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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

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Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC

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  1. Rain Gardens Laurie J. Fox Virginia Tech Hampton Roads AREC

  2. By Any Other Name… • rain garden • rainscaping • catchwater garden • bioretention basin • infiltration trench or swale • BMP – best management practice • aesthetic opportunity

  3. What Exactly? conservation & preservation tool water

  4. Water Quantity • Most abundant resource • 97% saltwater • Most of 3% in glaciers • Very small % in surface and groundwater for humans

  5. 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)

  6. Water Cycle

  7. Water Quality The degree of excellence relative to: color odor suspended solids nutrients dissolved oxygen pathogens (bacteria)

  8. Water Quantity & Quality Threatened by: point and non-point source pollution through leaching and runoff of sediments, nutrients, toxics

  9. Sediments - organic & inorganic solid particles • Nutrients - N & P • Toxics- pesticides,gas, oil, heavy metals, weeds, & pathogens

  10. Rain Gardens • Conserve water quantity • Preserve water quality

  11. Why? • remove pollutants • prevent erosion • recharge groundwater • prevent flooding • provide wildlife habitat • less $ alternative to ponds

  12. 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

  13. 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

  14. 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!

  15. Low Middle High Adams County SWCD Quincy, IL • 3 planting zones • 4 days or less • 5% of drainage area • 6” water

  16. NCSU

  17. NCSU

  18. NCSU

  19. Flow direction • splash block • extension pipe

  20. rate per hour

  21. Sizing the rain garden • Depth  Dimensions • Ponding depth 6” – Divide Impermeable area by 20 • Ponding Depth 3” – Divide impermeable area by 10 NCSU

  22. 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

  23. Marly-Holmes Neighborhood Assoc. Minneapolis, MN

  24. Rain Garden Workshop Blacksburg, VA

  25. NCSU

  26. NCSU

  27. Stoney Brook-Millestone Watershed Assoc. Pennington, NJ

  28. VersiTank

  29. Old Dominion University Norfolk, VA

  30. NCSU

  31. NCSU

  32. Filtera

  33. Virginia Tech Rain Garden • Virginia Tech • City of Virginia Beach HEC • Virginia Cooperative Extension • VB MG Water Stewards • Local Nurseries & SPSA • Local Media

  34. 2007

  35. 2.5” rain in 1 hour

  36. 2010

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