Stormwater Treatment Practices Flashcards
Why is permeable pavement an important tool?
For the retention and detention of stormwater, can reduce the need for de-icing chemicals, provides a durable and aesthetically pleasing surface.
What does permeable pavement do?
Allows stormwater runoff to filter through surface voids into an underlying stone reservoir for temporary storage and/or infiltration.
What is the structure of permeable pavement?
Consists of a surface layer, and underlying stone aggregate reservoir layer, optional underdrains, and geotextile over uncompacted soil subgrade.
Why are bioretention (rain gardens) an important tool?
They utilize vegetation and provide additional benefits such as cleaner air, carbon sequestration, improved biological habitat, and aesthetic value.
What is bioretention?
A terrestrial-based water quality and water quantity control process. It employs a simplistic, site-integrated design that provides opportunity for runoff infiltration, filtration, storage, and water uptake by vegetation.
Why are trees an important tool?
For the retention and detention of stormwater runoff. They also provide additional benefits including cleaner air, reduction of heat island effects, carbon sequestration ,reduced noise pollution, reduced pavement maintenance needs, and cooler cars in shaded parking lots.
What are some practices of tree use for stormwater management?
Tree trenches and tree boxes are the most common and most often located in upland areas. They are designed to retain solids and associated pollutants by filtering.
What is a stormwater pond?
Any constructed basin built for the purpose of capturing and storing stormwater runoff, either temporarily or for an extended period of time, in order to prevent or mitigate downstream water quantity or quality impacts.
What are media filters and vegetative filters?
Media filters include surface, underground, and perimeter. Vegetative filters include filter strips and grass channels and are more suitable as pre-treatment practices.
Where are media and vegetative filters used?
Media filters are well suited for sites with high percentages of impervious cover. They are not as aesthetically appealing which make them appropriate for commercial or light industrial land uses.
Vegetative filters can be incorporated into landscaped areas, providing dual functionality.
What does a sand filter do?
A sand filter does not reduce stormwater volume but provides annual pollutant load reductions.
How does a swale operate?
Stormwater can be retained through three separate methods; It can infiltrate into the soils as it travels through the main channel to the outflow. It can pond behind the check dam and infiltrate underlying soils. It can be stored in the pore spaces of an engineered bioretention base and infiltrate inot the underlying soils. Swale assist in reducing pollutants through filtration and sediment removal.
How to trees contribute to phosphorus in urban runoff?
Tree leaves, seeds, and flowers contain phosphorus which can leak out and contribute to the nutrient load in runoff. The amount of phosphorus found in leaf litter is equal to about 40-60% of the amount of phosphorus that is exported in runoff during the warm season.
How can phosphorus nutrient fluxes be reduced?
Careful selection of street tree species and timely removal of litterfall have significant impacts in reducing influxes from streets to storm drains.
