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Local Limits Evaluation: A Case Study

Local Limits Evaluation: A Case Study. Pacific Northwest Pretreatment Conference September 2002 Robbin Finch Boise City Public Works. Outline. Background Regulatory Setting Study Design Data Collection/Analysis Data Review Summary/Conclusions. Background. Acknowledgements

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Local Limits Evaluation: A Case Study

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  1. Local Limits Evaluation: A Case Study Pacific Northwest Pretreatment Conference September 2002 Robbin Finch Boise City Public Works

  2. Outline • Background • Regulatory Setting • Study Design • Data Collection/Analysis • Data Review • Summary/Conclusions

  3. Background • Acknowledgements • Team product • City Staff (Lab, pretreatment, SAM, management, consultants) • Boise Facilities: • 2 WWTFs, Lander 15 MGD, West Boise 24 MGD • Boise River discharge, Ag reuse of biosolids • Boise River uses: • PCR, Cold water boita, Salmonid spawning

  4. Photos: Boise River / WWTF

  5. Background • Water Quality-based Facilities Plan (1991) • Identify current and future WQ issues • Lower Boise Watershed group initiated (1991) • Pollution Prevention (HHW/CESQG program) • $2.5 M Lab facility 1995-98 (Clean Metals) • SWQS involvement (1992-present) • Lower Boise Trading Pilot (1998-present) • TMDLs (Lower Boise 1998, SR-HC 2002) • NPDES permits (1991 reapplication, 1999 permits, WERs, clean metals, local limits) • 2002 P2 Strategy and Implementation

  6. Background • 1999 NPDES Permits • Appeal and settlement; additional studies • Final Metals limits (ug/l): Pb (2.2-6); Cu (8.8-21) • Schedule of Compliance, Pb 2 years, Cu 4+ yrs • Submit Local Limits Study (1 year from mod) • Characterize Commercial & Industrial (C&I) • Keymanhole Sampling • 9 metals +CN • Accelerated monitoring (Clean effluent, river) • City initiated Cu & Pb Water Effect Ratios(WERs)

  7. Photos: Clean metals, river, effluent, lab

  8. Background • Boise • 185,000 population • Rapidly growing, high tech industries, government, medical, financial, retail, education, residential • Serve 4 sewer districts, 2 small cities • Boise Industrial Users • 2.88 mgd industrial flow (10.8%, 19.7 LS, 2.1 WB) • 17 SUIs, 2 dairies, 2 GW remediation, 2 food processors, 1 powder coater, 10 Hi-tech (469/433) • 1,200 MIUs, 780 potentially metals bearing

  9. Regulatory Setting • Idaho not NPDES Delegated state • EPA issues NPDES permits • Metals a concern since 1979 • monitoring in 1980 permits • WET and In-stream studies 1987 permits • Boise Local Limits Program approved 1985 • Initial program had local limits for 9 metals + CN • Local Limits removed in 1990, no technical basis

  10. Regulatory Setting • Need for local limits • 52 Federal Register 23477, 23480 (June 22, 1987) • 40CFR 403.5(c)(1) • Each POTW with an approved pretreatment program shall develop [local] limits as necessary and effectively enforce such limits. • 40CFR 403.8(f)(4) • The POTW shall develop local limits as required in 403.5(c)(1) or demonstrate that they are not necessary

  11. Regulatory Setting • 1988 Pretreatment General Revisions • Although the intent of the provision, as clearly spelled out in the preamble, was to allow a POTW to make the finding that local limits are not needed, the regulatory language could more clearly reflect this intent. Therefore, today’s regulatory language incorporates the phrase, “or demonstrate that they are not necessary.” (53FR 40568, October 17, 1988)

  12. Regulatory Setting • General Rule Preamble 53 Fed Reg 40562 (October 17, 1988) • All POTWs must evaluate need for local limits and if needed, adopt and enforce them • POTW may rely on specific prohibitions and categorical standards in lieu of local limits if: • determines industrial pollutants not a problem; • has adequate resources and procedures for monitoring and enforcement of prohibited discharges and categorical standards • full compliance with categorical stds will meet objectives

  13. Study Design • Submit Local Limit Study w/in one year of permit modification • 9 metals + CN • Five Core Tasks • Workplan and SOPs (C&I, Keymanhole, LL Study) • Data Collection • Lab analyses • Data Analysis • Report production

  14. Study Design • Multiple Studies (summer 2000-fall 2001) • Accelerated river and effluent sampling for Cu&Pb; • Water Effects Ratio (WER) for Cu/Pb; • Key manhole monitoring (domestic background, 9 +CN); • Commercial and Industrial monitoring (MIUs, 9+CN); • Process monitoring and other (inf, eff, river background, biosolids, primary clarifier, recycle streams… 9 metals + CN). • Clean Techniques (collection & analysis)

  15. Data Collection • Commercial & Industrial Study • Design: statistical sampling of 780 potential metal MIUs, 20 comm/ind groups • 10% of potential metals MIUs (78 sites, 10-12 samples each) • Data generated: >7,000 • Analysis: 8 metals in house; CN and Hg contract lab

  16. Data Collection • Key manhole Study • Study Plan: representative samples from 8 water supply districts by age of subdivisions (old/new) • Included residential and commercial (non-metals MIUs) • 15 residential & 2 commercial sites, 21 samples each. Additional data collected from districts & cities • Data generated: >4000 • Analysis: 8 metals in house; CN and Hg contract lab

  17. Data Review • Resources: • Region 10 Local Limits Spreadsheet • 1987 Local Limits Guidance • EPA Draft Local Limits Development Guidance • Draft EPA Region 8 Local Limits Guidance

  18. Data Review • EPA Draft Local Limits Development Guidance, August 2001 • MAHL Approach to local limits • Determine POCs • Collect analyze data • Calculate MAHLs • Designate and Implement Local Limits

  19. Data Review • Guidance Highlights • 15 POCs: BOD, TSS, NH3-N, Mo, Se • Hauled Wastes included • Sampling frequencies for initial and annual review • Statistical methods and < data guidance • Need for Local Limits thresholds • average load >60% MAHL • daily load > 80% MAHL • Allocation options • Annual review

  20. Data Review • WER and Clean Metals data necessary for accurate analysis of water quality needs • Clean metals data necessary (Dissolved & TR) • associated data (H, CTs, CFs) • WERs: Cu: 2.578 Pb: 2.049 • WERs may be “self-implementing” • Alaska Rule Fed Reg V 65 N 82, p 24641-24653 April 27, 2000

  21. Data Review • Commercial and Industrial Results • Loads were low • Median discharges for MIUs + SIUs • < contributory flow for 4 POCs: CN(0%), Hg, Ag, Cu (7%) • = contributory flows for 2 POCs: Zn(11%) • > contributory flows for 4 POCs: Pb (14%), Cd, Ni, As, Cr (44%)

  22. Data Review • Compiled data and Calculated MAHLs • Influent, effluent, process data • Critical flow and mixing zone • Calculation of instream water quality criteria • WER Results (Copper: 2.578; Lead: 2.049) • 503/biosolids ceiling threshold • Literature/actual values for inhibition • % removal data

  23. Data Review • MAHL analysis • All average and daily below EPA threshold except daily Hg • Mercury is a special case, • Not an industrial discharge • Lower Boise River data show compliance with WQC • AMSA and other POTW data suggest low discharge • City initiated P2 Strategy and Implementation Project, Hg is a priority • City has met with State Dental Association on Hg issue and cooperative control program

  24. Report Conclusions • City has collected a robust clean data set • MAHL analysis shows no limits are necessary • Mercury control (P2/BMPs) needed • P2 Strategy and Implementation Project initiated • Residential and dental Mercury control already initiated

  25. Summary/Conclusions • Water Quality-based facility planning a great tool • Local Limits are important tool for POTWs • Regulations allow substantial flexibility • Clean Metals data and WERs are needed to correctly assess water quality needs • Mercury is a special case, BMP/P2 approach appears most effective

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