Section R315-101-5 - Human Health and Ecological Risk Evaluation Criteria and Risk Assessment(a) When conducting the risk assessment, the responsible party shall use the conceptual site model, as defined in Subsection R315-101-13(o) and as described in Subsection R315-101-4(a)(3) or R315-101-4(f)(13), as applicable, and shall use applicable site characterization or confirmation data. For the areas of contamination as defined in Subsection R315-101-13(g), the following shall be included when conducting the risk assessment: (1) identification, concentration, and distribution of any suspected hazardous constituents identified in Section R315-101-4 and defined as contaminants of interest in Subsection R315-101-4(f)(8);(2) fate of contaminants of interest and any pathways and transport of contaminants of interest;(3) any potential exposure routes;(5) ecological receptors.(b) General Human Health Risk Assessment Methodology. (1) A risk assessment shall be conducted once the nature and extent of contamination has been adequately defined or corrective action completed. The risk assessment may be performed for impacted media by choosing either a Tier 1 approach in accordance with Subsection R315-101-5(f) or a Tier 2 risk assessment process in accordance with Subsection R315-101-5(g). Tier 1 shall be a screening risk assessment and Tier 2 shall be a refined risk assessment that may include site-specific exposure assumptions and allowance of alternative approaches, such as a Monte Carlo exposure risk analysis, probabilistic risk assessment. If excess risks are noted for the Tier 1 assessment, a Tier 2 assessment is required.(2) The concentration term for each medium and for each contaminant of interest identified in Section R315-101-4 and Subsection R315-101-4(f)(8) and determined to be a contaminant of potential concern following comparison to background shall be evaluated using either the maximum detected concentration or an upper confidence limit as derived using the US EPA ProUCL program.(3) The fate, pathways, and transport of contaminants of interest identified in Section R315-101-4, defined in Subsection R315-101-4(f)(8), and determined to be a contaminant of potential concern following comparison to background, shall be evaluated using the conceptual site model developed pursuant to Subsection R315-101-4(a)(3) or R315-101-4(f)(13), as applicable and approved by the director.(c) The exposure scenarios identified in the conceptual site model shall be estimated using reasonable maximum exposure parameters and shall be based on both current and potential future anticipated land use and receptors defined in Subsections R315-101-5(g)(1) and R315-101-5(g)(2).(d) The conceptual site model shall include a determination as to whether or not each of the following pathways is complete under both current and anticipated future conditions. Risks shall be quantified for those receptors where exposure pathways have a reasonable potential for being complete unless it may be demonstrated that the risk is less significant when compared to other quantified receptor risks. (1) Potential exposure pathways for surficial soils include: (i) leaching to groundwater;(ii) migration to a surface water body; and(iii) human exposure through ingestion of soil, dermal contact with soil, inhalation of vapors and particulates emitted by surficial soils.(2) Potential exposure pathways for subsurface soils include: (i) leaching or vapor migration, including sinking vapors, to groundwater;(ii) migration to a surface water body;(iii) volatilization and upward migration of vapors from subsurface soil and potential indoor or outdoor inhalation of these emissions; and(iv) human exposure through ingestion of soil, dermal contact, inhalation of vapors and particulates.(3) The soil exposure interval applicable to residents is defined as surface down to ten feet below ground surface. The soil exposure interval applicable to the industrial or commercial worker is defined as surface to one foot below ground surface. The soil exposure interval applicable to the construction worker is defined as surface down to depth of construction of ten feet below ground surface. Alternative soil exposure intervals shall be determined on a case-by-case basis as approved by the director.(4) Soil exposure pathways applicable to all receptors where the conceptual site model, in accordance with Subsection R315-101-4(a)(3) or R315-101-4(f)(13), identifies soil as a complete or potentially complete exposure pathway, shall include: (ii) dermal contact with soil;(iii) inhalation of vapor emissions; and(iv) inhalation of particulates from soil.(5) Groundwater exposure pathways applicable to all receptors where the conceptual site model, in accordance with Subsection R315-101-4(a)(3) or R315-101-4(f)(13), identifies groundwater as a complete or potentially complete exposure pathway, shall include:(ii) dermal contact with groundwater; and(iii) inhalation of vapor emissions.(6) Additional exposure to groundwater shall be considered on a site-specific basis which may include:(i) volatilization and upward migration of vapors from groundwater and potential indoor inhalation of vapor emissions;(ii) volatilization and upward migration of vapors from groundwater and potential outdoor inhalation of vapor emissions;(iii) potable use of groundwater, including ingestion of groundwater, dermal contact with groundwater during showering or bathing, and inhalation of vapors from domestic use of groundwater if pathway is complete; and(iv) migration to surface water body and potential impacts to surface water and potential exposures to surface water.(7) Other exposure pathways that may need to be considered on a site-specific basis may include the following: (i) contact with soils and ingestion of soils, sediments, inhalation of vapors and particulates, surface water and groundwater for any other anticipated human contacts, such as recreational and trespasser activities;(ii) ingestion of produce grown in impacted soils;(iii) use of groundwater for irrigation purposes;(iv) use of groundwater for industrial purposes;(v) ingestion of livestock or fish or other aquatic organisms that, as a result of media contamination, have bioaccumulated constituents of potential concern through the food chain; and(vi) ingestion, dermal contact, and inhalation of vapors from surface water such as from recreational activities, including swimming.(e) The responsible party shall develop a risk assessment work plan for review and approval by the director before the risk evaluation.(f) Tier 1 screening risk assessment. The Tier 1 evaluation shall assume no institutional or engineering controls in place, such as security, signage, pavements, personal protective equipment, fences, or remediation. The Tier 1 risk assessment evaluation may not be appropriate under circumstances when every complete exposure pathway is not covered by the screening values. The Tier 2 refined risk assessment approach may be more appropriate for evaluation in this circumstance.(1) Screening levels. The Tier 1 evaluation shall use one or more of the following screening levels: (i) US EPA Regional Screening Levels available at the US EPA Risk Assessment, Regional Screening Levels (RSLs) website;(ii) site-specific background 95% upper tolerance limit levels developed in accordance with the US EPA ProUCL model;(iii) vapor intrusion screening levels calculated using US EPA Vapor Intrusion Screening Level Calculator, as incorporated by reference in Section R315-101-12, available at the US E P A V a p o r Intrusion Screening Levels Calculator website;(iv) petroleum vapor intrusion screening guidelines developed in accordance with "Technical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites," US EPA, as incorporated by reference in Section R315-101-12;(v) site-specific confidence limits for groundwater background established for the site in accordance with "Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Unified Guidance," US EPA, as incorporated by reference in Section R315-101-12; or(vi) in instances where a US EPA Regional Screening Level is not available, a responsible party, with the approval of the director, may develop and calculate a site-specific screening value.(2)(i) The US EPA Regional Screening Levels, confidence limits, site-specific background levels, calculated site-specific screening values, and vapor intrusion screening levels shall be known collectively as screening values.(ii) Documents referenced in Subsections R315-101-5(f)(1)(i) through R315-101-5(f)(1)(vi) and other director approved sources shall be used as sources for obtaining screening values.(3) Determination of constituents of potential concern. (i) For inorganic contaminants of interest, the following steps shall be followed for determination of constituents of potential concern that shall be included in the risk evaluation. (A) The maximum detected concentration of each contaminant of interest for soil, sediment, and groundwater, or other site-specific media such as surface water, may be compared to the site-specific background reference level, defined as the 95% upper tolerance limit or a confidence limit. If the maximum detected site concentration is greater than the background reference level, the inorganic contaminants of interest shall be considered a constituent of potential concern. If site-specific background reference levels are not available, the detected inorganic contaminant shall be retained as a contaminant of potential concern.(B) For those inorganic contaminants of interest whose maximum concentrations are greater than the background reference, a test of means hypothesis shall be used to determine if inorganic contaminants of interest are present at elevated levels over background levels.(C) If the results of the test of means hypothesis indicate the detected inorganic contaminant of interest is elevated over background level, it will be retained as a constituent of potential concern.(D) If a test of means hypothesis cannot be performed due to sample size or if there is no established site-specific background reference level, the inorganic contaminant of interest shall be retained as a constituent of potential concern.(ii) For organic contaminants of interest, all contaminants with a minimum of one detection shall be retained as constituents of potential concern. If site-specific background reference levels are available for organics, additional refinement of organic contaminants of potential concern may be conducted in accordance with Subsection R315-101-5(f)(3)(i).(4) Exposure point concentration. (i) The initial exposure point concentration for all inorganic and organic constituents of potential concern shall be the maximum detected concentration for each medium evaluated in the Tier 1 assessment.(ii) If the maximum detected concentration results in a cancer risk greater than 1x10-6 or a hazard quotient greater than one, a refined exposure point concentration based on a 95% upper confidence limit on the mean may be calculated using the E P A ProUCL program. The lesser of the maximum concentration and the 95% upper confidence limit concentration shall be selected as the exposure point concentration.(iii) If the minimum required sample size of eight or more for calculating the 95% upper confidence limit cannot be met or there are insufficient numbers of detection, the maximum detected concentration, or an alternative concentration as approved by the director, shall be the exposure point concentration.(5) Cumulative risk shall be determined for all carcinogenic constituents of potential concern and a hazard index shall be determined for all noncarcinogenic contaminants of potential concern. (i) The cumulative effects screening cancer risk estimate is calculated as the sum of the ratios of exposure point concentrations and screening values for the combined land use exposure pathways, identified under the conceptual site model developed in accordance with Subsection R315-101-4(a)(3) or R315-101-4(f)(13) as applicable for impacted media, multiplied by 1x10-6.(ii) The hazard index is calculated as the sum of the ratios of exposure point concentrations and screening values for the combined residential land use exposure pathways identified under the conceptual site model in accordance with Subsection R315-101-4(a)(3) or R315-101-4(f)(13) as applicable for impacted media.(iii) If a contaminant of potential concern has both carcinogenic and non-carcinogenic toxicity, both toxicities shall be evaluated using both the carcinogenic and non-carcinogenic based US EPA Regional Screening Level or other screening levels.(iv) If the cumulative effects screening cancer risk is less than or equal to 1x10-6 and hazard index is less than or equal to one, then the cumulative effects screening risks posed by detected carcinogenic contaminants of interest at the site meet acceptable risk levels and additional evaluation for the receptor and scenario is not required.(v) If the cumulative effects screening cancer risk is greater than 1x10-6 or the hazard index is greater than one, then a Tier 2 risk assessment or further evaluation may be required.(6) Residential land use. (i) Risks to residents from ingestion of livestock grazing on a contaminated site shall be evaluated and added to the cumulative effects risk equation if it is determined to be a plausible and complete exposure pathway.(ii) Vapor intrusion pathway if complete, shall be evaluated and added to the cumulative effects screening risk equation.(iii) Any other relevant exposure pathway consistent with the residential exposure pathway shall be evaluated and added to the cumulative risk.(iv) If it is determined that the residential land use cumulative effects screening cancer risk posed by constituents of potential concern is less than or equal to the target cancer risk of 1x10-6 and the hazard index is less than or equal to one for each combined residential land use exposure pathways, and it is determined that there are no current and potential future impacts to groundwater as determined by site-specific attenuation factors derived using "Supplemental Guidance For Developing Soil Screening Levels," US EPA, as incorporated by reference in Section R315-101-12, Subsections R315-101-4(f)(15), R315-101-5(f)(8) and R315-101-5(f)(1)(vii), and ecological impacts are insignificant in accordance with Subsection R315-101-5(j), then the site meets the risk-based clean closure criteria for no further action or unrestricted land use as identified in Subsection R315-101-7(a).(v) If it is determined that the residential land use cumulative effects screening cancer risk posed by constituents of potential concern is greater than the target risk of 1x10-6 or the hazard index is greater than one for each combined residential land use exposure pathway, then further evaluation of the site may be conducted using either the Tier 2 refined risk assessment evaluation approach for a residential land use exposure scenario as identified in Subsection R315-101-5(g)(1) or a non-residential land use exposure scenario as identified in Subsection R315-101-5(g)(2), and site management as identified in Section R315-101-7, or the responsible party may choose to conduct corrective action as identified in Section R315-101-6 to mitigate risks at the site to residential acceptable levels.(vi) An ecological evaluation shall also be completed as part of the screening residential land use risk evaluation as described in Subsection R315-101-5(j).(vii) A groundwater impact evaluation shall also be completed as part of the screening residential land use risk evaluation as identified in Subsection R315-101-5(f)(8).(7) Industrial or commercial land use or construction worker. (i) If the cumulative effects screening risk is less than or equal to a cancer risk of 1x10-6 and the hazard index is less than or equal to one, then the cumulative effects screening risks posed by detected contaminants of potential concern at the site meets the industrial or commercial land use or construction worker risk, or both, and the site meets the criteria for restricted land use as identified in the Subsection R315-101-7(b).(ii) If the cumulative effects screening risk is greater than a cancer risk of 1x10-6 or the hazard index is greater than one, then the cumulative effects screening risks posed by the detected contaminants of potential concern at the site do not meet the industrial or commercial land use or construction worker, or both, and a Tier 2 assessment or further evaluation is required.(iii) If the cumulative effects screening risk is greater than cancer risk of 1x10-6 but less than 1x10-4 and the hazard index is less than or equal to one, then restricted land use closure with land use controls may be used in accordance with Subsections R315-101-7(b)(1) and R315-101-7(c).(iv) Exposure scenarios not covered in the screening values shall be evaluated separately and added to the cumulative effects risks. Evaluations may include the vapor intrusion pathway if it is determined to be complete using the vapor intrusion screening levels.(v) Other receptors relevant to the industrial or commercial land use or both scenario, such as a trespasser or recreational user, shall be evaluated.(vi) An ecological evaluation, as identified in Subsection R315-101-5(j), shall also be completed as part of the screening industrial or commercial land use or construction worker, or both, risk evaluation.(vii) A groundwater impact evaluation, as identified in Subsections R315-101-5(f)(8) and R315-101-4(f)(15), shall also be completed as part of the screening industrial or commercial land use or both risk evaluation.(8) For evaluation of potential future impacts to groundwater one or more of the following steps shall be used: (i) Step 1. Compare the maximum detected concentration for constituents of potential concern in soil to the US EPA Regional Screening Levels, groundwater protection soil screening level based on a dilution attenuation factor of 20, unless it may be demonstrated that background levels for the contaminants of concern at the site exceed the applicable soil screening levels. If the maximum detected concentrations exceed the US EPA Soil Screening Levels for groundwater protection, the potential exists for future impacts to groundwater. The groundwater protection soil screening level value shall be the greater of either the maximum contaminant level or the risk-based groundwater protection soil screening level value for evaluation. If the potential for future groundwater contamination exists, the responsible party may provide additional lines of evidence and a re-evaluation using a refined exposure point concentration of the 95% upper confidence limit. If sufficient data are not available to calculate a 95% upper confidence limit, the maximum constituent of potential concern concentration value shall be used for evaluation, or the director may approve an alternate value; or(ii) Step 2. Derive a site-specific dilution attenuation factor and a site-specific groundwater protection soil screening level value. The development of the site-specific dilution attenuation factor shall follow "Supplemental Guidance for Developing Soil Screening Levels," US EPA, as incorporated by reference in Section R315-101-12. If the 95% upper confidence limit concentration exceeds the calculated groundwater protection soil screening level, the potential exists for future impacts to groundwater. The groundwater protection soil screening level value shall be the greater of either the maximum contaminant level or the risk-based groundwater protection soil screening level value for evaluation. If the potential for future groundwater contamination exists, the responsible party may choose to submit a work plan for approval by the director describing actions that will be taken to protect groundwater from future impacts due to soil contamination. In addition, the work plan shall include a proposal for collection of sufficient monitoring data to evaluate both current and future groundwater conditions; or(iii) Step 3. The responsible party shall propose an alternate method for evaluating potential future impacts to groundwater due to soil contamination to the director for approval. If it is determined that the potential for future groundwater contamination exists, the responsible party shall submit a work plan for approval by the director describing actions that will be taken to protect groundwater from future impacts due to soil contamination. In addition, the work plan shall include a proposal for collection of sufficient monitoring data to evaluate both current and future groundwater conditions.(g) Tier 2 refined risk assessment. A Tier 2 refined risk assessment shall be conducted using the methodologies described in the "US EPA Risk Assessment Guidance for Superfund Sites," Parts A to F, as incorporated by reference in Section R315-101-12, and following standard land use exposure assumption scenarios listed in Subsections R315-101-5(g)(1) and R315-101-5(g)(2): (1) Residential Land Use. (2) Non-residential Land Use. (i) commercial or industrial or both;(ii) construction worker; and(iii) trespasser or recreationalist as applicable.(3)(i) The Tier 2 risk assessment shall assume no institutional or engineering controls in place, such as security, signage, pavements, personal protective equipment, fences or remediation.(ii) The risk assessment shall use US EPA standard default exposure parameters, variables and equations based on reasonable maximum exposure in the evaluation, unless scientific evidence suggests otherwise. If a US EPA standard default exposure parameter or variable is not available, the responsible party shall use the "Exposure Factors Handbook," US EPA, as incorporated by reference in Section R315-101-12, for default values, or other sources as approved by the director.(iii) A refined risk assessment may be conducted using site-specific exposure parameters and a Monte Carlo simulation in a probabilistic risk analysis with the approval of the director.(4) Evaluations shall be conducted in accordance with US EPA approved standards and methodologies and other methodologies as approved by the director. This may include the following guidance:(i) "Guidelines for the Health Risk Assessment of Chemical Mixtures," Risk Assessment Forum, EPA/630/R-98/002, as incorporated by reference in Section R315-101-12;(ii) "Risk Assessment Guidance for Superfund Volume 1: Human Health Evaluation Manual (Parts A-F)," Office of Emergency and Remedial Response EPA/504/1-89/002, Interim Final, as incorporated by reference in Section R315-101-12;(iii) "Human Health Evaluation Manual, Supplemental Guidance: Update of Standard Default Exposure Factors," US EPA OSWER Directive 9200.1-20, as incorporated by reference in Section R315-101-12;(iv) "Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures," US EPA, as incorporated by reference in Section R315-101-12;(v) "Soil Screening Guidance Technical Background Document," US EPA and "Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites," US EPA, as incorporated by reference in Section R315-101-12;(vi) "Guidelines for Carcinogen Risk Assessment," EPA/630/P-03/001F, as incorporated by reference in Section R315-101-12;(vii) "Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens," EPA/630/R-03/00F, as incorporated by reference in Section R315-101-12;(viii) "OSWER Technical Guidance for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air," US EPA OSWER 9200.2-154, as incorporated by reference in Section R315-101-12;(ix) "Technical Guide for Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites," US EPA, as incorporated by reference in Section R315-101-12; and(x) "Risk Assessment Guidance for Superfund, Part A, Volume III, Process for Conducting Probabilistic Risk Assessment," US EPA 540-0R-02 -002 OSWER 9285.7-45 PB 2002 963302, as incorporated by reference in Section R315-101-12.(5) In performing the Tier 2 risk assessment, the responsible party shall use toxicity information for carcinogenic and non-carcinogenic effects in accordance with Subsections R315-101-5(i) and R315-101-5(j)(8).(6) Risk characterization shall identify carcinogenic risks and non-carcinogenic risks for the constituents of potential concern.(7) The age dependent adjustment factors shall be applied to carcinogens with a mutagenic mode of action.(8) Risk characterization shall be based on cumulative risk effects and assumption of additivity in the absence of adequate evidence of toxicological interactions as follows. (i) For non-carcinogenic toxicants acting by similar modes of action or affecting common organs, dose addition shall be followed.(ii) For carcinogenic risks or toxicants acting independently, response addition shall be followed.(9) Carcinogenic cumulative risk may also be calculated as the sum of the probabilities of each chemical across the exposure pathways for cumulative risks less than 0.01. For cumulative risks greater than 0.01, the One-Hit Model, as specified in "Risk Assessment Guidance for Super Fund Volume 1: Human Health Evaluation Manual," Part A, US EPA, Office of Emergency and Remedial Response EPA/504/1-89/002, Interim Final, as incorporated by reference in Section R315-101-12, shall be used.(10) Non-carcinogenic hazard indices shall be calculated as the sum of the non-carcinogenic effects for each chemical across the exposure pathways. However, if the hazard index is greater than one, the hazard quotients should be summed separately by target organ or mode of action.(11) If total petroleum hydrocarbons are present, the risk assessment shall be evaluated using indicator compounds, and shall be conducted in accordance with Subsections R315-101-5(f), R315-101-5(f)(8), R315-101-5(g), R315-101-5(j), "Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures," EPA/630/R-00/002, as incorporated by reference in Section R315-101-12, and the US DOE Risk Assessment Information System website, and in accordance with other procedures approved by the director. (i) The cumulative risk of the petroleum mixture shall assume additivity, dose addition or response addition, unless there is data suggesting toxicological interaction.(ii) The risk assessment shall be based on the conceptual site model identified in Subsection R315-101-4(a)(3) or R315-101-4(f)(13) as applicable.(12) Current and future anticipated land use scenarios evaluation. (i) The evaluation shall be based on current and reasonably anticipated future uses of the property. Sources of information on land uses may include: (A) current zoning and comprehensive plan maps and applicable regulations provided by the local jurisdiction for the properties within the locality of the site;(B) inquiries made and responses as to whether there are regional trends that are relevant to land uses and activities in the locality of the site;(C) inquiries made of any environmental protection zones or regulations; and(D)(I) the property owner's planned use of land.(II) An inactive or vacant, fenced or non-fenced, property with no proposed land use in an area zoned for industrial or commercial land use or both shall be assumed to be reasonably used for industrial or commercial use or both in the future.(III) An inactive or vacant, fenced or non-fenced, property in an area zoned for residential land use shall be assumed to be reasonably used for residential land use in the future.(IV) For the protection of human health and the environment, if future anticipated land use conditions offer a more protective exposure scenario than the current land use scenario, the more protective future anticipated land use shall be evaluated.(V) A summary of the results and conclusions along with supporting documentation as to what the current and reasonably anticipated future land uses are for parcels within the locality of the site shall be submitted with the Tier 2 refined risk assessment for approval.(h) Data and results presentation. (1) A risk assessment report shall be submitted to the director for review and approval. The report may be a stand-alone document or included in a site characterization or closure report. The risk assessment, whether submitted by itself or included in a larger report, shall include, at a minimum, the following: (i) an executive summary;(ii) an overview of the site;(iii) a detailed discussion of areas of contamination;(iv) an exposure assessment identifying exposure levels for the exposure pathways identified in Subsections R315-101-5(c) and R315-101-5(j)(4)(i);(v) if fate and transport models are used, the user's manual, model theory, computer software for the model, installation verification data set for the model and input files for the model runs shall be provided upon request by the director;(vi) the output results of the model runs;(vii) background levels of identified hazardous constituents including any statistical methods used in evaluation of background data;(viii) identification and concentration of the contaminants of interest identified in Subsection R315-101-4(f)(8);(ix) a list of constituents of potential concern, contaminants of concern, and contaminants with mutagenic mode of action for human health and constituents of potential ecological concern;(x) US EPA Regional Screening Levels or, when US EPA Regional Screening Levels are not used, the toxicity information of identified constituents of potential concern, specifically listing mutagenic constituents of potential concern, including slope factors, inhalation unit risks, weight-of-evidence classification, non-carcinogenic chronic reference doses, age dependent adjustment factors, chronic deference concentrations and critical effects associated with reference doses and reference concentrations, toxicity reference values and any other ecological benchmarks used in the risk assessment;(xi) a list of identified ecological receptors;(xii) a list of identified ecological habitats;(xiii) risk characterization calculations including data used; and(xiv) the risk characterization identifying carcinogenic risk and non-carcinogenic risk for the constituents of potential concern, ecological hazard indices as determined in accordance with Subsection R315-101-5(j), uncertainties analysis, and a tabulation of the risk characterization data presented in a format approved by the director.(2) If the risk assessment report does not contain the required information of sufficient quality and detail, the director will notify the responsible party in writing of deficiencies and shall require resubmittal of the report in a designated time frame.(3) If the risk assessment report contains the required information of sufficient quality and detail, the director will approve, the risk assessment report in writing.(i) Identification of sources of toxicity information.(1) Sources of toxicity information gathered for identified hazardous constituents, weight-of-evidence classification and critical effects associated with reference doses and reference concentrations shall be in order of preference based on the US EPA hierarchy of human health toxicity values tiered system, "Human Health Toxicity Values in Superfund Risk Assessment," US EPA OSWER Directive 9285.7-53, as incorporated by reference in Section R315-101-12. The approved hierarchy, in order of acceptance is as follows: (i) US EPA Integrated Risk Information System.(ii) US EPA Provisional Peer Reviewed Toxicity Values.(iii) Additional sources may include US EPA and non-US EPA sources of toxicity information with priority given to sources that have been peer reviewed including the following: (A) California Environmental Protection Agency toxicity values;(B) Agency for Toxic Substances and Disease Registry Minimal Risk Levels;(C) US EPA additional sources; or(D) US EPA Health Effects Assessment Summary toxicity data.(2) US EPA Regional Screening Levels; and(3) US DOE Risk Assessment Information System website.(j) Ecological risk assessment. (1) Before conducting the risk assessment, the responsible party shall submit a work plan for approval.(2) An ecological risk assessment for the site shall include terrestrial and aquatic processes as appropriate using toxicity information for the constituents and biological processes relevant to the ecological evaluation. This shall include plants, soil invertebrates, benthic invertebrates, wildlife species and other ecological receptors as approved by the director. A list of all ecological receptors of interest shall also be included.(3) A waiver of Subsection R315-101-5(j) may be granted by the director if the responsible party demonstrates that ecological receptors will not be affected by any contamination using any of the following criteria: (i) environmental conditions at the site may be used to eliminate the need for ecological risk assessment;(ii) the affected property is not a viable habitat and the site cannot be used by potential ecological receptors as a habitat;(iii) complete or potentially complete exposure pathways do not exist due to prevailing conditions or property setting; or(iv) detected chemicals at the site are below the ecological screening benchmark levels.(4) An ecological risk assessment for a site shall be conducted to include the following information: (i) a problem formulation, identification of constituents of potential ecological concern, identification of habitats, media sampled, potential ecological effects, relevant ecological receptors, relevant exposure pathways, initial definition of assessment and measurement endpoints, with respect to current and reasonably anticipated future land and water uses as described in a conceptual site model;(ii) the data quality objectives for the ecological risk assessment shall be based on the conceptual site model, with emphasis on analytical detection limits appropriate for ecological receptors;(iii) an exposure analysis to include identification and selection of constituents of potential ecological concern, identification and selection of target or representative ecological receptors, an exposure pathway model relating target or representative receptors, exposure routes and measurement endpoints for both current and reasonably anticipated future land and water use scenarios;(iv) an ecological response analysis including a summary of current information regarding the toxicological effects, ecological effects, bioconcentration potential, bioaccumulation potential, biomagnification potential, persistence of the identified constituents of potential ecological concern and ecological benchmark values;(v) a risk characterization presenting the quantitative ecological risks potentially associated with the site, a discussion of any available site-specific ecological studies, a detailed discussion of risks associated with the bioconcentration potential, bioaccumulation potential, biomagnification potential, and persistence of each contaminant, and consideration of any other available, published and peer reviewed scientific information on other sources of adverse ecological conditions as appropriate;(vi) an evaluation of the potential for significant adverse effects on the health or viability of individual ecological receptors or local populations, including a weight-of-evidence analysis or population viability analysis. These evaluations may include field studies, laboratory investigations, appropriate population models, or any combination of these or other methods of evaluation as approved by the director; and(vii) a quantitative and qualitative uncertainty analysis as appropriate for each element of the risk assessment.(5) Ecological risk assessment estimates shall be conducted: (i) at the individual level for species present in the locality of the site if the species is listed as threatened or endangered, or is a state sensitive species; and(ii) at the population level for any other species of plants or animals in the locality of the site.(6) Cumulative hazard from multiple hazardous substances shall be assessed by summing the hazards posed separately by individual hazardous substances in the locality of the site, unless it is demonstrated that the summation assumption is not appropriate.(7) Ecological risk assessment shall be conducted in accordance with the following: (i) "Framework for Ecological Risk Assessment," EPA/630/R-92/001, as incorporated by reference in Section R315-101-12;(ii) "Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments Interim Final," EPA 540-R.97-006, OSWER 9285.7-25. PB97-963211, as incorporated by reference in Section R315-101-12;(iii) "Guidelines for Ecological Risk Assessment," US EPA, as incorporated by reference in Section R315-101-12;(iv) US EPA "Guidance for Developing Ecological Screening Levels," US EPA, as incorporated by reference in Section R315-101-12; and(v) any other sources as approved by the director.(8) Appropriate sources of exposure factor information and toxicological parameters may include the following:(i) "Wildlife Exposure Factors Handbook," US EPA, as incorporated by reference in Section R315-101-12;(ii) "Toxicological Benchmarks for Wildlife," Oak Ridge National Laboratory (ORNL), as incorporated by reference in Section R315-101-12;(iii) Los Alamos National Laboratory (LANL) ECORisk Database;(iv) US EPA Ecological Soil Screening Levels;(v) "Guidance for Developing Ecological Soil Screening Levels," US EPA, as incorporated by reference in Section R315-101-12; and(vi) any other sources as approved by the director.(9) In the absence of available and acceptable toxicity information, the director may require the development of site-specific toxicity information.(10) An ecological risk assessment shall be conducted using a tiered evaluation approach as described in Subsections R315-101-5(j)(10)(i) through R315-101-5(j)(10)(x). (i) A Tier 1 ecological screening risk assessment shall use conservative assumptions and shall include: (A) a conceptual site model;(B) an evaluation of fate and transport mechanisms;(C) an identification of constituents of potential ecological concern;(D) a characterization of the ecological setting; and(E) a selection of toxicity endpoints and receptors of ecological significance.(ii) Tier 1 ecological screening risk assessment - exposure pathways:(A) each ecological receptor is considered to be exposed to constituents of potential ecological concern in soil in the zero to two feet below ground surface interval. In addition, burrowing animals and deep-rooted plants may be considered to be exposed to constituents of potential ecological concern in soils deeper than two feet; and(B) exposure pathways may include ingestion, direct contact, exposure through uptake of biota exposed to constituents of potential ecological concern, and plant uptake of constituents of potential ecological concern.(iii) The exposure assessment for the Tier 1 ecological screening risk assessment shall be conducted by assuming: (A) the maximum detected concentrations as the exposure point concentration for calculating exposure doses;(B) the area use factor is equal to one indicating that the home range of the receptor is the entire contaminated area;(C) the bioavailability of contaminants is equal to 100%;(D) the maximum reported ingestion rate from literature;(E) the dietary composition consists of direct ingestion of 100% of the constituents of potential ecological concern levels in soil;(F) each calculation is performed on a dry-weight basis; and(G) minimum receptor body weight.(iv) The toxicity assessment for the Tier 1 ecological screening risk assessment shall be conducted by assuming: (A) for wildlife, the dose-based toxicity reference values, which are receptor, media, and chemical specific, shall be the applicable protective standards available in peer reviewed literature sources;(B) the toxicity reference values selected shall be those based on no observed adverse effects levels for evaluation;(C) the responsible party may use a literature search to determine availability of data for derivation of a toxicity reference value if detected constituents of potential ecological concern have no published toxicity reference values, and shall provide the following: (I) the responsible party shall provide supporting data to the director for approval of the newly derived toxicity reference value; and(II) if the responsible party cannot derive a toxicity reference value based on literature, the detected constituents of potential ecological concern shall be addressed qualitatively in the uncertainty analysis of the ecological risk assessment report;(D) for plants and other invertebrate receptors, such as soil organisms, benthic organisms and aquatic organisms, concentration-based effects benchmarks shall be used: (I) concentration levels identified in peer reviewed literature sources shall be used as measurement endpoints for evaluation of chemical effects on receptors;(E) the effects concentration levels shall be the no observed effects concentrations; and(F) the responsible party may use a literature search to determine availability of data for derivation of effects concentration levels if detected constituents of potential ecological concern have no published effects concentration levels: (I) the responsible party shall provide supporting data to the director for approval of the newly derived effects concentration levels; and(II) if the responsible party cannot derive effects concentration levels based on literature, the detected constituents of potential ecological concern shall be addressed qualitatively in the uncertainty analysis of the ecological risk assessment report.(v) The risk characterization of the Tier 1 ecological screening risk assessment.(A) For plants and other invertebrate receptors, a screening hazard quotient, shall be calculated as the maximum detected exposure concentration of constituents of potential ecological concern divided by the no observed effects concentration.(B) For wildlife, a screening hazard quotient shall be calculated as the estimated exposure dose or contaminant intake divided by the no observed adverse effects level-based toxicity reference value.(C) Tier 1 screening results.(I) If the calculated screening hazard quotient or hazard index is less than or equal to one, no further evaluation is required.(II) If the calculated screening hazard quotient or hazard index is greater than one, then there may be the potential for adverse ecological risk from the detected constituents of potential ecological concern at the site. The responsible party shall either conduct corrective action or conduct further evaluation in a Tier 2 refined ecological risk assessment.(vi) A Tier 2 refined ecological risk assessment shall: (A) use constituents of potential ecological concern with screening hazard quotients or hazard indices greater than one for a refined problem formulation; and(B) use site-specific exposure assumptions in Subsections R315-101-5(j)(10)(ii) and R315-101-5(j)(10)(iii) for the refined evaluation.(vii) The exposure assessment in the Tier 2 refined ecological risk assessment shall include exposure dose calculated utilizing site-specific exposure assumptions as follows: (A) exposure point concentration: (I) calculate exposure point concentration as the 95% upper confidence limit if sufficient data are available in accordance with US EPA ProUCL software; and(II) if sufficient data are not available to calculate the 95% upper confidence limit, an alternate value, as approved by the director, shall be used as the exposure point concentration;(B) estimate the site-specific area use factor for each representative receptor by dividing the receptor's average home range by the area of contamination or area of the solid waste management units:(I) this estimate shall have a value between zero and one;(C) the bioavailability of constituents of potential ecological concern shall be assumed to be other than 100% based on available literature or other sources as approved by the director;(D) the ingestion rate for each representative receptor shall be assumed to be the average reported ingestion rate in reported literature or estimated from average body weight using allometric equations;(E) the dietary composition shall be based on receptor specific percentages of plant, animal, and soil matter:(i) the non-dietary ingestion of soil shall be assumed to be in addition to the dietary intake rate to add up to 100%, soil and dietary items;(F) the concentrations of constituents of potential ecological concern in receptor dietary elements, plant and animal matter, shall be predicted by using bio uptake and bioaccumulation models;(G) each calculation shall be performed on a dry-weight basis;(H) if a bioaccumulation model is not available, 100% uptake factor shall be assumed;(I) each equation and variables used to estimate constituents of potential ecological concern in plants shall be listed;(J) the methodologies for determination of bioaccumulation factors for the constituents of potential ecological concern shall be documented; and(K) exposure doses for wildlife receptors shall be assessed using bio uptake and bioaccumulation modeling to predict the concentration of constituents of potential ecological concern in animal matter that may be ingested by wildlife receptors.(viii) The toxicity assessment for a Tier 2 refined ecological risk assessment shall be based on: (A) the lowest observed adverse effects levels for wildlife receptors and lowest observed effects concentrations for plants and invertebrate receptors; and(B) the toxicity reference values shall be based on the lowest observed adverse effects levels for each wildlife receptor and shall be based on lowest observed effects concentrations for any other receptors including invertebrates, with the exception of endangered, threatened and sensitive species for which a no observed adverse effects level applies.(ix) The risk characterization of the Tier 2 refined ecological risk assessment. (A) For wildlife vertebrate receptors, a hazard quotient shall be calculated as the ratio of the estimated receptor-specific contaminant intake or dose to the lowest observed adverse effects level-based toxicity reference value.(B) For plants and other invertebrate receptors, a qualitative discussion of the potential for adverse effects shall be provided in the assessment. The assessment shall be based on plant hazard quotients or hazard indices as well as site observations that were made during a habitat survey.(C) Hazard quotients shall be summed for the constituents of potential ecological concern with similar receptor-specific modes of toxicity.(D) Tier 2 assessment results. (I) If the hazard quotient or the hazard index is less than or equal to one, adverse ecological effects are not expected and no further action is needed.(II) If the hazard index is greater than one, there is potential for adverse ecological effects to occur at the site and the responsible party shall either conduct corrective action or conduct further evaluation in a Tier 3 refined ecological risk assessment as outlined in Subsection R315-101-5(j)(10)(x).(x) A Tier 3 refined ecological risk assessment shall be conducted based on:(A) a site-specific ecological evaluation;(B) uptake factors, bioaccumulation factors, bioavailability factors, and plant uptake factors determined from the analysis of animal and plant tissue collected at the site;(C) the evaluation of unique exposure pathways and effects of exposure to various life stages or other assessment endpoints as determined by the director;(D) the evaluation of habitat suitability including habitat quality; and(E) the calculation of refined hazard quotients and hazard indices for the constituents of potential ecological concern shall take into account information from Subsections R315-101-5(j)(10)(i) through R315-101-5(j)(10)(x).(xi) Tier 3 refined ecological risk assessment results and possible outcomes.(A) If the Tier 3 refined evaluation results in a hazard index greater than one, the responsible party, shall, in conjunction with the results of a Tier 2 refined evaluation, use several lines of evidence and a weight-of-evidence approach to facilitate a final determination regarding the need for corrective action.(B) Site remediation shall be required if unacceptable or potential significant adverse ecological effects are documented by the risk assessment results.(C) The director has the discretion to require corrective action at the site based on data and ecological significance as reported.(11) Results presentation. An ecological risk assessment report shall be prepared and submitted to the director in accordance with the requirements in Subsection R315-101-5(h).
Utah Admin. Code R315-101-5
Amended by Utah State Bulletin Number 2023-07, effective 3/15/2023