Options for Estimating BMP Performance (Load Reductions)

1. Options for Estimating BMP Performance (Load Reductions)

2. Presentation Overview • Informed implementation • Quantifying load reduction associated with management strategies • BMP evaluation • Sources of BMP effectiveness information • Determining which BMPs are appropriate • Tools that can be used to support the process

3. Informed Implementation • Determine load reduction necessary to meet objectives • Identify opportunities for implementation • Review design standards/ordinances that will dictate techniques • Identify and narrow down BMP options based on objectives • Identify scale for comparative analysis of alternatives/scenarios • Quantify BMP options • spreadsheet-based • watershed/site-scale model • Evaluate scenarios and select management strategy

4. Be Sure Objectives Have Been Clearly Defined • Example Objectives: • Meets NPDES Phase 1 & 2 stormwater regulations • Protect sensitive species • Protect water quality by addressing 303(d) listing concerns • Address detention for the control of stormwater volume and peaks

5. Quantifying Load Reduction to Meet Objectives • Sources of load quantification data • Watershed modeling/load quantification results (previously described), TMDL reports, etc. • Source and spatial targets for implementation

6. Identify Opportunities for Implementation • Impervious analysis • Political constraints and priorities • Physical constraints • Environmental constraints

7. Review Design Standards/Ordinances, if applicable • Zoning ordinances • Subdivision ordinances • Sedimentation and erosion ordinances • Stormwater/water quality management ordinances

8. Examples • Minimize the total volume of surface water runoff that flows from any specific site during and following development, in order to replicate pre-development hydrology to the maximum extent practicable • Achieve average annual 85% Total Suspended Solids (TSS) removal for the developed area of a site. Areas designated as open space that are not developed do not require stormwater treatment. All sites must employ Low Impact Development (LID) practices to control and treat runoff from the first inch of rainfall. Developed site hydrograph BMP influence on hydrograph

9. Identify BMP Options

10. Where can I Access Information on BMPs? • National Menu of Stormwater Best Management Practices: http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm • International Stormwater Best Management Practices (BMP) Database: http://www.bmpdatabase.org/ • Feedlots • DPRA Inc.1986. An evaluation of the cost effectiveness of agricultural best management practices and publicly owned treatment works in controlling phosphorus pollution in the Great Lakes basin. Prepared for U.S. Environmental Protection Agency, Washington, DC. • Edwards, W.M., L.B. Owens, and R.K. White. 1983. Managing runoff from a small, paved beef feedlot. Journal of Environmental Quality 12(2). • Edwards, W.M., L.B. Owens, R.K. White, and N.R. Fausey. 1986. Managing feedlot runoff with a settling basin plus tiled infiltration bed. Transactions of the ASAE 29(1):243-247. • Forest • Seyedbagheri, K. A. 1996. Idaho forestry best management practices: Compilation of research on their effectiveness. General Technical Report INT-GTR-339. USDA Forest Service, Intermountain Research Station, Ogden, Utah. • Cropland • U.S. Environmental Protection Agency (EPA). 1993. Guidance specifying management measures for sources of nonpoint pollution in coastal waters. EPA-840-B-92-002. Office of Water, Washington, DC.

11. Where can I Access Information on BMPs? • Urban • Athayde, D.N., P.E. Shelly, E.D. Driscoll, D. Gaboury, and G. Boyd. 1983. Results of the nationwide urban runoff program - volume I - final report. U.S. Environmental Protection Agency, Washington, DC. • Leeds, R., L.C. Brown, M.R. Sulc, and L.VanLieshout. 1994. Vegetative filter strips: Application, installation and maintenance. AEX-467-94. Ohio State University Extension, Columbus, Ohio. http://ohioline.osu.edu/aex-fact/0467.html • MDEQ (Michigan Department of Environmental Quality). 1999. Pollutants controlled: Calculation and documentation for section 319 watersheds training manual. Michigan Department of Environmental Quality, Lansing, Michigan, USA. • Northeastern Illinois Planning Commission (NIPC). 1994. Model best management practice selection methodology & Lake County decision-making framework. NIPC, Chicago, Illinois. • Schueler, T.R. 1987. Controlling urban runoff: A practical manual for planning and designing urban BMPs. Document No. 87703. Metropolitan Washington Council of Governments, Washington, DC. • Davis, A.P., Shokouhian, M., Sharma, H. and C. Minami. 2001. Laboratory study of biological retention for urban stormwater management. Water Environment Research 73:5-14 • Maryland Prince George's County and the U.S. Environmental Protection Agency. 1999. Low-Impact Development Design Strategies: An Integrated Design Approach. http://www.epa.gov/owow/nps/lid/lidnatl.pdf

12. Identify Specific BMP Options

13. Narrow Down BMPs Based on Objectives

14. Quantify BMP Options at a Subwatershed or Watershed Scale • Goals • Quantify selected BMP strategies (i.e., individual BMPs or BMP pairings) • Watershed scale • Local scale • Compare potential load reductions to target • Determine optimal strategy considering environmental benefits and $$ • Available Tools • Spreadsheet tools • Watershed/site-scale models

15. What Tool Should I Select? • Has a model already been used for load quantification? • What scale is important? • Is an annual load reduction estimate sufficient? • Should individual storms be evaluated? • Spreadsheet tools • Normally good for annual/overall reductions • Usually at a watershed scale – sometimes at the site scale • Watershed models • Allow for continuous/long-term simulation • Often can be used for storm evaluation • Ability to function at all scales – site and watershed

16. Example Spreadsheet Tool for Evaluation of Agricultural BMPs • Field study of BMP performance determines 75% reduction of pollutant load for a 120 acre site • Watershed loading model determined annual loading rates for multiple sites • Spreadsheet can be used to determine BMP load reductions at all sites

17. Using Watershed Models to Evaluate BMP Performance • Some watershed models are capable of directly evaluating management strategies • Agricultural practices: SWAT, AGNPS, GWLF • Urban practices: P8-UCM, SWMM • Mixed land use: HSPF • Techniques vary by model • Assumed BMP removal efficiencies • Simulation of storage and pollutant routing • Pollutant losses (e.g., decay, settling) • Volume losses (e.g., infiltration, evaporation)

18. Example Watershed Model BMP Simulation - GWLF • Often used to estimate existing loads • Different BMPs represented using general model functions • Considerations: • Universal Soil Loss Equation parameters • Curve #s • Manure/fertilizer application • Septic loads • User-specified removal rates

19. Example Watershed Model BMP Simulation - SWMM • Often used to estimate existing loads • Different BMP scenarios modeled to determine load reductions • Considerations • Street sweeping • Flow detention and pollutant removal • Varying hydrologic and pollutant loading assumptions

20. Summary of Management Practice Simulation Techniques in Selected Models

21. Additional Models for Detailed BMP Simulation • Detailed site-scale analysis • Specialize in particular types of BMPs • Example: • Prince George’s County (MD) BMP-DSS • Clinton River Watershed Site Evaluation Tool

22. BMP Optimization Find optimum BMP placement and selection strategies based on pre-selected potential sites and applicable BMP types • What is optimum? • Minimize cost • Maximize pollutant flow and/or load reduction • Combination of the above • How does one measure optimum? • Minimum cost, long-term flows, and/or pollutant load • Best-fit multi-storm curve with pre-developed condition

23. Identify Optimal SolutionExample of BMP-DSS Multiple Run Output Optimal Solution Initial Run Trade-Off Curve

24. Clinton River Watershed Site Evaluation Tool Output Output • Evaluate potential benefits of BMPs at the site development scale • Inputs • Site characteristics • BMP characteristics • Outputs • Peak discharge • Annual runoff • Pollutant Loads

25. Why Site Evaluation Tool? • Evaluate flow and water quality impact of proposed residential and commercial development • Identify most cost-effective suite of BMPs • Support decision-making activities • Tool used in combination with other data/information to make final management decisions at the site scale • Promote consistency • Help with Phase 2 reporting requirements

26. Who Will Use the Site Evaluation Tool? • Local planning review agencies • Help with the evaluation of proposed projects • Potentially could ask developers to use the tool, too

27. Example

31. Conclusions • Quantifying potential impacts from BMPs is critical to watershed planning • Provides a guide toward achieving load reduction goal • Informs selection of a management strategy • Spreadsheet and modeling tools are available • Spreadsheet tools • Most useful for watershed-scale analysis • Operate on a large time step • Watershed/site-scale models • Useful for local scale, as well as watershed-scale • Can operate on a short time-step (including individual storms) • Provide a key first step for engineering design • Again, one size doesn’t fit all!