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Phosphorus Treatment – Advanced Removal Mechanisms & Amended Design for Stormwater BMPs

Phosphorus Treatment – Advanced Removal Mechanisms & Amended Design for Stormwater BMPs. Scott Perry, CPSWQ. Nov. 17 th , 2011. Overview. Phosphorus Basics NPS Loads Stormwater BMP performance Ways to Increase Phosphorus Removal Advanced Removal Mechanism Amended BMP Designs

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Phosphorus Treatment – Advanced Removal Mechanisms & Amended Design for Stormwater BMPs

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  1. Phosphorus Treatment – Advanced Removal Mechanisms & Amended Design for Stormwater BMPs Scott Perry, CPSWQ Nov. 17th, 2011

  2. Overview • Phosphorus Basics • NPS Loads • Stormwater BMP performance • Ways to Increase Phosphorus Removal • Advanced Removal Mechanism • Amended BMP Designs • Things to Avoid

  3. Phosphorus Basics • Essential nutrient for life • Cyclic between land & water • Limiting nutrient in freshwater

  4. Millions of Years

  5. Phosphorus added Fisheries and Oceans Canada - 1973 Canadian Experimental Lakes Area # 226: • Plastic Curtain divides lake • Carbon & Nitrogen added to both sides • Phosphorus added to lower half

  6. Lake Erie - Oct. 2010 Lake Erie – Sept. 2009 Lake Erie – Sept. 2008

  7. Problem: • Excess Phosphorus in fresh water causes Eutrophication (over enrichment): • Algal blooms • Micro-toxins … Cyanobacteria • Hypoxia • Fish kills • Invasive species Lake Champlain AP & VPR News - 2010

  8. Additional Issues : • Taste & odor problems • Fish & aquatic community • Recreational quality • Property values • Drinking Water Cost Charles River – Boston Metro

  9. NPS Phosphorus Sources • Fertilizers • Animal & Pet Waste • Vegetation & Leaves • Detergents • Erosion & Sediment Loss • Hydrocarbons & Lubricants • Airborne Fallout: Dust, Pollen, Fossil Fuels • Waste Water (CSO / Septic)

  10. Chesapeake Bay Pollen Load from Outfalls APR09

  11. Turf --- fertilizer and compacted soils/lawns

  12. Chesapeake Bay Watershed Relative Responsibility for Pollution Loads to the bay Sediment Nitrogen Phosphorus

  13. Charles River Watershed

  14. Phosphorus Stormwater Loading by Land Use EPA Stormwater BMP Design Guide, 2004

  15. Imperviousness Cover &Phosphorus Load Center for Watershed Protection - Schueler and Caraco 2001

  16. Total Phosphorus (mg/L) % Tree Canopy USGS Water-Resources Investigations Report 99–4021 Phosphorus Load with Increasing % Tree Canopy

  17. Total Phosphorus (mg/L) % Tree Canopy USGS Water-Resources Investigations Report 99–4021 Roadway Phosphorus EMC with Increasing % Tree Canopy

  18. Sediment particle Total Phosphorus (TP) Partitioning • Particulate-Bound (PB) Phosphorus • Dissolved Phosphorus (DP) • Bio-available • “QUICK SUGAR” for Algal Blooms

  19. Phosphorus Partitioning by Land Use TP = Particulate-bound phosphorus & Dissolved Phosphorus DP = Dissolved Phosphorus PB = Particulate-bound Phosphorus National Stormwater Quality Database New York State DEC, 2008

  20. TSS Phosphorus in Stormwater

  21. Typical Urban Stormwater BMPs designed to captures 80% TSS: Dissolved Phosphorus (DP) Particulate-bound Phosphorus (PB) + or Sediment particle 50% TP --- Dissolved (< 0.45-mircons) 50% TP --- Associated with TSS (sediment) 80% TSS capture X 50% (particulate-bound phosphorus) = 40% (TP) Removal

  22. Range of Total Phosphorus (TP) % Removal per BMP Type Center for Watershed Protection, National Pollutant Performance Removal Database version3, Sept. 2007

  23. Factors impacting Phosphorus Fate & Transport • Water chemistry conditions • pH • Alkalinity • Temperature / Seasonality • Redox potential • Particle charge • Concentration • Time / Maintenance frequency

  24. Phosphorus Fate • Phosphorus speciation will shift • Examples • Runoff pH • Concrete Road > 7.0 vs Asphalt < 5.0 • Bottom of Lakes • Anaerobic activity / decaying organics

  25. Stormwater TP Removal Mechanisms & Generalized Capability

  26. Absorption Adsorption Sorption • Combination of physiochemical interactions; • Adsorption - surface attachment • Absorption - internal attachment (sponge) • Ion Exchange - displacement of ions (Ca, Mg, Na) • Sorption Capacity --- mg/g Compared to soils … • Ion Exchange Capacity --- meq/100g

  27. Sediment particle Methods to Increase TP removal & reduce variation

  28. Sediment particle 1 - Increase TSS Removal • Achieve > 80% TSS Removal • Remove the most particulate-bound phosphorus • Silt-sized particles (Filtration) (63-microns) • Prevent Resuspension

  29. TSS Particulate-Bound Phosphorus Silt & Clay

  30. 2 - Mitigate Phosphorus Speciation Shift • Prevent or mitigate anaerobic conditions • Maintenance (removal of decaying materials) • Catchbasins • Forebays • Wetlands • Underground Systems

  31. 3 - Runoff Reduction --- i.e. Infiltration Green Infrastructure • Reduce Impervious Cover and/or Impact • Maximize Infiltration • Maximize Evapotranspiration • Combine Technology with Green Infrastructure

  32. Range of Total Phosphorus (TP) % Removal per BMP Type Center for Watershed Protection, National Pollutant Performance Removal Database version3, Sept. 2007

  33. Advanced Removal Mechanisms

  34. Sediment particle 4 - Target ALL Phosphorus (i.e. ... The Dissolved Phase too) Particulate bound Dissolved Phosphorus

  35. Advanced Removal Mechanisms Practices that do not Infiltrate 100% • Engineer to Capture Dissolved Phosphorus • Amend & Design • Engineered Media • Displace conventional media or aggregate • Polish exfiltrating systems

  36. Quantifying Engineered Media • Isotherm – • Best Case Maximum capacity? • Kinetics – • How fast can it be sorbed? • Breakthrough – • Volume of Pollutant/WQv treated? (maintenance) • Desorption – • Retaining DP … is the bond strong enough?

  37. What is Breakthrough? Influent Effluent

  38. Applications Amended Low Impact Development Surface Filters that Exfiltrate Sorption based Media

  39. Applications Amended Surface Filters (sand filters / bioretention) Sorption based Media

  40. Amended Pervious Pavements Applications Sorption based Media Under Drain PVC

  41. 7-inches of growth media Green Roof Research • Previous Research Observed: • Runoff Reduction • Increased Phosphorus Discharge

  42. Green Roof Research • Previous Research Observed: • Runoff Reduction • Increased Phosphorus Discharge

  43. Greenroof Study Findings • 2009 Runoff Reduction = 42% • 2010 Runoff Reduction = 53% • August - 77% versus October - 15% • NET EXPORTER of Phosphorus • TP discharged: ≈ 2 mg/L to ≈ 0.6 mg/L • Engineered Media … Exfiltration Treatment: • TP Reduction (87%): 1.18 to 0.16 mg/L • SRP Reduction (82%): 0.63 to 0.11 mg/L

  44. Things to Avoid with “Sorption” Materials

  45. Things to Avoid with “Sorption” Materials • Monitor the use of materials prone to desorption • Organics / Compost / Soils • Evaluate Material • Prevent leaching of other Toxics • pH, Heavy Metals • Slag, waste by-products

  46. Things to Avoid with “Sorption” Materials Leaches Phosphorus

  47. Summary • Urban Runoff is a significant Phosphorus contributor • Infiltration should be the first tool to combat • Exfiltration should treat Dissolved Phosphorus (DP) with an Engineered Media

  48. Questions? Scott Perry 301-279-8827 sperry@imbriumsystems.com AP/Larry Dupont – Lake Champlain

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