Effective BMPs for Controlling
Copper and ZincACWA Stormwater Summit 2016
Aaron Poresky and Myles Gray,
Geosyntec Consultants
Outline
• Metals in stormwater
• Regulatory setting and trends
• BMP selection and
effectiveness
• Case studies and scientific
trends
Copper and Zinc Are Challenging to Control
• They are hazardous to aquatic
organisms (including salmon)
• They are ubiquitous
• They exhibit complicated
chemistry
• They are subject to tightening
environmental standards
• Achieving compliance can be
costly and complicated
BUT… BMPs can work and they can work better
Copper is Ubiquitous• Brake Pads (4-12%)
• Construction Materials (including
pressure treated wood)
• Pesticides & Fungicides
• Aerial Deposition
Land Use Total Copper (µg/L)1 Dissolved Copper (µg/L) 1
Commercial 15 (13-17) 6 (5-9)
Freeway 24 (21-29) 11 (9-12)
Industrial 16 (14-19) 8 (6-10)
Residential 11 (10-12) 5 (3-7)
Open Space 5 (5-7) --
1Total and Dissolved copper median values with 95% confidence intervalsSource: National Stormwater Quality Database
Washington Dept of Ecology Study2:
• Cars emit ~0.6 mg Cu/km
• 36,000 kg emitted in Puget Sound Region
• Copper Loading: 200-500 g Cu/km-yr
• Equivalent to App. 16 µg/L from highway
2Source: Washington Dept of Ecology, 2011, “Copper and Zinc Loading Associated with Automotive Brake-Pad and Tire Wear”
Commercial Industrial Open Space Residential
Source: Seattle Public Utilities Integrated Plan, Appendix F
6
Copper: Characteristics in Stormwater
Particulate-bound Copper
Particles retained on 0.45 micron
filter
“Dissolved” Copper
Free (or ionic) copper
Complexed Copper (e.g., CuDOM)
Colloidal copper (particles passing 0.45 micron filter)
Cu2+
Sorbed to clay
~50% <5%
Complexed with EDTA (i.e. Dissolved Organic Matter)
Combined 45-50%
7
Copper is Harmful to Aquatic Organisms
-BUT- Toxicity depends on Water Chemistry
EPA Biotic Ligand Model (BLM)
• Model to estimate free ions on gills
BLM Factors:
Temperature
pH
Dissolved Organic Carbon
Calcium
Magnesium
Sodium
Potassium
Sulfate
Chloride
Alkalinity
Humic Acid
Zinc is Even More Widespread!
• Tire Dust (~1% Zinc)
• Galvanized Metals
• Motor Oil
• Moss-Off
• Aerial Deposition
Land Use Total Zinc (µg/L)1 Dissolved Zinc (µg/L) 1
Commercial 130 (114-143) 56 (42-70)
Freeway 132 (120-162) 51 (42-62)
Industrial 155 (140-170) 114 (59-180)
Residential 70 (69-77) 27 (25-33)
Open Space 25 (25-25) 25 (25-25)
1Total and Dissolved zinc median values with 95% confidence intervalsSource: National Stormwater Quality Database
Washington Ecology Study2:
• Cars emit ~1.13 mg Cu/km
• 79,000 kg emitted in Puget Sound Region
• Copper Loading: 700-1,200 g Cu/km-yr
• Equivalent to App. 33 µg/L from highway
Zinc-Based Moss Off:
• $6.98 per 1.3 kg can
• 468 g Zinc/can
• Recommended use would
create rooftop effluent
with 66,000 µ/L during 1”
rainfall event
2Source: Washington Dept of Ecology, 2011, “Copper and Zinc Loading Associated with Automotive Brake-Pad and Tire Wear”
Commercial Industrial Open Space Residential
Source: Seattle Public Utilities Integrated Plan, Appendix F
10
Zinc: Characteristics and Toxicity
• Depending on sources, greater fraction “ionic”
• Less affinity for organic ligands = less toxic than copper
Particulate-bound Zinc
Particles retained on 0.45 micron
filter
“Dissolved” Zinc
Free (or ionic) ZincComplexed Zinc
(e.g., Zn-Carbonate)
Colloidal Zinc (particles passing 0.45 micron filter)
Zn2+
Regulatory Setting - Metals
Phase I MS4 Permits
– MEP and BMP-based, 80% capture sizing
standards, LID/GI approaches
– In-stream and stormwater monitoring
– Review of SWMPs for effectiveness in
addressing 303(d) listed pollutants
– Various provisions for TMDL pollutants
1200-Z Industrial Permit
– Copper: 20 ppb
– Zinc: 120 ppb
– MS4 permits require screening and
inspections
– Portland, Eugene, and CWS administer
programs on behalf of DEQ
SLOPES V Transportation, Utilities
Source control and treatment BMP-based, but larger design storm
Project-specific NMFS Biological Opinion – Example - Walmart, The Dalles, OR
5 ppb total copper, never to exceed, monitoring first flush after extended dry period, no mixing
zone allowance
0 20 40 60 80 100 120 140 160 180
Coast Fork WillametteLower ColumbiaLower John DayLower Owyhee
Lower WillametteMiddle Columbia-Hood
Middle WillametteNorth UmpquaSouth Umpqua
TualatinUmatillaUmpqua
Upper WillametteWallowa
Yamhill
2012 draft 303(d) listStream Miles in Category 5: TMDL Needed
Zinc
Copper
USGS 4th field HUC
Data from Oregon DEQ 2012 Draft Integrated Report
DEQ Copper Rulemaking
• Updates to criteria will
replace hardness-based
criteria
• EPA 2007 recommendations
include deriving criteria from
Biotic Ligand Model (BLM)
• DEQ developed BLM
technical support document
(Jan 2016)
1Source: Oregon DEQ 2016, “Technical Support Document: An Evaluation to Derive Statewide Copper Criteria Using the Biotic Ligand Model. Figure from Santore, 2015 and Pagenkopf, 1983
BLM Conceptual Model1
Source: Oregon DEQ 2016, “Technical Support Document: An Evaluation to Derive Statewide Copper Criteria Using the Biotic Ligand Model.
1Source: Oregon DEQ 2016, “Technical Support Document: An Evaluation to Derive Statewide Copper Criteria Using the Biotic Ligand Model.
Regulatory Summary
• More stringent BMP performance criteria
are likely to emerge
– WQ criteria rulemaking 303(d)/TMDL
process NPDES permits
– NMFS consultations/biological opinions/
SLOPES
Overall Framework for BMP Effectiveness
BMP
Bypass or Overflow
Volume Loss (Infiltration, ET,
Direct Use)
Combined Discharge
Treated Effluent
Influent
Source Controls
and Site DesignStructural BMPs
Site-specific criteria and
flow/WQ conditions
How effective is “effective enough”?
Reduce load and change chemistry
Source Control: First Option
Legislative:
Restrict use of high
metals materials
Washington and
California bans on
copper brakepads
Others: Zinc Moss-Off?
Material Selection:
Avoid specific materials:
• Galvanized Metals
• Copper Building
Materials
• Pressure-treated
Wood
• Copper-based Paints
• Copper-based
pesticides
Operations:
General good
housekeeping
Spill Cleanup
Street Sweeping (high
efficiency regenerative
vacuum)
Paint/Coat Galvanized
Materials
Site Design / LID / Green Infrastructure
• Impervious area dispersion
• Natural drainage pathways/swales
• Riparian buffer protection
• Soil and organic matter play multiple roles:
– Load reduction
– DOC source
– Buffering capacity
– Speciation change
1Source: Oregon Low Impact Development Overview Fact Sheet 2016. oeconline.org/stormwaterhttp://extension.oregonstate.edu/watershed/
Treatment BMP Effectiveness
BMP
Bypass or Overflow
Volume Loss (Infiltration, ET,
Direct Use)
Combined Discharge
Treated Effluent
Influent
• How much is captured and treated?
• How much is “lost” and not discharged to surface water?
• Is the change in concentrations significant?
• What is the effluent concentration?
Copper and Zinc Treatment MechanismsSpeciation/Partition Mechanism(s) BMP Types
Coarse Particulates Screening, Rapid Settling, and Swirling
Forebays, Hydrodynamic Separators
Medium TSS-range Particulates SettlingVegetative Entrapment
Ponds, Wetlands, Swales, Filters
Fine TSS-range Particulates Media FiltrationExtended SettlingCoagulation
Passive and Active Filtration BMPsWetlands
Ionic Ion Exchange (e.g., zeolite) Passive and Active Filtration BMPsWetlands/Bioreactors
Organically Complexed Physical Sorption (e.g., GAC)Biological uptake
Passive and Active Filtration BMPsWetlands/Bioreactors
Ionic, inorganically complexed Chemical Sorption & Precipitation Passive and Active Filtration BMPsWetlands/Bioreactors
BMP Study Types in International
BMP Database
BMP Category #Bioretention 43Composite 26
Detention Basin 43Green Roof 17Biofilter 89
Infiltration Basin 2LID 4
Manufactured Device 103Media Filter 40
Maintenance Practice 29Other 6
Porous Pavement 41
Percolation Trench/Well 13Retention Pond 77Wetland Basin 35
Wetland Channel 19Total BMPs 587Control Sites 2223
• 17 general BMP categories
• 190 to 240 plus Green
Infrastructure BMP Studies
www.bmpdatabase.org
1200Z
BLM avg(Will. Valley)
Source: Geosyntec Consultants and Wright Water Engineers, 2014. “International Stormwater BMP Database Pollutant Category Statistical Summary Report”
BMP Effectiveness for Total Copper
Source: Geosyntec Consultants and Wright Water Engineers, 2014. “International Stormwater BMP Database Pollutant Category Statistical Summary Report
0
10
20
30
40
0 10 20 30 40
Eff
luent D
Cu (mg/L
)
Influent DCu (mg/L)
All Data Pairs: N=89
In=Out
Bootstrap Medians: Span=13 R2=0.677
95% Confidence Interval
Vegetated Swales – Dissolved Copper
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
0
5
10
15
20
25
0 5 10 15 20 25
Eff
lue
nt D
Cu
(mg
/L)
Influent DCu (mg/L)
All Data Pairs: N=106
In=Out
Bootstrap Medians: Span=39 R2=0.859
95% Confidence Interval
Extended Detention Basins – Dissolved Copper
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Wet Ponds – Dissolved Copper
0
5
10
15
20
25
30
35
40
45
0 5 10 15 20 25 30 35 40 45
Eff
luent D
Cu (mg/L
)
Influent DCu (mg/L)
All Data Pairs: N=126
In=Out
Bootstrap Medians: Span=57 R2=0.014
95% Confidence Interval
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
1200Z
Hardness-based at 40 ppm
Source: Geosyntec Consultants and Wright Water Engineers, 2014. “International Stormwater BMP Database Pollutant Category Statistical Summary Report
BMP Effectiveness for Total Zinc
Source: Geosyntec Consultants and Wright Water Engineers, 2014. “International Stormwater BMP Database Pollutant Category Statistical Summary Report
Vegetated Swales – Dissolved Zinc
0
50
100
150
200
250
0 20 40 60 80 100 120 140 160 180 200 220 240
Eff
lue
nt D
Zn
(m
g/L
)
Influent DZn (mg/L)
All Data Pairs: N=89
In=Out
Bootstrap Medians: Span=37 R2=0.55
95% Confidence Interval
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Extended Detention Basins – Dissolved Zinc
0
20
40
60
80
100
120
140
160
180
200
0 20 40 60 80 100 120 140 160 180 200
Eff
luent D
Zn (m
g/L
)
Influent DZn (mg/L)
All Data Pairs: N=106
In=Out
Bootstrap Medians: Span=13 R2=0.781
95% Confidence Interval
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Eff
luent D
Zn (m
g/L
)
Influent DZn (mg/L)
All Data Pairs: N=127
In=Out
Bootstrap Medians: Span=13 R2=0.005
95% Confidence Interval
Wet Ponds – Dissolved Zinc
Source: Geosyntec Consultants. Unpublished analysis of International Stormwater BMP Database data; roving window median bootstrap analysis
Proprietary and Active BMPs
Passive Media Filters:TAPE Certified for Enhanced Dissolved Metals1:
• Filterra
• Modular Wetlands
• WSDOT Media Filter Drain
• WSDOT Compost Amended BiofiltrationSwale
• Others with conditional use
Criteria:
• 30 percent removal of DCu (at influent of 5 to 20 ppb)
• 60 percent removal of DZn (at influent of 20 to 300 ppb)
Active Treatment Technologies:
Electrocoagulation: WaterTectonics, EnPurion
Chitosan Treatment
Active Media Filters: EnPurion, StormwateRx
Chemical Treatment
WaterTectonics2
2Source: www.WaterTectonics.com
1Source: Washington Department of Ecology TAPE Website: http://www.ecy.wa.gov/programs/wq/stormwater/newtech/technologies.html
BMP Effectiveness Summary - Copper
• BMPs are generally effective for particulate-bound Cu, with appropriate unit processes
• Most BMPs have little effect on dissolved Cu, except:
– Specialized media
– Redoxic conditions and/or very long residence times (i.e., wetlands)
• Performance variability is high and ranges often overlap with WQ criteria
• Some BMPs can be a source (some bioretention)
• Recent research is showing that some BMPs can reduce toxic effects without reducing load
• Achievability needs to be considered in translating WQ criteria to BMP performance standards
BMP Effectiveness Summary - Zinc
• Most conventional BMPs address total and
dissolved Zn
• Some sources can still be hard to treat (e.g.,
galvanized roofs); focus on source controls
needed
• Achievability is a particularly consideration for low
hardness receiving waters
Case Studies: How can we do better?
• Reducing the irreducible concentration
• Improving consistency in effluent quality
• Maximizing volume reduction where
feasible and desirable
• Increasing system longevity
Case Study – SEATAC Airport• Stormwater discharges for the airport are regulated under an
individual industrial stormwater permit
• Project objective: Redesign and construct media filter beds to
comply with increasingly stringent permit limits for:
– Copper (hardness-based)
– Zinc (hardness-based)
• Comply with existing permit limits for:
– Turbidity
– Oil & Grease
– pH
• Team: Port of Seattle, RW Beck, and Geosyntec
SEATAC Retrofit Options
• Improve system hydraulics
– Improve residence time for smaller, more frequent storms
– Reduce potential for short circuiting
– Reduce pore velocities and potential for washout of fines
• Incorporate “designer” media components targeted to
pollutants/species
– Sorption
– Cation exchange
Media and Hydraulic Recommendations
for SEATAC Retrofits
Planting Mix < 25% well-aged compost
Treatment Mix50% rhyolite30% zeolite
20% GAC
Pea gravel bridging layer
Drain rock
12”
12”
2-4”
SEATAC Biofilter Monitoring Results
Storm DateStorm Depth,
inches TCu Influent, ug/L TCu Effluent, ug/L7/20/2012 0.57 35.3 4.6
10/12/2012 0.24 84.7 7.811/12/2012 0.72 8.9 2.511/29/2012 1.59 15.3 3.9
1/9/2013 1.51 6.5 2.12/6/2013 Not available 12.3 1.9
Average Influent
Average Effluent
TSS (mg/L) 12.6 2.2
Total Copper (ug/L) 27.2 3.8
Dissolved Copper (ug/L) 14.5 3.4
Total Zinc (ug/L) 63.7 11.8
Dissolved Zinc (ug/L) 46.3 10.8
Hardness (mg-CaCO3/L) 13.6 44.8
Total Copper by Storm Event
Source: SDS1 Bioretention Swale Performance Evaluation Report, Prepared for Port of Seattle by CardnoTEC. January 2104.
What is Biochar?Biochar = Bio-Energy ByProduct
• Nearly any Biomass Feedstock
• Different Production Conditions
Resists Decay = Sequesters Carbon
Unique Physical & Chemical Properties
= valuable filtration media
Image Source: Lehmann et al. 2007. “A handful of carbon”
Highly Porous; Surface Area up to 500 m2/g
Multiple pore sizes: from nm to mm range
Highly stable carbon structure with sorption
sites on edges
Sorption capacity increases over time
Biochar Properties and Metal Removal
Biochar = Green alternative to Activated Carbon
Biochar Design Considerations
Hazelnut Shell Douglas-Fir Cane Pith
Biochar is not created equal treatability testing
Raw Biochar Contains Fine Particles = Hydraulic Problems and Leaching
Raw Biochar Must be rinsed or sieved
Port of Port Townsend OverviewComprehensive Biochar Feasibility Study
Treatability Testing Pilot Testing Installation and Monitoring
Biochar Sourced from Neighboring Paper Mill• Rinsed, Screened, and Blended
Field Testing of 20 upflow filters and 2 in-ground filters• Upflow filter rated for ~20 GPM• In-Ground filters rated for ~150 GPM
Port of Port Townsend ResultsDownspout Filters Removal:
Mean Influent Mean EffluentMean
Removal
ug/L ug/L %
Total Copper 54.2 7.88 71.1%
Total Zinc 1018 39.0 92.6%
In-Ground Filters Removal:
Mean Influent Mean EffluentMean
Removal
ug/L ug/L %
Total Copper 2419 1336 52.6%
Total Zinc 1078 366 52.9%
Overall, Results Indicated:
• Excellent removal with downspout filters
• Variable removal with in-ground filters
• Media rinsing is critical to improve flow rates and contaminant removal and to prevent leaching of fine particles
• Port Townsend biochar can cause a short-term nutrient pulse, especially unrinsed
Source: Gray et al. 2015. “Port of Port Townsend Biochar Stormwater Filtration Feasibility Study”
Kitsap County Bioretention SoilIn response to copper and phosphorus export from bioretention soil
Multiple testing rounds to identify better media• Included rinsed biochar, GAC, designer sands, coconut coir• Also included control mix: 60% sand / 40% compost
Image Source: Herrera, Kitsap County, WSU, WSDOT, SPU, Geosyntec. 2015. “Analysis of Bioretention Soil Media for Improved Nitrogen, Phosphorus, and Copper Retention.”
Figure Source: Herrera Environmental Consultants, 2012. “Pollutant Export from Bioretention Soil Mix”
Kitsap County Bioretention Soil Testing
Total Cu
Biochar blends among top performers
Dissolved Cu Total Zn Dissolved Zn
Image Source: Herrera, Kitsap County, WSU, WSDOT, SPU, Geosyntec. 2015. “Analysis of Bioretention Soil Media for Improved Nitrogen, Phosphorus, and Copper Retention.”
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