Ga. Comp. R. & Regs. R. 391-3-19-.07 - Risk Reduction Standards

(1) Purpose and Scope. Rule 391-3-19-.07 specifies the information and procedures necessary to demonstrate compliance with requirements under HSRA for corrective action for all regulated substance releases at a site or individual property at a site listed on the Hazardous Site Inventory. All risk reduction standards will, when implemented, provide adequate protection of human health and the environment. Compliance with these requirements does not preclude the requirement to comply with any stricter standards that may be applicable under other state or federal laws or regulations. These risk reduction standards may be applicable, relevant, or appropriate requirements for remedial actions under the NCP.

(2) Derivation of health-based criteria. For a regulated substance that poses a risk to humans the cleanup standards shall be calculated as required under Rules 391-3-19-.07(6), (7), (8), (9) and (10) based on an excess lifetime cancer risk of 1X10^-5 and a hazard quotient of 1.0 for non-carcinogens. For a regulated substance that poses a risk of both cancer and one or more adverse health effects other than cancer, the standards shall be derived for the most sensitive effect.

(a) The standards for groundwater shall be determined using Equation 1 (cancer effects) or Equation 2 (non-cancer risk effects) from RAGS, Part B for ingestion, as modified using RAGS, Part E for dermal contact, and RAGS, Part F for inhalation exposures.

(b) The standards for soil shall be determined using Equation 6 (cancer effects) or Equation 7 (non-cancer risk effects) from RAGS, Part B for ingestion, as modified using RAGS, Part E for dermal contact, and RAGS, Part F for inhalation exposures.

(c) For mutagenic carcinogens, the standards shall be derived using the age dependent adjustment factors in Table 3 of Appendix III.

(3) Completion of corrective action. A required corrective action shall be considered complete when it is demonstrated that the site or individual property at a site meets any or a combination of the applicable risk reduction standards described in Rule 391-3-19-.07.

(4) Corrective action considerations. For corrective action to be in compliance with these standards, the following elements must be addressed where applicable:

(a) The corrective action shall, at a minimum, provide for the removal and/or treatment of free product to the extent practicable, including considerations such as mobility and recoverability.

(b) No soil remaining in place under Type 1, 2, 3, or 4 risk reduction standards shall exhibit the hazardous waste characteristics of ignitability, corrosivity, or reactivity as defined in 40 CFR 261Su bpart C.

(c) The corrective action shall not allow exposure to concentrations which would cause food chain contamination, damage to soils or to biota in the soils which could impair the use of soils for agricultural or silvicultural purposes, adverse effects on vegetation or wildlife, or the accumulation of vapors in buildings or other structures which pose a threat to human health or the environment.

(d) The corrective action shall protect waters of the State from releases that would cause surface water to experience concentrations of regulated substances in excess of any general criterion specified in the Georgia Rules and Regulations for Water Quality Control at 391-3-6-.03(5) or, if concentration values are not provided in said Rules, concentrations at levels that exhibit acute toxicity to aquatic life as demonstrated pursuant to protocols established by the Director.

(e) If the detection limit and/or the background concentration for a regulated substance is greater than the concentration specified in any risk reduction standard, the greater of the detection limit or background shall be used for determining compliance with the applicable risk reduction standard. "Detection limit" in this context implies the non-fraudulent use of an approved analytical test method that is appropriate for the particular application. Background shall be determined from samples taken from media that are unaffected by a release. Background determinations may consider anthropogenic sources and may also be based on regional background studies accepted by the Division. For radionuclides, background means background radioactivity.

(5) Multiple property sites. For sites consisting of more than one property, the Type risk reduction standard that shall apply to each individual property at that site shall be based upon the applicable use scenario for each individual property, i.e., residential or nonresidential.

(6) Criteria for Type 1 standards.

(a) Type 1 standards provide for regulated substance concentrations that pose no significant risk on the basis of standardized exposure assumptions and defined risk levels for residential properties. To comply with these standards, source materials must be removed or decontaminated to the Type 1 media criteria.

(b) Criteria for groundwater. At any point within groundwater that has been affected by a release, concentrations of regulated substances in groundwater samples shall not exceed concentrations given in Table 1 of Appendix III or, for those substances not listed, the background or detection limit concentration.

(c) Criteria for soil. Concentrations at any point above the uppermost groundwater zone in soil that has been affected by a release shall not exceed the concentrations given in Table 2 of Appendix III or, for those substances not listed, the least of the concentrations from Items 1 and 2 below:

1. Concentrations which will not cause contamination of groundwater at levels which exceed Type 1 groundwater criteria, determined as the highest of the soil concentrations in Items (i) and (ii) below:

(i) Soil concentrations in Appendix I, excluding any values given in square brackets;

(ii) Soil concentrations determined using the equation and default parameters provided in Table 4 of Appendix III. A dilution attenuation factor of 20 may be used unless the Division determines that another value is appropriate to protect human health and the environment.

2. The lesser of soil concentrations calculated in accordance with Rule 391-3-19-.07(2) using standard residential exposure assumptions in Table 3 of Appendix III.

[Note: Where concentrations are non-calculable under Items 1 or 2 above, the soil criterion shall be the higher of the background or detection limit concentrations.]

(7) Criteria for Type 2 standards.

(a) Type 2 standards provide for regulated substance concentrations that pose no significant risk on the basis of a site-specific risk assessment for residential land use. To comply with these standards, source materials must be removed or decontaminated to the Type 2 media criteria.

(b) Criteria for groundwater. At any point within any groundwater that has been affected by a release, concentrations of regulated substances in groundwater must not exceed the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using site-specific exposure factors for the residential use scenario. For those substances for which neither calculation can be made, the standard shall be the higher of concentrations in Table 1 of Appendix III, background concentrations, or detection limit concentrations.

(c) Criteria for soil. Concentrations above the uppermost groundwater zone in soil that has been affected by a release shall not exceed the least of the concentrations in Items 1 through 3 below, or, for those substances for which none of the calculations can be made, the highest of the concentrations in Table 2 of Appendix III, background concentrations, or detection limit concentrations:

1. Concentrations which will not cause contamination of groundwater at levels which exceed Type 1 or 2 groundwater criteria, whichever is higher, at a point of exposure defined as any point at which a drinking water well could be installed. These soil concentrations may be determined using a laboratory test and/or fate-and-transport model accepted by the Division. Other site-specific information, such as the age of the release and groundwater concentration trends, may be accepted by the Division to demonstrate that soil concentrations are protective of groundwater criteria.

2. The lesser of soil concentrations calculated in accordance with Rule 391-3-19-.07(2) using site-specific exposure factors for the residential use scenario.

3. For lead, soil concentrations at the site must not exceed those concentrations that would cause a resident 6-year old child (averaged across preceding 84 months) to have a probability of no greater than 5% of a blood lead level greater than 10 ug/dL as determined by the IEUBK model using site-specific exposure assumptions, including the ingestion of site groundwater as drinking water and the probability of subsurface soils being brought to the land surface. The soil criterion at Item 1 above shall also apply to the Type 2 standard for lead.

(d) Soil Averaging. For soil contaminated with regulated substances at sites where a Type 2 standard is being sought, exposure area averaging using methods recognized by USEPA and approved by the Division may be used to demonstrate that cumulative cancer and non-cancer risks are in compliance with soil criteria derived pursuant to Rule 391-3-19-.07(7)(c). These exposure area averaging methods may include statistical analysis of discrete sampling results or composite sampling methods.

(e) More stringent criteria may be established for a site than are specified under Rule 391-3-19-.07(7)(b) and (c) if the Director or the responsible party determines that it is necessary to protect human health or the environment.

(8) Criteria for Type 3 standards.

(a) Type 3 standards provide for regulated substance concentrations that pose no significant risk on the basis of standardized exposure assumptions and defined risk levels for the non-residential use scenario. To comply with Type 3 standards, source materials must be removed or decontaminated to the Type 3 media criteria.

(b) Type 3 standards are not applicable to residential properties. Type 3 standards are applicable where the responsible party documents that the activities being conducted on the property satisfy the definition for non-residential property at Rule 391-3-19-.02(2).

(c) Criteria for groundwater. At any point within groundwater that has been affected by a release, concentrations of regulated substances in groundwater shall not exceed the MCL or, for those substances not listed, the lesser of concentrations calculated in accordance with Rule 391-3-19-.07(2) using standard non-residential exposure assumptions in Table 3 of Appendix III. If no MCL exists and the calculations cannot be made, the groundwater standard shall be the higher of concentrations in Table 1 of Appendix III, background concentrations or detection limit concentrations.

(d) Criteria for soils.

1. Concentrations at any point above the uppermost groundwater zone in soil that has been affected by a release shall not exceed the concentrations described in Item 1 of Rule 391-3-19-.07(6)(c), based on Type 3 groundwater criteria.

2. Concentrations in surface soil (soil within one foot of the land surface) shall meet the criteria of Item 1 above and shall not exceed the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using standard nonresidential exposure assumptions in Table 3 of Appendix III. If the calculations cannot be made, the surface soil criterion shall be equal to the criterion of Item 1 above. In no event shall compliance with the surface soil criteria be achieved by applying one foot of clean soil onto the original land surface.

3. Concentrations in subsurface soil (soil greater than 1 foot from the land surface) shall meet the criterion of Item 1 above and shall not exceed the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using standard excavation worker exposure assumptions accepted by the Division. If the calculations cannot be made, the subsurface soil criterion shall be equal to the criterion of Item 1 above.

4. For lead, the standard is 400 mg/kg.

(9) Criteria for Type 4 standards.

(a) Type 4 standards provide for regulated substance concentrations that pose no significant risk on the basis of a site-specific risk assessment for non-residential land use. To comply with Type 4 standards, source materials must be removed or decontaminated to the Type 4 media criteria.

(b) Type 4 standards are not applicable to residential properties. Type 4 standards are applicable where the responsible party documents that the activities being conducted on the property satisfy the definition for non-residential property at Rule 391-3-19-.02(2) and documents that a monitoring program or an environmental covenant executed in accordance with Rule 391-3-19-.08(7) will assure continued compliance with the Type 4 standards.

(c) Criteria for groundwater. Concentrations of regulated substances in groundwater must not exceed, at any point that is not otherwise subject to site-specific groundwater use restrictions in accordance with Rule 391-3-19-.08(7), the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using site-specific exposure factors for the non-residential use scenario. For those substances for which neither calculation can be made, the standard shall be the higher of concentrations in Table 1 of Appendix III, background concentrations, or detection limit concentrations.

1. If groundwater use restrictions are utilized, groundwater contaminated with regulated substances in excess of appropriate Type 1 through 4 standards must not migrate beyond the limits of the institutional controls. The responsible party shall demonstrate that such migration will not occur or implement groundwater monitoring to ensure that migration is not occurring, unless the Division determines that monitoring is not needed.

(d) Criteria for soil. Concentrations in soil that has been affected by a release shall not exceed the relevant criteria listed below, or, for those substances for which none of the concentrations can be calculated, the highest of concentrations in Table 2 of Appendix III, background concentrations, or detection limit concentrations:

1. Concentrations in soil above the uppermost groundwater zone shall not cause contamination of groundwater at levels which exceed Type 3 or 4 groundwater concentration criteria, whichever is higher, at a point of exposure defined as any point at which a drinking water well could be installed. These soil concentrations may be determined using a laboratory test and/or fate-and-transport model accepted by the Division. Other site-specific information, such as the age of the release and groundwater concentration trends, may be accepted by the Division to demonstrate that soil concentrations are protective of groundwater criteria.

2. Concentrations in surface soil shall meet the criteria of Item 1 above and shall not exceed the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using site-specific exposure factors for the nonresidential use scenario. The depth of soil considered surface soil may be based upon site-specific exposure factors approved by the Director, or assumed to be soil within one foot of the land surface. In no event shall compliance be achieved by applying clean soil or any other barrier onto surface soil.

(i) For lead, surface soil concentrations at the site must not exceed concentrations that are determined by the procedures described in Appendix IV. In cases where children frequent the site, soil concentrations may be determined pursuant to Rule 391-3-19-.07(9)(f).

3. Concentrations in subsurface soil (soils extending to a specified excavation depth approved by the Director) shall meet the criterion of Item 1 above and shall not exceed the lesser of the values calculated in accordance with Rule 391-3-19-.07(2) using site-specific excavation worker exposure factors approved by the Director. If the calculations cannot be made, the subsurface soil criterion shall be equal to the criterion of Item 1 above.

(i) For lead, subsurface soil concentrations at the site must not exceed concentrations that are determined by the procedures described in Appendix IV, using site-specific excavation worker exposure factors approved by the Director.

(e) Soil Averaging. For soil contaminated with regulated substances at sites where a Type 4 standard is being sought, exposure area averaging using methods recognized by USEPA and approved by the Division may be used to demonstrate that cumulative cancer and non-cancer risks are in compliance with soil criteria derived pursuant to Rule 391-3-19-.07(9)(d). These exposure area averaging methods may include statistical analysis of discrete sampling results or composite sampling methods.

(f) More stringent criteria may be established for a site than are specified under Rule 391-3-19-.07(9)(c) and (d) if the Director or the responsible party determines that it is necessary to protect human health or the environment.

(10) Criteria for Type 5 Standards.

(a) Type 5 standards allow, in those instances where application of Type 1-4 standards is not appropriate under present circumstances, the use of measures to control the regulated substances or the property where the regulated substances are located. Such measures may consist of engineering controls such as construction of a fence, placement of a cap, installation of a slurry wall, or stabilization/ solidification/fixation of the waste or waste residues. Under Type 5 standards, removal, decontamination, or treatment are used where appropriate to remove the principal threats at a site. The responsible party has the burden of being able to demonstrate to the satisfaction of the Director that the particular mix of removal, decontamination, treatment and/or control measures is appropriate to eliminate or abate present and future threats to human health and the environment. Institutional controls should not be substituted for active remedial measures unless such active measures are determined not to be practicable.

(b) Compliance with Type 5 standards requires long-term monitoring and maintenance, as appropriate for implemented remedial measures, plus a restrictive covenant provided in accordance with Rule 391-3-19-.08(7).

(c) Compliance with Type 5 standards requires that Type 1, 2, 3, or 4 risk reduction standards, as applicable, be met beyond the boundary of the area for which compliance with Type 5 standards are sought whenever implementation of remedial measures is complete.

(d) Remedial measures designed to achieve compliance with Type 5 standards shall be consistent with the general requirements of Rule 391-3-19-.07(10)(a) and meet all the following performance criteria:

1. Carcinogens. For carcinogens, the measures shall be expected to permanently prevent exposures which exceed the upper bound on an estimated excess cancer risk of 10-5 for individual carcinogenic substances and individual exposure pathways. The cumulative excess cancer risk for multiple carcinogenic substances and exposure pathways shall not be greater than 10-5.

2. Systemic toxicants. For systemic toxicants, the measures shall be expected to permanently prevent exposures which exceed the dose to which the human population (including sensitive subgroups) could be exposed on a daily basis without appreciable risk of deleterious effect during a lifetime. Exposures shall not exceed a hazard quotient of one or a hazard index of one. The hazard quotient is the ratio of a single systemic toxicant exposure level for a specified time period to a reference dose for that systemic toxicant derived from the same time period. The hazard index is the sum of the hazard quotients for a single or multiple systemic toxicants which affect the same target organ, or which act by the same method of toxicity through single or multiple media exposure pathways.

3. Air. The measures shall be expected to permanently assure that any emission from the contamination being addressed under these rules does not cause ambient atmospheric concentrations to exceed the lowest of the following concentrations:

(i) NESHAP and NAAQ Standards, and other applicable federal and state standards and guidelines of the USEPA and EPD.

(ii) For residential exposure conditions, concentrations that satisfy Items 1 and 2 of Rule 391-3-19-.07(10)(d) above at exposure points located both at the property boundary and within the contaminated area.

(iii) For non-residential exposure conditions, either OSHA permissible exposure limits, threshold limit values or other criteria applicable to an industrial exposure setting within the property boundary, and concentrations that satisfy Items 1 and 2 of Rule 391-3-19-.07(10)(d) at the property boundary.

4. Groundwater. At a minimum, for all Type 5 cases, free product shall be removed and/or treated to the extent practicable, including considerations such as mobility and recoverability. For groundwater contaminated with regulated substances that the responsible party demonstrates is not appropriate to remove or treat to the Type 1-4 standards, the criteria under Items (i) and (ii) below shall be met.

(i) If all source material and soil is removed, or treated to concentrations that are protective of groundwater as specified in Rule 391-3-19-.07(6)(c)1., (7)(c)1., (8)(d)1., (9)(d)1., whichever are applicable, the responsible party shall implement engineering controls, institutional controls, and monitoring for groundwater, unless the Director determines that they are not needed, to ensure:

(I) Groundwater contaminated with regulated substances in excess of the Type 1 through 4 standards will not migrate beyond the limits of the engineering controls, institutional controls and monitoring;

(II) Regulated substances in groundwater will not increase in concentration or toxicity in excess of Type 1 through 4 standards at the limits of engineering and institutional controls and monitoring; and

(III) Exposure to regulated substances in groundwater in concentrations exceeding the Type 1 through 4 standards will not occur.

(ii) If all source material and soil is not removed or treated to concentrations that are protective of groundwater as specified in Rule 391-3-19-.07(6)(c)1., (7)(c)1., (8)(d)1., or (9)(d)1., whichever are applicable, the Director may require the removal or treatment of groundwater at the hydraulically downgradient limit of the engineering controls used to control source material and soil to prevent or eliminate the horizontal and vertical migration of regulated substances in excess of the Type 1 through 4 standards beyond the hydraulically downgradient limit of such engineering controls. Beyond the engineering controls for source material and soil, the responsible party shall implement engineering controls, institutional controls and monitoring for groundwater, unless the Director determines that they are not needed, to ensure that the criteria specified in Items 4. (i)(I)-(III) above are met.

5. Soil. For soil contaminated with regulated substances at sites where a Type 5 standard is being sought, exposure area averaging using methods recognized by USEPA and approved by the Director may be used to demonstrate compliance with soil criteria derived pursuant to this section, provided the engineering and institutional controls for soil will permanently maintain exposure conditions consistent with those used to calculate such criteria.

(e) More stringent criteria may be established for a site than are specified under 391-3-19-.07(10)(d) if the Director or the responsible party determines that it is necessary to protect human health or the environment.

Notes

Ga. Comp. R. & Regs. R. 391-3-19-.07

O.C.G.A. § 12-8-90 et seq.

Original Rule entitled "Risk Reduction Standards" adopted. F. July 1, 1994. eff. July 21, 1994 Amended: F. Nov. 3, 1999; eff. Nov. 23, 1999. Amended: F. July 3, 2003; eff. July 23, 2003. Amended: F. Sep. 5, 2018; eff. Sept. 25, 2018.