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NY: Vassar College NY: Rain Garden

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Vassar College NY: Rain Garden

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NY: Vassar College NY: Rain Garden

  1. 1. Rain Gardens at Vassar College: A Water Quality Assessment Emily Vail Collins Research Fellow Vassar College Environmental Research Institute Community Educator Environment Program Cornell Cooperative Extension Dutchess County
  2. 2. Stormwater and Water Quantity National Research Council, “Stormwater Management in the United States” (2008)
  3. 3. Stormwater and Water Quality• Sediment - erosion, bound to otherpollutants• Nutrients - eutrophication• Heavy metals - toxicity• Other contaminants - Ecological problems in streams (Walsh et al. 2005, Paul & Meyer 2001, Groffman et al. 2003, National Research Council 2008) - Water treatment is expensive
  4. 4. Rain gardens? NYS DEC, “New York State Stormwater Design Manual” (2008)
  5. 5. Town House Apartments Site
  6. 6. Redevelopment - 2008 Rain Garden 1Rain Garden 2
  7. 7. Rain Garden 2 Rain Garden 1
  8. 8. Water samples collected:• Precipitation• Stormwater runoff• Soil water• Catch basinsAnalyzed for:• Total suspended solids (TSS)• Dissolved inorganic nutrients (N, P)• Heavy metals (Cu, Pb, Zn)
  9. 9. Site Map
  10. 10. Rain Garden Catch Basin Unfiltered Catch Basin
  11. 11. Mean TSS in Catch Basins 25 20 Concentration (mg/L) 15 10 5 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basinn = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
  12. 12. Mean Dissolved Nutrient Concentrations in Catch Basins 1.2 Ammonium Nitrate 1 Phosphate Concentration (mg/L) 0.8 0.6 0.4 0.2 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basinn = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
  13. 13. Mean Total Heavy Metal Concentrations in Catch Basins 0.35 Copper 0.3 Lead Zinc Concentration (mg/L) 0.25 0.2 0.15 0.1 0.05 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basinn = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
  14. 14. Rain Garden 2 inlet Rain Garden 1 inlet
  15. 15. Mean Total Heavy Metal Concentrations in Catch Basins 0.35 Copper 0.3 Lead Zinc Concentration (mg/L) 0.25 0.2 0.15 0.1 0.05 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basinn = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
  16. 16. Summary• Rain gardens are effective at removing TSS – Consistent with other studies (Davis 2007, Davis 2009, Bratieres et al. 2008)• May be net exporters of nutrients (affected by the growing season) – Some studies found that although total N and P reduced, inorganic nutrients increased (Davis et al. 2009, Davis et al. 2006, US EPA 1999, Davis et al. 2007, Dietz & Clausen 2006, Kim et al. 2003)
  17. 17. Summary• Do not appear to moderate heavy metal loads (further studies needed) – Laboratory studies show 88-97% removal of Cd, Cu, Pb, Zn from synthetic stormwater (Sun & Davis 2006, Davis et al. 2001, Davis et al. 2003) – Field studies - slightly lower removal rates for metals (Davis 2007)• Increased retention time for stormwater quantity (Davis et al. 2009, Davis 2007, Hood et al. 2007, Hatt et al. 2009)
  18. 18. Conclusion• Rain gardens - an important aspect of Low Impact Design• Maintain pre-development hydrology• Local BMPs to address ecosystem-wide problems• Need for assessment• Aesthetics and function
  19. 19. Next steps• Do rain gardens continue to function the same way over the duration of a storm event? – Monitoring water quality – Assess flow patterns on site• What kind of maintenance is required? Is the design functioning as it was intended? – Visual observations and considerations for maintenance and potential design modifications
  20. 20. Monitoring water quality for the duration of a storm event
  21. 21. Concentration (mg/L) Concentration (mg/L) 17 0.00 2.00 4.00 6.00 8.00 10.00 12.00 10.00 15.00 20.00 25.00 30.00 0.00 5.00 17 :3 :3 17 1 17 1 :4 :4 18 6 18 6 :0 :0 18 1 18 1 :1 :1 18 6 18 6 :3 :3 18 1 18 1 :4 :4 19 6 19 6 :0 :0 19 1 19 1 :1 :1 19 6 19 6 :3 :3 19 1 19 1 :4 :4 20 6 20 6 :0 :0 20 1 20 1 :1 :1 20 6 20 6 :3 :3Time 20 1 20 1 Time :4 :4 21 6 21 6 :0 :0 21 1 21 1 :1 :1 21 6 21 6 Unfiltered Catch Basin on 10/14 :3 :3 TSS in Rain Garden 1 Catch Basin on 10/14 21 1 21 1 TSS in Rain Garden 1 Catch Basin and :4 :4 22 6 22 6 :0 :0 22 1 22 1 :1 :1 22 6 22 6 :3 :3 22 1 22 1 :4 Rain Garden 1 :4 23 6 23 6 :0 :0 R2 = 0.4652 23 1 23 1 :1 Unfiltered Catch Basin :1 6 6 y = -0.2302x + 7.2547
  22. 22. Total Heavy Metal Concentration and Water Depth in Rain Garden 1 Catch Basin, 10/14 1.4 0.45 0.4Concentration 1.2 Heavy Metal 0.35 Water Depth (m) 1 0.3 Total heavy metals 0.8 0.25 Water depth 0.6 0.2 0.15 0.4 0.1 0.2 0.05 0 0 17 1 6 1 6 1 6 19 1 6 19 1 6 1 6 1 6 1 6 1 22 6 1 22 6 1 23 6 1 6 :3 :4 :0 :1 :3 :4 :0 :1 :3 :4 :0 :1 :3 :4 :0 :1 :3 :4 :0 :1 :3 :4 :0 :1 17 18 18 18 18 19 19 20 20 20 20 21 21 21 21 22 22 23 Time
  23. 23. Water Depth (m) 17 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 :0 17 0 : 17 15 :3 17 0 :4 18 5 : 18 00 :1 18 5 :3 18 0 : 19 45 :0 19 0 :1 19 5 : 19 30 :4 20 5 :0 20 0 :1 20 5 : 20 30 :4Time 21 5 :0 21 0 : 21 15 :3 21 0 :4 22 5 : 22 00 :1 22 5 :3 22 0 : 23 45 :0 23 0 :1 Precipitation 23 5 Water Depth in Rain Garden 1 Catch Basin and : Rain Garden 1 Unfiltered Catch Basin and Precipitation on 10/14 23 30 :4 5 0: 00 Unfiltered Catch Basin 0 0.001 0.0005 0.0015 Precipitation (m)
  24. 24. Assessing Flow Patterns
  25. 25. Identifying maintenance concerns• Visual observation and data collection• Sediment build-up in inlets• Water flow through soil• Plant growth• Establishment of weeds
  26. 26. Acknowledgements Dr. Lynn Christenson, Dr. Mary Ann Cunningham,Dr. Stuart Belli, Dr. Kirsten Menking, Dr. David Gillikin,Dr. Jill Schneiderman, Dr. Mark Schlessman, Rick Jones,Keri VanCamp, Seth Stickle, Danielle Goldie, Cat Foley, Sandy Alles, & Will Jobs Vassar College Environmental Research Institute Vassar College Environmental Studies Program
  27. 27. Mean Nutrient Concentrations 30 Ammonium 25 Nitrate PhosphateConcentration (mg/L) 20 15 10 5 0 Precipitation Runoff Soil Water Rain Garden Catch Unfiltered Catch Basins Basin
  28. 28. Mean Heavy Metal Concentrations 3 Copper 2.5 Lead ZincConcentration (mg/L) 2 1.5 1 0.5 0 Precipitation Runoff Soil Water Rain Garden Catch Unfiltered Catch Basins Basin

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