With the growth in communities, there’s an increase in the requirement for diverting water. Stormwater runoff buries city sewers and can be hazardous to the surrounding rivers and streams through erosion. By managing the stormwater close to its source, you can end up saving thousands in expensive repairs that would probably be incurred in controlling flooding or correcting erosion. A popular method used for stormwater management is the construction of stormwater basins. A stormwater basin is designed to collect the water and later release it slowly such that erosion or flooding is avoided.

There are two significant types of stormwater basins. These are detention basins and retention basins. We’ve put together this guide to illustrate the difference between the two.

Detention Basins vs Retention Basins

The major difference between them is determined by the availability or lack of a permanent pond or pool of water. A low flow orifice usually manages the water level. The orifice is mostly a part of a riser, a concrete structure. For a dry/ detention pond, there’s an orifice level situated at the basin’s bottom and lacks a permanent pool of water. Also, all the water flows out in-between storms, and it mostly remains dry. On the other hand, a retention pond/ basin has an orifice and a riser situated at a higher point and so holds a permanent pool of water. Although a retention basin shares a similar appearance to a regular pond, it plays a significant role in stormwater runoff management.

The basins are crucial for storing and reducing stormwater runoff from surrounding areas, particularly areas with concrete or asphalt development. The main reason being stormwater runoff flows quicker from these surfaces compared to natural occurring regions and requires to be diverted to make sure the runoff takes place at the right rate. There’s a restriction in the extent of both cleaning and treatment. In short, detention basins only manage flood flows, but a retention pond can additionally offer some benefits in water quality by minimizing sediments and pollutants.

Detention Basins

Detention basins are best applied in areas where there are vast acres of land. It’s rather challenging to manage water quality, and alternative options might be more suitable. Generally, they use a tiny slope to divert water. It’s required that the inlet is slightly higher than the outlet to allow the precise amount of water flow via the system. Basically, the system functions by providing a large collection basin, or area, for the water. Afterwards, the water gradually drains out via the outlet situated at the structure’s bottom. Concrete blocks sometimes act as a deterrent to reduce the water flow and gather extra debris.

Retention Ponds

Retention ponds are a stormwater control structure that allows retention as well as treatment of infected stormwater runoff. Through capturing and retention of stormwater runoff, retention basins/ ponds manage stormwater quantity and quality. Pollutants are then eliminated through the natural processes experienced in the ponds. Retentions ponds ought to have natural vegetation surroundings to improve bank stability as well as aesthetic benefits. Storm drains are connected to the pond by underground pipes that divert water to a retention pond. The system allows a lot of water to enter the pond while the outlet gradually releases the water to maintain the expected water level.