RAIN GARDEN
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Native plants are recommended for rain gardens because of their adaptation to local environmental conditions and synergies with soil microorganisms that enable biological treatment processes. Rain gardens work well in a property’s low spots, although rain gardens may not be an appropriate choice for areas that stay persistently wet (see Constructed Wetland p130). Locate rain gardens in full sun to encourage drying out between storms. Properly designed rain gardens drain within 24 hours following a storm event and do not support conditions for mosquito breeding.
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Depending on existing site soil conditions, rain gardens may require soil amendment to increase infiltration rates. During installation or repair, avoid using heavy equipment in or around the area to protect underlying soil from compaction.
Stormwater Management - - Runoff reduction - - Retention - - Infiltration Additional - - Wildlife habitat - - Aesthetic quality - - Improves air quality
Rain gardens are planted depressions in the landscape designed to capture and infiltrate stormwater. Rain gardens reduce stormwater runoff through retention, infiltration and evapotranspiration. Suspended solids are removed through sedimentation and physical filtration by plant and soil media. Contaminants, such as nutrients and heavy metals, are mitigated by extended biological treatment.
Benefits
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- - Sedimentation - - Filtration - - Extended biological treatment - - Educational opportunity
Cost & Maintenance Considerations - - Cost: Low to Medium - - Maintenance: Low once vegetation is established - - Check for maintenance following intense storm events and amend any erosion of berm - - Apply/amend mulch layer annually - - Maintain permeability of soil to prevent ponding - - Retained water should infiltrate after 24 hours - - Avoid use of fertilizers Construction & Site Considerations - - Avoid heavy equipment on and around Rain Garden - - Locate at least 10’ from building foundations - - Locate in full sun - - May amend soil for adequate permeability Contaminant Removal - - Suspended Solids - - Nutrients - - Heavy Metals