IDEAL Stormwater BMP Modeling Framework

1. IDEALStormwater BMP Modeling Framework May 8, 2007 Brian T. Bates, PE

2. Integrated Design and Evaluation Assessment of Loadings Model • History/Background of IDEAL • Modeling Approach • State of the model • Demo • Discussion Woolpert IDEAL Demonstration

3. An OCRM Dilemma • Compliance with Antidegradation & TMDLs • Needed an explicit BMP model • Model Hydrology & Hydrualics and pollutant yield from urban areas. • Estimate BMP performance. • Base predictions on accepted predictive procedures. 1999 2000 2001 2002 2003 2004 Woolpert IDEAL Demonstration

4. IDEAL Initiated • Woolpert hired by OCRM • Scope of Model • Literature review • Watershed Framework • Post Construction BMP Design Aid Manual and IDEAL Spreadsheet 2001 2004 2005 2002 2003 Woolpert IDEAL Demonstration

5. IDEAL Development • Primary Researchers Dr Bill Barfield – Oklahoma State University Dr. John Hayes – Clemson University Woolpert IDEAL Demonstration

6. IDEAL OCRM version • BMP Trapping Sedimentology and soil isotherms • Hydrology Single storm and Total annual runoff • 4 pollutants • 3 BMPs • Pond routing • Single watershed • Post-construction Woolpert IDEAL Demonstration

7. Pervious Watershed Modeling Framework Pervious and Unconnected Impervious Directly Connected Impervious Impervious Imp BMP BMP Dry/Wet Detention Basin Outflow From Watershed Woolpert IDEAL Demonstration

8. Precip Amount Prob P Growing Season Dormant Season P=0.664 P=0.336 AMC 1 AMC 1 AMC 2 AMC 2 AMC 3 AMC 3 P=0.797 P=0.543 P=0.231 P=0.104 P=0.100 P=0.226 Rainfall Statistics 12 Storms 0.25’’ to 10.5’’ Values for Greenville,SC Woolpert IDEAL Demonstration

9. Sediment Yield • Pervious Areas - MUSLE • Impervious Areas - EMC Approach • EMC varies with type of impervious area • Modeling dependability improves as local data is collected • Model Sediment Size Distribution • Used to determine sediment trapping in Vegetated Filter Strip and in ponds • Nutrients and bacteria are sorbed on the exchange phase of the clay particles, hence need to know concentration of clay size particles • Pervious areas based on CREAMS equations • Impervious areas based on NURP data Woolpert IDEAL Demonstration

10. Nutrient and Bacteria Loading • Modeling Nutrients • Yield based on event mean concentrations (EMCs) for each chemical • EMCs vary based on land use • Modeling Indicator Bacteria • Yield based on event mean concentrations (EMCs) for bacteria • EMCs highly variable • National average ~ 15,000 number/100ml • Depends a great deal on presence of pets, wildlife, leaky sewers, etc Woolpert IDEAL Demonstration

11. BMP Trapping • Predicts trapping of sediments in ponds through overflow rate calculations for 5 particle classes. • Predicts nutrient trapping by settling of particulate matter and sorbed portion on trapped active clay content of the sediment by isotherms. • Predicts bacteria trapping using isotherms and mortality • VFS trapping uses the KY VFS model Woolpert IDEAL Demonstration

12. IDEAL OCRM Model Limitations • Only for use on the SC coast • Limited outlet configurations • Numerous spreadsheet constraints • Untested BMP algorithms • No resuspension, denitrification, direct loading on BMP, or bacteria growth. Woolpert IDEAL Demonstration

13. Greenville County • Woolpert hired by County • Isotherms and Rainfall Analysis • Continue to use spreadsheet 2002 2004 2005 2001 2003 Woolpert IDEAL Demonstration

14. Greenville County 2003 2004 2005 2001 2002 • Dry pond verification study Woolpert IDEAL Demonstration

15. Greenville County 2004 2003 2005 2001 2002 • VB GUI developed • Bioretention cell research begun • Multiple watersheds • Literature review • Swales & Engr. Devices Woolpert IDEAL Demonstration

16. Greenville County 2003 2004 2005 2001 2002 Sept • EPA BMP Design Manual EPA/600/R-04/121 Woolpert IDEAL Demonstration

17. Greenville County 2005 2003 2004 2006 2002 • Bioretention cell added and revised • Greenhouse study • Greenville Co. study Woolpert IDEAL Demonstration

18. Greenville County Woolpert IDEAL Demonstration

19. Greenville County 2005 2003 2004 2006 2002 • Bioretention cell added and revised • Greenhouse study • Greenville Co. study • FC loading function Woolpert IDEAL Demonstration

20. Greenville County Woolpert IDEAL Demonstration

21. Greenville County 2006 2003 2004 2005 2002 • Sand filter and bioswale added • Conceptual algorithms developed for engr. devices • Conveyance routing algorithms • Pipe, Channel, Simple translation • Model presented to EPA Region 4 • VB GUI revised to current layout • Distributed Jan 2007 to GC engineers Woolpert IDEAL Demonstration

22. Greenville County • Object oriented VB.net “Drag n Drop” version Woolpert IDEAL Demonstration

23. Ongoing Improvements • Technical Advisory Group • Barfield and Hayes • Dr. John Sansalone –University of Florida • Dr. Bob Pitt –University of Alabama • Mike Borst – EPA-Office of Research & Development • Mark Schlautman – Clemson University • Khaled Gasem – Oklahoma State University • Enhanced Bioswale research with EPA-ORD, Edison, NJ • User’s Manual Woolpert IDEAL Demonstration

24. Summary of versions Woolpert IDEAL Demonstration

25. IDEAL DEMONSTRATION

26. Uses • BMP design for small to large development projects • TMDL compliance • Antidegradation restrictions • Watershed master planning • LID design Woolpert IDEAL Demonstration

27. Future Enhancements • Expansion of Isotherms • Bacteria growth function • Rainfall statistics • Engineered device algorithms development • Bioswale algorithm revision • Conveyance design functionality • GIS/CAD interface • Optimization • Large scale watershed considerations • Performance enhancement and user support • Continue to use best science available Woolpert IDEAL Demonstration

28. Questions?