Local Limits Calculations – Methodologies for Development

1. Local Limits Calculations – Methodologies for Development California Water Environment Association P3S Annual Conference February 24, 2002 Presented by Rich von Langen and John W. Hart

2. Presentation Overview Summarizes local limits development highlighting the standard approach and including practical considerations based on EPA guidance documents and experience.

3. Local Limits Development Requirements • Management support • Stakeholder involvement • Adequate resources • Work Plan • RWQCB involvement • Continuous process

4. Local Limits DevelopmentStandard Approach • Determine POC • Collect data • Analyze data • MAHL and MAIHL calculations • Allocation IU local limits • Local Limits adoption and approval

5. Pollutants of ConcernStandard Approach • 15 Pollutants • Pollutants in discharge permits • Sludge disposal regulations • Review of IU discharge data • Identified pass-through or interference pollutants

6. Pollutants of ConcernPractical Considerations • EPA specific evaluation criteria • Does IU discharge the POC? • Pretreatment Program versus Source Control Program • Keep It Simple Sam (KISS)

7. Data CollectionStandard Approach • Sampling • Flow proportional composite • Time composite • Grab • Sample Analyses and Quality Assurance • Flow Information

8. Sample Locations • Domestic • Commercial • Industrial Users • Plant Process and Removal • Waste Haulers • Source Water

9. Sample LocationsPractical Considerations • Domestic • Representative • Sufficient flow • Over a weekend • Commercial • Same considerations as above

10. Sample LocationsPractical Considerations (continued) Industrial Users • Research before you sample • Categorical Industrial Users • Significant IndustrialUsers

11. Sample LocationsPractical Considerations (continued) Treatment Plant(s) • More than one • Hydraulic detention time • Proper sample locations • Sludge sample collection

12. Sample LocationsPractical Considerations (continued) Waste Haulers • Significant loading? • Sample collection technique • Different set of local limits?

13. Sample LocationsPractical Considerations (continued) Source Water • Different sources • Changes over time

14. Sample Analyses and Quality Assurance • Standard or Approved Methods • Minimum Detection Limits • What is needed? • What can be done? • Pre-qualify the laboratories • Quality Assurance

15. Sample AnalysesPractical Considerations • New/modified test techniques • Minimum number of samples • Electronic data • Duplicate samples analyzed by two laboratories

16. Flow Information • Flow proportional sampling • Minimum flow and monitoring equipment capabilities • Equalization • Inflow and infiltration impacts • Use actual, not design flows

17. Data AnalysesPractical Considerations • Enough data points? • The “< MDL” Dilemma—MDL, 50%, or 0? • Variability-- SD > 20%, NDs • Organic Total Dissolved Solids • Any pass-through or interference during sampling events?

18. MAHL and MAIHL Calculations • Mass Balances • Collection System = Headworks • Headworks = Plant Effluent and Sludge • Safety factor • Growth factor

19. Industrial Waste Residential Commercial Effluent Sludge Headworks Mass BalancesPractical ConsiderationsHeadworks data are the fulcrum point for mass balances

20. Headworks Mass BalanceIW + RES + COM = Headworks • Effect of collection system operations • No commercial samples • Headworks data versus plant removal

21. MAHL and MAIHL Practical Considerations • If the mass balance does not balance • Eliminate data > 2SD • Use median versus mean • Balance with ND’s = MDL, X%, and 0 • Note variability for safety factor • Compare to other data • Influent concentration vs % removal

22. Influent Concentration Impacts on Plant Removal

23. Safety and Growth Factors • Safety factor • Data variability • Slug loads • Plant performance • Growth factor • Pollutant specific • Domestic/commercial • Industrial

24. Sensitivity Analysis • NDs Calculate LL at different ND values; adjust headworks concentration to match mass balance • Variable Data Eliminate outliers; use median or geometric mean to calculate LL • Growth Factor Vary; compare to domestic, commercial, and IU contributions • Allocation Method Total IU flow, pollutant contributory IU flows • TDS Vary concentrations of source water, and uncontrolled sources Take a Global Perspective

25. Allocation • Meet stakeholders objectives • Mass-based • Uniform concentration • All industrial users • Only IU discharging that POC • If LL > CIU limit, allocate excess to others • Consistency

26. Allocation Practical Considerations • Are limits technically achievable? • Can compliance be determined? • Do limits reflect actual conditions?

27. Adoption and Approval • Local limits draft report • Stakeholders review • POTW adoption • Submit to RWQCB for approval • Issue when new permit or all at once • RWQCB may/may not accept LL

28. Annual Review and Re-Evaluationa • Assess current conditions • Compare MAHLs to current headworks loadings • Review compliance history • Collect and analyze data • Recalculate or determine LL • Implement LL • a) Unpublished presentation by Jeff Lape, US EPA

29. Continually Improving LL Existing Load MAHL New POC Compare Sample Calculate

30. EPA Resources • Draft Guidance Manual (www.epa.gov/reg3wapd/pretreatment/pdfs_txt/draftguidance912.pdf) • Region 8 Draft LL Development Strategy (www.epa.gov/Region8/water/wastewater/prethome/Pret_download/LLStrategy041103.pdf) • Region 5 LL Guidance (1995) (www.epa.gov/R5water/npdestek/npdprtg2.htm) • Region 3 LL Guidance Domestic> MAHL (www.epa.gov/R5water/npdestek/npdprtg3.htm) • Procuring Analytical Services (www.epa.gov/reg3wapd/pretreatment/pdfs_txt/procur.pdf)

31. Local Limits Calculations – Methodologies for Development QUESTIONS? California Water Environment Association P3S Annual Conference