Bioretention Areas

Bioretention Areas - Knox County Tennessee Stormwater...

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Knox County Tennessee Stormwater Management Manual Volume 2 (Technical Guidance) Page 4-91 4.3.5 Bioretention Areas General Application Stormwater BMP Description : Shallow stormwater basin or landscaped area that utilizes engineered soils and vegetation to capture and treat runoff. STORMWATER MANAGEMENT SUITABILITY Water Quality Channel Protection Overbank Flood Protection Extreme Flood Protection Provides pretreatment for SPAP land uses? Yes in certain situations KEY CONSIDERATIONS DESIGN GUIDELINES: Maximum contributing drainage area of 5 acres. Often located in “landscaping islands.” Treatment area consists of grass filter, sand bed, ponding area, organic/mulch layer, planting soil, and vegetation. Typically requires 5 feet of elevation difference from inflow to outflow. ADVANTAGES / BENEFITS: Applicable to small drainage areas. Good for highly impervious areas, particularly parking lots. Good retrofit capability. Relatively low maintenance requirements. Can be planned as an aesthetic feature. DISADVANTAGES / LIMITATIONS: Requires extensive landscaping. Not recommended for areas with steep slopes. MAINTENANCE REQUIREMENTS: Inspect and repair/replace treatment area components. FEASIBILITY CONSIDERATIONS Land Requirement Capital Cost Maintenance Burden Residential/Subdivision Use: Yes High Density/Ultra-Urban: Yes Drainage Area: 5 acres max. Soils: Planting soils must meet specified criteria; no restrictions on surrounding soils. M M L
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Knox County Tennessee Stormwater Management Manual Volume 2 (Technical Guidance) Page 4-92 POLLUTANT REMOVAL Total Suspended Solids Nutrients - Total Phosphorus / Total Nitrogen Metals - Cadmium, Copper, Lead, and Zinc Pathogens - Coliform, Streptococci, E.Coli OTHER CONSIDERATIONS: Use of native plants is recommended L =Low M =Moderate H =High 4.3.5.1 General Description Bioretention areas (also referred to as bioretention filters or rain gardens ) are structural stormwater controls that capture and temporarily store the water quality volume (WQv) using soils and vegetation in shallow basins or landscaped areas to remove pollutants from stormwater runoff. Bioretention areas are engineered facilities in which runoff is conveyed as sheet flow to the “treatment area,” which consists of a grass buffer strip, ponding area, organic or mulch layer, planting soil, and vegetation. An optional sand bed can also be included in the design to provide aeration and drainage of the planting soil. The filtered runoff is typically collected and returned to the conveyance system, though it can also permeate into the surrounding soil in areas with porous soils. There are numerous design applications, both on- and off-line, for bioretention areas. These include use
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This note was uploaded on 05/25/2010 for the course CE 798 taught by Professor Hunter during the Spring '10 term at Morgan.

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Bioretention Areas - Knox County Tennessee Stormwater...

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