Transcript ITRC’s Internet Training on Risk Assessment - CLU-IN

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ITRC’s Use of Risk Assessment in Management of
Contaminated Sites (RISK-2, 2008)
ITRC Risk-2 Training Course Supplement:
Use of Risk Assessment in Management
of Contaminated Sites
Five Retrospective
Case Studies
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Module 2 Learning Objectives

Risk assessment (RA) & Risk management (RM)
is a balancing act among:
•
•
•
•
•
“Players”
Communication
Data
Iteration
Variation
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Module 2 Learning Objectives
Risk assessment (RA) & Risk management (RM)
is a balancing act among:
Time
Money
Stakeholders
Cleanup
Data analysis
Certainty
Acceptable
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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
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Five Case Study Sites
Evergreen, WA
LUST Site, WI
Whitebridge, CA
Grand Street, NJ
Spring Valley,
WDC
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Case Study 1 – Evergreen, WA

Army to redevelop firing range for military housing

Active military base
Berm
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Triad Approach Investigation

Real time field data … for Risk Assessment(!)
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Portable X-Ray Fluorescence (XRF)
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Determined extent of area sampled
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Validated by 10% laboratory analyses
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Lead Characterization Goals
50 mg/kg
XRF lead detection limit
WA screening level for ecological assessment
250 mg/kg
WA human health screening level
IEUBK output
400 mg/kg
USEPA Region 9 screening level (PRG)
1,000 mg/kg
Hazardous waste screening level
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Cleanup Goal

No site-specific risk assessment
Impact Berm
Evergreen Avenue

Screening level = Cleanup goal

Impacted berm area only
remedial action candidate
Pyros
Side Berm
Pyros
Gun Gun Gun Gun
Command Island
(Not Drawn to Scale)
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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
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Summary 1 – Evergreen, WA

Triad Approach + Field data in Risk Assessment
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Background [Pb] < Screening level

RA/RM Balancing Act:
Limited time/More remedial effort
vs. higher screening and cleanup level
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Screening level = Cleanup Goal

Statistical approach to remedial criteria
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Case Study 2 – Whitebridge, CA


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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
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Risk Assessment – Three Tiers
Excess
Cancer
Risk
Excess Cancer
Excess
CancerRisk
Risk
1.0E-03
1.0E-03
Orchard
Orchard
Remote
RemoteFill
Fill
1.0E-04
1.0E-04
1.0E-05
1.0E-05
1.0E-06
1.0E-06
Tier1.
1.
Tier
1.
Screening
Screening
Screening
Tier2.
2.
Tier
2.
Deterministic
Deterministic
Deterministic
Tier3.
3.
Tier
3.
Probabilistic
Probabilistic
Probabilistic
Risk
RiskAssessment
Assessment
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Summary 2 – Whitebridge, CA

RA/RM Balancing Act:
Minimal soil removal vs. Risk analysis effort
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3 Tiered Iterative approach:
• Preliminary & Site-specific risk assessment  Risk Potential
• Probabilistic modeling  Reduced areas of concern & COCs
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Clear communication of goals
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Contaminated soil 
Roadway fill
Onsite deed-restricted containment cell
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Case Study 3 – LUST site, WI
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Operating gasoline station
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Release discovered during tank system replacement
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Benzene primary COC
with 13 mg/kg soil
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Case Study 3 – LUST Site, WI
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Benzene concentration exceeded
Direct-contact
(WI )
[Inhalation & ingestion] (USEPA SSG calculator)
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“Hot spot” beneath dispenser  Barrier cover
(2 ft clean soil)

Institutional control to prevent direct-contact exposure
“Detailed closure letter”
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Summary 3 – LUST Site, WI
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Soil sampling
• Contamination extent and magnitude
• Not systematic
• Not supportive of risk assessment
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RA/RM Balancing Act:
Limited soil data vs. Desire for case closure
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Single “Hot spot” drove management
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LUST sites Risk Assessment
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Case Study 4 – Spring Valley, DC
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Formerly Utilized Defense Site (FUDS), during World War I
Chemical warfare research and testing:
mustard, lewisite agents, adamsite, irritants, and smoke
Long established residents
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Phase I Investigation
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1921: Area restored,
owners reclaim property, redeveloped
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1993: Buried ordinance found
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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)
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Phase II: Uncertainty Management with
Different Sampling Strategies
Adjacent Area
Active Area
House
House
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Numerical Criteria
Arsenic
Concentration
Source and Use
0.43 mg/kg
EPA Region 3 residential risk-based concentration;
Initial site screening; ; 10-6 cancer risk
12.6 mg/kg
Site-specific statistical ‘background.’
Screening level triggering additional sampling
20 mg/kg
Risk-informed management goal Soil removal
43 mg/kg
Remedial goal with home owner approval to
preserve landscape features; 10-4 cancer risk
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Summary 4 – Spring Valley, DC
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Existing residents
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Background [As]
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Different sampling strategies for
management of different levels of uncertainty
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RA/RM Balancing Act:
 Screening level
Among “Players”, Communication,
Risk assessment, and Risk management
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Case Study 5 – Grand Street, NJ
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> 50 years Mercury gas-lamp & connector-switch production
Peter Cooper-Hewitt, 1902
“ the economy of operation
[of a mercury gas light
in contrast to an ordinary incandescent lamp]
will much more than compensate for the
somewhat unnatural colour given to illuminated
objects. "
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Exposure to Building Residents
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5-story former

industrial building
16 residences/studios
(1993-1995)

15/16 conversions completed prior to ID of site-wide
Hg contamination in flooring, porous wood, and brick.
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Residents relocated (1996)
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Urine analysis found 20 residents (inc. 5 children) with
Hg levels of concern for neuro- and hepatotoxicity

Superfund site
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Different Criteria
Criteria
EPA Region II
NJDEP
Site Remediation
Baseline HH RA Required
(Human Health Risk Assessment)
Yes
No
1x10-4 - 1x10-6
1x10-6
1
1
Yes
No
Typically 0-2’
for residential
“to a clean zone”
regardless of depth
Discrete vs. Composite
Surficial Sampling
Both
Discrete only
Grid or Biased Sampling
Either (Gridded)
Biased only
Risk Range - Carcinogen
Hazard Index - Noncarcinogen
Surface vs. Subsurface
Distinction
Depth of Delineation (RDC)
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Sampling, Goals, and Remediation
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Surficial soil cleanup goal = 23 mg/kg Hg (2003)
Soil ingestion + protective of inhalation
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Subsurface soil cleanup goal = 520 mg/kg Hg (2004)
Protective of utility workers
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Remediation = demolition, excavation,
and off-site disposal of contaminated
soil and building debris
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Summary 5 – Grand Street, NJ
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RA/RM Balancing Act:
Two regulatory authorities (USEPA and NJDEP )
Two set of criteria
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Acute hazard
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Remediation = demolition
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Redevelopment
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Summary Table 1 – Site Information
Site
Whitebridge,
CA
COC
Pesticides
Acres
Former Land Use
Future Land
Use
184
Commercial orchard
Residential
(future)
LUST Site,
WI
Benzene
0.70
Gasoline station
(currently operating)
Industrial
(ongoing)
Grand Street,
NJ
Mercury
0.34
Hg gas-lamp +
switch manufacture
Residential
(current)
Lead
4
US Army firing range
Residential
(future)
Evergreen,
WA
Spring Valley,
DC
Arsenic
USDOD chemical
0.25 warfare testing
Residential
(current)
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Summary Table 2 – Risk Assessment
Site
Risk Assessment
Whitebridge,
CA
• 3 Tiers (Preliminary, Deterministic, and Probabilistic)
LUST Site,
WI
• 1 Tier (No site-specific RA. Screening Level = Cleanup Level)
• State & USEPA risk-based screening values.
Grand Street, • 2 Tiers
• Both USEPA R2 and NJDEP criteria
NJ
Evergreen,
WA
• 1 Tier (No site-specific RA. Screening Level = Cleanup Level.)
• Triad. Statistical criteria.
Spring Valley, • 2 Tiers
• Integrated into risk management. Community participation.
DC
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Summary Table 3 – Risk Management
Site
Risk Management
Whitebridge,
CA
Developer + PRA  Limited soil excavation (and costs)
LUST Site,
WI
Hot spot beneath dispenser closed in place with barrier.
Detailed closure letter with land-use limitation
Grand Street, Demolition, excavation and off-site disposal .
New residential development planned.
NJ
Evergreen,
WA
Quick reuse desire balanced with soil management.
Soil excavation balanced by RA
Spring
Valley, DC
Integrated into risk assessment.
Community participation
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Conclusions

Risk assessment and risk management balancing act
• Players
• Iteration
• Data
• Communication
• Variation
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Programmatic and
Technical rationale  Variation

Transparency is important
“Everyone is on board!!”
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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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