Module 2 Learning Objectives Risk assessment



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Module 2 Learning Objectives

  • Risk assessment (RA) & Risk management (RM)

  • is a balancing act among:

    • “Players”
    • Communication
    • Data
    • Iteration
    • Variation


Module 2 Learning Objectives

  • Risk assessment (RA) & Risk management (RM)

  • is a balancing act among:



Case Study Features

  • Actual sites retrospectively evaluated

    • Site background
    • Sampling and data use
    • Risk-related information
  • “Simple” sites selected to elucidate key variables

  • NOT reanalysis or effort to “fix” these cases



Five Case Study Sites

  • Evergreen, WA



Case Study 1 – Evergreen, WA



Triad Approach Investigation

  • Real time field data … for Risk Assessment(!)

  • Portable X-Ray Fluorescence (XRF)

  • Determined extent of area sampled

  • Validated by 10% laboratory analyses



Lead Characterization Goals



Cleanup Goal

  • No site-specific risk assessment

  • Screening level = Cleanup goal

  • Impacted berm area only remedial action candidate



Statistical Criteria for Remedial Success

  • No excavation area with Pb sample >500 mg/kg

  • Entire site 95% UCL Pb < 250 mg/kg

  • ≤ 10% of samples Pb > 250 mg/kg

  • Entire site meet criteria for all contaminants



Summary 1 – Evergreen, WA



Case Study 2 – Whitebridge, CA

  • Former commercial orchard (1930’s to 1980’s) proposed for residential redevelopment

  • Eight COPCs: Lead, arsenic, dieldrin, DDT, DDE, endosulfan, sulfate, and endrin aldehyde.

  • Developer wanted minimal soil removal

  • to meet septic system requirements



Risk Assessment – Three Tiers



Summary 2 – Whitebridge, CA

  • RA/RM Balancing Act: Minimal soil removal vs. Risk analysis effort

  • 3 Tiered Iterative approach:

    • Preliminary & Site-specific risk assessment  Risk Potential
    • Probabilistic modeling  Reduced areas of concern & COCs
  • Clear communication of goals

  • Contaminated soil  Roadway fill Onsite deed-restricted containment cell



Case Study 3 – LUST site, WI



Case Study 3 – LUST Site, WI

  • Benzene concentration exceeded

    • Direct-contact (WI )
    • [Inhalation & ingestion] (USEPA SSG calculator)
  • “Hot spot” beneath dispenser  Barrier cover (2 ft clean soil)

  • Institutional control to prevent direct-contact exposure

  • “Detailed closure letter”



Summary 3 – LUST Site, WI

  • Soil sampling

    • Contamination extent and magnitude
    • Not systematic
    • Not supportive of risk assessment
  • RA/RM Balancing Act:

  • Limited soil data vs. Desire for case closure

  • Single “Hot spot” drove management

  • LUST sites Risk Assessment



Case Study 4 – Spring Valley, DC

  • Formerly Utilized Defense Site (FUDS), during World War I

  • Chemical warfare research and testing:

  • mustard, lewisite agents, adamsite, irritants, and smoke

  • Long established residents



Phase I Investigation

  • 1921: Area restored,

  • owners reclaim property, redeveloped

  • 1993: Buried ordinance found

  • 1993 to 1995: Phase I:

  • ID areas of concern

  • Biased grab samples

  • Background samples  12.6 mg/kg (95th percentile)

  • Arsenic (As) contaminant of potential concern (COPC)



Phase II: Uncertainty Management with Different Sampling Strategies



Numerical Criteria



Summary 4 – Spring Valley, DC



Case Study 5 – Grand Street, NJ



Exposure to Building Residents

  • 5-story former  16 residences/studios

  • industrial building (1993-1995)

  • 15/16 conversions completed prior to ID of site-wide

  • Hg contamination in flooring, porous wood, and brick.

  • Residents relocated (1996)

  • Urine analysis found 20 residents (inc. 5 children) with

  • Hg levels of concern for neuro- and hepatotoxicity

  • Superfund site



Different Criteria



Sampling, Goals, and Remediation

  • Surficial soil cleanup goal = 23 mg/kg Hg (2003) Soil ingestion + protective of inhalation

  • Subsurface soil cleanup goal = 520 mg/kg Hg (2004) Protective of utility workers

  • Remediation = demolition, excavation, and off-site disposal of contaminated soil and building debris



Summary 5 – Grand Street, NJ

  • RA/RM Balancing Act:

  • Two regulatory authorities (USEPA and NJDEP )

  • Two set of criteria

  • Acute hazard

  • Remediation = demolition

  • Redevelopment



Summary Table 1 – Site Information



Summary Table 2 – Risk Assessment



Summary Table 3 – Risk Management



Conclusions

  • Risk assessment and risk management balancing act

    • Players
    • Iteration
    • Data
    • Communication
    • Variation
  • Programmatic and Technical rationale  Variation

  • Transparency is important



Thank You

  • Links to Additional Resources at

    • http://www.clu-in.org/conf/itrc/ risk2/resource.cfm
  • ITRC Risk Team’s Website

    • http://www.itrcweb.org/Risk
  • ITRC Risk Team’s Documents

    • http://www.itrcweb.org/ guidancedocument.asp?TID=44


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