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Bioretention Cells
Bioretention cells reduce runoff by promoting infiltration and evapotranspiration and improve water quality by filtering through soil media and transformation by plants.
Bioretention Design Bioretention cells are shallow landscape depressions with
perforated storm sewer pipe below an engineered soil mix.
The landscaped ponding area allows 6 inches of water to pond
on the surface during storm events.
Native plants tolerant of moisture variation are planted within
the cell and promote pollution removal and runoff reduction.
A mulch layer minimizes soil erosion and promotes pollutant
removal.
Sandy soil mix (≥ 72% sand, ≤ 10% clay, 5-20% organic matter)
removes pollutants by filtering and microbial activity.
A mix of pea gravel and sand or geotextile fabric layer prevents
the planting soil from migrating into the larger gravel layer andin situ soil.
A perforated pipe underdrain is embedded in a 8-12 inch layer
of #57 washed stone gravel.
Pretreatment areas along the slope of the cell provide some
water quality treatment and decrease the velocity of water
entering the cell. A grassed area or stone trench will serve this
purpose.
Chagrin River Watershed Partners, Inc.
Detail Courtesy Land Design Consultants, Inc.
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Bioretention Maintenance Water plants regularly during first growing season.
Weed, prune, and replace dead or diseased plants
as necessary. Inspect pretreatment areas twice a year. If erosion
or deposition has occurred, repair damage.
Monthly, remove litter and debris and monitor for
salt damage to plants and soil.
Annually, add additional mulch to the cell.
Every 2 years, test soil pH, and check planting soil
and mulch layer for clogging.
Bioretention Benefits Lowers stormwater runoff volume
Reduces suspended solids, metals, &
nitrogen concentrations in runoff
Allows stormwater management to occur
in existing landscaped areas
Aesthetically pleasing
Frequently Asked Questions
Q1. For what type of land use are bioretention cells well suited?
Bioretention cells are well suited for commercial properties in parking lot
islands or other areas available for landscaping, some industrial areas,
apartments, and other residential areas.
Q2. What is the difference between a rain garden and a bioretention cell?
Bioretention cells usually have an underdrain; rain gardens do not. In
addition, bioretention cells typically have a much greater depth of
engineered soil mix, resulting in a greater amount of infiltration. Because of
their lower cost, rain gardens are used by homeowners more frequently
than bioretention cells.
Q3. Can bioretention cells be incorporated into redevelopment projects?
Yes! Former parking areas, landscaped areas, and parking lot islands can
be converted to bioretention cells.
Q4. I’d like to put a bioretention cell on my property. Who should I contact?
Landscape architects and engineers help their clients design bioretention
cells and can recommend installers. Instructions for rain garden design and
construction are available from:
Chagrin River Watershed Partners, Inc. Bioretention Cells
Chagrin River Watershed Partners, Inc.P.O. Box 229 Willoughby, Ohio 44096-0229Phone: 440.975.3870 www.crwp.org