There are many steps and factors involved with the design of a stormwater management system.
The following are ten common terms used in the area of stormwater management that you might see during the land development design process.
1) Impervious area
2) Stormwater runoff
3) Water quality
4) Stormwater volume control
5) Groundwater recharge
6) Rate control
7) Retention basin
8) Detention basin
9) Outlet structure
10) Drainage area
1. Impervious Area
Impervious area is ground cover that allows little to no rainwater through the area after the water reaches the ground. Impervious area (and more specifically the increase in impervious area in the post-development condition) is probably the largest factor involved with determining the size of a stormwater system.
2. Stormwater Runoff
Stormwater runoff is the rainwater that is not absorbed or infiltrated into the ground and flows downstream of the area where the water lands during a rainfall event.
3. Water Quality
Water quality refers the extent that stormwater runoff is kept free of pollutants through the use of appropriate stormwater management measures.
4. Stormwater Volume Control
Stormwater volume control refers to the controlling of excess rainwater volume that is generated from a proposed land development due an increase in impervious area in the post-development condition.
Many municipalities these days will require your land development project to have a stormwater management system that provides stormwater volume control usually in the form of something designed to retain on the site the excess water volume.
5. Groundwater Recharge
Groundwater recharge refers to the rainwater that is absorbed by and infiltrated into the ground and into the groundwater table after a rainfall event.
A common element of stormwater management system designs today is the retention of stormwater runoff for the purpose of groundwater recharge.
6. Rate Control
Rate control refers to the controlling of post-development flow rates to pre-development conditions.
7. Retention Basin
A retention basin is a stormwater management basin that is designed to collect and keep on the site a certain quantity of stormwater runoff to be infiltrated into the ground, evaporated into the air, or transpired into proposed vegetation.
8. Detention Basin
A detention basin is a stormwater management basin that is designed to collect and temporarily hold back stormwater runoff.
9. Outlet Structure
An outlet structure is the control structure (usually a drain inlet box with a grate and a designed orifice on at least one of the sides) that is used to allow out the flow of water from a stormwater management system at specific flow rates during rainfall events.
10. Drainage Area
A drainage area is the area of land that drains to a certain point that is used in preparing the hydrology calculations that are required for the design of a stormwater management system.
Stormwater Management Is a Complicated Topic
The above is just a sample of the terms that exist for the complicated topic of stormwater management. You will probably hear more as you work with your civil engineer to design your land development plans and any associated stormwater management systems.
Related: Stormwater Management (A Guide for the Non-Professional)
