How do detention ponds work?

How do detention ponds work?

PURPOSE: Detention ponds temporarily store stormwater runoff, thereby reducing the peak rate of runoff to a stream or storm sewer. They help to prevent localized flooding and, if designed to do so, provide some water quality benefits and reduce streambank erosion downstream.

Do detention ponds hold water?

A detention, or dry, pond has an orifice level at the bottom of the basin and does not have a permanent pool of water. All the water runs out between storms and it usually remains dry. A retention basin or pond has a riser and orifice at a higher point and therefore retains a permanent pool of water.

How is a retention pond usually built?

Usually a retention pond is constructed because of a high groundwater table (in other words, the groundwater is near the surface of the earth). The bottom of the pond is excavated below the water table elevation to establish a permanent pool. The outlet of the pond is placed at or above the desired pool elevation.

How deep is a detention pond?

A typical extended detention basin will range from 3 to 12 feet in depth. Depth is often limited by groundwater conditions or the need for positive drainage from excavated basins.

Do detention ponds smell?

Detention ponds often have sediment that settles at the bottom of a pond that needs to be removed once the pond has dried. In retention ponds, floating litter, algae and shoreline erosion are common, as well as stagnant water producing odors and breeding grounds for mosquitoes.

What is the purpose of detention ponds?

What is a Detention Pond? The main difference between a detention and a retention pond is whether or not it has a permanent pool of water. A detention pond is designed as a “dry pond.” Its purpose is to hold back flood waters and slowly release the water so that creeks and rivers do not become flooded.

How much does a detention basin cost?

According to the EPA, typical costs for wet detention ponds range from $17.50-$35.00 per cubic meter ($0.50-$1.00 per cubic foot) of storage area. Dry detention basins typically cost around $10 per square meter ($0.30 per cubic foot) for smaller basins and $5 per square meter ($0.15 per cubic foot) for larger basins.

Is it safe to live near a retention pond?

Retention ponds and detention ponds are raising safety concerns for those who live near them. A main safety concern regarding these ponds is that children are extremely attracted to them and can risk drowning or other water-related personal injures.

Is it safe to live near a pond?

Living near a pond is most definitely a safety issue for families with young children or families who may have frequent visits by youngsters.

Why do subdivisions have retention ponds?

Retention Ponds in Subdivisions You will often find them in subdivisions because these areas are full of roads, concrete, and homes. These ponds give stormwater a safe place to go. They prevent flooding and increase water quality in the community.

Are detention ponds hazardous?

Safety Hazards: Detention basins pose multiple potential safety hazards including drowning, exposure to contaminated water, and increased exposure of adjacent community to mosquito transmitted diseases.

Do detention ponds have fish?

A: It is legal to fish storm water retention ponds, so long as the angler has a valid fishing license, said Lisa Coleman of the city’s engineering department. Whether it’s fluids dripped from cars or from yard runoff, chemicals can enter the system even more easily than fish.

How is a detention pond different from a retention pond?

A detention, or dry, pond has an orifice level at the bottom of the basin and does not have a permanent pool of water. All the water runs out between storms and it usually remains dry. A retention basin or pond has a riser and orifice at a higher point and therefore retains a permanent pool of water.

How much does it cost to build a detention pond?

The cost of your detention pond project (or the cost of your retention pond, of course) depends on a few factors such as the size of the pond and the location where it will be dug. However, in many cases if the water from a pond is being repurposed, the pond will pay for itself very quickly.

How long does it take for a detention basin to empty?

This basin type differs from a retention basin, also known as a “wet pond,” which includes a permanent pool of water, and which is typically designed to protect water quality. While basic detention ponds are often designed to empty within 6 to 12 hours after a storm, extended detention…

What do you call a holding pond with no pool?

These basins are also called “dry ponds”, “holding ponds” or “dry detention basins” if no permanent pool of water exists. Detention ponds that are designed to permanently retain some volume of water at all times are called retention basins.