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8. Bioinfiltration and Evapotranspiration Controls in WinSLAMM v 10

8. Bioinfiltration and Evapotranspiration Controls in WinSLAMM v 10 . Robert Pitt, John Voorhees, and Caroline Burger PV & Associates LLC. Using WinSLAMM for Effective Stormwater Management Penn State Great Valley March 13, 2012.

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8. Bioinfiltration and Evapotranspiration Controls in WinSLAMM v 10

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  1. 8. Bioinfiltration and Evapotranspiration Controls in WinSLAMM v 10 Robert Pitt, John Voorhees, and Caroline Burger PV & Associates LLC Using WinSLAMM for Effective Stormwater Management Penn State Great Valley March 13, 2012

  2. Stormwater Constituents that may Adversely Affect Infiltration Device Life and Performance • Sediment (suspended solids) will clog device • Major cations (K+, Mg+2, Na+, Ca+2, plus various heavy metals in high abundance, such as Al and Fe) will consume soil CEC (cation exchange capacity) in competition with stormwater pollutants. • An excess of sodium, in relation to calcium and magnesium (such as in snowmelt), can increase the soil’s SAR (sodium adsorption ratio), which decreases the soil’s infiltration rate and hydraulic conductivity.

  3. Ground Water Mounding“Rules of Thumb” Mounding reduces infiltration rate to saturated permeability of soil, often 2 to 3 orders of magnitude lower than infiltration rate. Long narrow system (i.e. trenches) don't mound as much as broad, square/round systems

  4. Modeling Notes • Biofilter routing is performed using the Modified Puls Storage – Indication Method. • Time increments are established by the model, start at 6 minutes • Yield reductions due to runoff volume reduction through infiltration and filtering through engineered soil

  5. Control Practice Overview • Inflow rate – Low • All runoff flows through engineered soil • Native soil restricts below ground discharge • Water level below ground rises

  6. Control Practice Overview • Inflow rate – Moderate • All runoff flows through engineered soil • Native soil restricts below ground discharge • Water level below ground rises • Water discharges through underdrain

  7. Control Practice Overview • Inflow rate – High • Some runoff flows through engineered soil • Native soil restricts below ground discharge • Water level above ground rises • Water level below ground rises • Water discharges through underdrain

  8. Control Practice Overview • Inflow rate – High • Some runoff flows through engineered soil • Native soil restricts below ground discharge • Water level above ground rises • Water level below ground rises • Water discharges through underdrain and above ground

  9. Control Practice Overview • Inflow rate – Moderate • Some runoff flows through engineered soil • Native soil restricts below ground discharge • Water level above ground falls • Water level below ground falls • Water discharges through underdrain

  10. Control Practice Overview • Inflow rate – Moderate • All runoff flows through engineered soil • Native soil restricts below ground discharge • Water level above ground zeros out • Water level below ground falls • Water discharges through underdrain

  11. Control Practice Overview • Inflow rate – Zero • No runoff • Native soil restricts below ground discharge • Water level below ground falls • Water discharges through underdrain, eventually only through native soil

  12. Underdrain Effects on Water Balance 0.75 inch rain with complex inflow hydrograph from 1 acre of pavement. 2.2% of paved area is biofilter surface, with natural loam soil (0.5 in/hr infilt. rate) and 2 ft. of modified fill soil for water treatment and to protect groundwater. No Underdrain Conventional (3” perforated pipe) Underdrain Restricted Underdrain

  13. Biofilter Geometry Biofilter Datum is always zero ft.

  14. Biofilter Data Entry Form Biofilter Geometry Outflow Structure Information

  15. Biofilter Data Entry Form

  16. Biofilter Data Entry Form

  17. Biofilter Data Entry Form

  18. Other Output Options Time step detail Irreducible concentration Particulate reduction Stage outflow Stochastic seepage rates Biofilter Water Balance Additional Output • Stochastic seepage rates • Evapotranspiration

  19. Kansas City’s CSO Challenge • Combined sewer area: 58 mi2 • Fully developed • Rainfall: 37 in./yr • 36 sewer overflows/yr by rain > 0.6 in; reduce frequency by 65%. • 6.4 billion gal overflow/yr, reduce to 1.4 billion gal/yr • Aging wastewater infrastructure • Sewer backups • Poor receiving-water quality

  20. Kansas City Middle Blue River Outfalls • 744 acres • Distributed storage with “green infrastructure” vs. storage tanks • Need 3 Mgal storage • Goal: < 6 CSOs/yr 20

  21. Kansas City’s Original Middle Blue River Plan with CSO Storage Tanks 1/26/2009

  22. Adjacent Test and Control Watersheds

  23. Kansas City 1972 to 1999 Rain Series

  24. Water Harvesting Potential of Roof Runoff Irrigation needs for the landscaped areas surrounding the homes were calculated by subtracting long-term monthly rainfall from the regional evapotranspiration demands for turf grass.

  25. Reductions in Annual Flow Quantity from Directly Connected Roofs with the use of Rain Gardens (Kansas City CSO Study Area)

  26. Household water use (gallons/day/house) from rain barrels or water tanks for outside irrigation to meet ET requirements:

  27. Reductions in Annual Flow Quantity from Directly Connected Roofs with the use of Rain Barrels and Water Tanks (Kansas City CSO Study Area)

  28. 0.12 ft of storage is needed for use of 75% of the total annual runoff from these roofs for irrigation. With 945 ft2 roofs, the total storage is therefore 113 ft3, which would require 25 typical rain barrels, way too many! However, a relatively small water tank (5 ft D and 6 ft H) can also be used.

  29. Examples from plans prepared by URS for project streets. Construction will be completed in spring and summer of 2012.

  30. Annual Runoff Reductions from Paved Areas or Roofs for Different Sized Rain Gardens for Various Soils

  31. Clogging Potential for Different Sized Rain Gardens Receiving Roof Runoff Clogging not likely a problem with rain gardens from roofs

  32. Clogging Potential for Different Sized Rain Gardens Receiving Paved Parking Area Runoff Rain gardens should be at least 10% of the paved drainage area, or receive significant pre-treatment (such as with long grass filters or swales, or media filters) to prevent premature clogging.

  33. The most comprehensive full-scale study comparing advanced stormwater controls available. Available at: http://pubs.usgs.gov/sir/2008/5008/pdf/sir_2008-5008.pdf

  34. Parallel study areas, comparing test with control site

  35. Reductions in Runoff Volume for Cedar Hills (calculated using WinSLAMM and verified by site monitoring)

  36. Monitored Performance of Controls at Cross Plains Conservation Design Development WI DNR and USGS data

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