OH: Rain Garden Design and Monitoring

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  1. 1. Rain Garden Design & Monitoring Jay Martin, Ph.D., and Derek Schlea Ohio State University
  2. 2. What the results will be used for Increase guidance Lack of information on networks Engineering design standards Retrofits Promote the technology
  3. 3. Table 1. Summary of individual and laboratory studies of benefits of rain gardens or bioretention areas related to storm water flowand quality (Davis et al. 2009). Previous results have reported reductions of metals (Davis et al. 2003, Hunt et al. 2008) Site location /Parameter Load Reduction (%)Citationdescription Stormwater Flow ResultsBurnsville, MN flow90 Barr Engineering 2006Haddam, CN flow98 Dietz and Clausen 2006Greensboro, NC flow ~50 Hunt et al. 2006College Park, MD flow49-58Davis 2008Charlotte, NCflow96 Hunt et al. 2008 Water Quality ResultsCollege Park, MD TSS 59 Davis 2007College Park, MD TSS 54 Davis 2007Durham, NH TSS 97 UNHSC 2006Villanova, PATSS 99 USEPA 2006Haddam, CN Total N 32 Dietz and Clausen 2006Greensboro, NC Total N 40 Hunt et al. 2006Chapel Hill, NCTotal N 40 Hunt et al. 2006Louisburg, NCTotal N 65 Sharkey 2006Durham, NH Total N 97 UNHSC 2006Pilot boxesTotal N 30-99Davis et al. 2006College Park, MD Total P 79 Davis 2007College Park, MD Total P 77 Davis 2007Haddam, CN Total P-111Dietz and Clausen 2006Greensboro, NC Total P-240Hunt et al. 2006Chapel Hill, NCTotal P 65 Hunt et al. 2006Louisburg, NCTotal P 69 Sharkey 2006Villanova, PATotal P 28 USEPA 2006Pilot boxesTotal P 50-99Davis et al. 2006Laboratory columns Total P 63-85Hsieh et al. 2007College Park, MD Zn54 Davis 2007College Park, MD Zn69 Davis 2007Villanova, PAZn74 USEPA 2006Durham, NH Zn99 UNHSC 2006
  4. 4. Goals and Objectives Hydrology Quantify volume and peak flow reductions Compare to control neighborhood Water Quality Quantify nutrient reductions Modeling Application to additional watersheds
  5. 5. GardenLocations
  6. 6. Street-Side Garden Design Retrofit Space limited Utilities Tile drainage
  7. 7. Street-Side Garden Design Sizing Terracing
  8. 8. Street-Side Garden Construction Excavate In situ clay soil Backfill Higher % sand 20% organic matter Plant Mulch
  9. 9. Monitoring What to Measure Hydrology Rainfall Volume, peak flow, time to peak Rise in water table in gardens Water Quality Nutrients Solids
  10. 10. Monitoring - Equipment Tipping bucket rain gauge Storm sewer flow meters
  11. 11. Monitoring - Equipment Water quality grab samples Storm events Various locations Time intervals
  12. 12. Monitoring - Equipment Water level logger / pressure transducers Piezometers
  13. 13. Preliminary Results Hydrology Water level hydrograph
  14. 14. Preliminary Results Hydrology
  15. 15. Controlled Experiments What? Observe garden response to known watervolume and rate inputs Water balance equation
  16. 16. Controlled Experiments Eliminate the unknowns of water balance Inflow volume Bi-pass flow Tile drain flow
  17. 17. Controlled Experiment (12-10-10)
  18. 18. Controlled Experiment (12-10-10)
  19. 19. Controlled Experiment Results0.00 5-0.5Water Depth, feet bgs 10 Inflow, gpm-1.0 15-1.5 20K-2.0L25Inflow-2.5300:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 Time
  20. 20. Controlled Experiment Results Waterbalance Tiledrainage
  21. 21. Next Steps Quantify maximum volume retention = depth * width * length * porosity Quantify seepage losses Better estimations of water balance Compare with outfall flow data Mass balance for nutrients Load reductions
  22. 22. Ongoing Learning Modify methods to increase accuracy Develop a model Use data we have Gather data we need
  23. 23. Current Status Observations show the gardens areworking Working to quantify these observations Continuing controlled experiments More data Predict infiltration rates for different inflows
  24. 24. Thank you!

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