Using Innovative Technologies to Mitigate Phosphorus Impacts from Urban and Ag Runoff Andy Erickson, St. Anthony Falls Lab Mike Isensee, Middle St. Croix WMO Joe Jacobs, Wright SWCD BWSR Academy - October 28, 2015
Acknowledgements Collaborators: John S. Gulliver (UMN) Peter T. Weiss (Valparaiso University) Multidisciplinary Technical Advisory Committee Sponsors & Partners: UMN, EPA/MPCA, CWL, LRRB, City of Prior Lake, PLSLWD, Scott WMO, and others BWSR, RWMWD, MWMO, Carver County, Dakota County, Wright County, VLAWMO, CLFLWD, CRWD, and many others! THANK YOU!!
Stormwater UPDATES Newsletter Signup at
What s in Urban & Ag Runoff? Solids inorganic, organic Nutrients nitrogen, phosphorus, etc. Metals (Urban) copper, cadmium, zinc, etc. Deicing Agents (Urban) chloride, salts, etc. Hydrocarbons (Urban) Bacteria/Pathogens Others Photo Courtesy: USDA.gov Photo Courtesy: A. Erickson
Arsenic Cadmium Chromium Dissolved Pollutants are a Copper Lead Nickel Significant Fraction Total (Dissolved + Particulate) Dissolved Dissolved Fraction 45.5% 50.0% 29.7% 50.0% 18.9% 44.4% 0 5 10 15 20 25 30 Median Pollutant Concentration (mg/l) 0 50 100 150 200 250 300 Phosphorus Zinc 44.4% 45.5% Source (adapted from): Pitt, R., Maestre, A., Morquecho, R., Brown, T., Schueler, T., Cappiella, K., and Sturm, P. (2005). "Evaluation of NPDES Phase 1 Municipal Stormwater Monitoring Data." University of Alabama and the Center for Watershed Protection.
Total Phosphorus Concentration (mg/l) Total Phosphorus Load (kg/event) Percent of Data (%) Dissolved Fraction is Variable 0% 5% 10% 15% 20% 1000 Concentration Load 1000 100 100 10 10 1 1 0.1 0.1 0.01 0.01 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Dissolved Percent (of total phosphorus) Source (adapted from): Brezonik, P. L., and Stadelmann, T. H. (2002). Analysis and predictive models of storm water runoff volumes, loads, and pollutant concentration from watersheds in the twin cities metropolitan area, Minnesota, USA. Water Res., 36, 1743 1757.
Stormwater Treatment Processes Physical Better infiltration results in more water treated (less overflow) Better filtration results in more particles captured Chemical Sorption or precipitation to bind dissolved pollutants Biological Vegetation uptake to capture or bacterial degradation to transform pollutants
Current Treatment Practices % TSS Removal % TP Removal Dry Ponds Wet Ponds Constructed Wetlands Sand Filter Filter Strips/Grassed Swales 0% 20% 40% 60% 80% 100% Percent Removal Source (adapted from): P.T. Weiss, A.J. Erickson and J.S. Gulliver. 2007. Cost and pollutant removal of storm-water treatment practices, Journal of Water Resources Planning and Management,133(3),218-229, 2007.
Chemical: Phosphorus sorption to Alum Amendments Inflow Water treatment residuals (WTRs) are the residues resulting from coagulating dissolved organic acids and mineral colloids with either aluminum or iron sulfate. Source: Lucas, W.C. and Greenway, M. (2011) Phosphorus Retention by Bioretention Mesocosms Using Media Formulated for Phosphorus Sorption: Response to Accelerated Loads. Journal of Irrigation and Drainage Engineering-ASCE 137(3), 144-153.
Chemical: Alum Coagulation and Flocculation
Chemical: Phosphorus Sorption with Iron Photo Courtesy: A. Erickson Sand Filtration Particulate capture > 80% Enhanced Sand Filtration Steel wool increases dissolved phosphorus capture via surface sorption to iron oxide Source: Erickson, A.J., Gulliver, J.S. and Weiss, P.T. (2007) Enhanced sand filtration for storm water phosphorus removal. Journal of Environmental Engineering- ASCE 133(5), 485-497.
Dissolved Phosphorus Concentration (mg/l) Experimental Results (Iron Enhanced Sand Filtration, SAFL) 400 300 n = 112 n = 336 n = 336 n = 336 n = 112 18.4% 200 100 78.6% 88.3% 0 Influent 100% Sand 0.3% iron 2% iron 5% iron Detection limit
MN (Iron Enhanced) Filter (5% iron filings, Maplewood, MN) Photo Courtesy: A. Erickson
MN (Iron Enhanced) Filter (5% iron filings, Maplewood, MN) 2009-2011 Monitoring Data Total P Dissolved P Average Inflow (μg/l, ppb) 111 16 Average Outflow (μg/l, ppb) 29 11 Percent of samples below detection (10 μg/l, ppb) 6% 70% Photo Courtesy: A. Erickson
The Capacity for Phosphate Capture is Significant Maplewood Sand Filter (5% Iron) SAFL Experiments (5% Iron) Time Equivalent Volume 18.4 ft 3 /ft 2 -yr 566 ft 3 /ft 2 30.8 years Phosphate Concentration 120 μg/l* 340 μg/l - Load 0.00014 lb/ft 2 -yr (62.5 mg/ft 2 -yr) 0.012 lb/ft 2 (5449 mg/ft 2 ) 87 years *Average for urban stormwater used for projection. Source: Pitt, R., Maestre, A., Morquecho, R., Brown, T., Schueler, T., Cappiella, K., and Sturm, P. (2005). "Evaluation of NPDES Phase 1 Municipal Stormwater Monitoring Data." University of Alabama and the Center for Watershed Protection.
Iron Enhanced Filter Trenches wet detention ponds (Prior Lake, MN) Photos Courtesy: A. Erickson
Filter Trenches around wet detention ponds (Prior Lake, MN) Volume Treated by Trenches (Filter Volume) Normal Water Surface Elevation Overflow Grate Water Level Control Weir Drain tile Iron Enhanced Filter Drain tile outlet
MN Filter Trenches wet detention ponds (Prior Lake, MN) 2010 Field Testing Data Dissolved P Average Inflow (μg/l, ppb) 52.4 (n = 98) Average Outflow (μg/l, ppb) 16.9 (68% ) 2013 2015 Monitoring Data Dissolved P Average Inflow (μg/l, ppb) 69.1 (n = 28) Average Outflow (μg/l, ppb) 51.2 (26% ) Photos Courtesy: A. Erickson
MN Filter Trenches (Prior Lake MN) MN Filter Bioretention (Carver County, MN) Photo Courtesy: A. Erickson Photo Courtesy: W. Forbord MN Filter Bioretention (Maplewood, MN) MN Filter Weir (Vadnais Heights, MN) Photo Courtesy: Barr Engineering Company Photo Courtesy: VLAWMO and EOR
Phosphorus Leaching from Compost But what about from naturally organic soils? Source: Morgan, J. G., Paus, K. A., Hozalski, R. M., and Gulliver, J. S. (2011). "Sorption and Release of Dissolved Pollutants Via Bioretention Media." Project Report 559. St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN.
Designing for Phosphorus Capture with Iron As iron rusts, sorption sites for phosphorus are created, therefore: Design Iron Enhanced Filter systems for watersheds with significant dissolved phosphorus fraction Ensure the system is oxygenated to ensure iron oxides remain aerobic Design systems with 8% or less iron by weight to prevent clogging
Photo Courtesy: A. Erickson For more information, contact: Andy Erickson (eric0706@umn.edu)