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PCBs in San Francisco Bay Area Municipal Wastewater Effluents

PCBs in San Francisco Bay Area Municipal Wastewater Effluents. Donald Yee*, Jon Leatherbarrow, Jay Davis. Study Participants. Fairfield Suisun*, Palo Alto, San Jose, Sunnyvale - (SB/FS) (~200 MGD) November 1999 – July 2000 CCCSD, CCSF, EBDA, EBMUD, Millbrae* - (CB)

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PCBs in San Francisco Bay Area Municipal Wastewater Effluents

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  1. PCBs in San Francisco Bay Area Municipal Wastewater Effluents Donald Yee*, Jon Leatherbarrow, Jay Davis

  2. Study Participants • Fairfield Suisun*, Palo Alto, San Jose, Sunnyvale - (SB/FS) (~200 MGD) November 1999 – July 2000 • CCCSD, CCSF, EBDA, EBMUD, Millbrae* - (CB) (~300 MGD) December 2000 – February 2001 Total SF Bay Area Municipal Effluents ~600 MGD * did not sample for all events

  3. Why measure PCBs in effluent? • Evaluate potential for impacts • Water quality (fish tissue) criterion (170 pg/L total PCBs) • Ambient water concentrations • Estimate loads to SF Estuary • Effluent potentially controllable pathway • Evaluate in context of other loads • Limited number of previous measurements • Restricted use since 1979, expect decline

  4. PCBs only 2 sampling events 1 Lab FB system 4 L filled bottle (amber narrow neck solvent bottle) Second bottle taken as backup/ blind duplicate PAHs, PCBs, pesticides, dioxins 4 sampling events Intercomparison of 2 labs collecting (first event) 3 labs analyzing (all 4 events) Infiltrex (SPE) system 400 L solid phase extraction Glass fiber filter in series w/ 250 g or 2x70 g XAD2 columns SB/FS Sampling CB Sampling

  5. Advantages/disadvantages + Ease of collection (=4kg) ± Quick grab sample – Higher detection limits Advantages/disadvantages + Ease of sample handling (400 L = 400 kg = hernia) + Lower detection limits ± Slow composite sample – Potential incomplete recovery SPE Sampling (SB/FS) FB Sampling (CB)

  6. PCBs in Effluent (First Event) (SB/FS) Sampling differences • Lab A – one 250 g column • Lab B – two 70 g columns (140 g total XAD2) • Lab A recovery average 25% higher than Lab B Analytical differences • Lab C no prior experience in SPE water matrix

  7. Sampling Issues & Remedies (SB/FS) Issue: Collection differences? • Different column sizes: larger column = greater retention Remedies • Columns to collect breakthrough (in series) • Recovery improved but still incomplete (1/2 + 1/4 + 1/8…) • Whole effluent/water analysis • To be used for select 2002 RMP water samples • Limited number of analytes (e.g. PCBs only)

  8. PCBs in Effluent (All Events) (SB/FS) Lab B collected samples • Sum of PCBs 120-320 pg/L (RMP average 600 pg/L) • Event differences generally insignificant and < 2x • Plant differences generally insignificant • Annual loads < 0.1 kg/yr • (mean flow x concentration]

  9. Analytical Variability (SB/FS) • Intra-lab replicate analyses of XAD2 extracts or blank spikes RSD < 20% • Inter-lab splits of XAD2 extracts RSD 20-80% (max:min = 1.5-9x) • Average RSD = 51% with Lab C, 33% without Lab C

  10. Analytical Issues and Remedies (SB/FS) Issues • Inter-lab variability >> intra-lab • Surrogate recovery handling (ECD vs MS) • Interferences, peak shifts Remedies • Intercalibration exercises • NIST (sediment, tissue) acceptable Z-scores ± 50% • ERA WP-83 (water) limits 30-150% (Aroclor 1242 @ 11 µg/L)

  11. PCBs in Effluent (CB) • SFEI/POTW staff collected 4 L grabs • No sample splits • Replicate sample

  12. Sampling & Analytical Variability (CB) • Samples from each event • ~2 month separation • Event flow differences up to ~2x • Sum PCBs RSD ~ 25% or less at a site • Blind replicate sample • ~10 minutes separation • Sum PCBs RSD < 5%

  13. Summary • Measurable PCBs in effluents • Sum PCBs 100-7900 pg/L • Municipal wastewater loads ~2 kg/yr • Small inter-season/event differences • Inter-lab >> intra-lab variability • Familiarity with particular matrix important • Need reliable lab and/or additional QA/QC

  14. What Next? Filling in PCB budget • PCBs in refinery effluent (underway) • Preliminary results - also small component of loads • Local tributary loads • (including stormwater) • Delta loads • Even more sensitive to accuracy/precision issues

  15. Next • Refined RMP sampling • Representative site selection • Improved measurement accuracy • Organics QA/QC workshop • Further the state of the art • @SFEI March 29, 2002 10am-3pm

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