Module 2 Learning Objectives Risk assessment

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

• Soil ingestion
• Shallow soil contamination
• One to few chemicals of concern

• 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

• Operating gasoline station

• Release discovered during tank system replacement

• Benzene primary COC with 13 mg/kg soil

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

• > 50 years Mercury gas-lamp & connector-switch production

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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