Updates to HSRA Risk Reduction Standards

Transcription

1 Updates to HSRA Risk Reduction Standards Georgia AWMA Regulatory Update Conference May 11, 2017 Chris Saranko, Ph.D, DABT Atlanta, GA

2 Presentation Outline 2017 Hazardous Site Response Rulemaking Phased approach Initial phase focused on updates to (Risk Reduction Standards) Overview of EPD recommendations Implications Proposed timeline Chemical-specific issues Benzo(a)pyrene / PAHs Lead

3 Process Chart for the development of RRS (Rule )

4 Initial EPD Proposed Update Concepts (#1) (4) Essential Features of Corrective Action Modify vapor intrusion language Add clarification on when ecological risk assessment may be required at a site Note that features apply for all Acts that refer to risk reduction standards (RRS) (6)-(10) Criteria for Type 1 through 5 Standards Add language regarding the toxicity and chemical-specific parameter hierarchy (i.e., OSWER Directive and EPA s RSL Chemical-specific Parameters Summary table) Update the volatilization factor (Equation 8) and particulate emission factor equations * * * * * Update RAGS Equations 1,2, 7 and 8 consistent with EPA RSL risk equations (dermal exposure pathway, relative bioavailability, exposure time intervals) Remove language pertaining to Class C carcinogens assessed at target cancer risk. Allow use of chemical surrogates approved by EPD Allow site-specific soil bioavailability to be used in site-specific RRS calculations for arsenic If MCL established residential standard defaults to that value For site-specific soil RRS, allow site-wide averaging Redefine surface soil depth interval as 0-1 foot Clarify that Type 4 soil criteria should include consideration of subsurface workers For non-residential add flexibility for unique site-specific conditions such as rails-to-trails Omit Appendix III, Table 2 (metals) as part of the default RRS determinations For Type 1 leaching, replace the App. III, Table value with a default SSL. Add SPLP option.

5 Initial EPD Proposed Update Concepts (#2) Appendix III Table 1 - Update Groundwater Criteria Values, but retain as basis for Type 1 and 3 * Incorporate mutagenic age adjustment factors (for mutagenic carcinogens) Update the inhalation exposure pathway consistent with EPA s RAGS Part F Update exposure factors used in criteria calculations consistent with OSWER Directive (EPA 2014) Remove all a-flags and the associated footnote (detection limits) Indicate instances where criterion is based on a chemical surrogate Add additional common constituents of concern Appendix III Table 3 - Update Parameters, Definitions and Standard Assumptions * Update all exposure factors consistent with OSWER Directive (EPA 2014) * Add mutagenic age-dependent adjustment factors (for mutagenic carcinogens) Add dermal-related exposure factors for soil and groundwater Remove 10-4 target risk for Class C carcinogens Update PEF and VF equations listed consistent with EPA RSL calculations Include equation and default parameters for construction workers exposed to volatiles emanating from groundwater into a trench (VDEQ model) Miscellaneous Update Appendix IV to cite EPA s Adult Lead Model (instead of GA Lead Model) Correct Property Notice language [ (1)(a)] Add potential for Director to designate an EPA Removal Action as meeting Type 5 [ (7)] Minor corrections

6 Updates to RAGS Equations (#1) Current equations for direct contact exposure come from EPA s RAGS Part B (1991) Dermal pathway not considered Inhalation pathway calculations follow guidance that has been updated Example Equations: Groundwater carcinogens (Eq. 1) Soil non-carcinogens (Eq. 8)

7 Updates to RAGS Equations (#2) Updated equations will mirror those used by EPA to calculate the Regional Screening Levels (RSLs) Dermal pathway included Inhalation pathway follows RAGS Part F (EPA, 2009) Will EPD continue to calculate separate child and adult Type 2 RRS values for carcinogens, or use a time-weighted aggregate scenario according to EPA?

8 Updates to RAGS Equations (#3) RSL Residential GW Equation (carcinogens) Ingestion Inhalation Dermal

9 Mutagenic Adjustment Factors EPA uses age-dependent adjustment factors (ADAFs) to adjust the intake/exposure for carcinogens identified as acting via a mutagenic mode of action Current EPA mutagen list includes 16 chemicals, including: trichloroethylene, vinyl chloride, and benzo(a)pyrene ADAFs applied as multipliers to intake/exposure Children 0 < 2 years Children 2 to < 16 years Adults 16 and older 10x 3x 1x Result is an approximate 2.5-fold decrease in the calculated RRS values

10 Mutagenic Adjustment Factors (#2) RSL Residential GW Equation (mutagenic carcinogens) Ingestion Inhalation

11 Mutagenic Adjustment Factors (#3) RSL Residential GW Equation (mutagenic carcinogens) Dermal

12 Exposure Factor Updates Appendix III, Table 1 EPD recommends updating default exposure factors to mirror current EPA recommendations (OSWER , 2014) Adult body weight increases from 70 to 80 kg ( RRS) Residential exposure duration decreases from 30 to 26 years ( RRS) Changes to soil and water ingestion rates will depend on how EPD incorporates age-averaging (generally RRS)

13 Potential Effects of Changes (#1) Table below shows comparison of current HSRA Type 2 residential direct contact values compared to EPA default residential RSLs. Soil (mg/kg) Chemical Type 2 EPA RSL Chloroform Methylene Chloride Naphthalene Tetrachloroethylene Arsenic* Cadmium Type 2 EPA RSL MCL Chloroform Methylene Chloride Naphthalene Tetrachloroethylene Arsenic Cadmium Water (μg/l) Chemical

14 Potential Effects of Changes (#2) Table below shows comparison of current HSRA Type 4 industrial direct contact values compared to EPA default industrial RSLs. Soil (mg/kg) Chemical Type 4 EPA RSL Naphthalene Tetrachloroethylene Arsenic* Cadmium Chloroform Methylene Chloride

15 Rulemaking Timeline June 2017 Public Workshop August 5, 2017 Draft to Board of Natural Resources December 2017 Rule adoption

16 Chemical-Specific Issues (#1) Benzo(a)pyrene EPA s IRIS Program released final updated toxicity values in Jan 2017 Impacts to RSLs

17 Chemical-Specific Issues (#2) Lead EPA currently evaluating updates to IEUBK Model Driven by CDC s elimination of the childhood blood lead level of concern of 10 μg/dl in 2012 in favor of a reference level currently 10 μg/dl

18 Questions / Discussion Chris Saranko, PhD, DABT Geosyntec Consultants (678) csaranko@geosyntec.com