ML20196L616

Draft Technical Position on Alternate Concentration Limits for U Mills,Std Format & Content Guide & SRP for Alternate Concentration Limit Applications

ML20196L616
Person / Time
Issue date:	06/30/1988
From:	NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
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ML20196L614	List: ML20196L613 ML20196L616
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RULE-PR-40-MISC NUDOCS 8807080066
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.l DRAFT TECHNICAL POSITION ON ALTERNATE CONCENTRATION LIMITS FOR URANIUM MILLS STANDARD FORMAT AND CONTENT GUIDE AND STANDARD REVIEW PLAN FOR ALTERNATE CONCENTRATION LIMIT APPLICATIONS JUNE 1988 TECHNICAL BRANCH DIVISION OF LOW-LEVEL WASTE MANAGEMENT AND DECOMMISSIONING OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS U.S. NUCLEAR REGULATORY COMMISSION 0

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DRAFT TECHNICAL POSITION ON ALTERNATE CONCENTRATION LIMITS FOR URANIUM MILLS STANDARD FORMAT AND CONTENT GUIDE AND STANDARD REVIEW PLAN FOR ALTERNATE CONCENTRATION LIMIT APPLICATIONS Section Page Number 1 REGULATORY POSITION 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Purpose of the Guidance. . . . . . . . . . . . . . . . . . 3 1.3 ACL Implementation . . . . . . . . . . . . . . . . . . . . 4 2 APPLICATION CCNTENT AND FORMAT 2.1 Application Content. . . . . . . . . . . . . . . . . . . . 8 2.2 Application Format . . . . . . . . . . . . . . . . . . . . 9 3 APPLICATION REVIEW PROCEDURES .

3.1 Areas of Review. . . . . . . . . . . . . . . . . . . . . . 13 l 3.2 Acceptance Criteria. . . . . . . . . . . . . . . . . . . . 14 3.3 Review Procedures. . . . . . . . . . . . . . . . . . . . . 26 3.4 Review Findings. . . . . . . . . . . . . . . . . . . . . . 45 l

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1. REGULATORY POSITION 1.1 Introduction Pursuant to the Uranium Mill Tailings Radiation Control Act of 1978 (UKTRCA),

the U. S. Environmental Protection Agency (EPA) promulgated Environmental Standards for Uranium and Thorium Mill Tailings at Licensed Commercial Processing Sites (40 CFR Part 192, Subparts D a:id E) on Septenber 30,1983[48 FR 45926]. These standards incorporated groundwater protection regulations previously developed by EPA under authority of the Solid Waste Disposal Act.

The incorporated regulations include provisions for establishing alternate concentration limits (ACLs) as a part of site-specific groundwater protection programs. These provisions have been subsequently incorporated into the U. S.

Nuclear Regulatory Commission (NRC's) regulations governing the disposal of uranium mill tailings (10 CFR Part 40, Appendix A) on Novenber 13,1987[52FR 43553].

The site-specific groundwater protection programs are comprised of four eleirents: (1) a list of hazardous constituents; (2) groundwater concentration limits for these constituents; (3) a location where compliance with the concentration limits is verified; and (4) a time period during which compliance is required. Concentration limits may be established as concentrations representative of background groundwater quality (background limits),

concentrations listed in Table SC of Criterion 5 of Appendix A to 10 CFR Part 40 (drinking water limits), or ACLs. Under 40 CFR Part 192.32(a)(2)(iv), NRC may approve ACLs for contaminants in groundwater provided that these concentration liniits are as low as is reasonably achievable considering practicable corrective actions, and that the contaminants will not pose a substantial present or potential hazard to human health or the environment, as long as the ACLs are not exceeded at the conipliance point.

Soon after EPA promulgated its regulations for active uranium mills in 1983, NRC and EPA staffs agreed to develop a mutually-acceptable ACL methodology for

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l establishing ACLs at uranium mills. This Technical Position provides the mutually acceptable methodolugy to review and approve ACLs at uranium mills on I a site-specific basis.

This Technical Position has been tailored for general characteristics of uranium and thorium mill tailings sites that exist or are likely to exist during the next several decades in the United States. The Position applies only to review of ACL applications for uranium and thorium mill tailings sites regulated under UMTRCA. It does not apply to reviews of ACL applications at hazardous waste management sites regulated by EPA or authorized States under Resource Conservation and Recovery Act (RCRA) or Comprehensive Environ:nental Response, Compensation, and Liability Act (CERCLA). This Positinn is based on ,

and is generally consistent with EPA's "Alternate Concentration Limit Guidance, Part 1: ACL Policy and Information Requirements," which EPA published in July 1987 for establishing ACLs at hazardous waste management sites under RCRA.

This Position provides a uniform framework for consideration of the 19 criteria ;

listed in 40 CFR Part 264.94(b) as referenced in 40 CFR Part 192.32(a)(2)(iv) I and incorporated into NRC's regulations in Criterion SB(6) of Appendix A to 10 l CFR Part 40.

i 1.2 Purpose of Guidance The purpose of this Technical Position is to establish: (1) NRC staff's interpretation of requirements for establishing ACLs in Criterion 5B(6) of Appendix A to 10 CFR Part 40; (2) standard format and content of applications for ACLs at uranium mills; and (3) NRC staff review procedures for ACL applications. This Position is intended to help licensees assemble, assess, NRC staff anticipates that EPA will formally endorse the Technical Position as a notually acceptable methodology after completing its formal agency review during the public cc ment period.

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and prepare information in the form of an application to the NRC for establishing site-specific ACLs at uranium mills. In addition, the Position describes the characteristics of an ACL application that the NRC staff would find generally acceptable under Criterion SB(6) of 10 CFR Part 40, Appendix A.

This Technical Position also provides guidance to the NRC staff about the conduct of and criteria for reviews of licensee applications for ACLs. The principal purpose of Chapter 3 is to ensure quality and unifonnity of staff l reviews and to present a well-defined basis from which to evaluate changes in l the scope and requirements of reviews. This Technical Position documents the regulatory process that the NRC staff will use to develop findings about the i acceptability of licensee applications for ACLs, thus improving public understanding about the staff review process. Although Chapter 3 of this Technical Position is intended to be used by NRC staff, it can also be used by Agreement States and other interested parties responsible for conducting reviews of ACL applications.

1.3 ACL Impler:entation ACLs may be established as part of site-specific groundwater protection standards. In accordance with NRC's requirements for uranium mills in Appendix A of 10 CFR Part 40, licensees implement detection monitoring programs to detect early release of hazardous constituents from mill tailings impoundments.

These programs progress into compliance monitoring if they indicate that constituent concentrations and parameter values exceed background concentration limits. Site-specific groundwater protection standards provide the framework for the conduct of compliance monitoring programs. These standards consist of a list of hazardous constituents, concentration limits for the hazardous constituents, a point of compliance (POC) in the uppermost aquifer, and a period of compliance.. The concentration limits are generally specified as either background concentrations or as the concentration limits selected from the table in Criterion SC of Appendix A to 10 CFR Part 40. As an. alternative to background concentrations or the limits listed in Criterion SC, licensees

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may propose ACLs for specific hazardous constituents, provided that they demonstrate that: (1) the constituents will not pose a substantial present or potential hazard to human health or the environment as long as the ACLs are not I exceeded; and (2) the ACLs are as low as reasonably achievable considering i practicable cortective actions.

Upon approval by the Commission, ACLs will be established as the concentration limits for hazardous constituents at the POC. If concentrations of hazardous constituents in groundwater exceed these limits, compliance monitoring progresses into corrective action, the third phase of the graduated groundwater monitoring and response programs at uranium mills. Licensees may not propose ACLs to delay implementation of corrective action. However, licensees may propose revised ACLs if new information indicates that the ACLs should be increased or decreased to protect humans or the environment or to maintain concentrations that are as low as reasonably achievable.

The NRC staff considers two locations in reviewing applications for ACLs at uranium mill sites: theP0Candpointsofexposure(POEs). The Introduction to Appendix A to 10 CFR Part 40 defines the POC as the site-specific location in  !

the uppermost aquifer where the groundwater protection standard must be met. l In contrast, POEs are defined for the purposes of this Technical Position as the locations where humans, wildlife, or other environmental species could reasonably be exposed to hazardous constituents from the groundwater in the uppermost aquifer. For example, humans could construct a domestic well at the POE and withdraw contaminated groundwater for consumption as drinking water.

As another example, the POE could be the locations where aquatic biota may be exposed to hazardous constituents as a result of contaminated groundwater l discharge to a river. Thus, groundwater quality at the POEs must be at levels l that are protective of potential human and environmental receptors.

The NRC staff expects that there nay be multiple plures of groundwater contaminated with hazarcous constituents and multiple POEs at uranium tailings sites. These two aspects of actual groundwater contamination contribute

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additional complexity in the establishment of ACLs. ACL applications need to consider the site-specific characteristics that significantly affect the hazards posed by hazardous constituents and the practicability of corrective l

actions. In all cases, ACLs applications must demonstrate that hazardous constituent concentrations will not pose substantial present or potential hazards to humans or the environment at the POEs, and that the ACLs are as iow as reasonably achievable considering practicable corrective actions for existing and projected groundwater contamination.

Understanding the spatial relationship between the POC and POEs is critical to implementation of ACLs at uranium mills. Natural processes such as dilution, dispersion, decay, and sorption may attentuate hazardous constituent )

concentrations between the POC and POEs. Thus, hazardous constituent concentrations nsay oe established at the POC that are greater than appropriate health and environmental concentration limits for hazardous constituents established at the POEs.

For example, the two cases depicted in Figure 1 illustrate the importance of considering the POC and POE in establishing ACLs at uranium mill tailings I sites. Both of these cases could exist at the sane site, where the migration of one hazardous constituent has been retarded relative to another constituent.

In the first case, groundwater monitoring may indicate limited contamination of I groundwater by a hazardous constituent associated with seepage from the tailings impoundment. ACLs may be established at the POC by considering attenuation of the transport of the hazardous constituent between the POC and POE. If hazardous constituent concentrations do not exceed the ACL at the P0C presently or in the future, then the licensee would not be required to imp 1 ment a carre-tive action program to attain compliance with the groundater protection s te'a rd. Compliance with the ACL at the POC would prevent substantial pa at or potential hazards to humans or the environment at the

, POE(s). However, the licensee would be required to implement corrective action if groundwater monitoring at the POC indicates that the ACLs have been l

exceeded. Such corrective action would be expected to limit the migration of

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l Figure 1 Plumes of contaminated groundwater for constituents "X" and "Y"; P0C is the point of compliance and POE is the point of exposure; groundwater flow direction is from left to right.

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the hazardous constituent above appropriate health and environmental levels to thePOE(s).

In contrast, the groundwater contaminant plume for another hazardous constituent may extend considerably downgradient from the P0C as a result of i seepage from a uranium mill tailings impoundment. In this case, the NRC staff would place special errphasis on the contaminated groundwater between the POC l and POE(s) in its review of an ACL application, to assure that the ACL prevents substantial present and potential nazards to humans and the environment at the POE(s). In this case, the ACL would be applied at the POC and downgradient from the POC, in conjunction with the corrective action program, to ensure that the ACL prevents substantial present and potential hazards to humans or the l environment, and that the ACLs are as low as reasonably achievable.

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2. APPLICATION CONTENT AND FORMAT l

2.1 Application Content Table 1 provides on outline of a generic ACL applicatic1. ACL applications shculd contain or reference sufficient information to demonstrate that: (1) hazardous constituent concentrations will not pose a substantial present or potential hazard to human health or the environment as long as the ACLs are not exceeded; and (2) ACLs are as low as reasonably achievable considering j practicable corrective actions. The demonstration should consist of an assessment of the hazards associated with present and potential exposure to hazardous constituents, and an assessment of the reasonableness of concentration limits, considering cor' active actions. The demonstration should consider the 19 factors listed in Criterion 5B(6) and in Table 2 of this Position. In general, hazard assessments should evaluaM the: (1) existing distribution and extent of hazardous constituents as well as the potential source (s) for future releases of these constituents; (2) transport of hazardous l constituents in groundwater and hydraulically-connected surface water; and (3) risks associated with exposure of humans and the environment to hazardous constituents. Corrective action assessments should include: (1) identification of alternative corrective actions; (2) assessment of the technical feasibility of alternative corrective actions; (3) assessment of the costs and benefits associated with performance of precticable corrective actions; and (4) selection of practicable corrective actions to achieve hazardous constituent concentrations in groundwater that are as low as is reasonably achievable.

Section 3.2.2 of this Position provides a more detailed description of the content of ACL applications that the NRC staff would find acceptable.

ACL applications prepared by licensees should be sufficiently detailed to permit the NRC staff to verify inocoendently that the ACLs will not pose a substantial present or potential hazard to humans or the environment and that they are as low as reasonably achievabit, considering practicable corrective actions. It is expected that much of the ;nformation required to support a 4

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successful ACL application is already available in other documents submitted in support uf the license reviews. For example, information about hydrogeologic characteristics should already be included in environmental reports, license applications, previous cetection monitoring submittals, or documents prepared by the licensees to resolve licensing issues identified by the staff.

Additional information needed to support the ACL application may include d$sessments of transport rates and directions of hazardous constituents, and effects of human and environmental exposure to hazardous ton.etituents.

The content of site-specific applications is expected to vary from site to site because of differences in site characteristics, milling processes, disposal operations, and ore composition. Licensees are encouraged to reflect these differences in the content of site-specific ACL applications. Detailed information related to each of the 19 factors listed in Criterion SB(6) of Appendix A to 10 CFR Part 40 is not necessarily required. For example, a ;

licensee may not need to consider impacts of contaminated groundwater discharge to surface water if contaminated groundwater does not and is not projected to oischarge to any surface water bodies near the facility. In this example, a licensee may not need to provide detailed information such as stream flow characteristics and transport assessments within surface water, liowever, the burden of proof resides with the licensee to demonstrate that selected factors do not need to be considered in the demonstration.

2.2 Application Format This section provides guidance about the Standard Format of ACL applications for uranium mill tailings sites. Use of a Standard Forrat for ACL applications will: (1) help assure that applications contain the information required in 10 CFR Part 40, Appendix A; (2) aid the licensee and the NRC staff in ensuring that the informaticn is complete; (3) help persons reading the application to locate information; and (4) contribute to reducing the time needed for the ACL application review process. Conformance with this format is not required. The NRC staff will accept applications with different formats if these applications

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adequately demonstrate the suitability of the proposed ACLs. However, staff  !

reviews of ACL applications with different formats may require more time, because the staff is familiar with thi Standard Format described in this section, and the staff's review procedures are based on receipt of applications in this Standard Format.

The licensee should present the information contained in the ACL application as l clearly as possible. Technical bases should support the licensee's demonstration of the adequacy of the ACLs relevant to the requirements in Criterion 5B(6) of Appendix A to 10 CFR Part 40. Licensees should follow the I numbering system and headings of the Standard Format. Licensees are encouraged i to use appendices to the application to provide supplementary information not specifically identified in this section. Conventional abbreviations should be used consistently throughout the ACL application. Any abbreviations, symbols, l or special terms should be defined where they first appear in the text. Where appropriate, calculated error bands or estimated uncertainties should be included along with numerical values. Graphic presentations such as maps, ,

graphs, drawings, and tables should be used to present information more clearly or more conveniently than text descriptions. Licensees should ensure that graphic materials are legible and that the physical scales are sufficiently l large so that details and notations can be easily read. Symbols should be l clearly defined. l ACL applications should conform to the following physical specifications: (1) i paper size should be 8 1/2 x 11 inches with larger charts and maps folded into the application so that the bound size does not exceed 8 1/2 x 11 inches; (2) ink must be sufficiently dense to record th( application on microfilm or image-copying equipment; (3) text should be single spaced and printed on both sides; (4) pages should be punched for a standard three-hole looseleaf binder;  !

(5) revisions to the application should be provided on pages that will replace j the original pages, with the changes indicated by a "change line," which is a vertical lire placed in the outside margin next to the portion of the text that was changed; (6) the date of changes and change numbers should be indicated in 1

the bottom outside margin of each change page, and each change submittal should include a listing of all pages changed in that submittal.

As noted, Table 1 provides an outline of a generic ACL application. This outline is based on the general types of information that the NRC staff considers necessary to address the two criteria and nineteen factors listed in Section 3.1. As previously discussed, however, licensees should adjust the j content of ACL demonstrations to acconnodate facility-specific characteristics.

Therefore, the format and content of ACL applications may vary somewhat because j of site-specific differences in compliance demonstrations.

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1 Table 1 Standard Format of an Alternate Concentration Limit Application at a Uranium Mill Tailings Site EXECUTIVE

SUMMARY

1. GENERAL INFORMh.i10N 1.1 Introduction 1.2 General Facility Description 1.3 Extent of Groundwater Contamination 1.4 Proposed Alternate Concentration Limits

2. HAZARD ASSESSMENT 2.1 Source and Contamination Characterization 2.2 Transport Assessment 2.3 Exposure Assessment

3. CORRECTIVE ACTION ASSESSMENT 3.1 Alternate Corrective Actions 3.2 Feasibility of Corrective Actions 3.3 Corrective Action Costs 3.4 Corrective Action Benefits 3.5 Selection of Corrective Actions 4 PROPOSED ALTERNATE CONCENTRATION LIMITS 4.1 Proposed Alternate Concentration Limits 4.2 Proposed Implementation Measures

5. REFERENCES

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3. PROCEDURES FOR NRC REVIEW 0F APPLICATIONS l

3.1 Areas of Review Based on NRC's regulations in Criterion SB(6) of Appendix A to 10 CFR Part 40, NRC staff has developed a systematic approach to review ACL applications. As components of this approach, the NRC staff has identified two major and eight minor elements of its review of ACL applications to approve or deny proposed ACLs for hazardous constituents in groundwater at uranium mill tailings sites. ,

The two major elements include:

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1. Ha:ard Assessment Review j l

l The NRC staff reviews the licensee's assessment of the: (1) existing 1 distribution and extent of hazardous constituents, as well as potential l source (s) for future releases of constituents; (2) transport of hazardous constituents in groundwater and hydraulically-connected surface water; and (3) risks associated with exposure of humans and the environment to j hazardous constituents.

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2. Corrective Action Review The NRC staff reviews the licensee's: (1) identification of alternative corrective actions for groundwater contamination; (2) assessment of the technical feasibility of the corrective actions; (3) estimated costs of practicable corrective actions; (4) estimated benefits of practicable corrective actions; and (5) selection of practicable corrective actions for controlling, reducing, mitigating, or eliminating groundwater contamination. Based on the hazard assessment and corrective action reviews, the staff evaluates the licensee's proposed ACLs and accompanying selection of measures necessary to ensure compliance with proposed ACLs.

4 3.2 Acceptance Criteria f

Upon receipt of an ACL application, the NRC staff performs an acceptance review to determine whether the types and amounts of information submitted in the application provide a sufficient basis for reviewing the proposed ACLs relative l to the requirements in Criterion 5B(6) of Appendix A to 10 CFR Part 40. If the staff concludes that the information submitted in the application is  !

insufficient, the NRC staff will return the application to the applicant and identify what additional information is necessary before the staff can begin  ;

its review. If the application contains sufficient information, the NRC staff l will accept the application and begin its review in accordance with the procedures described in this Technical Position. Acceptance of the ACL application af ter the completion of the acceptance review does not preclude subsequent requests for additional information by the NRC staff during the course of the review, 1

3.2.1 Regulatory Basis and General Criteria j l

l EPA issued standards for control of uranium and thorium mill tailings at  !

comercial, licensed mill sites (40 CFR Part 192, Subparts 0 and E) pursuant to Section 275 of the Atomic Energy Act (42 U.S.C 2022) as amended by UMTRCA, et seq. EPA standards in 40 CFR Part 192.32(a)(2)(iv) provide for the establishment of site-specific ACLs. NRC has incorporated this provision in its requirements in Criterion 5B(6) of Appendix A to 10 CFR Part 40. Criterion 5B(6)providesforestablishmentofACLsasfollows:

Conceptually, background concentrations pose no incremental hazards and the drinking water limits in paragraph SC state acceptable hazards but these two options may not be practically achievable at a specific site.

Alternate concentration limits that present no significant hazard may be proposed by licensees for Comission consideration. Licensees must provide the basis for any proposed limits including the demonstration that limits are as low as reasonably achievable considering practicable

corrective actions and information on the factors the Commission must consider. The Commission will establish a site specific alternate concentration limit for a hazardous constituent as provided in 5B(5) of this criterion if it finds that the proposed limit is as low as reasonably achievable considering practicable corrective actions, and that the constituent will not pose a substantial present or potential hazard to human health or the environment as long as the alternate concentration limit is not exceeded. In making the present and potential hazard finding, the Comission will consider the factors listed in Table 2.

To approve licensee-proposed ACLs, the NRC must find with reasonable assurance that (1) the ACLs will not pose a substantial present or potential hazard to human health or the environment as long as the ACLs are not exceeded and (2) the ACLs are as low as is reasonably achievable, considering practicable corrective actions. Successful ACL demonstrations, therefore, synthesize  ;

site-specific, regional, and generic information to demonstrate that hazardous constituents in groundwater will meet these two criteria. The ACL application should provide or reference sufficient information to allow the NRC, as an independent reviewer, to verify the demonstration used to support the proposed ACLs and to reach comparable, but not necessarily identical, conclusions. l

Table 2 Factors for Consideration in Establishing Alternate ConcentraticnLimits[10CFR40,AppendixA, Criterion 5B(6))

A. Potential Adverse Effects on Groundwater Quality

1. Physical and chemical characteristics of the waste in the licensed site including its potential for migration

2. Hydrogeological characteristics of the facility and surrounding land

3. Quantity of groundwater and the direction and rate of groundwater flow

4. Proximity and withdrawal rates of groundwater users

5. Current and potential future uses of groundwater in the area

6. Existing quality of groundwater, including other sources of contamination and their cumulative impact on groundwater quality

7. Potential for health risks caused by human exposure to waste constituents

8. Potential damage to wildlife, livestock, crops, vegetation, and physical structures caused by exposure to waste constituents

9. Persistence and permanence of potential adverse. effects B. Potential Adverse Effects on Surface Water Qual'ty

1. Volume and physical and chemical characteristics of waste in the licensed site

2. Hydrogeological characteristics of the facility and surrounding land

3. Quantity and quality of groundwater, and the direction and rate of groundwater flow 4 Patterns of rainfall in the region

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Table 2 Factors for Consideration in Establishing Alternate ConcentrationLimits[10CFR40,AppendixA, Criterion l 5B(6)](continued)

5. Proximity of the licensed site to surface waters

6. Current and potential future uses of surf ace waters in the area and water quality criteria established for those surface waters I

7. Existing quality of surface water, including other sources  ;

of contamination and their cumulative impact on surface water  !

quality

8. Potential for health risks caused by human exposure to l

waste constituents j

9. Potential damage to wildlife, livestock, crops, vegetation, and l l

physical r.tructures caustd by exposure to waste constituents

10. Persistence and permanence of potential adverse effects 1

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3.2.2 Specific Criteria 3.2.2.1 Review Element 1: Hazard Assessment Review The hazard assessment review includes three minor elements that are based on -

the 19 criteria provided in Criterion 5B(6) of Appendix A to 10 CFR Part 40.

These elements are: (1) characterizaticn of the source (s) and extent of i

. groundwatercontamination;(2)assessmentofhazardousconstituenttransportin I groundwater and hydraulically-connected surface water; and (3) assessment of  !

risks associated with exposure of humans and the environment to hazardous constituents. Information from these three elements should be synthesized into l a deconstration that the proposed ACLs will not pose a substantial present or )

potential hazard to human health or the environment as long as the ACLs are not exceeded. <

l 3.2.2.1.1 Source and Contamination Characterization l

l Characterization of the contaminant source (s) and extent of contamination provides the source term for contaminant transport assessments, which are needed to estimate the hazards associated with potential human and environmental exposure to hazardous constituents. Sourc'e characterization is acceptable if it provides reliable estimates of or conservatively limits existing and potential release rates of hazardous constituents and characterizes existing distributions of these constituents. Source i characterization includes characterization of the uranium milling facility, on-site wastes, and groundwater and soil contaminated with hazardous constituent-Facility characterization is acceptable if it includes such informetton as detailed descriptions of: (1) the eranium recovary process (es) used at the facility; (2) types and relative quantities of the reagents used in the milling process; (3) ore compositions milled at the facility; and (4) waste management practices (e.g., location of waste discharges, retaining structures for wastes,

relative amounts of wastes, and history of waste discharges). This information should be considered in conjunction with the physical and chemical composition of the waste and properties of the waste constituents, to estimate the source term for contaminant transport.

Waste characterization is acceptable if it includes such information as (1) identification of hazardous constituents in the waste, including any degradation products of the constituents; (2) assessment of the lesching potential of the hazardous constituents from the waste, described as a

! relationship between estimated aqueous concentrations of constituents and the composition of the waste; and (3) spatial distribution of hazardous constituents in the waste. Additional information may be necessary to support acceptable waste characterization depending upon the hazardous constituents present in the waste, such as: (1) physical and chemical characteristics of the hazardous constituents such as density, solubility, valence state, vapor pressure, viscosity, and octanol-water partitioning coefficient; (2) presence and effect of complexing ligands and chelating agants, to the extent that they ]

may enhance constituent mobility; (3) potential for constituents to degrade as j a result of chemical, biological, and physical processes; and (4) attentuation !

properties of constituents and affected hydrogeologic media to characterize processes as ion exchange, adsorption, absorption, precipitation, dissolution, and ultrafiltration. Waste characterization includes those characteristics that significantly influence or control the release or transport of hazardous l constituents. I l

l At sites where release of hazardous constituents has contaminated extensive volumes of groundwater, soils, sediments, or rocks, characterization of the extent of contamination should include assessment of the distribution of hazardous constituents in groundwater and contaminated soils at the facility.

This information is needed to calibrate contaminant transport models and to evaluate whether humans and environmental ' populations are currently being exposed to elevated concentrations of hazardous constituents. Characterization of the extent of contamination is acceptable if it provides such information

as: (1) the distribution of hazardous constituents in groundwater; (2) the distribution of hazardous constituents in contaminated materials other than the uranium tailings; (3) concentrations and values of indicatory water and soil quality constituents and parameters determined in the detection monitoring program, including pH, Specific Conductance, major ions, minor ions, trace constituents, uranium (natural), radium-226/228, and thorium-230; and (4) documentation of sampling, analysis, and quality assurance programs used to sample groundwater and soil, analyze the samples, and assess the distribution of hazardous constituent concentrations.

3.2.2.1.2 Transport Assessment The transport assessment provides the basis for assessing the site-specific, projected distribution of and exposure to hasardous constituents.

Characteristics of the transport assessment should be tailored to be consistent with site-specific characteristics that affect the significance and extent of hazardous constituent transport. For some aspects of the transport assessment, applicants may develop estimates that conservatively bound the magnitude of l' processes or phenomena that affect hazardous constituent transport. The transport assessment gene ally consists of the following subelements: (1) hydrogeologic characteristics: (2) groundwater flow direction and quantity; (3) rainfall patterns; (4) background water quality; and (5) estimated rates of transport and concentrations of hazardous constituents in groundwater and hydraulically-connected surface water. The information in subelements 1-4 )

should be used to estimate the rates and directions of hazarnous constituent l transport and constituent concentrations in grnundwater and hydraulically-connected surface water.

Acceptable characterizations of site hydrogeology, groundwater flow rates and directions, and rainfall patterns should consider advection of groundwater and surface water, as well as advection and dispersion of contaminants from the -

sources of contamination. The scope of hydrogeologic characterization should be commensurate with the anticipated magnitude of potential hazards associated l

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with groundwater contamination, as well as the relative distance of human and environmental populations frem existing and projected contamination.

Acceptability of hydrogeologic characterization is determined based on its completeness and adequacy to support assessment of hazardous constituent j transport. Such assessments may either provide conservative limits or reasonably likely estimates of hazardous constituent concentrations. ,

j Acceptable characterizations of site hydrogeology should generally include: l

) (1) identification of hydrogeologic units tl.at have been or may be affected by  ;

transport of hazardous constituents; (2) representative characteristics of  ;

i hydrogeologic units (including unsaturated units that may significantly influence contaminant transport) such as geometry, stratigraphy, structural geology, 11thology/ mineralogy, hydrauli.. conductivity, effective porosity, l hydraulic head distribution and gradients, recharge / discharge locations and rates, and dispersivity; (3) representative conceptual models of the ground-i water flow system that is or ray be affected by contaminant transport; (4) reliable surface water characteristics to be used in assessing-the sigr.ificance of surface water transport of hazardous constituents, such as location, volume,  !

flow rate, bed and suspended load fracticas, channel morphology, current j patterns, and hydrographic modifications; (5) representative climatic characteristics such as distributions and amounts of precipitation, potential  ;

evapotranspiration, temperature distributions, and estimated infiltration rates

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into contaminated materials, and the effects of variable recharge on ground-l water and surface water flow characteristics; (6) representative lateral and

) vertical groundwater flow rates and directions, including information such as 3

groundwater flow nets, estimated discharge and recharge rates, temporal

) variations in flow rates and directions, and the calculations and assumptions used to estimate flow rates and directions; and (7) descriptions of generally

, accepted characterization and monitoring practices, procedures, and quality j

assurance programs used to characterize site hydrogeology.

1 j Background water quality is defined as the quality of water that would be

!, expected if contamination had not occurred from the designated facility.  ;

L- _ _ .__ _ _ _ . _ - ___

Background groundwater quality should be established based on monitoring data collected at the site. Background water quality characterization is acceptable if it includes the following types of information, as appropriate: (1)mapsof sufficient detail showing the locations of background monitoring locations; (2) characteristics of background e toring s devices, including wells, springs, comunity water supplies, surf a . mr samplers, suction lysimeters, and other devices; (3) descriptions of ts !wtribution of wastes at and near the site; (4) descriptions of historical crunges in hydraulic heads, flow directions, and flow rates celevant to the location of background locations; (5) analytical background water quality dats; (6) descriptions and analysis of potential sources of off-site contamination; and (7) descriptions et general ? accepted and reliable protocols for sampling, analysis, preserva.) transportation, and quality assurance used to characterize background water quality.

Estimates of contaminant transport are based on the licensee's assessment of hydrogeologic characteristics, background water quality, extent of contamination, and sources of contaminaticn discussed previously. The objective of the hazardous constituent transport assessment is to develop conservative, but realistic, exposure estimates based on reasonable projections of contaminant concentrations in groundwater and surface water. This assessment should consider anticipated future events that may significantly perturb exposure or transport pathways and consider transfer of hazardous constituents from aqueous media to other environmental media as necessary on a site-specific basis. Transport assessments are acceptable if they include:

(1) reasonably conservative or best estimates of the rate of transport of hazardous constituents in groundwater and hydraulically-connected surface water; (2) reliable estimates of the duration of constituent migration and deterministic or statistical representation of constituent concentrations relativetodurationofexposureandconstituentcharacteristics(i.e., average daily concentrations over an exposed individual's lifetime for carcinogenic constituents, mean daily concentrations for acutely toxic constituents, and ir,ean annual concentrations for chronically toxic constituents); (3) projected temporal variability of constituent concentrations; (4) projected spatial

~

distributionofhazardousconstituents;(5)solidcompositionandwaterquality monitoring data used to validate projections of constituent transport; (6) assessments of the long-term potential for release of contaminants from the.

4. lid phase into groundwater or hydraulically-connected surface water (e.g.,

desorption); (7) characterization of the source term for hazardous constituents for groundwater and surface water transport (see Section 3.2.2.1.1); and (8)

(.omplete assessment of uncertainties associated with the projected concentrations and distributions of hazardous constituents.

3.2.2.1.3 Exposure Assessment The objective of the exposure assessment is to assess the risks associated with human and environmental exposure to hazardous constituants, to determine whether projected cencentrations of hazardous constituents pose substantial p esent or potential ha'ards to human health or the environment, and to identify maximum levels below which such hazards do not occur. The maximum allowable concentrations provide the basis for the proposed ACLs. The exposure assessment element is composed of three component asssssments: (1) resource classification and water uses, (2) evaluation of human health hazards, and (3) evaluation of erMronmental hazards.

Assessment of grourdwater and surface water uses supports the analysis of human exposure to hazardous constituents. The rigor of the human exposure analysis, in part, depends on the extent to which people are likely to use water resources that may be affected by contamination from the site. Acceptable analysis of current and future uses of groundwater and surface water includes assessment of factors as existing and anticipated water uses, such classif ;ation of water resources, institutional controls on water uses, relevant water quality standards, and tF eves n bility ed characteristics of alternative water supplies. The follow:m es of information should be included in assessments of existing and future water uses: (1) characteristics of existing water uses in the vicinity of the site (e.g., locations, types, ir. tended uses, rates of withdrawal / injection, statutory and legal constraints 1

e on water use); (2) relevant water quality criteria, standards, and guidelines; (3) classifications of groundwater resources based on EPA's Groundwater j Protection Strategy or comparable State water protection strategies; and (4) availability and characteristics of alternative water supplies and comparison i of these resources with present water supplies. Types of water uses to be f considered include agricultural, industrial, domestic / municipal, environmental, and recreational uses.

Health and environmental hazard assessments are composed of four components:

exposure pathway identification, hazard identification, dose-response assessment, and risk characterization. Acceptable hazard assessments project the response of human and environmental populations to exposure to hazardous constituents based on projected constituent concentrations, anticipated exposure pathways, and available toxicological and epidemiological information.

Hazard assessments consider two potential human exposure pathways: ingestion of contaminated water and incestion of contaminated foods (e.g., aquatic organisms or irrigated produce). Hazard assessments also evaluate inhalation and dermal exposure pathways, if these pathways could result in substantial hazards to people or the environment based on the properties of the hazerdous constituents and projected levels of exposure. The assessments distinguish l between health impacts associated with threshold' and non-threshold constituents. Mutagenic, teratogenic, and synergistic effects are considered in the analysis, if availa;1e information indicates their occurrence based on ,

toxicological testing, structure-activity relationships, or epidemiological  !

studies. Information supporting the hazard assessment justifies significant assumptions invoked in preparing the assessment and identifies uncertainties  ;

l associated with projected health and environmental impacts.

Hazard assessments also assess potential responses of environmental (non-human) populations to exposure to hazardous constituents, if such populations may reasonably be exposed to contaminated groundwater or hydraulically-connected surface water. Acceptable environmental exposure assessments consist of analyses of projected responses of terrestrial and aquatic wildlife, plants,

j livestock, and crops from estimated exposures to hazardous constituents. The ,

assessments should provide: (1) inventories of potentially exposed l environmental populations; (2) recommended tolerance or exposure limits; (3) l interactions of contaminants and their cumulative effects on exposed populations; (4) projected responses of environmental populations from exposure to hazardous constituents; and (5) anticipated changes in populations independent of exposure to hazardous constituents. Alternatively, an applicant may demonstrate that environmental hazards are not anticipated because exposure  !

to wildlife, livestock, plants, crors, and aquatic biota does not and vill not ]

occur.  !

Acceptable hazard assessments evaluate potential damage to physical structures l caused by exposure to hazardous constituents in groundwater and hydraulically-connected surface water. Such assessments examine potential exposure pathways, waste characteristics (e.g., corrosivity), environmental 1 variables that may influence damage (e.g., temperature), and structural l materials that may be exposed to hazardous constituents. Alternatively, an applicant may demonstrate that damage to physical structures is not anticipated because exposure does not and will not occur.

Acceptable hazard assessments conclude with a brief statement of the concentration limits below which hazardous constituents do not pose substantial present or potential hazards to human health or the environment. The concluding section also provides sumary descriptions of the basis for each proposed concentration limit.

3.2.2.2 Review Element 2: Corrective Action Review Acceptable assessments of corrective actions are composed of six elements, including: (1) identification of alternative corrective actions; (2) assessment of the technical feasibility of the corrective actions; (3) evaluation of the costs associated with implementation of practicable corrective actions; (4) evaluation of the benefits associated with

implementation of practicable corrective actions; (5) selection of practicable corrective actions for implementation based on appropriate optimization of the costs and benefits associated with the corrective actions; and (6) demonstration that the proposed concentration limits are as low as reasonably achievable, considering practicable corrective actions. Acceptable assessments provide supporting calculations and identify important assumptions uset in estimating the costs and benefits of alternative corrective actions.

The assessments are linked with the proposed concentration limits identified in the concluding portion of the hazards assessment section. Acceptable assessments demonstrate that ACLs will be no higher than the maximum allowable concentration limits identified in the hazards assessment. If these concentration limits are higher than the lowest concentrations that can be achieved by practicable corrective actions, the corrective action assessment considers at least three different target concentration limits that represent a reasonable range of limits that may be attained by practicable corrective actions. The assessment identifies and evaluates costs and benefits associated l with eacn set of target concentrations. Evaluation of the costs and benefits .

associated with corrective action to attain the target concentrations assures that the proposed ACLs are as low as reasonably achievable, considering practicable corrective actions.

3.3 Review Procedures l l

3.3.1 General In conducting reviews of ACL applications, the NRC staff may conduct literature surveys, data assessments, and performance evaluations as needed to audit the basis for the proposed ACLs and to verify that the proposed ACLs satisfy the two general criteria listed in Section 3.2.1, NRC staff identifies open issues that preclude approval of the proposed ACLs if reviews indicate that supporting information is ambiguous, incomplete, inadequate, or incorrect. These issues will be communicated to the licensee in the form of written comments. The

l comments document the issue, provide the basis for the staff's comment, discuss the relative significance of the comment in terms of the proposed ACLs, and suggest, if appropriate, at least one approach that the NRC staff would find acceptable to resolve the issue. In general, the staff focuses its review on information that significantly affects the selection and justification of the proposed ACLs.

3.3.2 Review Element 1: Hazard Assessment Review NRC staff reviews the hazard assessment used to suppurt ACL der .trations to ensure that the following criteria are satisfied:

1. Has the source term of hazardous constituents been adequately characterized with respect to transport assessments?

2. Have the rates and directions of hazardous constituent migration been adequately determined with respect to exposure assessments?-

3. Have the routes, amounts, and effects of human and environmental exposure to hazardous constituents been adequatel ad?

4. Do the proposed concentration limits for hazardous constituents ensure prevention of substantial present or potential hazards to hurnans and the environment?

3.3.2.1 Source Term Characterization The reviewer evaluates information relevant to the characterization of the source term of hazardous constituents as necessary to support the transport assessment. Source term includes existing contaminated groundwater, contaminated soils, and tailings and other wastes that may cause future.

releases of hazardous constituents. Based on the adequacy of this information, the reviewer determines whether source term characterization is sufficient to

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l provide a conservative or realistic estimate of the types, characteristics, and .

release rates of hazardous constituents that have been or are anticipated to be released from contaminated groundwater, soils, and tailings at a given facility.

The reviewer will ensure that the demonstration: (1) identifies hazardous constituents present in the tailings or in leachate derived from the tailings; i (2) identifies hazardous constituents potentially derived from the degradation or reaction of waste constituents; (3) identifies the extent and characteristics of contaminated groundwater and soils; (4) characterizes the properties of the hazardous constituents that affect their transport and fate in the environment surrounding a facility; and (5) estimates release rates of hazardous constituents as a function of time and space, as appropriate.

Adequacy of the demonstration is reviewed with respect to the source term required in the assessment of contaminant transport rates and directions.

The reviewer assesses: information on the extraction process used at the facility to recover uranium; the relative amounts and types of reagents used in the extraction process; composition of ores; likely chemical and l l

biologically-mediated reactions within the tailings; transport characteristics of the hazardous ccnstituents (e.g., solubility, sorption / desorption, complexation, degradation information); leachability of dissolved and solid species present within the tailings; total volume of waste materials at the facility; physical characteristics of the waste materials as they would affect leaching potential, composition and distribution of uranium tailings and contaminated soils; composition and distribution of contaminated groundwater; .

and the leaching characteristics of the waste materials, considering both the duration of leaching and magnitude of leached concentrations. The reviewer may also assess information about characteristics such as volatility, octanol-water partitioning coefficient, viscosity, degradation rate constants, and density, if these properties may significantly affect transport or toxicity of hazardous constituents. Based on this assessment, the reviewer either confirms the licensee's characterization of the source term or determines that the source I

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term has not been conservatively or realistically characterized with respect to hazardous constituent transport assessment.

3.3.2.2 Rate and Direction of Transport In reviewing the adequacy of the licensee's determination of the rate and direction of hazardous constituent transport in groundwater, the reviewer verifies the licensee's characterization of: (1) site hydrogeology; (2) rate and direction of hazardous constituent transport in groundwater and surface water; and (3) rainfall patterns near the facility as they may affect transport of hazardous constituents. The reviewer also verifies the licensee's characterization of background water quality to support assessment of existing and potential future uses of water resources.

In reviewing the licensee's characterization of the rate (s) and direction (s) of hazardous constituent transport, the reviewer determines whether the hydrogeologic characterization of the site is adequate to support assessments and conclusions about the projected extent and distribution of hazardous constituents. The scope of the staff review includes consideration of site-specific and regional (i.e., beyond the imediate zone of influence of the 1 facility) information on the physical and hydrogeologic characteristics of groundwater and surface water systems, as appropriate. The reviewer determines whether the licensee's hydrogeologic characterization employed accepted and defensible practices, techniques, methods, and approaches supporting the l determination of transport rates and directions. The reviewer also evaluates:

(1) anticipated and potential changes in transport rates and directions caused by reasonably foreseeable events; and (2) historic changes in transport rates and directions that may have been caused by the construction or operation of the facility. The reviewer also confirms assessments of the effects of existing and likely distributions of rainfall at and around the facility to the extent that such patterns may significantly affect transport rates and directions. This assessment includes consideration of: temporary increases in recharge into waste materials; effects on releases of hazardous constituents;

changes in the location of recharge and discharge of groundwater systems; and modifications to surface water-groundwater relationships.

The reviewer verifies assessments of the transport of hazardous constituents in groundwater. This review includes evaluation of hazardous constituent ,

transport in surface water, if contaminated groundwater discharges or is l projected to discharge to surface water. The reviewer determine:; whether estimated hazardous constituent concentrations and projected distribution of hazardous constituents are best estimate or reasonably conservative representations of the rate, extent, and directior, of constituent transport based, in part, on the existing distribution of constituents in contaminated groundwater. The reviewer confirms that all likely and significant pathways of constituent transport in groundwater and surface water have been identified and adequately assessed with respect to estimating conservative or realistic effects caused by human or environmental exposure to hazardous constituents.

In addition, the reviewer verifies that the assessments used to estimate I

constituent transport are appropriate for use in support of regulatory decisions. For best estimate projections, the reviewer confirms that the projections have been sufficiently validated and calibrated based on available site-specific information. The reviewer confirms that temporal and spatial estimates of hazardous constituent concentrations are adequate to support assessments of the risks of human and environmental exposure to the constituents.

The reviewer evaluates information relevant to the establishment of background water quality at facilities, including, but not limited to, water quality data, facility characteristics, protocols ased to establish background concentrations, vicinity characteristics, and conceptual and analytical hydrogeologic models. Based on the adequacy of this information, the reviewer determines whether the assessment reasonably characterizes the background quality of groundwater and surface water that has been or may be impacted by the facility. Establishment of background water quality may be complicated at sites where existing or potential water contamination may affect water quality

j in several aquifers or water bodies. The reviewer determines whether the I assessment establishes background water quality for each aquifer potentially affected by water contamination, and for surface water bodies that are l hydrculically connected with hydrogeologic units that are downgradient from the facility.

At sites where water samples representative of background quality cannot be collected (e.g., where entire aquifers are contaminated by seepage of tailings leachate), the reviewer evaluates (1) the licensee's justification for not characterizing background quality and (2) the licensee's assessment that proposes reasonably conservative concentration and value estimates for appropriate water quality constituents and parameters. The reviewer evaluates site and facility information and either confirms the determination of background water quality or determines that the estimates are not reasonably conservative. The reviewer ensures that estimates of background water quality are sufficient to support analyses of potential us. of water resources and adverse effects associated with human and environmental exposure to hazardous constituents that may be transported in the groundwater and surface water.

3.3.2.3 Exposure Assessment Based on the confirmed characterizations of the source term and rates and I directions of hazardous constituent transport, the reviewer evaluates the l assessment of the risks associated with human and environmental exposure to' hazardous constituents. The scope of the assessment includes characterization of existing and potential uses of water resources that may be affected by the facility, evaluation of human and environmental exposure to hazardous constituents, and essessment of the permanence and persistence of any adverse effects associated with exposure.

The reviewer determines whether the characterization of exposure pathways is adequate with respect to relevancy, completeness, reliability, and accuracy of input to the assessments of human and environmental exposure to hazardous

constituents. The scope of this characterization includes quantitative and/or qualitative description of physical and biological pathways of constituent transport via groundwater and surface water to exposed populations. The reviewer confirms the licensee's identification and characterization of l sensitive human and environmental populations. The reviewer also confirms that I sensitive populations have been adequately considered in the exposure assessment. The reviewer determines whether the assessment adequately characterizes physical and biological exposure pathways. The reviewer verifies that the licensee has at least assessed the following two pathways in assessing human exposure: drinking water ingestion and ingestion of contaminated food products.

Based on the confirmed characterization of exposure pathways, the reviewer verifies the licensee's assessment of adverse effects associated with present and potential human exposure to hazardcus constituents. The scope of the huraan exposure assessment includes: (1) classification of affected water resources; (2) assessment of existing and potential uses of water resources; (3) evaluation of the likelihood that people will be exposed to hazardous constituents; and (4) evaluation of adverse effects associated with exposure to hazardous constituents, including assessment of the permanence and persistence ,

of adverse effects. l l

3.3.2.3.1 Resource Classification and Water Use The reviewer assesses the classification of water resources at the facility and the existing and potential uses of these water resources. The reviewer confirms that the licensee considers the following uses of surface water and groundwater in the area surrounding the facility: domestic and municipal drinking water, fish and wildlife propagation, industrial, agricultural (livestock watering and irrigation), recreation, and special ecological cortmunities. The reviewer verifies the licensee's: (1)assessmentofexisting and potential uses of water resources; (2) assessment of potential and safe yields of water resources in relation to requisite supply rates; (3) evaluation

i of the relative costs for development of water resources for beneficial uses; and (4) assessment of legal, statutory, or other administrative constraints on use and development of the water resources. The reviewer assesses the licensee's evaluation of existing and potential water uses for both surface water and groundwater. The reviewer verifies that the licensee's assessment of existing and potential uses of water at the facility is generally consistent with evaluations prepared by Federal, State, and local governmental organizations (e.g., State water well inventories, U.S. Geological Survey (USGS) summary appraisals of groundwater resources, state water use sunnary reports). The reviewer confirms that the evaluation of water uses provides an adequate basis on which to assess existing and potential human and environmental exposure to hazardous constituents.

The reviewer ensures that the assessment conservatively estimates the probability of human exposure to contaminated water. Such estimates are often difficult to establish quantitatively, so defensible qualitative estimates may suffice in lieu of quantitative determinations. Examples of such qualitative dete-hations include the following:

(1) Reasonably lihely - exposure has or could have occurred in the past, or available information indicates that exposure may reasonably occur during the duration of the contamination; and (2) Reasonably unlikely - exposure could have occurred in the past, but will probably not occur in the future, because initial incentives for water use have been removed, or available information indicates that no incentives for water use are currently identifiable, based on foreseeable technological developments.

Review of qualitative determinations of exposure probability considers existing and potential water uses and comparison of background water quality with appropriate water quality criteria. In general, the reviewer considers existing and potential uses of water resources that may be affected by the

facility. Existing use may include past use, even though water resources are i not presently being used. Potential uses include anticipated and possible uses. Anticipated water use includes only those uses that are reasonably sure l

to occur. Possible uses are those that are compatible with background water l quality without water treatment before use.

In reviewing long-term water use, the reviewer also considers aquifer classifications consistent with EPA's Groundwater Protection Strategy (August 1984) and the "Guidelines for Groundwater Classification under the EPA Groundwater Protection Strategy" (December 1986). The reviewer assumes that exposure is li kely to occur for Class I groundwaters, unless the licensee demonstrates that exposure to people using the Class I groundwater is impossible. The reviewer considers potential uses of Class II groundwaters, but such uses are not considered for Class III groundwaters, unless they l currently supply water for beneficial purposes.

1 The reviewer confirms the assessment of existing and anticipated uses of water l by comparing background water quality with relevant Federal, State, and local wate.' quality standards. Appropriate water quality standards are selected for comparison based on background water quality, existing and potential water l uses, and legal considerations. When standards are inconsistent, the most stringent criteria prevail, unless the licensee demonstrates that less stringent standards preempt the more stringent criteria, based on legal or ,

technical arguments. In addition to information provided in the assessment, the reviewer may assemble and consider information on water use from such organizations as local water supply companies or agencies, regional water comissions, State and Federal agencies, and local water users. In addition, the reviewer considers water use based on demography of the facility vicinity, demographic projections, zoning patterns, and average and maximum projected estimates of population growth.

The reviewer generally assumes that the most significant pathway for human exposure to waterborne contaminants is through consumption of contaminated

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drinking water, unless scoping assessments indicate that other exposure pathways (e.g., dermal contact, inhalation, food ingestion) may be of equal or greater significance. Consistent with this assumption, the reviewer classifies the water resources in accordance with EPA's Groundwater Protection Strategy (August 1984). The reviewer further classifies Class II groundwater as either Class A or B resources in support of the exposure assessment. As an initial approach, the staff considers that Class A resources have a mean annual total dissolved solids (TDS) concentration less than 3,000 mg/l in water representative of background quality. Class B resources are defined os aquifers or surface water bodies in which the mean annual TDS concentration equals or exceeds 3,000 mg/l in water representative of background quality.

However, the reviewer may determine whether the water is Class A or B, on a l site-specific basis, by considering concentrations of other constituents that affect human exposure to hazardous constituents. l l

For class A resources, the reviewer assumes that humans withdraw water from l affected aquifers and/or surface water bodies at any point beyond the site boundary in the direction that is hydraulically downgradient from the facility. l This assumption applies for Class A resources regardless of whether water l resources are currently being used. For class B resources, the reviewer i evaluates adverse effects on human health due to exposure to hazardous constituents considering the location (s) and purpose (s) of the nearest, downgradient, existing or potential water use. In, general, the reviewer does not consider evaluation of human health effects due to exposure from the use of Class III groundwater resources (EPA's Groundwater Protection Strategy) and water resources with background 'nean annual TDS concentrations in excess of 10,000 mg/1, unless such an evaluation is warranted because of existing or anticipated uses.

3.3.2.3.2 Evaluation of Health Hazards The reviewer determines whether the licensee's assessment provides reasonably l conservative or best estimates of potential health effects caused by human l _

exposure to hazardous constituents associated with existing or potential uses of wat9r resources. This determination is based on comparisons of existing and projected constituent concentrations with appropriate exposure limits and dose-response relationships from available literature. The reviewer confirms i that the licensee considers Maximum Contaminant Levels (MCLs) for drinking  !

water, referenes doses (RfDs), or risk specific doses (RSDs) in assessing i poten*ial health hazards for each hazardous constituent for which an ACL is l 1

proposed. In the absence of applicable MCLs, RfDs, or RSDs, the reviewer confirms that the licensee has assessed dose-response relationships for the constituents, based on comprehensive literature searches or toxicological research. The reviewer verifies that the exposure analysis distinguishes between threshold (toxic) and non-threshold (carcinogenic) effects associated with human exposure. The reviewer also verifies that the licensee. considers other adverse effects such as teratogenic, fetotoxic, mutagenic, and l

synergistic effects, based on available information. l The RfDs discussed above are amounts of toxic constituents to which humans can be exposed on a daily basis without suffering any adverse effect. RSDs characterize the potency of carcinogenic constituents or suspected / potential carcinogens. RSDs are amounts of constituents to which humans can be exposeo on a daily basis without increasing their risk of contracting cancer above a I specified risk level. RSDs and RfDs for most hazardous constituents in uranium mill tailings can be obtained from EPA. Both of these types of values are calculated based on laboratory testing and/or epidemiological research. I n' reviewing the RfDs and RSDs selected by the licensee, the reviewer verifies that the licensee assumes a human mass of 70 kg and consumption of 2 liters of drinking water per day, unless sensitive populations are likely to be exposed to the hazardous constituents. The reviewer also confirms that the licensee's assessment assumes reasonable exposure to hazardous constituents via pathways other than ingestion of drinking water (e.g., consumption of food containing thehazardousconstituent). The reviewer confirms that the licensee adequately characterizes for sensitive populations the exposure variables that significantly influence the adverse effects due to hazardous constituent

exposure. In calculating the RSDs, the reviewer confirms that the licensee has used an appropriate risk level. In general, risk levels of the order of IE-6 lifetime risk associated with exposure should be assumed. The reviewer confirms the licensee's selection and justification of an alternate risk level in the range of 1E-4 to IE-7 considering: (1) facility-specific considerations that influence the likelihood of human adverse effects associated with exposure; (2) other environmental health factors borne by the affected population; and (3) uncertainties associated with the data and assessments used to evaluate potential adverse effects.

The reviewer will ensure that the licensee considers the cumulative effects of human exposure to hazardous constituents. The reviewer verifies that the licensee's assessment evaluates effects associated with exposure to hazardous constituents for which ACLs are proposed and other constituents present in contaminated groundwater. As a minimum, the reviewer confirms that the licensee uses an additive approach in assessing adverse effects associated with exposure to constituents that produce the same adverse effects by similar toxicological mechanisms.

The reviewer confirms that the licensee identifies and adequately justifies a maximum allowable human exposure level for each ACL constituent. The reviewer verifies that the justifications for the maximum exposure levels identify uncertainties inherent in estimating the risk of adverse exposure to constituents. The reviewer verifies that the licensee considers the persistence and permanence of adverse effects on people. The reviewer l determines whether the proposed human exposure levels are reasonably conservative, defensible, and sufficiently protective of human health to avoid i a substantial present or potential hazard to people for the estimated duration l of the contamination.

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l 3,3.2.3.3 Evaluation of Environmental Hazards Similar to the review of human health effects, the reviewer verifies the licensee's assessment of risks associated with hazardous constituent exposure to environmental populations. The scope of the review includes consideration j of adverse effects to aquatic and terrestrial wildlife, plants, agricultural crops and animals, and physical structures. The reviewer verifies that the assessment especially considers potential adverse effects on endangered species and critical aabitats. The reviewer confirms that the eyeluation adequately identifies endangered species and critical habitats by consulting with appropriate organizations within the U.S. Fish and Wildlife Service. The i reviewer confirms that the assessment adequately identifies and evaluates adverse effects such as contamination-induced biotic changes, loss or reduction of unique or critical habitats, and jeopardization of endangered species. The reviewer also confirms that the assessment is adequate with respect to relevancy, completeness, reliability, and accuracy to justify maximum allowable environmental exposure levels.

For each potential exposure pathway, the reviewer compares existing and predicted constituent concentrations with chronic toxicity levels for plants and anirnals. The reviewer may cor. sider acute and subchronic effects, when warranted, based on estimated constituent concentrations and limits for acute and subchronic environmental exposure. For physical structures, such as foundaticns, underground pipes, and roads, the reviewer ensures that estimated constituent concentrations will act result in any substantial degradation or l

loss of function as a result of exposure to the contamination. The reviewer verifies that the licensee's assessment adequately identifies all environmental ]

species or representative groups of species and physical structures that may reasonably be exposed to contaminated groundwater and hydraulically-connected surface water, as appropriate. The reviewer confirms that the assessrrent adequately identifies and assesses potential adverse effects associated with environmental exposure to hazardous constituents and other constituents that may be present in contaminated water.

• ~ .

In reviewing adverse effects, the reviewer ensures that bioaccumulation and food web interactions are adequately considered, based on available literature.

For effects on aquatic wildlife, the reviewer confirms that estimates of water i 1

dilution potential are reasonably conservative with respect to maximizing potential constituent concentrations and environmental exposures. The reviewer l generally evaluates aquatic wildlife effects by comparing estimated constituent concentrations with appropriate Federal and State water quality criteria. The reviewer ensures that the licensee considers terrestrial wildlife exposure to constituents via direct exposure and food web interactions. At sites where terrestrial wildlife may be exposed to hazardous constituents, the reviewer confirms that the assessment adequately identifies and assesses dominant terrestrial habitats in the vicinity of the facility, and that community

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diversity assessments of these habitats includa consideration of species j richness and community structure. The reviewer confirms the licensee's characterization of terrestrial habitats based on comparisons with representative background data.

Review of agricultural effects considers both direct and indirect exposure pathways, including crop impacts, reduced productivity, and bioaccumulation of constituents. Similar to the review of aquatic wildlife effects, the reviewer compares reasonably conservative estimates of' constituent concentrations with relevant Federal and State water quality criteria and literature values to estimate agricultural effects associated with constituent exposure. The .

I reviewer verifies that the assessment considers crop exposure via contaminated soil, shallow groundwater uptake, and irrigation. The reviewer also verifies 1

that the assessment considers livestock exposure via direct ingestion of contaminated water and indirect exposure via foraging and grazing. The reviewer ensures that the agricultural assessment is consistent with any assessment of human exposure to hazardous constituents via ingestion of contaminated food products.

For both human and environmental hazard assessments, the reviewer confirms that the assessment provides an reasonably conservative or best-estimate basis for

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establishing ACLs to prevent substantial present and potential hazards associated with exposure of people and the environment to hazardous constituents.

3.3.3 Review Elemert 2: Corrective Action Review In conjunction with the NRC staff hazard assessment review, the staff reviews the licensee's assessment of the need for and selection of corrective actions.

The scope of the evaluation includes previous, ongoing, and future corrective actions. The reviewer determines whether the licensee adequately demonstrates that the proposed ACLs are as low as reasonably achievable, considering practicable corrective actions. The scope of the demonstration includes identification of alternative corrective actions, assessment of the technical feasibility of these actions, evaluation of the costs and benefits associated with implementation of feasible corrective actions, and selection of practicable corrective actions, based on a comparison of the costs and benefits of feasible corrective actions for contaminated groundwater.

The NRC staff reviews the corrective action assessment used to support ACL demonstrations to ensure that the following criteria are satisfied:

1. Have a relatively complete set and range of alternative correctiva actions been identified?

2. Does the assessment adequately identify feasible corrective actions that are appropriate to reduce hazardous constituent concentrations in contaminated groundwater at the site?

3. Have the corrective act' as been designed adequately to optimize their effectiveness in reducing hazardous constituent concentrations and to mitigate potential hazards that may be associated with their implementation?

4. Does the assessment provide an objective comparison of the costs ana benefits associated wits the performance of feasible corrective actions?

5. Does the assessment demonstrate that the proposed ACLs are as low as reasonably achievable, considering practicable corrective actions?

The reviewer verifies that the assessment identifies and assesses a reasonable range of corrective actions and that these actions have been designed to optiinize their effectiveness in protecting people and the environment. The reviewer confirms that optimization calculations provide representative approximations of the perfonnance of the affected hydrogeologic system. The reviewer also ensures that the set of corrective actions represents a reasonable range of actions that are appropriate to reduce, control, mitigate, or eliminate water contamination.

After reviewing the identification of a range of corrective actions, the reviewer verifies the licensee's assessment of the technical feasibility of implementing these actions. P,eviews of the technical feasibility vary, based on site-specific considerations, such as hydrogeologic characteristics, extent of contamination, and potential for human and environmental exposure. The reviewer verifies the feasibility assessment based on the hydrogeolopic characterization and hazard assessment reviewed under Review Element 1 and the

)ptimization calculations discussed above. The reviewer confirms that the licensee's feasibility assessment is also based on proven applications of corrective action techniques and methods at other contaminated sites with similar characteristics. The reviewer ensures that the assessment considers combinations of corrective action measures, including natural restoration, where appropriate. The reviewer confirms that the licensee identifies a range of feasible corrective actions, based on the assessment.

The reviewer determines whether corrective actions have been designed to optimize their effectiveness in reducing hazardous constituent concentrations and to mitigate hazards associated with their implementation. The reviewer

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confirms that conceptual designs of the corrective actions are sufficiently detailed to implement the corrective actions upon selection. The scope of the review varies based on the: selection of feasible corrective actions; characteristics of the affected hydrogeologic system; probability of human and environmental exposure; and potential hazards associated with exposure. For example, the review of a corrective action that includes a slurry wall would include confirmation of: (1) the compatibility of the wall with anticipated geochemical conditions; (2) barrier wall composition and mixture ratios; (3) design specifications; (4) methods of determining the effectiveness of the slurry wall; (5) method of trench excavation and wall construction; (6) contact with :.djacent confining beds; (7) hydraulic properties and geochemical characteristics; (8) projected changes in the hydrogeologic system caused by wall construction; and (9) contingency measures. For an aquifer restoration program, the reviewer would confirm such design aspects as: (1) the characteristics of contaminated water treatment techniques; (2) installation and construction of withdrawal and injection wells or trenches; (3) projected performance of the restoration system; (4) pumping rates and ' locations; (5) disposal of treatment wastes (both liquid and solid); (6) characteristics of l the treatment wastes; (7) methods of determining restoration effectiveness; (8) '

restoration target levels; (9) estimated duration of restoration, (10) the l monitoring program during restoration; a'nd (11) contingency measures.

The reviewer confirms that corrective action programs can effectively enhance protection of the public and environment from hazardous constituents in water, which includes confirmation that: (1) the actions are reasonable (i.e.,

actions are appropriate and achievable at the facility); and (2) the actions are specific, clearly documented, and designed such that their implementation and the results of their implementation can be verified through subsequent field observations.

The reviewer confirms that performance of the feasible corrective actions complies with relevant Federal, State, and local regulations and statutes. A comitment by the licensee to comply with these provisions satisfies the

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reviewer's responsibilities, unless the reviewer is aware of other regulations -l or provisions that have not been specifically identified. In this case, the omitted regulations will be identified through the commenting process.

Authority for determining compliance with all such regulations and statutes resides with the agency or administrative body charged with implementing these regulatory programs (e.g., the or authorized State for the National Pollutant Discharge Elimination System (NPDES) program).

The reviewer confirms that the direct and indirect benefits of performing the corrective actions have been objectively compared with the costs of such l actions. Adequacy of the cost estimates is based on completeness and accuracy of cost asses ment, including consideration of such components as: capital costs for implementation; operation and maintenance costs for continued operation; and depreciation and discount modifications to projected costs.

Adequacy of the benefits assessment is evaluated on a similar basis, considering such benefits as: avoidance of adverse health effects; protection and recovery of the value of contaminated groundwater resources; prevention of land value depreciation; benefits accrued directly from performance of the corrective action; and other benefits realized by avoiding adverse environmental effects identified in the hazard assessment under Review Element 1.

The reviewer verifies estimates of the current and projected value of contaminated water resources by first confirming that the resources have been identified and appropriately valued in the licensee's assessment. The reviewer confirms that the estimates are reliable, based on information such as:

appropriated water rights; costs of bottled water; availability of alternative water supplies; and projected water use demands. The reviewer generally considers the value of potentially contaminated water resources to be equal to either: (1) the product of the safe yield of the water resources and the unit cost of supplied water for its intended purpose (e.g., cost of potable water for domestic or municipal drinking water supplies); or (2) the cost of supplied water to replace the contaminated resources. The reviewer determines whether

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proposed alternate water supplies would be adequate to replace contaminated l supplies considering the availability and characteristics (e.g., capital and )

operational costs, suppliable rates, .and quality) of alternative supplies. The absence of alternative supplies on a local or regional scale increases the relative value of potentially contamina!.ed d er resources.

The reviewer assesses the adequacy of the licensee's consideration of practicable corrective actions and demonstration that proposed ACLs are ts low l l

as reasonably achievable. The reviewer confirms that the assessment provides a reasonable balance between the cost of the corrective actions and the societal, environrental, and economic benefits to be accrued in the imediate future and over the long-term through performance of the corrective actions. The reviewer considers relevant guidance such as the as low as reasonably achievable philosophy in Appendix I to 10 CFR Part 50, National Council on Radiation Protection and Measurements Report Number 39, and International Comission on Radiological Protection Publication 22. The reviewer verifies that the licensee's assessment demonstrates that the propost.d ACLs are as low as reasonably achievable, considering practicable corrective action. 1

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. l 3.4 Review Findings if the licensee's ACL application satisfies the acceptance criteria ano the NRC staff's review confirms the basis for the proposed ACLs, the reviewer concludes l I

that the demonstration provides reasonable assurance of compliance with NRC's requirement in Criterion SB(6) of Appendix A to 10 CFR Part 40. Based on this conclusion, the reviewer recommends approval of the site-specific alternate concentration limits for the constituents requested by the licensee. The reviewer documents the recomendation, provides the technical basis for the recomendation, and concludes the reconnendation as follows:

Based on NRC staff review of the alternate concentration limits (ACLs) proposed by [specify naine of licensee] on [specify date] in accordance with Criterion 5B(6) of Appendix A to 10 CFR Part 40 for [specify name and locction of facility], the staff recomends that ACLs be established for

[specify hazardous constituent (s)] in groundwater at this facility because (1) the proposed ACLs will not pose a substantial present or potential hazard to human health or the environinent as long as constituent concentrations do not exceed the ACLs, and (2) the proposed ACLs are as low as reasonably achievable considering practicable corrective actions.

The reviewer may also recomend establishing ACLs for only those constituents for which the licensee's demonstration is sufficient to sa tisfy NRC's requirement in Criterion SB(6) of Appendix A to 10 CFR Part 40. In this case, the reviewer would docuinent the recommendation as above and include a description of the ACLs proposed by the licensee that were not reconnended for establishment. Such descriptions shuuld list the unapproved ACLs, cite specific inadequacies that caused the licensee's demonstration to fail for selected constituents, describe the technical basis for the review conclusions, and identify alternative technical approaches that the NRC staff finds acceptable to resolve the inadequacies, if appropriate.

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. 1 If the reviewer concludet that the licensee's demonstration fails to demonstrate compliance with Criterion SB(6) of Appendix A to 10 CFR Part 40, then the reviewer documents the basis for failure, cites specific inadequacies that caused the demonstration to fail, describes the technical basis for the review conclusions, and identifies alternative approaches for the licensee to  ;

resolve the inadequacies, if appropriate. I In addition, documentation of recommendations for or against establishment of ACLs identify: (1) aspects of the 'CL review that were particularly emphasized; (2) deviations of the review from the review criteria and procedures detailed in this technical position; (3) justifications for these deviations; and (4) any conclusions that require confirsatory monitoring or surveillance to ensure consistency with assumptions invoked in support of the ACL demonstration.  ;

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