STORMWATER QUALITY MANAGEMENT PRACTICES
"Slow It, Spread It, Sink It... Re-Think It."

KOR believes in bridging Site Planning and Civil Engineering with innovative and comprehensive Stormwater Quality Management practices. As Landscape Architects, we have a responsibility to practice sustainable site planning with the long-term future in mind.

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HYDROLOGY AND STORMWATER MANAGEMENT PLANS

KOR works closely with Civil Engineers to create a graphic representation of the stormwater management practices proposed for the development. These graphic tools depict the site with an explanation of distributed BMPs and provide a greater understanding of how each individual stormwater management practice contributes to an overall cleansing process.

STORMWATER CONTROL AND TREATMENT MEASURES

1. Bioswales/Biofiltration Swales

Bioswales and Biofiltration Swales provide temporary stormwater runoff storage locations, but primarily contribute to infiltration, filtration, and sediment dropout.

Vegetated Swale: Vegetated swales are often referred to as bio-swales, enhanced swales, or water quality swales and can be classified as wet swales, dry swales, and grassed channels. A dry swale (bio-swale) incorporates additional elements with the vegetated swale design. Water treatment is aided by a soil bed (not necessarily natural soil) with an underdrain system composed of a perforated pipe surrounded by gravel. Check dams may be used to temporarily retain stormwater runoff. A wet swale is capable of temporarily retaining stormwater runoff, but, unlike the dry swale, lacks an underdrain system. The wet swale is marshlike and relies on and supports wetland vegetation.

Grass Swale Filter: A broad, shallow channel used for conveying stormwater runoff. Grass on the side slopes and bottom acts to slow runoff velocity, trap particulates, and promote infiltration.

Filter Strip/Vegetated Buffer: Vegetated filter strips are vegetated surfaces used to reduce stormwater velocities from nearby less pervious surfaces. They also filter out pollutants from stormwater and allow infiltration into underlying soil.

Grass Strip Filter: Uniformly graded and densely vegetated strips of turf grass that are easy to design, install, and maintain.

Green Roofs : Green roofs are vegetated and reduce surface runoff from the rooftop by absorbing stormwater and slowing stormwater flow rates.

Vegetated Swale; Infiltration Trench at Parkway

2. Detention Basins

Retention of stormwater on-site allows for infiltration, evapotranspiration and reuse of rainfall in order to reduce off-site transportation of flow. Detention Basins primarily serve to detain and store stormwater runoff, reducing peak flows and offering filtration and infiltration opportunities. Detention Basins can also be dual-use facilities, providing recreation during dry seasons.

Detention Basin (Dry Pond): A stormwater control structure into which storm runoff is directed to control both water quality and quantity. The outlets to the basin are designed to detain and treat stormwater runoff through settling over a period of time. The storm runoff storage also decreases downstream peak flow rates. Dry ponds are not designed to permanently contain water.

Wetland Basin: Similar A stormwater control structure that incorporates wetland plants. Storm runoff is directed into the basin to control both water quality and quantity. Basin outlets are designed to detain and treat the stormwater runoff: 1) for a minimum duration (e.g. 24 hours) for no permanent pool and 2) until the water is displaced by runoff from a later storm (permanent pool).

Constructed Wetland: A man-made basin that contains water, a substrate (soil, gravel, rock, organic materials, ect.), plants (vascular and non-vascular), and organisms similar to those usually found in natural wetlands. The number of plants and the biodiversity of a constructed wetland are greater than that of a wet retention pond. Constructed wetlands usually use a relatively impermeable subsurface layer to prevent water from seeping into the ground.

Retention Basin (Wet Pond): A stormwater control structure with a permanent pool of water into which storm runoff is directed to control both water quality and quantity. Runoff from each storm is retained and treated, and sediment particles and associated pollutants settle out, until the water is displaced by runoff from a later storm.

Raingarden/Bioretention: A system for controlling runoff using soils and plants. Surface runoff is directed into shallow, landscaping depressions. These depressions are designed to incorporate many of the pollutant removal mechanisms that operate in forested or other natural (prairies, wetlands, ect) ecosystems.

Rain Barrel: A storage tank that captures stormwater runoff. Rain barrels are typically adapted from existing barrels, sit above ground, and have a storage capacity of approximately 50-80 gallons.

Permeable Pavement: Pavement composed of a permeable pavement material, which allows infiltration into the subsoil. There may also be an underlying stone resevoir that temporarily stores the surface runoff before it infiltrates into the subsoil.

Cisterns: Large storage devices that are often built below ground for storing captured stormwater and can be integrated with more sophisticated pumping devices. For example, some cisterns collect stormwater that is subsequently used for non-potable plumbing, such as flushing of toilets, or irrigation applications.

3. Infiltration

Infiltration Basins and Infiltration Trenches are areas constructed with naturally pervious soils and usually flat bottoms to maximize the square-footage for stormwater to infiltrate and filter into the natural soil profile, reducing runoff while recharging local groundwater.

Infiltration Basin: An earthen basin constructed in naturally pervious soils with a flat bottom and provided with an inlet structure to dissipate energy of incoming flow and with an emergency spillway to control excess flows. Infiltration Basins can be large enough to effectively remove pollutants, control runoff volume, and reduce downstream erosion for areas up to 50 acres.

Infiltration Trench: A rock-filled trench with no outlet. Typically stormwater first passes through a swale or other stormwater management application before reaching the trench. The stormwater filters through the soil.

Catch Basin: A chamber or sump, typically at curb level, through which stormwater runoff enters a conveyance system. Sediment may be retained in a low area beneath the outlet to the conveyance system. Inserts for catch basins are designed to remove oil and grease, trash, and sediments. Examples include filter fabrics and a system of trays with media filters.

Media Filters: Filters that stormwater passes through for removal of solids. Filters can be made out of sand, peat, foam, crushed glass, or textile.