Connecticut Remediation Criteria: Technical Support Document Proposed Revisions to the Connecticut Remediation Standard Regulations

Transcription

1 Connecticut Remediation Criteria: Technical Support Document 2008 Proposed Revisions to the Connecticut Remediation Standard Regulations Connecticut Department of Environmental Protection Bureau of Water Protection and Land Reuse October 20, 2008

2 Table of Contents Overview Proposed Revisions to Connecticut Remediation Criteria Chemical Constituents Human Health Risk-based Remediation Criteria Updated Toxicity Information Exposed Populations Childhood Exposure Concerns Analytical Achievability Ceiling Concentrations Other Considerations Evaluation of Proposed Changes to Criteria Contained in the Remediation Standard Regulations Soil Criteria: Direct Exposure Criteria Soil Criteria: Pollutant Mobility Criteria Groundwater Criteria: Groundwater Protection Criteria Groundwater Criteria: Surface Water Protection Criteria Groundwater and Soil Vapor Criteria: Volatilization Criteria List of Figures Appendix A: Appendix B: Appendix C: Appendix D: Chemical Characteristics Table A1: Chemical Constants Table A2: Bioconcentration Factors Toxicity Data Table B1: Oral Toxicity Values Table B2: Inhalation Toxicity Values Table B3: Mutagenic Substances Toxicological Monographs Direct Exposure Criteria Table D1: Residential DEC Formulas Table D2: Residential DEC Calculation Table

3 Table D3: Residential DEC Comparison Table Table D4: Industrial/Commercial DEC Formulas Table D5: Industrial/Commercial DEC Calculation Table Table D6: Industrial/Commercial DEC Comparison Table Appendix E: Appendix F: Appendix G: Appendix H: Pollutant Mobility Criteria Table E1: GA Areas Formulas Table E2: GA Areas Calculation Table Table E3: GA Areas Comparison Table Table E4: GB Areas Formulas Table E5: GB Areas Calculation Table Table E6: GB Areas Comparison Table Groundwater Protection Criteria Table F1: Formulas Table F2: Calculation Table Table F3: Comparison Table Connecticut Tier 2 Aquatic Life Criteria Surface Water Protection Criteria Table H1: Aquatic Life Water Quality Benchmarks based on Criteria Established in Accordance with Great Lakes Water Quality Initiative Table H2: Chronic Aquatic Life Water Quality Benchmarks Table H3: Formulas for Calculating Human Health Based Water Quality Benchmarks Table H4: Calculation of Human Health Water Quality Benchmarks Table H5: Calculation of Surface Water Protection Criteria Table H6: Surface Water Protection Criteria: Comparison of Current Criteria to Proposed Criteria

4 Appendix I: Appendix J: Target Indoor Air Concentrations Table I1: Residential Formulas Table I2: Residential Calculation Table I3: Residential Comparison Table I4: Industrial/Commercial Formulas Table I5: Industrial/Commercial Calculation Table I6: Industrial/Commercial Comparison Volatilization Criteria Table J1: Volatilization Criteria Formulas Table J2: Residential Groundwater Vol. Criteria Calculation Table J3: Residential Groundwater Vol. Criteria Comparison Table J4: Industrial/Commercial Groundwater Vol. Criteria Calculation Table J5: Industrial/Commercial Groundwater Vol. Criteria Comparison Table J6: Residential Soil Vapor Vol. Criteria Calculation Table J7: Residential Soil Vapor Vol. Criteria Comparison Table J8: Industrial/Commercial Soil Vapor Vol. Criteria Calculation Table J9: Industrial/Commercial Soil Vapor Vol. Criteria Comparison Appendix K: Appendix L: Appendix M: Appendix N: 2003 Proposed Revisions: Connecticut Remediation Standard Regulation s Volatilization Criteria. Ceiling Concentrations Additional Conditions for Management of Clean Fill Bibliography

5 Overview: In 1996, the Connecticut Department of Environmental Protection (CTDEP) promulgated the Remediation Standard Regulations (RSRs) that establish the requirements for the remediation of contamination within the State. The regulations are organized by environmental media and rely, in part, on riskbased criteria that establish acceptable concentrations of contaminants at remediation sites. Numerical criteria for 88 compounds were established for soil, groundwater, and soil vapor. (Figure 1) Criteria for sediment were addressed on a case-by-case basis. Criteria for surface water were not included since impacts to surface waters are addressed through the control on contaminants in the various media, typically groundwater or sediment, which could cause or contribute to any exceedances of the Connecticut Water Quality Standards and Criteria. Figure 1 Remediation criteria were established using a process that considered risks to exposed populations, achievable analytical levels, and policy concerns such as general ambient concentrations for certain common constituents and ceiling concentrations to prevent excessive contamination from being left in place. Provisions were also included to allow for site-specific modifications to existing criteria or the development of remediation criteria for substances not included in the 1996 regulations. Proposed revisions to the RSRs include a comprehensive update of the criteria contained in the regulations. Each component in the derivation of the proposed remedial criteria was evaluated and updated as necessary. (Figure 2) As such, any changes to criteria for substances currently in the regulations are a

6 result of one or more changes in the derivation of the value, such as changes in toxicity values, calculation methods or updated analytical values, and not typically dependent solely upon a change in any single input into the derivation process. Updating the criteria was a joint effort of the CTDEP and the Connecticut Department of Public Health (CTDPH). The Environmental and Occupational Health Assessment Section of CTDPH updated toxicity values and risk-based models as described below. CTDPH Analytical Services staff assisted with the evaluation of the risk-based cleanup targets in terms of achievable analytical levels. CTDEP calculated the criteria in accordance with CTDPH specifications and adjusted the criteria, as necessary, to address policy considerations, ceiling concentrations, and analytical achievability.

7 Figure 2 Remediation Criteria Decision Tree: Calculate Risk Based Criterion Compare Ceiling Value Analytical Level Policy Determination Selection Process: 1. If risk based criterion is higher than ceiling value, criterion value is lowered to ceiling concentration 2. If risk based criterion is not achievable using standard laboratory practices, criterion value is raised to the analytical level that would be achievable. 3. In all cases, policy determination supersedes all other determinations Final Criterion

8 Proposed Revisions to Connecticut Remediation Criteria Chemical Constituents The list of chemical constituents for which criteria are proposed within these revisions has been expanded to include 122 additional chemicals, for a total of 210 chemicals included in the proposed regulations. (Figures 3 & 4) These chemicals typically have been the subject of requests to the CTDEP for additional remediation criteria based on their presence at active remediation sites within Connecticut. Inclusion of these chemical within the regulations will provide remedial endpoints for self-implementation at other sites within the state where these substances may be found, eliminating the need for the development of criteria for these substances on a case-by-case basis. Figure 3

9 Figure 4 Human Health Risk-based Remediation Criteria Standard risk assessment practices are used to calculate health-protective concentrations of chemicals in the various media. These calculations take into account which groups of people could be exposed to the contamination including sensitive populations, the degree of exposure to the various media and the toxicity of each substance. Updated Toxicity Information: The toxicity information for each chemical was updated from the values used in Updated toxicity values were obtained from several sources and selected to reflect the most current understanding of the toxicology for each substance. (Figure 5) Values from United States Environmental Protection Agency (USEPA) Integrated Risk Information System (IRIS) database, California Environmental Protection Agency, the Agency for Toxic Substances and Disease Registry (ATSDR) of the United States Department of Health and Human Services, USEPA Superfund Health Effects Assessment Summary Tables (HEAST) and other derivations by USEPA program offices were considered. In a few cases where toxicology evaluations were not available from national sources, assessments were conducted by the Connecticut Department of Public Health. While USEPA s IRIS database has traditionally been thought of as the primary source of toxicity information for risk assessment, it has not been updated on a regular basis and there are numerous cases where other sources have more current assessments for particular chemicals. Therefore, a rigid hierarchy of

10 source information was not established for toxicity values; rather a chemicalspecific determination was made for each substance as to the most current and robust source. Non-cancer toxicity values take into account major uncertainties and gaps in a chemical s database, including uncertainties regarding potential carcinogenicity. In certain cases, these uncertainties warranted modification of a toxicity value available on IRIS or elsewhere. Additional information in support of toxicity values used to calculate risk-based cleanup targets is presented in Appendices B and C. Figure 5 For substances with criteria in the current regulations, changes to the toxicity values may result in a calculated risk-based criterion that is either more or less restrictive than the current criterion contained in the regulations. The magnitude and degree of change will depend upon the nature of the change to the toxicity value (indicating a greater or lesser degree of toxicity) as well as any other changes in the calculation of the proposed criteria values. Exposed Populations: Remediation criteria have been established for two typical exposure groups: people within residential settings and those in an industrial/commercial setting. Within a residential setting, both adults and children may be present and are, therefore, included in the criteria calculations. It is assumed that within an industrial/commercial setting, only working adults are the population of concern. These general exposure scenarios have not been changed from the existing regulations.

11 Childhood Exposure Concerns: Children are recognized as a sensitive population when establishing health-protective remedial criteria. In general, children have a greater rate of exposure to contaminants than do adults because children drink more water, ingest more soil and inhale more air per body weight than adults. (Figure 6) Also, children are more sensitive to the toxic effects of certain types of chemicals, such as mutagenic carcinogens, than are adults. Mutagens are chemicals that can interact with and cause changes to genetic material. The current regulations explicitly include consideration of exposure of children to soil, as expressed in the Residential Direct Exposure Criteria. Additionally, the changes to the Volatilization Criteria drafted in 2003 included, for residential settings, both a consideration of increased exposure rates for children as well as recognizing their increased sensitivity to certain carcinogens. Figure 6 Much work has been conducted on a national level since the regulations were originally established to understand the vulnerability of children to chemical contaminants. Many scientific and technical papers have been published and federal guidance issued. These sources were reviewed and considered in updating the inclusion of children s health issues in the calculation of risk-based remediation criteria for residential settings, including direct exposure to soil and volatilization criteria. Risk equations for the derivation of these criteria have defined exposure rates for children consistent with current EPA guidance. One key factor in determining the proper exposure rate is the age of the child, a determination that is made in relation to windows of vulnerability during childhood. For example, the most critical period for exposure to carcinogens occurs within the first two years of life (EPA 2005; Barton, et al. 2005). Children are growing and developing at

12 an accelerated rate within this period and are more susceptible to having genetic damage be converted into cancer (Ginsberg, 2003). Therefore, the exposure period for children used in the risk-based equations for carcinogenic substances is set at 2 years, a change from that used in the current Direct Exposure Criteria but consistent with the changes proposed to the Volatilization Criteria in For non-carcinogens, there is no uniform window of increased vulnerability, as this will vary depending upon the chemical s toxic mechanism of action. Instead, the risk-based calculations rely upon USEPA s determination of the Minimal Chronic Exposure Period as 10% of a person s lifespan or 7 years (USEPA, 2002A). This Minimal Chronic Exposure Period is taken as the first 7 years of life to ensure that children s higher exposure rates are captured in the regulations. Current residential Direct Exposure Criteria assumes a 6 year exposure period. No change is proposed to this exposure period since it closely approximates the Minimal Chronic Exposure Period recommended by EPA. This exposure period is also used for the derivation of residential volatilization criteria for non-carcinogens. In addition to adjusting exposure estimates for children, toxicity concerns were also evaluated. For noncarcinogenic substances, the use of the Reference Dose without any modification for children remains appropriate in the general case and no changes have been proposed to address the incorporation of toxicity estimates for noncarcinogens. However, as described above, children can be more sensitive to carcinogenic substances, as animal studies with vinyl chloride and a variety of other carcinogens show that brief exposures early in life can lead to an equivalent cancer risk as chronic exposure beginning during adulthood (USEPA, IRIS file for Vinyl Chloride, 2000; Ginsberg, 2003, Barton, et al. 2005). The cancer slope factor, the estimate of potency for carcinogenic substances, is therefore provided equal weight for early life exposures as adult exposures, without pro-rating or averaging such exposures over a lifetime, which would underestimate potential effects on children. Although the data are limited, it appears that non-mutagenic carcinogens are less potent in this regard as the early life vulnerability period is less important for total lifetime cancer risk than with mutagenic agents. Therefore, the childhood cancer slope factor is modified by dividing the adult value by 8 to reflect this difference as reported in the scientific literature (Hattis, et al. 2004).

13 Figure 7 Updating the residential criteria for direct exposure and volatilization in this manner will provide protection to children consistent with current scientific understanding of early life vulnerabilities. These changes will not affect Direct Exposure calculations for noncarcinogens since the current equations are still appropriate and remain unchanged. For carcinogenic substances, the calculated risk-based values for mutagens and nonmutagens will decrease by factors of 9.26 and 1.41, respectively. For Residential Target Indoor Air Concentrations, which support the derivation of residential volatilization criteria, the calculated risk-based values for carcinogens (mutagens and nonmutagens) will decrease by factors of 5.1 and 1.5, respectively. These changes may or may not translate to a direct change in the criteria due to the consideration of other factors such as changing toxicity values, analytical levels or policy considerations. Analytical Achievability: All risk-based criteria have been reviewed, with the assistance of CT DPH Analytical Laboratory personnel, to determine whether the resulting concentrations for each constituent could be reliably quantified using Connecticut Reasonable Confidence Protocols, or equivalent procedures, and approved laboratory analytical methods. Adjustments to criteria based on analytical achievability were made when necessary and based on standard laboratory practices such as EPA Contract Laboratory Program requirements and allowable analytical modifications for performance-based analytical methods. Note: It is expected that actual quantification levels for each analysis will be established consistent with Connecticut Reasonable Confidence Protocols (CTDEP 2007),

14 and will be able to achieve quantification at or below the concentrations in the proposed revisions to the remediation criteria values. Ceiling Concentrations: In order to prevent excessive contamination from being left in place, upper limits on the acceptable concentration for remediation criteria have been retained for use in establishing remediation criteria. In the 1996 RSRs, ceiling concentrations were established for Direct Exposure Criteria and Groundwater Volatilization Criteria. In 2003, proposed revisions the Volatilization Criteria also introduced a ceiling concentration for Target Indoor Air Concentrations. These ceiling values are proposed for continued use and additional values are proposed (Figure 8). Figure 8 Other Considerations: While the goal of the RSRs is to develop health protective, risk-based criteria, it is recognized that there are cases in which other factors other than risk calculations may govern the establishment of a particular criterion. These factors were used in the derivation of the 1996 RSR criteria and are being carried forward into the draft 2008 values. General Ambient Concentrations: For values that are below general ambient environmental concentrations in Connecticut, the criteria in the table are adjusted up from the risk-based value to one consistent with estimated Connecticut-based conditions. Examples include soil criteria

15 Arsenic and certain Polynuclear Aromatic Hydrocarbons as well as expected indoor air concentration for certain volatiles. Consistency with Federal Regulatory Programs: Criteria for Polychlorinated Biphenyls are established consistent with federal regulatory requirements. Evaluation of Proposed Changes to Criteria Contained in the Remediation Standard Regulations The proposed revisions to the regulations contain criteria for soil, groundwater and soil vapor. New types of criteria or criteria for any additional media type have not been proposed within these revisions. Criteria for remediation of polluted sediment will still be handled on a case-by-case basis and further guidance developed by the Department to address concerns regarding sediment contamination. While the types of criteria within the proposed revisions are consistent with those in the existing regulations, some changes have been proposed in the calculation of certain criteria types. The various types of criteria are reviewed below and any proposed changes highlighted. Soil Criteria: Direct Exposure Criteria Direct Exposure Criteria are designed to establish health-protective concentrations of constituents in soil assuming that people may be exposed to such chemicals through incidental ingestion of soil. As in the current regulations, two exposure scenarios are considered, residential exposures which include the potential exposure of both adults and children and exposures in industrial/commercial settings which include working adult populations. Proposed Changes: While the current Direct Exposure Criteria for Residential Settings include an explicit consideration of children in the calculation of risk-based remedial standards, the equations for calculating risk-based criteria for carcinogens have been updated to reflect the new scientific understanding regarding exposure scenarios and toxicology for children. In particular: The critical exposure period for children exposed to carcinogens is currently considered by the scientific community to be between the ages of 0-2 years. In the calculations within the existing regulations, an exposure period of 0-6 years is used. Therefore, the equations used to derive residential risk-based direct exposure criteria have

16 been modified to reflect this change. In the new equations, the exposure duration for children exposed to carcinogens is 2 years. Childhood and adult exposures are not pro-rated but are considered two equally important exposure periods for carcinogenesis. The risk-based criteria for residential exposures in the existing regulations do not distinguish between mutagenic and non-mutagenic carcinogens. The equations proposed within the current revisions to the regulations have been updated to explicitly address the difference in toxicological response in children to these two broad groups of carcinogens. Specifically, in the equation for non-mutagenic carcinogens the early-life cancer potency factor is reduced 8-fold in accordance with the information obtained from cancer studies in juvenile animals. Cancer potency factors for mutagenic carcinogens are used without modification for both children and adults within the equations for these substances. The current regulations incorporate ceiling values for volatile and semivolatile substances. These values have been retained and ceiling values for metals and pesticides proposed. Summary of Proposed Criteria: Residential Direct Exposure Criteria Residential Direct Exposure Criteria have been proposed for 198 substances. The majority of the criteria are established using risk-based calculations with criteria set based on ceiling values or current criteria to a lesser decree. Analytical adjustments only account for a small portion of the proposed values. (Figure 9)

17 Figure 9 Residential Direct Exposure Criteria Basis 12% 5% 1996 RSRs Analytical Adjustment 57% 26% Ceiling Risk-based Value The existing regulations currently have Residential Direct Exposure Criteria for 87 substances. The proposed criteria for these substances were compared with the current criteria. Approximately one third of the criteria are proposed to remain unchanged while slightly more than one half have been proposed to decrease, leaving a smaller group where criteria will increase. (Figure 10) The number of criteria that are proposed to decrease by a greater amount (50% or more) is approximately one third of the total number of substances and similar to the number of chemicals for which criteria will remain unchanged. Criteria are proposed to increase substantially (50% or more) for just under 10% of the total number of substances. (Figure 11) Figure 10 Proposed Residential Direct Exposure Criteria Comparison with Current Criteria 14% 34% Increase Decrease No Change 52%

18 Figure 11 Proposed Residential Direct Exposure Criteria Comparison with Current Criteria # Substances <=5% 6-10% 11-25% 26-50% % >100% No Change New Criteria Increase Decrease No Change New Criteria % Change Industrial/Commercial Direct Exposure Criteria Industrial/Commercial Direct Exposure Criteria are proposed for 198 chemicals. Criteria based on risk calculations or set at ceiling values account for 87% of the proposed values with the number of criteria similar for each of these categories. A much smaller percentage of the criteria are based on current regulations or analytical adjustments. (Figure 12) Figure 12

19 The proposed criteria for the 87 substances that currently have Industrial/Commercial Direct Exposure Criteria in the existing regulations were evaluated to determine the magnitude of proposed changes. No change in criteria is proposed for more than half of these substances with proposed increases or decreases approximately equally divided between the remaining substances. (Figure 13) A limited number of substances were proposed to have significant increases or decreases in criteria values (50% or more change), representing 11% and 15%, respectively of the 87 substances originially included in the regulations. (Figure 14) Figure 13 Proposed Industrial Commercial Direct Exposure Criteria Comparison with Current Criteria 20% Increase 59% 21% Decrease No Change Figure14 Proposed Industrial Commercial Direct Exposure Criteria Comparison with Current Criteria # Substances >100% % 26-50% 11-25% 6-10% <=5% No Change 0 New Criteria No Change New Criteria Decrease Increase % Change

20 Soil Criteria: Pollutant Mobility Criteria The Connecticut Water Quality Standards establish designated uses for the Connecticut s groundwater resources. For GA groundwaters, designated uses include, but are not limited to, drinking water resources and baseflow for hydraulically-connected surface water bodies. For GB groundwaters, provision of drinking water is not a designated use but baseflow for hydraulically-connected surface water bodies remains a concern. For both groundwater classifications, the groundwater must support other existing uses and must not pose a threat to public safety or public health. It is assumed that substances in soil may leach from the soil and enter groundwater. The pollutant mobility criteria are designed to establish environmentally protective concentrations of substances in soil that would support the attainment and maintenance of these designated uses for groundwater at remediation sites. Proposed Changes: The current Pollutant Mobility Criteria are based on protecting groundwater as a drinking water resource in GA areas, using the Groundwater Protection Criteria as the basis for the calculation of the criteria. In GB areas, the criteria are intended to prevent unacceptable impacts to groundwater resources and also use the Groundwater Protection Criteria with the addition of a dilution factor to establish the criteria for GB areas. This paradigm is not entirely consistent with the Water Quality Standards given that there are other designated uses for groundwater in GA areas and drinking water protection is not appropriate for the majority of GB areas. The proposed Pollutant Mobility Criteria are more closely tied to supporting the designated uses for groundwater established in the Connecticut Water Quality Standards. GA Pollutant Mobility Criteria are based on the lesser of the Groundwater Protection Criteria (for drinking water protection), Surface Water Protection (for protection of surface water resources) and Residential Groundwater Volatilization Criteria (for additional protection of public health). The proposed GB Pollutant Mobility Criteria are based on the lesser of the Surface Water Protection Criteria and the Residential Groundwater Volatilization Criteria. A dilution factor of 10 is used to modify the Surface Water Protection Criteria, approximating the default dilution of on-site groundwater to establish consistency with the Surface Water Protection Criteria at the property boundary. (Figure 15)

21 Figure 15 Calculation of Pollutant Mobility Criteria: Calculation of Pollutant Mobility Criteria Groundwater Protection Criteria (GA Areas Only) Surface Water Protection Criteria x 10 Residential Groundwater Volatilization Criteria Compare & Select Lowest Value Lowest Risk Based Value Analytical Level Policy Determination Selection Process: Criteria are set equal to the lowest risk based value except: 1. If risk based criterion is lower than analytical level, criterion value is raised to analytical level 2. In all cases, policy determination supersedes all values Final Criterion

22 Summary of Proposed Criteria: GA Pollutant Mobility Criteria Pollutant Mobility Criteria for GA areas have been proposed for 202 substances and are primarily based on the Groundwater Protection Criteria. For almost 90% of the substances, the Groundwater Protection Criteria represent the controlling risk-based value selected for use in criteria derivation. In some cases, while the proposed criteria were based on the Groundwater Protection Criteria, it was necessary to adjust the values for analytical considerations. (Figure 16) Figure 16 In the current regulations there are GA Pollutant Mobility Criteria for 86 chemicals. The proposed criteria for these substances were evaluated to determine the magnitude of proposed changes. Since the proposed values are predominantly derived using the Groundwater Protection Criteria, the basis for the existing GA Pollutant Mobility Criteria, many of the proposed criteria are not different from existing criteria. The proposed criteria have decreased for slightly for more than one third of the substances while the criteria are proposed to increase for a smaller portion of the group. (Figure 17) Criteria for 35 of the 86 substances are proposed to change by more than 50%; criteria for 27 will decrease and criteria for 8 will increase. Criteria for 7 of these substances will increase by more than 100%. (Figure 18)

23 Figure 17 Figure 18 GB PMC GB Pollutant Mobility Criteria have been proposed for 196 substances. For the majority, slightly more than two thirds, the criteria are based on the Surface Water Protection Criteria. Slightly less than one third are based on the Residential Groundwater Volatilization Criteria. (Figure 19)

24 Figure 19 In the current regulations, GB Pollutant Mobility Criteria are established for 86 substances. While these values are based on 10 times the Groundwater Protection Criteria, the majority of the proposed values are based on 10 times the Surface Water Protection Criteria. This results in an increase in the criteria for more than half of the substances. Criteria for slightly more than one third of the substances decrease with the criteria for a smaller number of substances remaining the same. (Figure 20) For 86% of the substances, the changes in criteria are substantial. Values for 30 substances decrease by 50% or more but values for 34 substances increase by more than 100%. (Figure 21) Figure 20

25 Figure 21 Groundwater Criteria: Groundwater Protection Criteria Groundwater Protection Criteria are designed to establish healthprotective concentrations for constituents in groundwater assuming that people use the groundwater as a drinking water resource. The criteria are modeled upon the risk-based assumptions used to derive federal drinking water standards. These standards focus on the exposure of adults to potential constituents in drinking water. Proposed Changes: The equations used to derive Groundwater Protection Criteria have not been modified from those used in the current regulations. Toxicity values and analytical considerations have been updated. A ceiling value of 1,000 ug/l to limit excessive environmental exposures has been proposed for use in deriving Groundwater Protection Criteria. Summary of Proposed Criteria: Groundwater Protection Criteria have been proposed for 203 substances. The majority of the criteria are established using risk-based calculations with criteria set based on Federal drinking water standards (Maximum Contaminant Levels, MCLs) or analytical adjustments to a lesser degree. Ceiling values are the proposed basis for less than 10% of the substances. Current remediation

26 criteria or Action Levels, drinking water values for private wells as set by CTDPH, account for a small portion of the proposed values. (Figure 22) Figure 22 Groundwater Protection Criteria Basis 0% 5% 4% 41% 15% 9% 1996 RSRs Action Level Analytical Adjustment Ceiling Value MCL Risk-based Calculation Taste/Odor 26% The existing regulations have Groundwater Protection Criteria for 87 substances. The proposed criteria for these substances were compared with the current criteria. For the majority of the substances, no change has been proposed in the criteria. The criteria for one quarter of the substances are proposed to decrease while more than 15% of the criteria are proposed to increase. (Figure 23) For 16 of the 87 substances, the criteria are proposed to decrease by more than 50% while for 10 of the 87 substances, the criteria are proposed to increase by more than 50%. (Figure 24) Figure 23 Proposed Groundwater Protection Criteria Comparison with Current Criteria 25% Decrease 59% 16% Increase No Change

27 Figure 24 Proposed Groundwater Protection Criteria Comparison with Current Criteria # Substances <=5% 6-10% 11-25% 26-50% % No Change 0 New Criteria Decrease Increase No Change New Criteria % Change Groundwater Criteria: Surface Water Protection Criteria Surface Water Protection Criteria are criteria, applicable to groundwater, designed to prevent unacceptable impacts to surface waters and the people and aquatic communities that use this resource. As in the current regulations, Surface Water Protection Criteria are established using water quality criteria for surface water bodies, including Ambient Water Quality Criteria for the Protection of Human Health, which assumes that fish may be caught and consumed from the surface water body, and also Ambient Water Quality Criteria for the Protection of Aquatic Life from chronic toxic impacts. These values are established in accordance with EPA procedures and consistent with the Connecticut Water Quality Standards. Proposed Changes: No changes to the derivation of the human health based water quality criteria have been proposed. As in the current regulations, these values are derived using the equations and assumptions published in 1980 by the U.S. Environmental Protection Agency in the Federal Register (45 FR 79318) and are consistent with current Connecticut Water Quality Standards. Bioconcentration Factors used in the calculation of water quality criteria protective of human health were obtained from individual documents for water quality criteria for individual chemicals published by the EPA (see EPA 2008 for individual references) or were derived using structure activity relationships based on the octanol/water partition coefficient for each chemical. Octanol/water partition coefficients were

28 obtained from the ChemIDplus database (US National Library of Medicine 2007). Bioconcentration Factors were calculated using the BCFwin module (Meylan et al 1999) of the USEPA Estimation Programs Interface Suite software (USEPA 2007a). Human health based surface water criteria are designed for application at longer duration flows than standard low flow conditions, such as the 7-day-10 year flow statistic used to represent low flow conditions in freshwater streams. EPA recommends the use of the 30-day-5-year flow rate for non-carcinogenic substances and the mean harmonic flow, a 70 year average flow, for carcinogenic substances (EPA 1994), to better correspond to the exposure periods associated with the various types of toxicity estimates. These streamflow flow rates are greater than 7Q10 flows. Flow factors of 2 and 3 are used to approximate the increase in these design flows over 7Q10 flows. As in the current regulations, human health criteria are adjusted using these flow factors to allow application of the criteria at low flow conditions. Aquatic life based surface water criteria are selected from available current ambient water quality criteria established by CTDEP (CTDEP 2002) or EPA (USEPA 2008). Aquatic Life Criteria presented in these sources were derived using the procedures developed in 1985 by the USEPA (USEPA, 1985) For substances for which a chronic aquatic water quality criteria was not available from these sources or other USEPA sources, water quality benchmarks for aquatic life were obtained using the Tier 2 procedures established in the Water Quality Guidance for the Great lakes System (USEPA 1995). Tier 2 criteria were either derived by CTDEP using the USEPA 1995 protocols or were obtained from other states that had used this protocol (EPA 2008). Such criteria derived by CTDEP utilized aquatic toxicity information available from the USEPA EcoTox Database (EPA 2007) and are presented in Appendix H to this document. If sufficient toxicity information was not available using the EcoTox database, Tier 2 criteria were derived using the toxicity information presented in Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision (Suter and Tsao 1996). Criteria values were recalculated consistent with the adopted Tier 2 procedures. The use of Tier 2 Water Quality Criteria to support the derivation of the Surface Water Protection Criteria is a new proposal. Using this approach to obtaining water quality criteria or benchmarks to support Surface Water Protection Criteria derivation expanded the number of substances for which aquatic life values were available. Of the water quality benchmarks proposed for use, the majority of the values were obtained using Tier 2 procedures.

29 Figure 25 As in the current regulations, the final proposed Surface Water Protection Criteria are set based on the lower of the chronic aquatic life water quality benchmark and the flow adjusted human health water quality value. A default dilution factor of 10 is applied to complete the criteria calculation. A ceiling value of 10 mg/l was established for Surface Water Protection Criteria, a new component for criteria derivation. Summary of Proposed Criteria The proposed regulations have Surface Water Protection Criteria for 197 substances. The majority of the criteria are based on the aquatic life benchmark, with human health water quality benchmarks and ceiling values responsible for lesser but approximately equal percentages of values. (Figure 26) Figure26

30 The current regulations have Surface Water Protection Criteria for 62 substances. The proposed criteria for these substances were compared with the current criteria. The majority of proposed criteria are lower than the current criteria while approximately one third of the values increase. (Figure 27) Only a small portion of the values remain the same. The criteria for 29 of the substances decrease by a factor more than 50% while the criteria for 16 substances increase by more than 100%. (Figure 28) Surface Water Protection Criteria Figure 27 Figure 28

31 Volatilization Criteria Substances from releases may be located under structures. For volatile compounds, these substances may migrate from groundwater or soil vapor beneath a building into that structure. The volatilization criteria are healthprotective concentrations for volatile substances in these media designed to insure that any volatilization of substances into overlying structures is protective of potential exposures to building occupants. The criteria are derived using riskbased estimates of health protective concentrations of substances in indoor air. These values are then applied to a fate and transport model to derive associated environmental concentrations in groundwater and soil vapor consistent with the Target Indoor Air concentrations. A detailed discussion of the fate and transport model can be found in the Proposed Revisions: Connecticut Remediation Standard Regulation s Volatilization Criteria (CTDEP 2003) and provided as Appendix K to the document. Proposed Changes The current proposed changes to the Volatilization Criteria incorporate the changes as proposed in the CTDEP 2003 draft update of the volatilization criteria. Specifically, 1) the criteria have been calculated using an updated fate and transport model, the Johnson and Ettinger (1991) model, incorporating its extensions developed in 1998 and 1999 (Johnson et al and Johnson et al. 1999); 2) for residential scenarios, child-specifc exposure rates and vulnerability to carcinogens are explicitly included; and 3) a ceiling concentration is adopted for Target Indoor Air Concentrations. Toxicity values, chemical-specific estimates such as Henry s Law Constants and analytical considerations have been updated within the current criteria proposal. Additionally, the exposure frequency for residential exposures has been updated to be consistent with the residential exposures assumed for Direct Exposure Criteria and Groundwater Protection Criteria calculation. The exposure frequency currently used in the calculation of Target Indoor Air Concentrations for residential settings is 350 days/year. The proposal is based on an exposure frequency of 365 days/year for residential settings. In the current proposal, the equations incorporating child-specific considerations are stated in a manner, using Children s Vulnerability Factors, consistent with current proposal for incorporating children s health considerations into the Residential Direct Exposure Criteria. The form of the equation is, therefore, changed from the 2003 proposal, but there is no change in the assumptions used for incorporating children s health concerns. Finally, a definition of volatile substances is included in the proposed regulations to identify which substances are considered volatile for the purposes of the Volatilization Criteria. Volatile substances have been defined as any substance with Molecular Weight < 200 AMU and a Henry s Law Constant > atm-m 3 /mole (EPA 1991a). This has resulted in some changes to the list of volatile chemicals. Two chemicals, Bromoform and Dibromochloromethane, previously included in the

32 calculation of Volatilization Criteria are no longer considered sufficiently volatile to warrant criteria derivation. Other chemicals not previously considered volatile are now considered volatile and criteria have been derived. These chemicals are listed below. Additionally, the units used to express the soil vapor volatilization criteria have been changed from ppm to ug/cubic meter to be consistent with the units used by analytical laboratories to report data for soil vapor concentrations. The change in the units should streamline evaluation and interpretation of soil vapor data. However, due to the change in units, the proposed soil vapor volatilization criteria are not directly comparable to the current criteria. Tables have been provided in Appendix J which express the proposed criteria using the units consistent with the current criteria as well as the proposed new units and thus allow for comparison of current and proposed values. Chemicals in Current RSRs without Volatilization Criteria but now considered volatile Acenaphthylene Acrylonitrile Anthracene Bis(2-chloroethyl)ether 2-Chlorophenol cis-1,2-dicholoroethylene trans-1,2-dichloroethylene Fluorene Naphthalene Phenanthrene Polychlorinated Biphenyls Summary of Proposed Criteria Target Indoor Air Concentrations Target Indoor Air Concentrations have been proposed for 78 volatile substances. The majority of the values are based on risk-based calculations. Other considerations such are ceiling values and background considerations form the basis of only a small portion of the proposed values. (Figure 29)

33 Figure 29 The current regulations contain Residential Target Indoor Air Concentrations for 34 substances while the 2003 proposed revisions addressed 47 substances. The current proposed values were compared separately to the current and 2003 criteria. In general, most of the values decrease when compared to the current values. (Figures 30 & 31) This is likely due to the changes in criteria calculation methodologies, updated toxicity values and updated physical constants. There are fewer differences in values when compared to the proposed 2003 concentrations, which use similar methodologies to derive the criteria. (Figure 32 & 33) However, changes to exposure estimations and updated toxicity values and physical constants provide for differences between 2003 draft values and the current proposal.

34 Figure 30 Figure 31

35 Figure 32 Figure 33

36 Industrial Commercial Target Indoor Air Concentrations for Industrial/Commercial settings have been proposed for 78 substances. More than half of the values are based on risk calculation but slightly more than one quarter of the values are derived using ceiling concentrations. (Figure 34) Comparison with the 1996 values show that the criteria for similar numbers of substances increase as decrease. Of those substances for which the criteria is proposed to change by more than 50%, criteria for 13 substances decrease while criteria for 10 increase. (Figures 35 & 36) When compared with the 2003 proposed values, criteria for 15 of the 47 substances are not proposed to change. Of the remaining substances from 2003, more criteria are proposed to decrease than increase. (Figures 37 & 38) Figure 34

37 Figure 35 Figure 36

38 Figure 37 Figure 38

39 Groundwater Volatilization Criteria - Residential Groundwater Volatilization Criteria for residential settings have been proposed for 77 substances. The majority of the criteria are derived using risk based calculations. (Figure 39) When compared with either the current or 2003 values, most of the criteria are proposed to decrease due to the changes in the Target Indoor Air Concentrations. (Figures 40 43) Figure 39 Figure 40

40 Figure 41 Figure 42

41 Figure 43 Groundwater Volatilization Criteria Industrial/Commercial Groundwater Volatilization Criteria for industrial/commercial settings have been proposed for 77 substances. The majority of the criteria are derived using risk based calculations. (Figure 44) As with the proposed criteria for residential settings, when the current proposed values are compared to existing RSR criteria or the values proposed in 2003, the criteria for more substances decrease rather than increase, reflecting changes in the Target Indoor Air Concentrations. (Figures 45 48) Figure 44 Basis for Proposed Industrial Commercial Groundwater Volatilization Criteria 4% 19% 2003 Draft Volatilization Criteria Ceiling Value Risk-based Calculation 77%

42 Figure 45 Figure 46

43 Figure 48 Figure 47

44 Soil Vapor Volatilization Criteria Soil Vapor Volatilization Criteria have been proposed for 77 substances. The majority of the criteria are derived using risk based calculations followed by values set using ceiling concentrations. (Figure 49 & 54) When the current proposed values are compared to existing RSR criteria, the criteria for more substances decrease rather than increase. (Figures 50, & 56) When the current proposed values are compared to the 2003 proposed values, criteria for a similar number of substances increase as decrease. (Figures 52, 53, 57 & 58) Figure 49

45 Figure 51 Figure 50

46 Figure 53 Figure 52

47 Figure 54 Figure 55

48 Figure 56 Figure 57

49 Figure 58