Capture.PNG
Comparison of Existing Contamination to Risk Reduction Standards 391-3-19-.07
** Note: The Rules for Hazardous Site Response (Rules) were revised effective September 25, 2018, and include changes to the methodology for calculating Risk Reduction Standards (RRS). In general, users may refer to EPA’s Regional Screening Level (RSL) calculator to derive direct contact values using a target excess lifetime cancer risk of 1 × 10⁻⁵ and a hazard quotient (HQ) of 1. This webpage provides summary information, including tables of select Type 1 and 3 RRS. However, this does not supersede the Rules for Hazardous Site Response; in the event of conflict, the Rules take precedence.**
Page Table of Contents:
- Description
- RRS Process Chart
- Type 1 and Type 3 Default RRS
- Adult Lead Model
- Toxicity Factors and Physical Properties
- Common Mistakes
- Ecological Health
Description
Risk Reduction Standards (RRS) should be calculated for each regulated substance. The appropriate RRS “Type” should be selected based on the current and reasonably anticipated future land use, as well as the potential exposure pathways at the site. The Rules establish five RRS Types, each corresponding to a different combination of land use assumptions and exposure conditions:
- Type 1 RRS will pose no significant risk on the basis of standardized exposure assumptions and defined risk level for residential properties.
- Type 2 RRS will pose no significant risk on the basis of site-specific risk assessment for residential properties.
- Type 3 RRS will pose no significant risk on the basis of standardized exposure assumptions and defined risk level for non-residential properties.
- Type 4 RRS will pose no significant risk on the basis of site-specific risk assessment for non-residential properties.
- Type 5 RRS may be applied only in instances where Type 1-4 standards are not appropriate. This standard allows contamination to remain in place provided the principal threats at the site are controlled by engineering and institutional controls. Under the Rules, Type 5 is intended for sites where removal or treatment of the source area is determined to be impracticable (e.g., landfills or similar waste disposal areas). Institutional controls should not be substituted for active remedial measures where such measures are practicable. However, the Voluntary Remediation Program (VRP) Act provides an alternative to the Rules and does not include the impracticability requirement. ** NOTE: Please contact a compliance officer at our office (404-657-8600) for additional information regarding the minimum requirements relating to a Type 5 RRS and/or additional VRP guidance. **
Any report containing RRS for EPD approval (e.g., Compliance Status Report) should include:
- A discussion of the RRS calculated for each regulated substance.
- An explanation of the RRS Type(s) selected for the site and the rationale for their selection based on current and reasonably anticipated future land use and exposure conditions.
- A tabular comparison of maximum detected concentrations (MDC) and maximum method detection limits (MaxDLs) of regulated substances to the applicable RRS.
- If non-default exposure parameters are used to calculate Type 2 or Type 4 RRS, justification demonstrating why the alternative exposure parameters are appropriate and representative of site-specific conditions should be provided.
- If RRS are not obtained from EPD Default RRS tables, a table containing all exposure parameters and toxicity factors, with references, used in risk-based calculations, as well as any equations and the results or RSL Calculator inputs and outputs.
A site where concentrations of regulated substances in soil or groundwater exceeds the RRS, does not meet state cleanup standards, and a Corrective Action Plan is required.
** Note: Please be advised that calculating site-specific RRS (Type 2 and/or Type 4) may NOT always result in higher cleanup standards. **
HSRA RRS Process Chart
Process Chart
** Note: Descriptions relating to the calculations of the RRS have been simplified wherever possible to address common regulated substances; however, this guidance does not supersede the Rules for Hazardous Site Response. In the event of conflict, the Rules for Hazardous Site Response take precedence. **
Type 1 and 3 Default RRS
Soil
and Groundwater Default Type 1 & 3 RRS Tables
2026
Type 1 & 3 RRS Summary of Updates
** Note: These tables are not an exhaustive list of regulated substances. EPD has compiled this dataset using the best available information at the time of publication. While quality assurance efforts have been undertaken, EPD does not warrant or guarantee the accuracy, reliability, or completeness of these RRS, which are subject to change without notice. EPD provides this data for convenience and without warranty, either express or implied.
All site-specific RRS submitted to EPD are subject to review and approval by EPD. These tables do not supersede the Rules for Hazardous Site Response. In the event of conflict or inconsistency, the Rules take precedence. Please contact the Risk Assessment Unit at 404.657.8600 or [email protected] with questions or if you believe that inaccurate or incomplete data is presented in these tables. **
Adult Lead Model
As part of the 2018 Rule change, Type 4 (non-residential) RRS for lead in soil are now calculated using EPA’s Adult Lead Model (ALM). The formulas and inputs are provided in Appendix IV of the Rules. Unfortunately, extraneous symbols and errors were introduced in the formula during the Rule change process, which will be corrected in the next revision. In the interim, the correct equations are provided below:
The soil direct contact Type 4 RRS for lead is 1,050 mg/kg for surface soils based on central tendency values for a commercial/industrial worker and 1,278 mg/kg for subsurface soils based on central tendency exposure assumptions for an excavation worker. These values are calculated in accordance with Rule 391-3-19-.07(9)(d)2.(i) and 3.(i). Alternative site-specific exposure assumptions may be proposed, subject to EPD review and approval. In addition, a site-specific leaching value must be calculated in accordance with Rule 391-3-19-.07(9)(d)1. The final Type 4 soil RRS for lead is the lower of the applicable direct-contact and leaching-based values.
For additional information, please see EPA’s ALM guidance and spreadsheet.
www.epa.gov/superfund/lead-superfund-sites-software-and-users-manuals.
Toxicity Factors and Physical Properties
- Toxicity Factors:
For toxicity assessment, EPD adopts EPA’s Office of Solid Waste and Emergency Response (OSWER) recommended hierarchy of toxicity information (OSWER Directive 9285.7-53, 2003). Note that EPA uses this toxicity data hierarchy for the Regional Screening Level (RSL) tables. See http://www.epa.gov/risk/risk-based-screening-table-generic-tables. A benefit of these tables is that they act as single source of information concerning toxicity factors and chemical specific parameters used in the risk assessment process. Please note that the information in this table is periodically updated. If a value for only one of the two variables in a variable pair (RfDo/RfC or SFo/IUR) is not available for a substance, the term containing that variable in an equation can be omitted or equated to zero. If neither value is available for a variable pair, a concentration cannot be calculated with the U.S. EPA Risk Assessment Guidance for Superfund (RAGS) equations unless an appropriate surrogate compound is available for use in assessing its risk. - Inhalation Reference Concentrations and Inhalation Unit Risk Factors:
Consistent with U.S. EPA RAGS, Part F (2009), the inhalation exposure pathway has been updated to allow for direct use of inhalation toxicity values as concentrations in lieu of doses when assessing cancer and non-cancer inhalation risks. As a result, it is no longer necessary to apply a conversion method to convert from concentration to dose metric. Instead, the inhalation equation from RAGS, Part F when used allows for use of toxicity concentrations as they appear in EPA’s Regional Screening Levels table. - Physical Properties:
Sources for Chemical Specific Properties for the leachability criteria.- Regional Chemical Specific Properties:
http://www.epa.gov/risk/risk-based-screening-table-generic-tables - Superfund Soil Screening Guidance:
http://www.epa.gov/superfund/superfund-soil-screening-guidance - Superfund Chemical Data Matrix:
http://www.epa.gov/superfund/superfund-chemical-data-matrix-scdm
- Regional Chemical Specific Properties:
Common Mistakes
- Failure to use the default groundwater standards for the Type 1 RRS for groundwater. For Type 1 groundwater RRS, concentrations shall not exceed those listed in Table 1 of Appendix III of the rules. For regulated substances not listed in this table, concentrations shall not exceed the background or detection limit concentration.
- Failure to include concentrations listed in Table 2 of Appendix III (GA R&R - GAC - Appendix (391-3-19) III. MEDIA TARGET CONCENTRATIONS AND STANDARD EXPOSURE ASSUMPTIONS) when calculating the Type 1 RRS for metals in soil.
- Failure to address the protection of groundwater via migration from soil as it pertains to soil RRS.
- Improperly calculating Soil Screening Level (SSL) values:
- Improperly calculating site-specific distribution coefficient (Kd).
- Using a referenced Kd value from an improper reference.
- Not properly determining the dilution attenuation factor when calculating soil concentrations protective of leaching for site-specific (Type 2 and 4) RRS.
- Using a foc of 0.02 instead of 0.002
- Not utilizing the toxicity factor hierarchy and/or using incorrect input parameters for RAGS equations. For derivation of the default RRS, the values provided in Table 3 of Appendix III should be used.
- For Type 2 and 4 RRS, failing to provide supporting documentation for site-specific exposure assumptions.
- Failure to eliminate the inhalation pathway for non-volatile regulated substances in groundwater. In groundwater, if the regulated substance is not volatile, then the inhalation pathway is incomplete and can be removed from the RAGS equation.
- Failure to eliminate the inhalation pathway for non-volatile regulated substances in soil. In soil, if the regulated substance is not volatile, then the inhalation pathway due to volatiles is incomplete and the (1/VF) term can be removed from the RAGS equation. However, the inhalation pathway due to particulates (1/PEF) must be addressed.
- For non-Carcinogenic risk, not setting the Averaging Time (AT) equal to the Exposure Duration (ED). For example, if the exposure duration for a construction worker is 6 months, then the averaging time for these workers would be 182 days/year (i.e., 0.5 years x 365 days/year).
- Failure to run the Integrated Exposure Uptake Biokinetic (IEUBK) Model for Lead in children in the determination of the overall Soil Type 2 RRS for Lead. Please provide all model input and output parameters for review.
- Failure to run the Standard Adult Lead Model (ALM) in the determination of the overall Soil Type 4 RRS for Lead. Please provide all model input and output parameters for review.
- Entering a groundwater concentration for lead in the IEUBK model that exceeds the federal action limit of 15 micrograms/liter.
- Using the notification concentrations as de facto soil RRS.
Ecological Health
- Ecological receptors are evaluated using EPA's Ecological Risk Assessment Framework, which follows the eight-step Ecological Risk Assessment (ERA) process for Superfund sites. Region 4 EPA's Ecological Risk Assessment Supplemental Guidance (ERASG).
- The ERA process is divided into two stages:
- Screening Level Ecological Risk Assessment (SLERA) – Steps 1 and 2
- Baseline Ecological Risk Assessment (BERA) – Steps 3 thru 8
- The Georgia Risk Assessment Guidance (GRAG) recommends a phased approach for evaluating ecological risk. Please see the GRAG for additional information on evaluating ecological risk.