Risk Based Corrective Action

1. Risk Based Corrective Action Using site-specific risk assessment to achieve Regulatory Closure

2. Manage Risk at Sites • Identify levels of exposure • Assess if level of exposure is acceptable: • “Risk Characterization” • Change level of exposure if risk is unacceptable: • Reduce concentration, reduce exposure, eliminate exposure

3. What is Risk Assessment? A tool that supplies information about risks to human or ecological “receptors” due to exposure to identified hazards Use it to focus remediation on identified risks or to demonstrate NFA Relies on environmental media data, site use, fate and transport, and toxicological information

4. What is Risk Assessment?

5. The House is Only as Good as the Foundation it is Built On Nature and extent of contamination (vertical and horizontal) must be characterized Site boundaries must be defined Data usability must be assessed and data must be adequate Current and future site activities and uses must be understood

6. Steps in a Human Health Risk Assessment Hazard Identification Exposure Assessment Toxicity Assessment Risk Characterization Uncertainty Analysis

7. Evaluate Key Risk Questions WHO? Is Exposed? Workers, future residents (children, adults) WHAT? Are they exposed to and at what concentrations? What are potential toxic effects? WHEN? Does exposure occur? Current site conditions? In the future? WHERE? Does exposure occur (Exposure point)? HOW? Does exposure occur and how often?

8. Example: Facility Worker

9. …To Produce Quantified Results Site Concentration Calculated Risk (4.3 x 10-4) CALCs Incremental cancer risk (e.g., 1/100,000, 1/1,000,000) Non-cancer risk (Hazard Quotient, relative to 1)

10. Risk-Based Decision Making Who: regulator, owner, client, consultant, buyer, neighbor What: risks from current and future land use When: now, near future, 30+ years

11. Risk-based Decision Making Where: on-site, off-site Why: regulatory, liability, business profile How: balanced consideration and weighting of factors within your control and/or influence

12. Making Risk-Based Decisions • Cost-benefit analysis • Risk-benefit analysis

13. Risk Management Applications Risk = f(Conc, Exposure, Toxicity) Which element can managed, and how?

14. Case Study #1: Human HealthCleanup goals for a Beach Area for Lead • Site is on Harbor area and includes numerous habitats and exposure points such as: - Harbor sediment and surface water - Beach area - Bike path - Upland area slated for residential development

17. Case Study 1 Cont. • Back calculated cleanup goals for a recreational receptor, (on the beach, jumping off a bridge, swimming), construction worker, utility workers • Lowest cleanup goal among three receptors was selected as remedial target • Guided remediation by removing maximum location and calculated residual mean (EPC) until achieved target • Mapped remedial areas based on this: Regulators reviewed this approach and approved it

19. Derivation of Risk-Based Concentration - Lead

20. Derivation of Risk-Based Concentration – Ratio Formula Risk-Based Cleanup Level = Concentration in media = X Associated risk level Target risk level 3892 = X 2.8 1 X = 1390

22. Risk Management • Site specific action levels and compliance points result in targeted remediation • Be creative in application of various remedial approaches • Consider partial closure strategies • Time sequencing/prioritizing cleanup efforts

23. Case Study 2: EcologicalMonitored Natural Recovery for Cadmium in Reservoir • Exceedance of AWQC for Cd but Comprehensive Ecological Risk Characterization says No Significant Risk • SW concs > AWQC but all the other lines of evidence said it is not a risk; considered this as part of Feasibility study • Correlated SW and Sediment data, used a regression equation to target what sediment concentration in sediment would give an allowable SW value

28. Risk Management • Although exceeded AWQC, ERC indicated NSR • Risk for implementing “active” remediation outweighed benefits • Future assessment of MNR processes reduce exposure and risk with minimal disruption

29. Case Study #3 - Risk Management Approaches for PCBs Can use risk-based approach to gain flexibility in sampling, soil management, response actions and disposal Consider use of exposure mitigation rather than remediation Can “mix and match” Self Implementing (SIP) and Risk-based Approaches

30. PCB Case Study for TSCA & State SuperfundSite Former record manufacturing facility that included vehicle maintenance Current use as offices (corporate headquarters) LNAPL with elevated PCB concentrations (>260 mg/L) identified

31. PCB Case Study Cont. Comprehensive characterization of soils outside of and below building footprint Sediments and groundwater also evaluated Soil concentrations up to 570 mg/kg No clear gradient from suspected sources (waste oil USTS) due to redevelopment

32. PCB Case Study Cont. • Approach combined SIP and Risk-based closure • Outside of Building: • Deed restriction for “low occupancy” • Used either 25 ppm or 100 ppm with clean soil cap • Building Footprint: • Deed restriction for Commercial/Industrial use and maintenance of slab • Used Risk Assessment to show residual concentrations (up to 350 ppm) posed NSR

33. Overall Themes Must satisfy regulatory requirements Client goals and needs Flexibility and choices Risk balancing Creative conservatism