States now have regulations limiting impervious surface area. Impervious surfaces on your property are those that do not allow water to pass through. When the proportion of impervious to pervious surface of your property reaches the limit, you must use alternate means to improve the pervious surface and keep storm water contained within your property boundary.
A primary method used to contain larger amounts of storm water is to utilize a French drain. The French drain is built beneath the surface of your land and can be designed to manage large amounts of storm water. The design takes storm water from the roof of a house or other structure via the downspouts and pipes the water into the French drain.
The French drain solution provides a way for smaller properties to add buildings or other structures. The storm water management plan keeps them from exceeding the impervious surface area limit of the property.
An additional benefit is keeping storm water erosion from becoming a problem and keeping storm water away from the foundation of the house.