PCBs in San Francisco Bay Area Municipal Wastewater Effluents

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PCBs in San Francisco Bay Area Municipal
Wastewater Effluents

• Donald Yee, Jon Leatherbarrow, Jay Davis

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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

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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

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SB/FS Sampling CB Sampling

• 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

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SPE Sampling (SB/FS) FB Sampling (CB)

• 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

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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

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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)

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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 lt
  2x
• Plant differences generally insignificant
• Annual loads lt 0.1 kg/yr
• (mean flow x concentration

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Analytical Variability (SB/FS)

• Intra-lab replicate analyses of XAD2 extracts or
  blank spikes RSD lt 20
• Inter-lab splits of XAD2 extracts RSD 20-80
  (maxmin 1.5-9x)
• Average RSD 51 with Lab C, 33 without Lab C

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Analytical Issues and Remedies (SB/FS)

• Issues
• Inter-lab variability gtgt 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 _at_
  11 µg/L)

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PCBs in Effluent (CB)

• SFEI/POTW staff collected 4 L grabs
• No sample splits
• Replicate sample

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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 lt 5

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Summary

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

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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

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Next

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