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Local Limits Review

Pacific Northwest Pretreatment Conference September 2002 Raj Kapur Oregon DEQ. Local Limits Review. Outline. Local limits development process Unattainable Limits What we learn from local limits analysis Draft EPA Guidance Looking Ahead…WQ criteria, Human Health Criteria & TMDLs.

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Local Limits Review

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  1. Pacific Northwest Pretreatment Conference September 2002 Raj Kapur Oregon DEQ Local Limits Review

  2. Outline • Local limits development process • Unattainable Limits • What we learn from local limits analysis • Draft EPA Guidance • Looking Ahead…WQ criteria, Human Health Criteria & TMDLs

  3. Local Limits in a Nutshell Industrial Domestic Biosolids Commercial

  4. Headworks Loading Method 1. Collect & analyze data 2. Develop allowable headworks loading 3. Determine allowable industrial loading 4. Allocate allowable industrial loading

  5. Step 1: Collecting Data Collect site specific data from: Treatment Plant Industrial Users Background Sources Determine applicable environmental criteria Identify pollutants of concern

  6. Mass Balance Check Field data vs. plant data • Add background + industrial loading and compare with influent loading • Indication of quality of data collected • Indication of expected accuracy of analysis • May need to re-evaluate data/assumptions • Background sampling is typically a weak link • use influent as background • limitations

  7. Mass Balance Check - Visually Industrial Domestic InfluentWastewater Commercial

  8. Mass Balance of Pollutant Fate • Compare influent loadings vs effluent + sludge loadings • If mass balance is poor, re-evaluate: • sampling data • removal efficiencies • assumptions • detection limits • literature default values • conservative pollutants

  9. Step 2: Develop MAHLs • MAHLs may be based on: • NPDES permit limits/WQ criteria • Inhibition levels • Sludge disposal options • Need to back calculate to influent value

  10. Step 2: WQ Headworks Loading NPDES Permit Limits or Water Quality Standards Data needs: ZID/MZ dilutions, and stream background Chronic toxicity - protect against long-term effects. Use dilution at edge of mixing zone Acute toxicity - protect against short-term lethality. Use dilution at edge of ZID Point Discharge ZID and Mixing Zone

  11. Inhibition Headworks Loading • Literature values provided in EPA’s local limits guidance • activated sludge • Trickling Filters • Nitrification • Anaerobic digestion • Need primary removal efficiencies and removal through secondary if facility has tertiary treatment

  12. Sludge Headworks Loading • 40 CFR 503 regulations establish sludge quality for land application • Ceiling values • Pollutant concentrations (clean sludge values) • Cumulative loading rates • Annual application rates (for compost)

  13. Back Calculate to Influent Value Secondary Clarifier Activated Sludge INFLUENT EFFLUENT Primary Clarifier Land Application

  14. Allocation of MAHLs • Step 3: Determine maximum allowable industrial loading (MAIL) • Select most stringent MAHL • Safety factor

  15. Step 4: Allocate Industrial Loading • Two methods are typically used for conservative pollutants: • Uniform Concentration Method • Industrial Contributory Flow Method • Can also use a combination of these two methods

  16. No IU Loading/Unattainable Limits • Domestic contributions • Detection limits • Mass Balance • Removal efficiencies • Safety factor • Allocation methods To summarize, review all data and assumptions

  17. No IU Loading/Unattainable Limits • Use clean sampling/analytical techniques • Dissolved metals • EPA values for converting total recoverable to dissolved do not offer much of a reduction • will likely need to develop site specific conversion factors • Water Effects Ratio

  18. Increase Treatment Reduce Sources Reuse/re-evaluate mixing zone No IU Loading/Unattainable Limits

  19. What we learn from local limits analysis • Highlights underlying issues in collection system and WWTP • Dilution issues – facilities plans did not focus on metals • Domestic loading – can account for large % of MAHLs for some pollutants • IU loading – May learn that IUs do not contribute certain pollutants (Hg, Ag) • Can use this info to determine how best to control pollutants

  20. Draft EPA Guidance • Issued Aug. 2001 • Literature values not updated • Inhibition values • Removal efficiencies • Background domestic levels • Provides guidelines for determining when to establish a local limit • Ave loading: 60% of MAHL • Max loading: 80% of MAHL • Ave loading: 80% of MAHL for BOD/TSS/NH3

  21. Looking Ahead…WQ Criteria Update • Water quality criteria for toxic pollutants being revised • List includes As, Cd, Cr, Cu, Hg, and Ni • Advisory committee grappling with dissolved vs. total issue • May need to review local limits once these are adopted

  22. Looking Ahead… Human Health Criteria • With few exceptions, these have not been applied in NPDES permits/local limits • For most pollutants, HH criteria is higher than aquatic life criteria • Very low numbers for carcinogens & some others • HH criteria based on long-term exposure • Limits would be developed based on a year-around mean stream flow • NPDES permits and local limits analysis will likely include evaluation of HH criteria

  23. Section 303(d) of the CWA requires states to identify streams that do not meet WQ standards streams that do not meet water quality standards are referred to as being “water quality limited” Oregon has more than 1,000 stream segment listed on the 303 (d) list Looking Ahead…TMDLs

  24. General TMDL Process WQStandardsAchieved ProtectiveWQ CriteriaEstablished Beneficial Uses Designated WQ Monitored Develop TMDLs Implement Controls WQLimited

  25. What is a TMDL? TMDL = Sum (WLA) + Sum (LA) + MOS Where: WLA =waste load allocations (point-sources) LA = load allocations (non-point sources) MOS = margin of safety (background, factor for uncertainty, future growth)

  26. Schedule for TMDL development

  27. TMDLs and Local Limits • Most streams listed for temperature, DO, pH, nutrients • Unlikely to affect local limits issues • Some exceptions • Mercury listing in Willamette River • Arsenic listing in Lower Columbia River

  28. TMDLs and Local Limits • Hg: point source contributions being debated • If TMDL includes WLA, may need to revise local limits • Will likely see more listings for toxic pollutants in the future

  29. Wasteload allocation Developing local limits for pollutants with WLAs Industrial Domestic Headworks Commercial

  30. Why should you be involved in TMDL process? • If your facility discharges to a stream that is WQL, DEQ will be developing a TMDL • Could result in stricter limits • May require significant capital expenditures • To give a reality test to the assumptions and approaches used by DEQ

  31. Opportunities to get involved in TMDL development • TMDL process typically takes 2 - 4 years depending on the complexity of the basin. • Many opportunities to get involved • Steering committees • Data collection • Model selection/calibration • Draft TMDL review

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