Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC
Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC By Any Other Name… rain garden rainscaping catchwater garden bioretention basin infiltration trench or swale BMP – best management practice aesthetic opportunity What Exactly? conservation & preservation tool water
Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC
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Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC
By Any Other Name… • rain garden • rainscaping • catchwater garden • bioretention basin • infiltration trench or swale • BMP – best management practice • aesthetic opportunity
What Exactly? conservation & preservation tool water
Water Quantity • Most abundant resource • 97% saltwater • Most of 3% in glaciers • Very small % in surface and groundwater for humans
Water Quantity • Surface - water on or near the earth’s surface (rivers, lakes, springs, storm water) • Ground - water in the saturated zone below the water table (aquifer)
Water Quality The degree of excellence relative to: color odor suspended solids nutrients dissolved oxygen pathogens (bacteria)
Water Quantity & Quality Threatened by: point and non-point source pollution through leaching and runoff of sediments, nutrients, toxics
Sediments - organic & inorganic solid particles • Nutrients - N & P • Toxics- pesticides,gas, oil, heavy metals, weeds, & pathogens
Rain Gardens • Conserve water quantity • Preserve water quality
Why? • remove pollutants • prevent erosion • recharge groundwater • prevent flooding • provide wildlife habitat • less $ alternative to ponds
Pioneered in Prince George County, MD • $2-5K per lot savings • additional lots in lieu of storm water ponds • no BMP maintenance fees + added value landscape features
How? • catch rain and runoff water (6” deep) • temporarily hold it (< 4 days) • soil & plants filter sediments, nutrients, pollutants • water percolates down to recharge aquifers • water moves into atmosphere through transpiration and evaporation
How? • existing or created depression • > 10’ house, 25’ septic field • high organic sandy loam soil • flood & drought tolerant plants • mulch, mulch, mulch • Voila! Instant Rain Garden!
Low Middle High Adams County SWCD Quincy, IL • 3 planting zones • 4 days or less • 5% of drainage area • 6” water
Flow direction • splash block • extension pipe
Sizing the rain garden • Depth Dimensions • Ponding depth 6” – Divide Impermeable area by 20 • Ponding Depth 3” – Divide impermeable area by 10 NCSU
Sizing Example • Roof area: 60 X 60 = 3600 sq. ft. • ¼ of the flow to downspouts: (3600 sq.ft) X 25% = 900 sq.ft • Roof area plus driveway: 900 + 500 = 1400 sq. ft • Divide square footage by 20: 1400/20 = 70 sq. ft. ANSWER: The water garden should be at least 70 square feet. A 5 x 14 or 7 x 10 foot garden design would be sufficient NCSU
Marly-Holmes Neighborhood Assoc. Minneapolis, MN
Rain Garden Workshop Blacksburg, VA
Stoney Brook-Millestone Watershed Assoc. Pennington, NJ
Old Dominion University Norfolk, VA
Virginia Tech Rain Garden • Virginia Tech • City of Virginia Beach HEC • Virginia Cooperative Extension • VB MG Water Stewards • Local Nurseries & SPSA • Local Media
