New York; Rain Garden - Vassar College
Content
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
Stormwater and Water Quantity
National Research Council, “Stormwater Management in the United States” (2008)
Stormwater and Water Quality
• Sediment - erosion, bound to other pollutants • 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
Rain gardens?
NYS DEC, “New York State Stormwater Design Manual” (2008)
Town House Apartments Site
Redevelopment - 2008
Rain Garden 1 Rain Garden 2
Rain Garden 2
Rain Garden 1
Water samples collected:
• Precipitation
• Stormwater runoff
• Soil water • Catch basins
Analyzed for:
• Total suspended solids (TSS) • Dissolved inorganic nutrients (N, P)
• Heavy metals (Cu, Pb, Zn)
Site Map
Rain Garden Catch Basin
Unfiltered Catch Basin
Mean TSS in Catch Basins
25
Concentration (mg/L)
20
15
10
5
0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Mean Dissolved Nutrient Concentrations in Catch Basins
1.2 1 0.8 0.6 0.4 0.2 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Concentration (mg/L)
Ammonium Nitrate Phosphate
Mean Total Heavy Metal Concentrations in Catch Basins
0.35 0.3 Copper Lead Zinc
Concentration (mg/L)
0.25 0.2 0.15 0.1 0.05 0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Rain Garden 2 inlet
Rain Garden 1 inlet
Mean Total Heavy Metal Concentrations in Catch Basins
0.35 0.3 Copper Lead Zinc
Concentration (mg/L)
0.25 0.2 0.15 0.1 0.05 0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
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)
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)
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
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
Monitoring water quality for the duration of a storm event
Concentration (mg/L)
Concentration (mg/L)
10.00 12.00 0.00 2.00 4.00 6.00 8.00
10.00
15.00
20.00
25.00
30.00
0.00
5.00
17
TSS in Rain Garden 1 Catch Basin on 10/14
TSS in Rain Garden 1 Catch Basin and Unfiltered Catch Basin on 10/14
Time
Time
R2 = 0.4652
Rain Garden 1 Unfiltered Catch Basin
17 :3 17 1 :4 18 6 :0 18 1 :1 18 6 :3 18 1 :4 19 6 :0 19 1 :1 19 6 :3 19 1 :4 20 6 :0 20 1 :1 20 6 :3 20 1 :4 21 6 :0 21 1 :1 21 6 :3 21 1 :4 22 6 :0 22 1 :1 22 6 :3 22 1 :4 23 6 :0 23 1 :1 6
:3 17 1 :4 18 6 :0 18 1 :1 18 6 :3 18 1 :4 19 6 :0 19 1 :1 19 6 :3 19 1 :4 20 6 :0 20 1 :1 20 6 :3 20 1 :4 21 6 :0 21 1 :1 21 6 :3 21 1 :4 22 6 :0 22 1 :1 22 6 :3 22 1 :4 23 6 :0 23 1 :1 6
y = -0.2302x + 7.2547
Total Heavy Metal Concentration and Water Depth in Rain Garden 1 Catch Basin, 10/14
1.4
0.45 0.4
Heavy Metal Concentration
1.2 1 0.8 0.6 0.4 0.2 0
17 :3 17 1 :4 6 18 :0 1 18 :1 6 18 :3 1 18 :4 6 19 :0 19 1 :1 6 19 :3 19 1 :4 6 20 :0 1 20 :1 6 20 :3 1 20 :4 6 21 :0 1 21 :1 6 21 :3 1 21 :4 22 6 :0 1 22 :1 22 6 :3 1 22 :4 23 6 :0 1 23 :1 6
Total heavy metals Water depth
0.3 0.25 0.2 0.15 0.1 0.05 0
Time
Water Depth (m)
0.35
Water Depth (m)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0
Water Depth in Rain Garden 1 Catch Basin and Unfiltered Catch Basin and Precipitation on 10/14
Time
0
17 :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 :4 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 23 5 : 23 30 :4 5 0: 00
Unfiltered Catch Basin Rain Garden 1 Precipitation
0.001
Precipitation (m)
0.0005
0.0015
Assessing Flow Patterns
Identifying maintenance concerns
• Visual observation and data collection • Sediment build-up in inlets • Water flow through soil • Plant growth • Establishment of weeds
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
Mean Nutrient Concentrations
30
25
Ammonium Nitrate Phosphate
Concentration (mg/L)
20
15
10
5
0 Precipitation Runoff Soil Water Rain Garden Catch Basins Unfiltered Catch Basin
Mean Heavy Metal Concentrations
3 2.5 2 1.5 1 0.5 0 Precipitation Runoff Soil Water Rain Garden Catch Basins Unfiltered Catch Basin
Copper Lead Zinc
Concentration (mg/L)
Emily Vail
Collins Research Fellow Vassar College Environmental Research Institute
Community Educator Environment Program Cornell Cooperative Extension Dutchess County
Stormwater and Water Quantity
National Research Council, “Stormwater Management in the United States” (2008)
Stormwater and Water Quality
• Sediment - erosion, bound to other pollutants • 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
Rain gardens?
NYS DEC, “New York State Stormwater Design Manual” (2008)
Town House Apartments Site
Redevelopment - 2008
Rain Garden 1 Rain Garden 2
Rain Garden 2
Rain Garden 1
Water samples collected:
• Precipitation
• Stormwater runoff
• Soil water • Catch basins
Analyzed for:
• Total suspended solids (TSS) • Dissolved inorganic nutrients (N, P)
• Heavy metals (Cu, Pb, Zn)
Site Map
Rain Garden Catch Basin
Unfiltered Catch Basin
Mean TSS in Catch Basins
25
Concentration (mg/L)
20
15
10
5
0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Mean Dissolved Nutrient Concentrations in Catch Basins
1.2 1 0.8 0.6 0.4 0.2 0 Rain Garden 2 Rain Garden 1 Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Concentration (mg/L)
Ammonium Nitrate Phosphate
Mean Total Heavy Metal Concentrations in Catch Basins
0.35 0.3 Copper Lead Zinc
Concentration (mg/L)
0.25 0.2 0.15 0.1 0.05 0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
Rain Garden 2 inlet
Rain Garden 1 inlet
Mean Total Heavy Metal Concentrations in Catch Basins
0.35 0.3 Copper Lead Zinc
Concentration (mg/L)
0.25 0.2 0.15 0.1 0.05 0
Rain Garden 2
Rain Garden 1
Unfiltered Catch Basin
n = 6, samples from December 2008, March 2009, April 2009, August 2010, and October 2010
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)
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)
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
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
Monitoring water quality for the duration of a storm event
Concentration (mg/L)
Concentration (mg/L)
10.00 12.00 0.00 2.00 4.00 6.00 8.00
10.00
15.00
20.00
25.00
30.00
0.00
5.00
17
TSS in Rain Garden 1 Catch Basin on 10/14
TSS in Rain Garden 1 Catch Basin and Unfiltered Catch Basin on 10/14
Time
Time
R2 = 0.4652
Rain Garden 1 Unfiltered Catch Basin
17 :3 17 1 :4 18 6 :0 18 1 :1 18 6 :3 18 1 :4 19 6 :0 19 1 :1 19 6 :3 19 1 :4 20 6 :0 20 1 :1 20 6 :3 20 1 :4 21 6 :0 21 1 :1 21 6 :3 21 1 :4 22 6 :0 22 1 :1 22 6 :3 22 1 :4 23 6 :0 23 1 :1 6
:3 17 1 :4 18 6 :0 18 1 :1 18 6 :3 18 1 :4 19 6 :0 19 1 :1 19 6 :3 19 1 :4 20 6 :0 20 1 :1 20 6 :3 20 1 :4 21 6 :0 21 1 :1 21 6 :3 21 1 :4 22 6 :0 22 1 :1 22 6 :3 22 1 :4 23 6 :0 23 1 :1 6
y = -0.2302x + 7.2547
Total Heavy Metal Concentration and Water Depth in Rain Garden 1 Catch Basin, 10/14
1.4
0.45 0.4
Heavy Metal Concentration
1.2 1 0.8 0.6 0.4 0.2 0
17 :3 17 1 :4 6 18 :0 1 18 :1 6 18 :3 1 18 :4 6 19 :0 19 1 :1 6 19 :3 19 1 :4 6 20 :0 1 20 :1 6 20 :3 1 20 :4 6 21 :0 1 21 :1 6 21 :3 1 21 :4 22 6 :0 1 22 :1 22 6 :3 1 22 :4 23 6 :0 1 23 :1 6
Total heavy metals Water depth
0.3 0.25 0.2 0.15 0.1 0.05 0
Time
Water Depth (m)
0.35
Water Depth (m)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0
Water Depth in Rain Garden 1 Catch Basin and Unfiltered Catch Basin and Precipitation on 10/14
Time
0
17 :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 :4 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 23 5 : 23 30 :4 5 0: 00
Unfiltered Catch Basin Rain Garden 1 Precipitation
0.001
Precipitation (m)
0.0005
0.0015
Assessing Flow Patterns
Identifying maintenance concerns
• Visual observation and data collection • Sediment build-up in inlets • Water flow through soil • Plant growth • Establishment of weeds
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
Mean Nutrient Concentrations
30
25
Ammonium Nitrate Phosphate
Concentration (mg/L)
20
15
10
5
0 Precipitation Runoff Soil Water Rain Garden Catch Basins Unfiltered Catch Basin
Mean Heavy Metal Concentrations
3 2.5 2 1.5 1 0.5 0 Precipitation Runoff Soil Water Rain Garden Catch Basins Unfiltered Catch Basin
Copper Lead Zinc
Concentration (mg/L)
