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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

PCBs in San Francisco Bay Area Municipal Wastewater Effluents

Donald Yee*, Jon Leatherbarrow, Jay Davis

study participants
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

why measure pcbs in effluent
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
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

SB/FS Sampling CB Sampling
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

SPE Sampling (SB/FS) FB Sampling (CB)
pcbs in effluent first event sb fs
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
sampling issues remedies sb fs
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)
pcbs in effluent all events sb fs
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]
analytical variability sb fs
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
analytical issues and remedies sb fs
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)
pcbs in effluent cb
PCBs in Effluent (CB)
  • SFEI/POTW staff collected 4 L grabs
  • No sample splits
  • Replicate sample
sampling analytical variability cb
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%
summary
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
what next
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
slide15
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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