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RISK-BASED APPROACH TO CLEANUP. Presented by: Jere “Trey” Hess, P.E. MS Brownfields Program Coordinator. What is a Brownfield?. Any property with real or perceived contamination; Remediation is necessary; Has redevelopment potential; Limited Use; and
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RISK-BASED APPROACH TO CLEANUP Presented by: Jere “Trey” Hess, P.E. MS Brownfields Program Coordinator
What is a Brownfield? • Any property with real or perceived contamination; • Remediation is necessary; • Has redevelopment potential; • Limited Use; and • Liability concerns and financial risk exist.
Background • Mississippi Brownfields Voluntary Cleanup and Redevelopment Act (1998) • Offers LIABILITY PROTECTION; • Allowed MDEQ to develop and implement a RISK-BASED remediation program; • Currently, does not include financial incentives like some other States.
LIABILITY PROTECTION • Once a property has been remediated to the satisfaction of MDEQ, MDEQ will not require further remediation in the future. • Needed assurance for: • Prospective purchasers • Lenders • Developers • It is similar to having an INSPECTION of a home before buying it and then having it repaired.
Site Characterization • Similar to the Home Inspection • The planning, sampling, analysis, and reporting that results in a three dimensional delineation of contamination at the Site. • A COMPLETE Site Characterization should result in the development of soil and groundwater plume maps.
What is a“Risk-Based”Site Evaluation? • The Traditional Site Evaluation of contaminant exposure has been driven by the actual or POTENTIAL on-site residential receptor (i.e., future day-care facility) • A Risk-Based Site Evaluation takes into account land use and engineering controls which may be used to reduce or eliminate exposure to contaminants or risk.
Introduction to the Brownfields Tiered Approach • The cornerstone of the Brownfields Program is a three-tiered risk-based process for evaluating human health and environmental risks. • Land use restrictions and engineering controls play integral roles in the three-tiered approach by reducing or eliminating the potential for exposure to contaminants and risk.
TIER 1 - Look-up Table • The highest concentration of each contaminant in each media (soil and groundwater) is compared to the values in the Tier 1 TRG Table. • The values in the Tier 1 TRG Table can either be used as DEFAULT remediation goals or as a screening tool that will trigger a Tier 2 Evaluation.
TIER 2 OPTIONS • Statistical Methods • Site Background • Regionally Prevalent Chemicals • Site-Specific Data • Eliminate/Minimize Exposure Routes • TPH Fractioning • Other Approved Methods
TIER 2 OPTIONS • Statistical Methods • The Upper Confidence Level (UCL) of the Mean concentration is compared to the Tier 1 TRG instead of the highest concentration. UCL of the Mean Mean Concentration Highest Concentration
TIER 2 OPTIONS • The background concentration can be used instead of the Tier 1 TRG level. • Must be statistically valid (typically, lognormal) • Must be collected from “clean” locations; • Locations must approved by MDEQ; and • Must be collected in a manner consistent with EPA Guidance. • Site Background • Naturally occurring chemical concentrations
TIER 2 OPTIONS • Regionally Prevalent Chemicals • Example: Arsenic in the Delta Region as a result of aerial application (crop dusting). • The regionally prevalent chemical concentration can be used instead of the Tier 1 TRG level in most cases. • Must follow the same criteria as described for background concentrations.
TIER 2 OPTIONS • Site-Specific Variables • Site-specific variables can be used to calculate “Site-specific” Remediation Goals • Examples: • exposure duration, • moisture content, • Porosity • Use the “Site-specific” Remediation Goals instead of the Tier 1 TRG levels.
TIER 2 OPTIONS • Eliminate/Minimize Exposure Routes • Institutional Controls and Engineering Controls can be used provided: • All complete exposure pathways eliminated; or • Contamination exposure is minimized to levels that will be protective to human health and the environment. • Example: • Engineering Control –Parking lot that CAPS contamination • Institutional Controls – Deed Notice and Brownfield Agreement • Contamination must remain confined within site boundaries and monitoring may be necessary.
TIER 2 OPTIONS • TPH Fractioning • Primarily utilized in cases where indicator constituent concentrations cannot be determined due to dilution and/or interference. • Massachusetts Method • Compare TRGs for six (6) Hydrocarbon Ranges • http://www.state.ma.us/dep/bwsc/vph_eph.htm • Other Approved Methods
TIER 2 OPTIONS • Other Approved Methods • Risk-Based Corrective Action (RBCA) • “EPA Mega-Rule” Risk Evaluation for PCBs • Illinois TACO Program • EPA Soil Screening Guidance Document Procedures
TIER 3 Risk Assessment • SITE-SPECIFIC RISK ASSESSMENT • Human Health Risk Assessment • Ecological Risk Assessment • Should be based on current EPA risk assessment guidance • Risk Assessment Guidance for Superfund (RAGS)
More Information • Internet Address: • http://www.brownfields.ms • MDEQ Contacts: • Trey Hess - Brownfields Program Coordinator • (601) 961-5654 • email: Trey_Hess@deq.state.ms.us • Jerry Banks - Hazardous Waste Division Chief • (601) 961-5221 • email: Jerry_Banks@deq.state.ms.us