Brian Hitchens and Sam Williams PCBs in the Urban Environment: Implications for Long-Term Sustainability Of Low-Threshold Remediation

Introduction PCBs – a problem of persistence and regulation Regional Background PCB Concentrations Current Sediment Regulatory Framework Case Study: Sand Cap Performance and Monitoring Implications for future sediment remediation/investigation

Ambient PCB Levels PCBs Production ceased 35 years ago (1977) Use in open systems banned in 1979 Currently found globally at low ambient levels: Air Concentrations 0.1 to 3 ng/m 3 Ocean/Great Lakes 0.02 to 6 ng/L Rain Water 0.1 to 20 ng/L Drinking Water 1 ng/L to 5 ng/L Antarctic Snow ng/kg

Levels of PCB Regulation FDA: 200 ug/kg in infant/children’s foods 2,000 ug/kg fish 3,000 ug/kg red meat/poultry 10,000 ug/kg food packaging EPA: 0.22 mg/kg - Residential Soil Screening Level (Region IX) 0.74 mg/kg - Commercial Soil Screening Level (Region IX) 0.5 ug/L - Drinking Water Sanitary Sewer Discharge: 3 ug/L California Drinking Water: ug/L California Surface Water: ug/L

California Bays and Estuaries Plan Establishes sediment quality objectives (SQOs) which are protective of benthic communities, resident finfish, and human health. Provides tools which will be used to assess ambient sediment quality (prescriptive adapted triad investigation approach). Regional Boards are implementing the SQO through investigative orders, where they may require SQO evaluations if there is even a suspicion that a release may have occurred.

Sediment Quality Objectives Only applicable in enclosed bays and estuaries Applied in 3 phases: – Protection of (benthic) aquatic life – Protection of human health – Protection of wildlife and resident finfish Narrative objectives currently developed for all 3 parts. – Prescriptive implementation requirements for benthic study. – Human health and wildlife assessment currently limited to site specific risk assessment, guidance underway. San Diego RWQCB is currently anticipating SQO evaluation at all outfalls throughout bay and proposing biannual evaluation for all MS4 discharges SQO (in a nutshell)

Benthic Community SQO A prescriptive Triad approach evaluating: – Sediment Toxicity – lab toxicity testing – Benthic Community Condition – (taxonomic counts) – Sediment Chemistry – Analytical Data Minimum of 5 station assessments required (~$50,000/station) Results compared to baseline index values applied to all of California – No Reference Stations Used SQO

Benthic Community SQO Prescriptive evaluation of results contains multiple iterations of averaging data and rounding up, making it very likely to find possible or likely impacted stations Possible impact leads to further stressor analyses to identify potential source of benthic community stress SQO continued

Sand Cap Case Study

Cap Layout THIN CAP

Cap Construction Impacted Sediments Gravel Sand Geotextile Layer

– After 10 years, Cap remains stable and has maintained it’s structure as designed. Min – 1.8’ Max – 3.1’ Mean – 2.8’

Post-Cap PCB Data (2007) ND<0.05 mg/kg 0.05 – 1.0 mg/kg 1.0 – 4.6 mg/kg 4.6 – 10 mg/kg 10 – 100 mg/kg Cap boundary

PCBs are identified throughout the off-site SWCS Detected in 75% of locations sampled Significant PCB contributions from surrounding “urban background” ~ 1 mg/kg average Is this characteristic of typical urban storm drain systems? Total PCBs (ppm) Non- Detect > 0.5t –

Background PCBs in Sediment Sediment from 162 catch basins surrounding San Francisco Bay Mean PCB concentrations (mg/kg): – Industrial: 4.45 – Residential/Commercial: 2.22 – Mixed Use: 0.72 – Open Space: 0.01 * Joint Storm Water Agency Project to Study Urban Sources of Mercury, PCBs, and Organochlorine Pesitcides. April 2002 (Kinnetic Labs Inc./EOA Inc.)

Sediment Remediation Goals for PCBs Very dependent on regulatory agency and area of the country EPA cleanups often have goals around 1 mg/kg SQOs identify moderate PCB concentrations as > mg/kg, high as > mg/kg California water boards begin with a background goal (non-detect) Economic and technical feasibility justification is required for any goal above background

Where is this headed? 1.Lots of sediment quality evaluations 2.Lots of sediment stressor analyses 3.Lots of arguing about background 4.Lots of dredging 5.Wait 10 years 6.Repeat step 1

How to get out of this loop 1.Improve understanding of the cause before treating the symptoms 2.Improve understanding of ecological uptake in environment to develop protective and maintainable goals 3.Prioritize sediment evaluation to focus on truly high concentration areas which will have meaningful, lasting affects on the environment 4.Use economic resources where the greatest environmental benefit can be gained