When heavy floods happen, and the sewer systems cannot bear the amount of water flowing through them, the stormwater needs to be managed in some way as to protect Dallas’ citizens along with preventing excess erosion of earth due to massive amounts of water. The solution to this prominent issue is the use of water detention.
What is water detention?
(Hint: it’s not the punishment you received in school after misbehaving in class) Water detention is the control of excess water runoff in a dry detention basin.
How is this different from water retention?
Water retention is very similar to the dry pond of detention except that its pond is consistently full of water. A detention pond fills during a flood but then releases the water immediately after the high waters have ceased.
When do I need water detention?
Stormwater detention is required whenever the city ordinance dictates so. The most common instances are when existing downstream storm drainage facilities are designed for less than 100-year capacity, when increased zoning results in a significant increase in runoff, or when downstream cities have their own detention requirements.
How do I go about it?
- Detention basins will either follow the Modified Rational Method (when the land space is less than 130 acres) or the Hydrograph Method (when the land space is greater than 130 acres).
- You may need to construct embankments (a wall of earth or stone) as a type of detention. In this case, the embankment must be at least 2 feet above the level at which the water will rise to in 100 years.
- The full list of detention regulations for the city of Dallas can be found here under section II, 3.4.