A stormwater detention vault is an underground structure designed to manage excess

stormwater Stormwater, also written storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed lan ...

runoff on a developed site, often in an urban setting. This type of best management practice may be selected when there is insufficient space on the site to infiltrate the runoff or build a surface facility such as a

detention basin A detention basin or retarding basin is an excavated area installed on, or adjacent to, tributaries of rivers, streams, lakes or bays to protect against flooding and, in some cases, downstream erosion by storing water for a limited period of time. ...

retention basin A retention basin, sometimes called a retention pond, wet detention basin, or storm water management pond (SWMP), is an artificial pond with vegetation around the perimeter and a permanent pool of water in its design. It is used to manage ...

. Detention vaults manage stormwater ''quantity'' flowing to nearby

surface water Surface water is water located on top of land, forming terrestrial (surrounding by land on all sides) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean. The vast majority of surfac ...

s. They help prevent

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

ing and can reduce

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

in rivers and streams. They do not provide treatment to improve

water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through tr ...

, though some are attached to a

media filter A media filter is a type of filter (water), filter that uses a bed of sand, peat, shredded tires, foam, crushed glass, geo-textile fabric, anthracite, crushed granite or other material to filter water for drinking, swimming pools, aquaculture, i ...

bank to remove pollutants.

Design and installation

Underground stormwater detention allows for high volume storage of runoff in a small footprint area. The storage vessels can be made from a variety of materials, including corrugated metal pipe,

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

fiberglass Fiberglass (American English) or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened i ...

, pre-cast or poured-in-place

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

. The vault is typically buried under a

parking lot A parking lot or car park (British English), also known as a car lot, is a cleared area intended for parking vehicles. The term usually refers to an area dedicated only for parking, with a durable or semi-durable surface. In most jurisdi ...

or other open land on the site. In the latter case, this underground vault may be preferable to a surface

detention pond Detention may refer to: Types of detention * Detention (confinement), the restriction of liberty of someone suspected or accused of a crime * Detention basin, an artificial flow control structure that is used to contain flood water for a limite ...

if other uses are intended for the land (e.g. a pedestrian plaza or park). In other situations, a vault is used because installing a pond might pose other problems, such as attracting unwanted

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

or other animals. In some sites, a vault may be installed in the basement of a building, such as a parking garage. Tunnels may be bored to serve as detention vaults. Tunnels may be cheaper than basins, as they do not require pumps to move the water. The outlet is generally a restricted-flow drain from the detention vessel, with a weir for containing detritus. Detention vessels delay water's delivery downstream, and possibly creates a later water level peak post-rainfall. It is important to consider timing of water release and the types of reservoirs feeding a waterway.

References

{{Sewerage Environmental engineering Hydraulic engineering Hydrology Stormwater management

Design and installation

See also

References