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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 Effluents

  • 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? Effluents

  • 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 Effluents

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 Effluents

+ 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) Effluents

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) Effluents

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) Effluents

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) Effluents

  • 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) Effluents

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) Effluents

  • SFEI/POTW staff collected 4 L grabs

  • No sample splits

  • Replicate sample


Sampling analytical variability cb
Sampling & Analytical Variability (CB) Effluents

  • 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 Effluents

  • 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? Effluents

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


Pcbs in san francisco bay area municipal wastewater effluents
Next Effluents

  • 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