Quantifying nutrient removal by street sweeping -LID talk

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Quantifying nutrient removal by street sweeping -LID talk

  1. 1. University of Minnesota Paula Kalinosky, Lawrence Baker, Sarah Hobbie, Chris Buyarski, In Partnership with the City of Prior Lake, MN Ross Bintner LID Symposium, August 20, 2013 Quantifying Nutrient Load Recovery through Targeted, Intensive Street Sweeping
  2. 2. Summary of Questions Addressed Why Revisit Street Sweeping? What’s Different About the Prior Lake Street Sweeping Study? What was found in Prior Lake? How is this information useful?
  3. 3. Statement of Problem Nutrient management is a significant concern in urban watersheds Streets act as a conduit for pollution to the storm drainage network Meeting watershed management goals (TMDL, permits) can be costly $$ Is Street Sweeping a Cost-effective Source Control BMP?
  4. 4. Study Design Nine Study Routes LOW Canopy MEDIUM Canopy HIGH Canopy 1 X, 2X, 4X/month 1 X, 2X, 4X/month 1 X, 2X, 4X/month Q: What is the relationship between overhead tree canopy and recovered solids, nutrients?
  5. 5. Distribution of Sweeping Routes
  6. 6. Focus on Recovered Material Collection Protocol WEIGH INSPECT DUMP INSPECT SAMPLE INSPECT Material Removed From the Street is Not Available for Transport
  7. 7. Lab Methods: Unique Fractionation Scheme Suited to Focus on Nutrients Fines (<2mm) Coarse Organics (≥2mm) Rocks (≥2mm)* TP, TN, TOC (Leached during separation process) TS, TP, TN, TOC, % Organic TS, TP, TN, TOC, % Organic * Dry mass only, nutrient contribution assumed negligible. Sweeper Waste
  8. 8. Findings: Recovered Solids Average Load Recovered per Month Dry Solids (lb/curb-mile) Sweeping Frequency Low Canopy Med Canopy High Canopy 1X/mo 183 219 435 2X/mo 269 423 664 4X/mo 478 849 649 Big Picture – Loads increase as tree canopy cover increases.
  9. 9. Seasonal Trends 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 Jan Feb Mar Apr May Jun Jul Aug Se[ Oct Nov Dec TotalDrySolids(lb) Month Year 1 Year 2 Winter Weather Influence Sep Influence of month/season on load intensity is significant.
  10. 10. Role of Coarse Organics 0% 20% 40% 60% 80% 100% Jun-10 Jul-10 Sep-10 Oct-10 Nov-10 Jan-11 Feb-11 Mar-11 May-11 Jun-11 Jul-11 Sep-11 Oct-11 Nov-11 Jan-12 Feb-12 Mar-12 May-12 Jun-12 Jul-12 Aug-12 PercentLoadasCoarseOrganics Dry Solids Phosphorus Nitrogen Coarse organics are a significant source of nutrients
  11. 11. Trends in Cost Effectiveness $0 $100 $200 $300 $400 $500 $600 $700 2 4 6 8 10 12 AverageCost-effectiveness,$/lb RecoveredPhosphorus Month L4 H2 Least cost effective Most cost effective In high canopy areas, phosphorus can be recovered for less than $100/lb
  12. 12. Correlation between Tree Canopy Cover and Recovered Phosphorus R² = 0.84 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 0% 5% 10% 15% 20% CumulativePLoad,Snow-freeseason (lb/curb-mile) Percent Tree Canopy Cover Over the Street Study Total P Load Intensity 1X/mo 2X/mo 4x/mo
  13. 13. General Model for Predicting Recoverable Loads E(Load│m, f, c)= o + 1(month) + 2(frequency) + 3(canopy) Goal: Produce a tool for estimating nutrient recovery based on easily obtained inputs. TIMING of sweeping event FREQUENCY of sweeping events CANOPY COVER for sweeping route
  14. 14. Model Validation Predicted Study Load, Five Fold Cross-Validation MEASURED MLR Prediction RT Prediction Fresh Solids 853855 756549 (-11%) 793020 (-7%) Dry Solids 618622 547977 (-11%) 565047 (-9%) Total Phosphorus 502 424 (-16%) 443 (-12%) Total Nitrogen 1945 1645 (-15%) 1682 (-14%)
  15. 15. Spreadsheet Planning Tool: User Inputs Users define sweeping routes for which nutrient recovery will be estimated.
  16. 16. Spreadsheet Planning Tool: User Inputs Use supplies a default cost per curb-miles (Prior Lake Method available in Guidance Manual).
  17. 17. Spreadsheet Planning Tool: Estimate Nutrient Recovery 1. Choose Route 2. Define Sweepings 3. Check Estimates 4. Save Routine
  18. 18. Spreadsheet Planning Tool: Output, Annual Summary of Sweepings by Route
  19. 19. Spreadsheet Planning Tool: Output, Summary of Planned Sweepings by Month
  20. 20. Spreadsheet Planning Tool: Output, Monthly Subtotals for Planned Sweeping
  21. 21. Predicted vs. Measured, Prior Lake
  22. 22. Predicted vs. Measured, Prior Lake
  23. 23. Potential Application: Tracking Nutrient Recovery Five –Fold Cross-Validation Exercise using Predicted P-concentrations, Regression Trees P (lb) Measured Recovered Phosphorus 505 Estimate based on: Curb-miles Swept 457 (-9.4%) Fresh Load (lb) 505 (-0%) Dry Load (lb) 495 (-1.9%)
  24. 24. Next Steps EXTRAPOLATE OPTIMIZE QUANTIFY

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