Compare Document – Pre and Post E.O. 12866 Review 

ENVIRONMENTAL PROTECTION AGENCY 6560-50-P

40 CFR Part 192

[EPA-HQ-OAR-2012-0788; FRL-9909-20-OARXXXX-X]

RIN 2060-AP43

Health and Environmental Protection Standards for Uranium 

and Thorium Mill Tailings

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

___________________________________________________________

SUMMARY: The Environmental Protection Agency (EPA) is 

proposing to add new health and environmental protection 

standards to regulations promulgated under the Uranium Mill 

Tailings Radiation Control Act of 1978 (“UMTRCA” or “the 

Act”). The proposed standards will regulate byproduct 

materials produced by uranium in-situ recovery (ISR),

including both surface and subsurface standards, with a 

primary focus on groundwater protection, restoration and 

stability. ISR has a greater potential to directly affect 

groundwater than does conventional milling. Therefore, by 

explicitly addressing the most significant hazards

represented by ISR activities, these proposed standards are 

intended to address the shift toward ISR as the dominant 
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form of uranium recovery that has occurred since the 

standards for uranium and thorium mill tailings were 

initially promulgated in 1983. The general standards 

proposed today, when final, will be implemented by the 

Nuclear Regulatory Commission (NRC). This action also 

proposes to amend specific provisions in the current Health 

and Environmental Protection Standards for Uranium and 

Thorium Mill Tailings rule to address a ruling of the Tenth 

Circuit Court of Appeals, to update a cross-reference to 

another environmental standard and to correct certain 

technical and typographical errors that have been 

identified since the 1983 promulgation. 

DATES: Comments must be received on or before [INSERT DATE 

90 DAYS AFTER PUBLICATION IN THE FEDERAL REGISTER.], 90

days after publication in the Federal Register. ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-HQOAR-2012-0788, by one of the following methods:

 www.regulations.gov: Follow the on-line instructions 

for submitting comments.

 Email: a-and-r-docket@epa.gov

 Fax: 202-566-9744

 Mail: Air and Radiation Docket, Environmental 

Protection Agency, Mailcode: 2822T, 1200 Pennsylvania 
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Ave., NW, Washington, DC 20460. 

 Hand Delivery: EPA West Building, Room 3334, 1301 

Constitution Ave., NW Washington, DC 20004. Such 

deliveries are only accepted during the Docket’s 

normal hours of operation; special arrangements should 

be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPAHQ-OAR-2012-0788. EPA's policy is that all comments 

received will be included in the public docket without 

change and may be made available online at 

www.regulations.gov, including any personal information 

provided, unless the comment includes information claimed 

to be Confidential Business Information (CBI) or other 

information whose disclosure is restricted by statute. Do 

not submit information that you consider to be CBI or 

otherwise protected through www.regulations.gov or e-mail. 

The www.regulations.gov website is an “anonymous access” 

system, which means EPA will not know your identity or 

contact information unless you provide it in the body of 

your comment. If you send an e-mail comment directly to EPA 

without going through www.regulations.gov, your e-mail 

address will be automatically captured and included as part 

of the comment that is placed in the public docket and made 

available on the Internet. If you submit an electronic 
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comment, EPA recommends that you include your name and 

other contact information in the body of your comment and 

with any disk or CD-ROM you submit. If EPA cannot read your 

comment due to technical difficulties and cannot contact 

you for clarification, EPA may not be able to consider your 

comment. Electronic files should avoid the use of special 

characters, any form of encryption, and be free of any 

defects or viruses. For additional information about EPA’s 

public docket visit the EPA Docket Center homepage at 

http://www.epa.gov/epahome/dockets.htm.

Docket: All documents in the docket are listed in the 

www.regulations.gov index. Although listed in the index, 

some information is not publicly available, e.g., CBI or 

other information whose disclosure is restricted by 

statute. Certain other material, such as copyrighted 

material, will be publicly available only in hard copy. 

Publicly available docket materials are available either 

electronically in www.regulations.gov or in hard copy at 

the Office of Air and Radiation Docket, EPA/DC, EPA West, 

Room 3334, 1301 Constitution Ave., NW, Washington, DC. The 

Public Reading Room is open from 8:30 a.m. to 4:30 p.m., 

Monday through Friday, excluding legal holidays. The 

telephone number for the Public Reading Room is (202) 566-
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1744, and the telephone number for the Air and Radiation 

Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Ingrid RosencrantzAndrea 

Cherepy, Office of Radiation and Indoor Air, Radiation 

Protection Division, Mailcode 6608T6608J, U.S. 

Environmental Protection Agency, 1200 Pennsylvania Ave., NW 

Washington, DC 20460; telephone number: 202-343-92869290;

fax number: 202-343-2304; email address:

Rosencrantz.ingridcherepy.andrea@epa.gov.

EXECUTIVE SUMMARY: The Environmental Protection Agency 

(EPA) is proposing to add new health and environmental 

protection standards to regulations promulgated under the 

Uranium Mill Tailings Radiation Control Act of 1978 

(“UMTRCA” or “the Act”). The proposed standards will 

regulate byproduct materials produced by uranium in-situ 

recovery (ISR), including both surface and subsurface 

standards, with a primary focus on groundwater protection, 

restoration and stability. ISR has a greater potential to 

directly affect groundwater than does conventional milling. 

Therefore, by explicitly addressing the most significant 

hazards represented by ISR activities, these proposed 

standards are intended to address the shift toward ISR as 

Commented [UEUoC1]: Added per interagency review.
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the dominant form of uranium recovery that has occurred 

since the standards for uranium and thorium mill tailings 

were initially promulgated in 1983. The legal authority for 

this action is in Section 275 of the Atomic Energy Act 

(AEA) of 1954, as amended by Section 206 of the Uranium 

Mill Tailings Radiation Control Act (UMTRCA) of 1978. 

Health and environmental protection standards established 

by EPA under UMTRCA are implemented by NRC. See 42 U.S.C. 

2022(b),(d).

This action also proposes to amend specific provisions 

in the current Health and Environmental Protection 

Standards for Uranium and Thorium Mill Tailings rule to 

address a ruling of the Tenth Circuit Court of Appeals, to 

update a cross-reference to another environmental standard, 

and to correct certain technical and typographical errors 

that have been identified since the 1983 promulgation.

The major provisions of today’s proposal include the 

following: 

• We are proposing to add an additional subpart within 

40 CFR part 192 to explicitly address groundwater

protection at uranium ISR operations. A new subpart F is 

being proposed that would set standards that would apply to 
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uranium ISR facilities only. The overall purpose of this 

subpart is to address the most significant hazards 

represented by ISR activities. This subpart adds the 

following:

1. A section on applicability – § 192.50 

Applicability – that specifies the subpart will apply 

to the management of uranium byproduct materials 

during and following the processing of uranium ores 

using ISR methods.

2. A section containing definitions - § 192.51 

Definitions and cross-references. 

3. A section – § 192.52 Standards – in which EPA 

proposes to specify the minimum 13 constituents for 

which groundwater protection standards must be met. 

The list includes the following: arsenic, barium, 

cadmium, chromium, lead, mercury, selenium, silver, 

nitrate (as N), molybdenum, combined radium-226 and 

radium-228, uranium (total), and gross alpha-particle 

activity (excluding radon and uranium). 

4. A section discussing monitoring requirements – § 

192.53 Monitoring programs – that details the specific 

requirements of monitoring programs to be conducted 

during the preoperational, operational, restoration, 

stability and long-term stability phases.
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5. A section establishing requirements for 

corrective actions - § 192.54 Corrective action 

program.

6. A section detailing the effective date of the new 

subpart - § 192.55 – Effective date.

• As noted above, we are also proposing to amend certain 

provisions within the existing 40 CFR part 192 to address a 

ruling of the Tenth Circuit Court of Appeals, delete 

reference to an outdated standard and correct minor 

technical and typographical errors.

The costs and benefits of this rulemaking are 

described briefly in the tables presented below. Costs 

quantified in Table 2 address costs of the rule that 

reflect appropriate characterization of the background 

data, and then ensuring that: (1) the post-operational 

groundwater is restored to that of the initial groundwater

conditions and (2) the post-restoration groundwater

conditions will remain stable.

The proposed rule requires affected facilities to 

monitor groundwater for a longer period of time compared to 

current practice (estimated to be 9.5 additional years if 
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geochemical modeling indicates that conditions will remain 

stable, and estimated 32.5 additional years if long-term 

stability monitoring continues for 30 years. The major 

costs associated with the proposed rule are the costs of 

these monitoring activities. National total annualized 

incremental costs of the proposed rule, based on likely 

implementation represented by the average cost of 30-year 

long-term stability monitoring with geochemical modeling to 

shorten the duration, is $13.5 million(in 2011 dollars), as 

shown in Table 2 below. EPA also examined potential impacts 

on small businesses that own and operate ISR operations. 

Using existing owner companies as examples of the firms 

that may own ISR operations subject to the proposed rule, 

EPA found that the estimated costs of complying with the 

proposed rule are 0.6% to 1.7% of estimated 2015 revenues 

for three small firms that own ISR operations. Because 

costs do not exceed 2% of estimated sales, and because EPA 

projects that fewer than 10 small businesses will be 

affected by the rule at any given time, EPA concluded that 

the proposed rule would not result in significant impacts 

for a substantial number of small entities. For information 

on how EPA estimated these costs, see Section 3 and 

Appendix D of the Economic Analysis.
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EPA conducted a qualitative assessment of the benefits

of the proposed rule. EPA recognizes that groundwater is a 

valuable resource, and is becoming more valuable as 

groundwater use increases. While the aquifers in the 

vicinity of ISR operations are currently providing little 

extractive value (because of their locations and, for some 

areas, the fact that groundwater quality is low), in future 

years these resources may have increased value. A recent 

analysis (Poe et al, 2001) estimated the value to today’s 

households of protecting groundwater for future use ranged 

from $531 to $736 per household. For this reason, EPA 

believes it is necessary to take a longer view of 

groundwater protection than taken in the past. Currently, 

monitoring groundwater conditions after restoration is 

typically conducted for a short period of time (EPA assumes 

6 months for cost estimate purposes), which may not be long 

enough to detect instability in groundwater conditions. 

EPA’s proposed rule requires a 30 year long-term stability 

monitoring period, which may be shortened if geochemical 

modeling demonstrates that conditions in the restored 

wellfield will remain stable over time.

The proposed rule will reduce the risk of undetected 

excursions of pollutants into adjacent aquifers. This in 
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turn will reduce the human health risks that could result 

from exposures to radionuclides in well water used for 

drinking or agriculture in areas located down-gradient from 

an ISR. Because radionuclides are human carcinogens, the 

main health risk averted would be cancer. There is a 

benefit (estimated to be at least $8 million per premature 

death avoided) of reducing cancer deaths, but because we 

were unable to estimate how many cancer deaths would be 

averted, or when they would occur, EPA is unable to 

quantify this benefit.

In addition to avoiding human health impacts, the 

proposed rule has the potential to detect excursions sooner 

and thus enable a faster remedial response. Because plumes 

detected during long-term stability monitoring would be 

smaller, costs of remediation would be potentially much 

lower. For a model mine unit, EPA estimated the averted 

remediation costs to range from $8.8 million to more than 

$500 million. EPA is unable to extrapolate this estimate to 

a national value, because we do not have a basis for 

estimating which, if any, wellfields would experience an 

undetected contaminant plume in the absence of the proposed 

rule.
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Table 1—Characterization of the Costs and Benefits of 40 

CFR Part 192, Subpart F

Costs Benefits

Annualized monitoring costs 

ranging from $12.5 to $14.1 

million

Protection of groundwater

quality

Maintenance of financial 

assurance for up to 30 

additional years per facility

Possible protection of 

surface water quality

Potentially reduced risk of 

exposure of human or 

ecological receptors to 

radiological pollutants

Potentially reduced human 

health impacts, including 

cancer

Reduced remediation cost 

savings ($8.8 million to 

$560 million for CMU)

Table 2—Summary of the Costs and Benefits of 40 CFR Part 

192, Subpart F with options(millions of 2011 dollars)

Requirement

Capital 

cost

Annual 

cost Net benefit

30 years with 

geochemical modeling

$25.2a $13.5 Not 

Quantified

30 Years, no 

shortening

$19.3 $15.1

aCapital costs are higher for the geochemical modeling 

option because more wells would be required.
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SUPPLEMENTARY INFORMATION: 

Outline. The information in this preamble is organized as 

follows:

I. General Information

A. Does this action apply to me?

B. What should I consider as I prepare my comments to 

EPA?

1. Submitting CBI

2. Tips for preparing your comments

C. When would a public hearing occur?

D. What documents are referenced in today’s proposal?

E. Acronyms and abbreviations

F. Definitions

II. Background Information

A. What is the scope of this action?

B. Uranium extraction

1. Conventional mining and milling

2. Heap leach

 3. In-situ recovery (ISR)

C. What is the statutory authority for the proposed 

amendments?

D. What are the existing requirements under 40 CFR 

part 192?

E. Why does EPA believe new standards are necessary?

1. What are the environmental impacts of uranium 

 ISR?

2. What analysis has EPA done to support the 

 proposal?

3. What came out of the Advisory from EPA’s Science 

 Advisory Board?

4. What efforts has the Nuclear Regulatory 

 Commission taken recently?

F. What other EPA statutes and regulations are 

relevant?

1. Safe Drinking Water Act (SDWA)

2. Clean Water Act (CWA)

3. Clean Air Act (CAA) 

4. Resource Conservation and Recovery Act (RCRA)

III. Summary of today’s proposal

A. Proposed standards – Subpart F

1. Proposal of new subpart – Subpart F-Public 

Health, Safety and Environmental Protection 

Standards for Byproduct Materials 

Produced by Uranium In-situ Recovery
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2. Addition of new section on applicability - § 

 192.50 Applicability 

3. Addition of new section containing definitions -

 § 192.51 Definitions and cross-references

 4. Addition of new section detailing standards - § 

 192.52 Standards

 5. Addition of new section discussing monitoring 

 requirements - § 192.53 Monitoring Programs

 6. Addition of new section discussing requirements 

 for corrective actions - § 192.54 Corrective 

 Action Program

 7. Addition of new section detailing the effective 

 date of the new subpart - § 192.55 – Effective 

 Date

B. Other proposed amendments

1. Revision to Subpart C - Implementation

2. Revision to Subpart D – Standards for the

 Management of Uranium Byproduct Materials

IV. What is the rationale for today’s proposal?

A. How does today’s proposal relate to existing 40 CFR 

 part 192?

B. What groundwater protection standards are we 

 proposing for ISR facilities?

1. Generally applicable groundwater standards

2. Alternate concentration limits (ACLs)

C. Adequate characterization of groundwater prior to 

 uranium recovery

1. Establishing restoration goals

D. Excursions

E. Long-term stability monitoring

1. Thirty-year long-term stability monitoring 

period, with provisions for shortening that 

time period

2. What other options did EPA consider for the 

 long-term stability monitoring period?

a. Required thirty-year long-term stability

 monitoring period

b. Narrative standard with no fixed 

 monitoring period

3. How will groundwater stability be determined?

a. What do we propose for determining 

 stability?

b. Where will the determination of stability 

 be made?

F. Institutional control

G. Other proposed amendments

1. Judicial decision
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2. Miscellaneous updates and corrections

a. Outdated cross-reference

b. Technical corrections

V. Summary of Environmental, Cost and Economic Impacts

A. What are the impacts to groundwater?

B. What are the benefits of avoiding impacts to 

 groundwater?

C. What are the cost impacts?

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and 

Review and Executive Order 13563: Improving 

Regulation and Regulatory Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and 

Coordination with Indian Tribal Governments

G. Executive Order 13045: Protection of Children from 

Environmental Health and Safety Risks

H. Executive Order 13211: Actions Concerning 

Regulations That Significantly Affect Energy 

Supply, Distribution or Use

I. National Technology Transfer Advancement Act

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and 

Low-Income Populations

I. General Information

A. Does this action apply to me?

The regulated categories and entities potentially 

affected by the proposed standards include:

Category NAICS 

code1

Examples of regulated

Entities

Industry:

Uranium Ores Mining 

and/or Beneficiating

212291 Facilities that extract 

or concentrate uranium

from any ore processed 

primarily for its 

source material content
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Leaching of Uranium, 

Radium or Vanadium 

Ores

212291 Facilities that extract 

or concentrate uranium 

from any ore processed 

primarily for its 

source material content 

1 North American Industry Classification System.

This table is not intended to be exhaustive, but 

rather provides a guide for readers regarding entities 

likely to be affected by this proposed action. 

B. What should I consider as I prepare my comments to EPA?

1. Submitting CBI. Do not submit CBI information to 

EPA through www.regulations.gov or e-mail. Clearly mark the 

part or all of the information that you claim to be CBI. 

For CBI information contained on a disk or CD ROM that you 

mail to EPA, mark the outside of the disk or CD ROM as CBI 

and then identify electronically within the disk or CD ROM 

the specific information that is claimed as CBI. In 

addition to one complete version of the comment that 

includes information claimed as CBI, a copy of the comment 

that does not contain the information claimed as CBI must 

be submitted for inclusion in the public docket.

Information marked as CBI will not be disclosed except in 

accordance with procedures set forth in 40 CFR part 2.

2. Tips for preparing your comments. When submitting 

comments, remember to:

• Identify the rulemaking by docket number and 
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other identifying information (subject heading, 

Federal Register date and page number).

• Follow directions - The agency may ask you to 

respond to specific questions or organize 

comments by referencing a Code of Federal 

Regulations (CFR) part or section number.

• Explain why you agree or disagree, suggest 

alternatives, and substitute language for your 

requested changes.

• Describe any assumptions and provide any 

technical information and/or data that you used.

• If you estimate potential costs or burdens, 

explain how you arrived at your estimate in 

sufficient detail to allow for it to be 

reproduced.

• Provide specific examples to illustrate your 

concerns, and suggest alternatives.

• Explain your views as clearly as possible, 

avoiding the use of profanity or personal 

threats.

Make sure to submit your comments by the comment period 

deadline identified.

C. When would a public hearing occur?

If anyone contacts the EPA requesting to speak at a 
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public hearing concerning this proposed rule by [INSERT 30 

DAYS AFTER PUBLICATION IN THE FEDERAL REGISTER], we will 

hold a public hearing. If you are interested in attending 

the public hearing, contact Mr. Anthony Nesky at (202) 343-

9597 to verify that a hearing will be held. If a public 

hearing is held, we will announce the date, time and venue 

on our website at 

http://www.epa.gov/radiation/tenorm/40CFR192.html.

D. What documents are referenced in today’s proposal?

We refer to a number of documents that provide 

supporting information for our uranium and thorium mill 

tailings standards. All documents relied upon by EPA in 

regulatory decision making may be found in our docket (EPAHQ-OAR-2012-0788) accessible via 

http://www.regulations.gov/. Other documents, e.g., 

statutes, regulations, and proposed rules, are readily 

available from public sources. The EPA documents listed 

below are referenced most frequently in today’s proposal.

EPA 402/D-14-001 Item No. (OAR-xxxx-xxxx-xxxx)

xxxx “Considerations Related to Post Closure 

Monitoring of Uranium In-Situ Leach/In-Situ 

Recovery (ISL/ISR) Sites,” Environmental 

Protection Agency, 2014.
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EPA 402/R-14-003 xxxx “Economic Analysis: Proposed 

Revisions to the Health and Environmental 

Protection Standards for Uranium and Thorium Mill 

Tailings Rule (40 CFR part 192),” Environmental 

Protection Agency, 20142013.

EPA 530/R-09-007 xxxx “Statistical Analysis of 

Groundwater Monitoring Data at RCRA Facilities –

Unified Guidance,” Environmental Protection 

Agency, 2009.

E. Acronyms and Abbreviations

The following acronyms and abbreviations are used in 

this document:

ACL – alternate concentration limit

AEA – Atomic Energy Act

BID – Background information document

CAA – Clean Air Act

CWA – Clean Water Act

CBI – Confidential Business Information

CFR – Code of Federal Regulations

DOE – U.S. Department of Energy

EIA – economic impact analysis

EO – Executive Order

EPA – U.S. Environmental Protection Agency

FR – Federal Register

ISR – in-situ recovery, also known as insitu leaching (ISL)

l - liter

MCLs – Maximum Contaminant Levels

mg – milligram

MOU – Memoranda of Understanding

N - nitrate

NRC – U.S. Nuclear Regulatory Commission

NTTAA – National Technology Transfer and Advancement Act

OMB – Office of Management and Budget

RAC – Radiation Advisory Committee
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RCRA – Resource Conservation and Recovery Act

RFA – Regulatory Flexibility Act

SAB – Science Advisory Board

SDWA – Safe Drinking Water Act

UIC – underground injection control

U.S. - United States

USD – United States dollar

UMRA – Unfunded Mandates Reform Act of 1995

UMTRCA – Uranium Mill Tailings Radiation Control Act of 

1978

U.S.C. – United States Code

USDW – underground source of drinking water

WL – Working Level

F. Definitions

The following terms are used in this document:

Terminology Definition

Adjacent 

Aquifer

An aquifer or portion of an aquifer that 

shares a border or end point with the 

exempted aquifer or the exempted portion of 

an aquifer.

Alternate 

Concentration 

Limit (ACL)

Concentration limit approved by the 

regulatory agency for a groundwater 

constituent that has not been restored to 

its restoration goal after best practicable 

restoration activities have been completed

following the process prescribed in 40 CFR 

192.52(c)(2)thru 192.52(c)(5).

Aquifer A geological “formation,” group of 

formations, or part of a formation that is 

capable of yielding a significant amount of 

water to a well or spring. See 40 CFR 

144.3.

Aquitard A confining bed that retards but does not 

prevent the flow of water to or from an 

adjacent aquifer.
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Background The condition of groundwater, including the 

radiological and non-radiological 

constituent concentrations, in the exempted 

aquifer, adjacent aquifers, and in both 

overlying and underlying aquifers, prior to 

the beginning of ISR operations. The 

background groundwater constituent 

concentrations in the production zone prior 

to the beginning of ISR operations is 

commonly referred to by the industry and 

regulatory bodies as the “baseline.”

Beneficiation The initial attempt at liberating and 

concentrating a valuable mineral from 

extracted ore. This is typically performed 

by employing various crushing, grinding, 

and froth flotation techniques. 

Byproduct 

Material

See “Uranium Byproduct Material.”

Constituent A detectable component within the 

groundwater.

Exceedance An exceedance has occurred when, during 

stability or long-term stability 

monitoring, a groundwater protection 

standard is exceeded at any point of 

compliance well.

Excursion The movement of fluids containing uranium 

byproduct material from an ISR production 

zone into surrounding groundwater. An 

excursion is considered to have occurred 

when, during operational or restoration 

phase monitoring, any two indicator

parameters (e.g., chloride, conductivity, 

total alkalinity) exceed their respective 

upper control limits in any overlying, 

underlying, or perimeter monitoring well. 

Horizontal excursions refer to the lateral 

movement of the water, while vertical 

excursions indicate movement of water 

through aquitards above or below the 

production zone aquifer.
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Excursion 

Monitoring 

Well

Wells located around the perimeter of the 

production zone (horizontal excursion 

wells) and in overlying and underlying 

aquifers (vertical excursion wells), which 

are used to detect any excursions from the 

production zone. Excursion monitoring wells 

can serve as the “point(s) of compliance” 

during all phases of ISR.

Exempted 

Aquifer

An “aquifer,” or its portion, that meets 

the criteria in the definition of 

“underground source of drinking water” in 

40 CFR 144.3, but which has been exempted 

according to the procedures in 40 CFR 

144.7. See 40 CFR 144.3.

Extraction 

Well

Well used to extract uranium enriched 

solutions from the ore-bearing aquifer; 

also known as a “Production Well.” 

Extraction and injection wells may be 

converted from one use to the other.

Facility See “Uranium Recovery Facility.”

Groundwater Water below the land surface in a zone of 

saturation. See 40 CFR 144.3.

Indicator 

Parameter

A constituent, such as chloride, 

conductivity, or total alkalinity, whose 

“upper control limit” is used to identify 

an excursion. Indicator parameters are not 

contaminants, but relate to geochemical 

conditions in groundwater.

Injection Well A well into which fluids are being 

injected. See 40 CFR 144.3.

In-Situ 

Recovery (ISR)

A method of extraction by which uranium is

leached from underground ore bodies by the 

introduction of a solvent solution, called 

a lixiviant, through injection wells 

drilled into the ore body. The process does 

not require the extraction of ore from the 

ground. The lixiviant is injected, passes 

through the ore body, mobilizes the 

uranium, and the uranium-bearing solution 

is pumped to the surface from extraction 

wells. The pregnant leach solution is 

processed to extract the uranium.
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Ion Exchange TheA typical water treatment process in 

which ionswhereby constituents of concern

are exchanged between a solution and an 

insoluble solid.

Listed 

Constituent

One of the thirteen groundwater 

constituents specified in Table 1 to 

subpart F of part 192.

Lixiviant A liquid medium used to recover uranium 

from underground ore bodies through in-situ 

recovery. This liquid medium typically 

contains native groundwater and an added 

oxidant, such as oxygen and/or hydrogen 

peroxide, as well as sodium 

carbonate/bicarbonate or carbon dioxide.

The lixiviant is introduced through 

injection wells into the ore body to 

mobilize the uranium. The resulting 

solution is then pumped via extraction 

wells to the surface, where the uranium is 

recovered from the solution for further 

processing, after which the lixiviant may 

be re-injected.

Long-Term 

Stability 

Phase

The period after the groundwater protection 

standards have been met, as determined by 

the regulatory agency.

Maximum 

Constituent 

Concentration 

The maximum permissible level of a 

constituent in groundwater, as specified in 

Table 1 to subpart A of part 192.

Maximum 

Contaminant 

Level (MCL)

The maximum permissible level of a 

contaminant in water which is delivered to 

any user of a public water system. See 40 

CFR 141.2. 

Mobilization Increasing the migration of constituents in 

groundwater by various chemical treatments.

Commented [UEUoC2]: Change made per interagency review.
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Monitoring 

Wells

Wells used to obtain groundwater levels and 

water samples for the purpose of 

determining the hydrologic regime and the 

amounts, types, and distribution of 

constituents in the groundwater. Wells are 

located in the production zone, around the 

perimeter of the production zone 

(horizontal excursion monitoring wells), 

and in overlying and underlying aquifers 

(vertical excursion monitoring wells).

Operational 

Phase

The time period during which uranium 

extraction by in-situ recovery occurs. 

Operations begin when injection of 

lixiviant starts; operations end when the 

operator permanently ceases injection of 

lixiviant and recovery of uranium-bearing 

solution..

Ore The naturally occurring material from which 

a mineral or minerals of value (e.g., 

uranium) can be extracted.

Overlying 

Aquifer

An aquifer that is immediately vertically 

shallower than (i.e., directly above) the 

production zone aquifer.

Point(s) of 

Compliance

Site-specific location(s) where groundwater 

protection standards must be met. During 

all phases of ISR, excursion monitoring 

wells can serve as the points of 

compliance; during the restoration, 

stability and long-term stability phases, 

points of compliance may also include 

monitoring, injection and extraction wells 

in the production zone, as determined by 

the regulatory agency.

Point(s) of 

Exposure

Intersection of a vertical plane with the 

boundary of the exempted aquifer.

Precipitate To separate a substance (such as uranium) 

out of a solution as a solid. 

Preoperational 

Monitoring

Measurement of groundwater conditions in 

the production zone, and in the groundwater 

up and down gradient from the production 

zone, as well as in overlying and 

underlying aquifers, prior to the 

operational phase.

Commented [UEUoC3]: Change made per interagency review.
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Production 

Zone

The portion of the aquifer in which ISR 

activities occur. The production zone lies 

within the wellfield.

Regulatory 

Agency

The Nuclear Regulatory Commission (NRC) or 

an Agreement State.

Restoration 

(Act of)

The process of returning groundwater 

quality to preoperational conditions for 

the purpose of achieving restoration goal 

values for identified constituents.

Restoration 

Goal

A concentration limit for an identified 

constituent in groundwater after 

restoration has occurred. The limit is

obtained from the most protective 

regulatory standards in 40 CFR 141.62, 

141.66, 141.80, 143.3, 264.94, and Table 1

to subpart A of this part, and from 

preoperational background levels in the 

wellfield, whichever is higher.

Restoration 

Phase

The period immediately after lixiviant 

injection permanently ceases, during which 

restoration activities occur.

Site The land or water area where any facility 

or activity is physically located or 

conducted, including adjacent land used in 

connection with the facility or activity. 

See 40 CFR 144.3.

Stability 

Phase

The period after the restoration phase when 

groundwater protection standards are met 

and monitored to test for temporal 

stability.

Solubilize To make a substance (such as uranium) 

soluble or more soluble.

Underground 

Source of 

Drinking Water 

(USDW)

An aquifer or its portion: (a)(1) Which 

supplies any public water system; or (2) 

Which contains a sufficient quantity of 

groundwater to supply a public water 

system; and (i) Currently supplies drinking 

water for human consumption; or (ii) 

Contains fewer than 10,000 mg/l total 

dissolved solids; and (b) Which is not an 

exempted aquifer. See 40 CFR 144.3.
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Underlying 

Aquifer

An aquifer that is immediately vertically

deeper (i.e., directly below) than the 

production zone aquifer.

Upper Control 

Limit (UCL)

Preoperational concentrations of indicator 

parameters in horizontal and vertical 

excursion monitoring wells, as determined

by the regulatory agency and contained in 

the license.

Uranium 

Byproduct 

Material

Waste produced by the extraction or 

concentration of uranium from any ore 

processed primarily for its source material 

content. Ore bodies depleted by uranium ISR

operations and which remain underground do 

not constitute "uranium byproduct 

material.”

Uranium 

Recovery 

Facility

A facility licensed to process uranium ores

for the purpose of recovering uranium and 

to manage uranium byproduct materials that 

result from during and following the 

processing of uranium ores. Common names 

for these facilities include, but are not 

limited to, the following: a conventional 

uranium mill, an in-situ recovery (or 

leach) facility, and a heap leach facility 

or pile.

Wellfield The area of an ISR operation that 

encompasses the array of injection, 

extraction, and monitoring wells and 

interconnected piping employed in the 

uranium in-situ recovery process. The area 

of the wellfield exceeds that of the 

production zone.

II. Background Information 

A. What is the scope of this action?

In 1983, EPA originally promulgated regulations at 40 

CFR part 192, Health and Environmental Protection Standards 

for Uranium and Thorium Mill Tailings, in response to the 

statutory requirements of the Atomic Energy Act of 1954, as 
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amended by the Uranium Mill Tailings Radiation Control Act 

of 1978 (UMTRCA). These standards have been amended several 

times, most recently in 1995, with the addition of 

standards to correct and prevent contamination of 

groundwater beneath and in the vicinity of inactive uranium 

processing sites.1,2 Pursuant to UMTRCA, our standards have 

beenare implemented by the Department of Energy (DOE) at 

inactive uranium millingprocessing sites and nearby 

contaminated “vicinity properties” managing residual 

radioactive material and by the Nuclear Regulatory 

Commission (NRC) or NRC Agreement States at active sites

managing byproduct material.3,4

Today’s proposal is limited to the following changes. 

We are proposing to add an additional subpart within 40 CFR 

part 192 to explicitly address groundwater protection at 

uranium ISR operations. We are also proposing to amend

certain provisions within the existing 40 CFR part 192 to 

 

1 See 42 U.S.C. § 7911(6) for the definition of a “processing site.”

2 See 60 FR 2854 (January 11, 1995) and 58 FR 60340 (November 15, 1993).

3 Byproduct material includes the is defined as “tailings or wastes 

produced by the extraction or concentration of uranium or thorium 

(source material) from any ore processed primarily for its source 

material content..” AEA section 11e.(2), 42 U.S.C. 2014(e)(2).

4 Under Section 274 of the AEA, the NRC may enter into an agreement with 

a State for discontinuance of the NRC’s regulatory authority and the 

State’s assumption of regulatory authority over specified radioactive 

materials and activities. The NRC must review and find the State’s 

regulatory program is adequate to protect public health and safety and 

compatible with the NRC’s regulatory program before entering into the 

Section 274 agreement. The NRC continues oversight responsibilities of 

the Agreement State’s regulatory program through the Integrated

Materials Performance Evaluation Program (IMPEP).

Commented [UEUoC4]: Footnote 3 revised per interagency 

review.
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address a ruling of the Tenth Circuit Court of Appeals, 

delete reference to an outdated standard and correct minor 

technical and typographical errors. We request public 

comment only on these proposed standards and amendments. We 

are not requesting, and will not respond to, public 

comments on any other 40 CFR part 192 provisions since they 

are beyond the scope of today’s proposal.

B. Uranium extraction

The major deposits of uranium ores in the United 

States are located in the Colorado Plateau, the Wyoming 

Basin, the Texas Coastal Plain, and Nebraska. Recovery and 

processing of these ores have historically occurred by one 

of three methods: (1) conventional mining and milling

operations; (2) heap leach operations; and (3) in-situ 

(i.e., in place) recovery. Below we present a brief 

explanation of these uranium recovery methods.

1. Conventional mining and milling

Conventional mining and milling is one of the primary 

recovery methods currently used to extract uranium from 

uranium-bearing ore in much of the world and was formerly 

the predominant means of obtaining uranium in the United 

States. “Remoteness from populated areas” and “isolation of 

contaminants from groundwater” are key considerations in 

selecting mill locations under current siting criteria 
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found in NRC regulations.5 Only one conventional mill in the 

United States is currently operating; all others are in 

standby status, in decommissioning (closure) or have 

already been decommissioned.

Conventional uranium mines are either open-pit 

operations, where large volumes of uranium bearing material 

are excavated, or underground mines, where the uraniumbearing ore is extracted via mined openings into the 

subsurface. The extracted ore is then moved to the milling 

operation where the uranium is extracted by chemical 

treatments of the ore. The ores are crushed mechanically 

and then leached at the milling site. In most cases, 

sulfuric acid is the leaching agent, but alkaline solutions 

can also be used to leach the uranium, generally extracting

90 to 95 percent of the uranium from the crushed ore. 

The mill then processes the uranium from the solution 

by solvent extraction using organic chemicals, or by an ion 

exchange process using resins designed to extract the 

uranium from the leaching solutions used to remove uranium 

from the crushed ore, then further extracts, precipitates, 

and finally dries the recovered uranium to produce a 

uranium oxide material, called “yellowcake” because of its 

 

5 See 10 CFR part 40, Appendix A, Criterion 1.
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yellowish color.6 Finally, the yellowcake is packaged in 

special 55-gallon drums and transported to uranium 

conversion, enrichment and fuel fabrication facilities to 

produce fuel for use in nuclear power and research

reactors. The recovery process produces both solid and 

liquid wastes (i.e., uranium byproduct material, or 

“tailings”), which are transported from the extraction 

location to an on-site uranium byproduct material 

impoundment or pond.

Uranium byproduct materials/tailings deposited into an 

impoundment or “mill tailings pile” must be carefully 

monitored and controlled. This is because the mill tailings 

contain radioactive or heavy metal constituents, including 

thorium and radium. The radium decays to produce radon, 

which may then be released into the environment. Radon is a 

radioactive gas that may be inhaled into the respiratory 

tract; EPA has determined that exposure to radon and its

daughter products contribute to an increased risk of lung 

cancer.7

2. Heap leaching

 

6 The term “yellowcake” is still commonly used to refer to this 

material, although in addition to yellow, the uranium oxide material 

can also be black or grey in color.

7 http://www.epa.gov/radon/risk_assessment.html
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Another method of uranium extraction that some 

facilities may use is known as heap leaching. This method 

has been used in situations where the uranium ore is of low 

grade or the geology of the ore body is such that 

conventional mining and milling is not cost effective.

Although no such facilities currently operate in the United 

States, the heap leach process is used for uranium recovery 

in other parts of the world and has, to a limited extent,

been used in the United States in the past. There are plans 

for at least one new heap leach facility to open in the 

U.S. within the next few years.

With the heap leach process, small pieces of ore are 

placed in a large pile, or “heap,” on an impervious pad of 

plastic, clay, concrete, or asphalt, with perforated pipes 

under the heap. An acidic solution is then applied through 

drips or sprinklers over the ore to dissolve the uranium it 

contains. The uranium-rich solution drains into the 

perforated pipes, where it is collected and transferred to 

an ion exchange system to recover the uranium from the 

leaching solution. The heap is “rested,” meaning that there 

is a temporary cessation of application of acidic solution 

to allow for oxidation of the ore before leaching resumes. 

The ion exchange system extracts the uranium from the 

solution, which is processed into yellowcake either at the 
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site or at another uranium recovery facility. The 

yellowcake is packed in special 55-gallon drums to be 

transported to uranium conversion, enrichment and fuel 

fabrication facilities to produce fuel for use in nuclear 

power and research reactors.

3. In-situ recovery (ISR)

In-situ recovery (ISR), also referred to as in-situ 

leach (ISL) (we will use the term ISR throughout this 

document), is now the dominant method of uranium recovery 

in the United States and much of the world. ISR research 

and development projects and associated pilot projects 

began in the 1960s in Wyoming with limited field 

applications. From the mid-1960s to the mid-1970s, interest 

in ISR methods increased, particularly in Texas and 

Wyoming, with 18 commercial and 9 pilot-scale operations in 

place by 1980. During the 1980s, production of uranium by 

ISR was limited, but by the mid-1990s, uranium production 

by ISR reached 90 percent of United States production. 

Commercial and pilot operations demonstrated ISR as a 

viable uranium recovery technique where site conditions 

(e.g., geology and hydrology) are amenable to its use. This 

technology can produce a better return on investment than 

conventional mining and milling since it does not involve 

excavation of large volumes of ore or disposal of large 
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volumes of byproduct material. Therefore, the cost to 

produce uranium is generally lower. The trend in uranium 

production has shifted toward the ISR process. In 2013,in 

the United States, there were sixThere are currently five

operating ISR facilities in the United States; another 

three have been licensed and 12 facilities11 proposed for

licensing, licensed but not operating, or undergoing 

restoration.

In-situ recovery is defined as the underground 

recovery by oxidation/solubilization of uranium from the 

ore body (host rock – typically sandstone) into the 

groundwater by using native groundwater into which has been 

added oxidizing and complexing chemicals have been added.

This solution is known as lixiviant. Lixiviant is pumped 

into the ore zone through a set of injection wells and 

removed through extraction wells, followed by recovery of 

uranium at the surface by processing of the extracted 

waters.

The ore bodies most amenable to ISR are known as “roll 

front” deposits, which are formed when uranium in the 

oxidized groundwater encounters an area of the host 

formation where chemically reducing conditions exist. These 

reducing conditions are strong enough to chemically reduce 

and precipitate the uranium into a less soluble form, thus 

Commented [UEUoC5]: Change per interagency review. 
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forming the ore zone. As new oxidized uranium enters the 

front, it continues to be chemically reduced, precipitate 

and deposit in successive “rolls”. The injection of a 

lixiviant essentially reverses the geochemical reactions 

that originally formed the uranium deposit. The oxidizing 

agents in the lixiviant create an oxidizing environment 

that solubilizes the uranium from the formation and allows 

it to enter into the groundwater. Other components of the 

lixiviant (usually bicarbonate ions) act to enhance the 

solubility of the oxidized uranium in the groundwater. The 

uranium, along with other constituents present in the 

formation that have been mobilized (e.g., metals such as 

molybdenum, selenium, and arsenic), are then collected from 

the ore zone by extraction wells that pump the solution to 

the surface. At the surface, the uranium is collected by a 

system of piping that feeds to a processing facility, where 

the uranium is recovered in ion exchange columns and either 

further processed on-site into yellowcake, or transported 

to another facility for processing into yellowcake. After 

processing, the extracted and processed waters are 

recharged with the lixiviant chemicals and pumped back down 

into the ore zone for reuse in extracting more uranium. The 

yellowcake is subsequently transported to uranium 

conversion, enrichment, and fuel fabrication facilities to 
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produce fuel for use in nuclear power and research 

reactors.

Two general types of lixiviant solutions can be used, 

loosely defined as “acidic” or “alkaline” systems. Acidic

lixiviants were used early in the development of ISR in the 

United States, but site-specific conditions at the sites 

showed that acidic lixiviants were generally unsuitable.8,9

In the United States, the geology and geochemistry of the 

majority of the uranium ore bodies favors the use of 

alkaline lixiviants such as bicarbonate/carbonate and 

oxygen. Other factors in the choice of the lixiviant are 

the uranium recovery efficiencies, operating costs, and the 

ability to achieve satisfactory groundwater restoration

after production ceases.

In order to control and contain the flow of 

groundwater within the production zone, an inward hydraulic

gradient is established using the injection and extraction 

(also known as production) wells.10 To create and maintain 

this gradient, more water is removed from the production 

 

8 Acidic lixiviants react with carbonates (calcite and dolomite) 

contained in the host rock and precipitate calcium sulfate. The calcium 

sulfate clogs the well screens and process lines, significantly 

decreasing the efficiency of the leaching process.

9 Mudd, G.M (2001). “Critical review of acid in situ leach uranium 

mining: 1. USA and Australia,” Environmental Geology, 41:390-403.

10 The gradient controls the direction of flow of water within a waterbearing formation. Used here, the purpose of a gradient is to contain 

water within the production zone so that it does not migrate beyond the 

wellfield.
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zone than is injected (commonly referred to by industry as 

the “bleed rate”). The extracted liquid (groundwater mixed 

with lixiviant) goes through the recovery process to 

extract uranium. The processed water may be either 

recharged with lixiviant and re-injected to continue the 

recovery process or used to flush out the remaining 

lixiviant and mobilized uranium during the restoration 

process. Any waste water not reused may be injected into a 

deep well for disposal or be sent to an impoundment on site 

(often called an evaporation pond or a holding pond). The 

waste water generated during and after operations at an ISR 

facility, as well as all evaporation pond sludges derived 

from such waste waters, have been determined to be uranium 

byproduct material by the NRC, bringing them under the 

jurisdiction of UMTRCA.11

The wellfield of an ISR operation is configured to 

efficiently exploit the underlying uranium ore zone based 

on the subsurface data collected prior to construction of 

the wellfield. The wellfield typically includes a series of 

closely spaced arrays of injection wells (each array 

typically has 4 to 6 injection wells spaced on the order of 

many tens to, at most, a few hundred feet apart) with an

 

11 NRC (2000). “Recommendations on Ways to Improve the Efficiency of NRC 

Regulations at In Situ Leach Uranium Recovery Facilities.” Staff 

Requirements – SECY-99-013.
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extraction well in the center of each array.12 Each of these 

arrays is intended to work as a unit to control the flow of 

groundwater bearing the lixiviant so that the injected 

solution is captured by the extraction wells. The spacing 

of the injection and extraction wells is determined by the 

hydrologic properties of the ore zone, as evidenced by 

hydrologic testing during the exploration of the site, 

wellfield construction and monitoring well construction and 

operation. 

During operations there is a risk of the lixiviant 

and/or mobilized constituents spreading beyond the capture 

zone of the wellfield. This poses a risk of groundwater 

contamination off site and in some cases surface water 

contamination where groundwater discharges to surface 

water. Monitoring wells are positioned around the 

production zone to detect increases in indicator parameters 

that would signal an excursion of the lixiviant or 

mobilized constituents from an ISR wellfield into 

surrounding groundwater. The operator of the ISR facility 

typically remediates any detected excursions by taking 

corrective actions such as ceasing injection and pumping 

 

12 See EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery (ISL/ISR) Sites.” This document 

can be found in the docket for today’s proposed rule. (Docket EPA-HQOAR-2012-0788).

Commented [UEUoC6]: Change made per interagency review.
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water out of wells near the excursion. The detection and 

remediation of excursions is a major regulatory operational 

concern and needs to be carefully monitored by the 

operators and the regulatory agencies.

After the ore body has been depleted to uranium levels 

that are no longer economically valuable, the operator will 

cease injecting lixiviant and begin restoration of the ore 

zone aquifer within the wellfield(s) to return conditions 

to their preoperational state to the extent practicable. 

Extracted water, typically treated through reverse osmosis 

and often in combination with added reducing agents, is 

injected into the ore zone to flush out the remaining 

lixiviant and to attempt to restore the geochemistry of the 

ore zone to its original background (baseline) condition. 

Other procedures also may be used to bring about chemically 

reducing conditions in an attempt to immobilize the uranium 

(along with any other mobilized metals) remaining within 

the ore zone.

Once the groundwater at the site has gone through 

restoration and sufficient time has passed such that the 

licenseesowner/operators can demonstrate that chemical 

conditions are stable, the injection and extraction wells 

Commented [UEUoC7]: Globally changed owner/operator to 

licensee per interagency review.
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are properly plugged and abandoned,;13 the wellfield 

infrastructure (pipes, header houses, etc.) is removed,;

and surface operations equipment (impoundment liners, 

buildings, etc.) is dismantled and shipped offsite for 

appropriate reuse or disposal. The site is officially 

decommissioned when the radioactive materials license is 

terminated by the regulatory agency (i.e., NRC or NRC 

Agreement State). Because no long-term disposal facilities 

remain at decommissioned ISR sites, there is no perpetual 

care and monitoring as occurs with conventional mill

tailings sites.

C. What is the statutory authority for the proposed 

amendments?

EPA is proposing these new standards and amendments 

under its authority in Section 275 of the Atomic Energy Act 

(AEA) of 1954, as amended by Section 206 of the Uranium 

Mill Tailings Radiation Control Act (UMTRCA) of 1978.14

Section 206 of UMTRCA authorizes EPA to promulgate 

general standards for the protection of public health, 

safety, and the environment from radiological and nonradiological hazards associated with (a) residual 

radioactive materials located at specifically listed 

 

13 See 40 CFR 146.10, “Plugging and Abandoning Class I, II, III, IV, and 

V Wells.”

14 See 42 U.S.C. 2022.
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inactive uranium milling sites, nearby contaminated 

“vicinity properties,”mill tailings sites and depository 

sites for such materials selected by the Secretary of 

Energy (commonly referred to as Title I sites); and (b) the 

processing and the possession, transfer, and disposal of 

byproduct material at sites at which ores are processed 

primarily for their uranium and thorium source material 

content15 or which are used for the disposal of such 

byproduct material (commonly known as Title II sites). See 

42 U.S.C. 2022.16 These health, safety and environmental 

standards are contained in 40 CFR part 192 and are 

implemented by the NRC and its Agreement States, and the 

DOE.

Title I of UMTRCA covers inactive uranium millingmill 

tailings sites , nearby contaminated “vicinity properties,”

and depository sites. EPA was directed to set general 

standards that were consistent with the requirements of the 

Solid Waste Disposal Act (later amended as the Resource 

Conservation and Recovery Act, or RCRA) to the maximum 

extent practicable.

 

15 “Source material” is defined as “(1) Uranium or thorium or any 

combination of uranium or thorium in any chemical or physical form; or 

(2) Ores that contain, by weight, one-twentieth of one percent (0.05 

percent), or more, of uranium or thorium, or any combination of uranium 

or thorium.” See 42 U.S.C. 2014(z), 10 CFR 20.1003.

16 Although the statute covers both uranium and thorium mill tailings 

sites, there are no existing thorium mill tailings sites.
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Title II of the Act covers operating uranium 

processing or disposal sites licensed by the NRC or 

Agreement States. EPA was directed to promulgate generally 

applicable standards to protect public health, safety, and 

the environment from hazards associated with processing, 

possession, transfer and disposal of byproduct material.

Such standards were to address both radiological and nonradiological hazards; further, standards applicable to nonradiological hazards were to be consistent with the 

standards required under Subtitle C of the Solid Waste 

Disposal Act (i.e., RCRA).17 NRC was required to implement 

these standards at Title II sites. See 42 U.S.C. 2022(b), 

(d).

D. What are the existing requirements under 40 CFR part 

192?

Requirements for inactive uranium millingmill tailings

sites, vicinity properties, and depository sites (i.e., 

Title I sites) are addressed under subparts A, B, and C of 

40 CFR part 192. Since today’s proposal does not impact 

Title I sites, they will not be discussed further in this 

section. 

 

17 With the restriction that EPA not require any RCRA permit for the 

processing, possession, transfer, or disposal of byproduct material.
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Requirements currently applicable to active uranium 

processing and disposal sites, including ISR sites (i.e., 

Title II sites) can be found in subpart D of 40 CFR part 

192 (hereafter “subpart D”). Subpart D contains provisions 

for managing uranium byproduct materials during and 

following the processing of uranium ores, and restoration 

of disposal sites following any such use of those sites. 

For purposes of today’s proposal, provisions related to 

groundwater protection are of most interest. To fulfill the 

statutory mandate described in section II.C of this 

preamble, we derived these provisions from the RCRA 

groundwater monitoring framework applicable to hazardous 

waste disposal sites.18 Today’s proposal further adapts that

framework to better address the specific situation 

presented by ISR technology. 

Though standards at subpart D apply to ISR facilities, 

ISR was not the predominant uranium extraction method at 

the time the standards were promulgated. Subpart D 

addresses contamination of aquifers resulting from releases 

of contaminants from uranium mill tailings impoundments, 

which are surface structures (engineered units) designed to 

contain uranium byproduct material (e.g., conventional 

 

18 See 40 CFR part 264, “Standards for Owners and Operators of Hazardous 

Waste Treatment, Storage, and Disposal Facilities.” See particularly 

subpart F, “Releases from Solid Waste Management Units.”
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tailings impoundments, evaporation or holding ponds). The 

RCRA hazardous waste framework, which is intended to 

prevent, detect, and mitigate contamination of groundwater 

resulting from releases of hazardous waste being held in an 

engineered unit, is directly applicable to this situation.19

A basic RCRA hazardous waste management unit is an 

engineered unit, designed, constructed, and installed to 

prevent any migration of wastes out of the unit to the 

adjacent subsurface soil, groundwater or surface water at 

any time during the unit’s operatingactive life, during

(including the closure and during post-closureperiod) of 

the unit.

At ISR sites, however, the groundwater has already 

been influenced by the natural mineralization associated 

with the uranium roll front deposits. In essence, the 

“management unit” that is the potential source of 

contamination is the natural setting itself, though 

extraction of the uranium from the deposit alters the 

geochemistry of the ore-bearing formation and may increase 

the concentration of radionuclides and other metals in the 

water. Restoration activities attempt to restore the 

original geochemistry to the subsurface. However, at 

 

19 The design and construction requirements for surface impoundments are 

also taken from 40 CFR part 264. See subpart K, “Surface Impoundments,” 

specifically 40 CFR 264.221.

Commented [UEUoC8]: Change made per interagency review.

Commented [UEUoC9]: Changes made per interagency review.
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present, monitoring to verify restoration generally lasts 

for only a period of a few years at most. We are proposing 

to establish standards that will require licenseesowners 

and operators to ensure that the results of their 

restoration process(es) persist through time, thereby 

limiting the future potential for groundwater to be 

degraded from undetected, long-term changes in groundwater 

from ISR operations.

E. Why does EPA believe new standards are necessary?

We believe that ISR-specific standards are necessary 

because uranium ISR operations are verysufficiently

different from conventional uranium mills and the existing 

standards do not adequately address their unique aspects. 

In particular, we believe it is necessary to take a 

longer view of groundwater protection than has been typical 

of current ISR industry practices. Although the presence of 

significant uranium deposits typically diminishes 

groundwater quality, we are not confident that current 

industry practices for restoration and monitoring of the 

affected aquifer may not beare adequate to prevent either 

the further degradation of water quality or the more 

widespread contamination of groundwater that is suitable 

for human consumption.

Commented [UEUoC10]: Change made per interagency 

review.

Commented [UEUoC11]: Change made per interagency 

review.
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Because monitoring after restoration is typically 

conducted for only a short period, we find it difficult to 

characterize the probability or magnitude of future 

contamination problems, or the costs involved in 

remediating such future contamination. Such costs are not 

now borne by ISR licenseesowners/operators, nor is there 

any guarantee that they could be held responsible if 

contamination were detected by new monitoring implemented 

years, decades or even longer after the end of site 

activities once the facility is officially decommissioned 

and the license is terminated by the NRC or Agreement 

State. It is likely, however, that the costs of such future 

remediation would far exceed the costs of the more 

extensive monitoring (in all phases of site activity) that 

we are proposing today, together with the costs of any 

additional restoration or prompt corrective action that may 

be required to address any issues identified as a result of 

the more extensive monitoring. In this sense, perhaps a 

generalized future cost of groundwater remediation can be 

viewed as a proxy for the value of groundwater and its 

protection. Similarly, because ISR activities often take 

place in areas that are sparsely populated, and any 

subsequent contamination may take years, decades or even 

longer to reach groundwater being consumed by humans, it is 

Commented [UEUoC12]: Change made per interagency 

review.
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difficult to characterize the benefits of our proposal by 

applying typical Agency metrics, such as the number of 

cancers averted.

We also recognize, however, that our efforts to 

protect groundwater must consider the use, value, and 

vulnerability of the resource, as well as social and 

economic values. We believe it is important to protect 

groundwater to ensure the preservation of the nation’s 

currently used and potential underground sources of 

drinking water (USDWs) for present and future generations. 

Also, we believe it is important to protect groundwater to 

ensure that where it interacts with surface water it does 

not interfere with the attainment of surface-water-quality 

standards; these standards are also necessary to protect 

human health and the integrity of ecosystems.

Thus, taking a more qualitative view of the situation 

leads us more broadly to consider the impacts on future 

groundwater uses. In many areas of the country, 

particularly in western states where ISR activities are 

most likely to take place, groundwater is a scarce and 

valuable resource that is being rapidly depleted to support 

increased demands. There is evidence that some communities 

are making efforts to utilize groundwater that is not of 
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“good” quality, and in our view this trend will only 

increase.

Another critical issue in groundwater protection is 

that groundwater generally is not directly accessible. 

Thus, it is much more difficult to monitor and/or 

decontaminate groundwater than is the case with other 

environmental media. Because of the expenses and 

difficulties associated with remediation of contaminated 

groundwater, we believe it is prudent and cost-effective to 

prevent the occurrence of such contamination rather than 

rely on the cleanupclean-up of preventable pollution.

Thus, the Agency believes that it is in the national

interest to preserve the quality of groundwater resources 

to the extent practicable, and that the best way to do so 

is to prevent contamination by addressing its source.20 We 

believe today’s proposal, which focuses on the source of 

potential contamination at ISR sites by stricter 

application of groundwater standards and more extensive 

monitoring to ensure that groundwater restoration will 

endure, is a reasonable and responsible approach to 

achieving this goal.

1. What are the environmental impacts of uranium ISR?

 

20 EPA (1991). “Protecting the Nation’s GroundwaterGroundwaterGround 

Water: EPA’s Strategy for the 1990s,” 21Z-1020.
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As noted earlier, ISR facilities affect the 

environment in ways that are both distinct from, and more 

complicated than, conventional mill tailings sites. The 

alteration of large subsurface areas through injection of 

chemical solutions also has the potential to cause changes 

in groundwater at significant distances downgradient. The 

migration of constituents liberated from the subsurface is 

controlled during the operational phase through the use of 

extraction wells.21

Once uranium recovery operations at a wellfield are 

complete, efforts to restore groundwater in the wellfield 

begin. Without such efforts, contaminants could migrate 

hydrologically downgradient from the ISR site. Restoration 

efforts largely consist of injecting and extracting water 

to flush out the remaining mobilizing solutions (i.e., 

lixiviant) and chemical treatments designed to reverse the 

chemical process and return the prevailing chemical 

conditions (oxidizing) in the subsurface to their 

preoperational chemically reducing state.

Much remains unknown about the geochemical stability 

of restored wellfields once ISR operations have ceased. 

Long-term environmental impacts may result if restoration 

 

21 Extraction wells are also used during the restoration phase to 

control the migration of constituents liberated from the subsurface.
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processes do not return aquifers to their preoperational 

state, or if restored levels do not persist over time and

groundwater degrades through the slow release of residual 

contaminants. Most ISR sites historically have been unable 

to meet restoration goals for all constituents even after 

extensive effort.22 Because the past practice of monitoring 

after restoration has typically been for a very limited 

time period, we do not know if the goals that are met for 

the short-term are maintained for a longer time.

The restoration process itself is extremely complex 

and difficult to control. The fact that significant 

quantities of uranium and other constituents have been 

removed from the natural setting may affect flow patterns 

and create discontinuities that further complicate or 

retard the restoration process. Originally, uranium was 

precipitated from groundwater moving through pore spaces in 

the host medium, which altered the flow paths on a local 

level throughout the deposit as the deposition of uranium 

continued and changed the porosity and permeability of the 

host medium. Once uranium extraction processes begin, 

fluids are pumped into the deposit to mobilize the 

precipitated uranium and remove it; the porosity and 

 

22 Hall, Susan (2009). “Groundwater Restoration at Uranium In-Situ 

Recovery Mines, South Texas Coastal Plain.” U.S. Geological Survey.
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permeability of the host rock are also affected. Because 

the uranium is not initially distributed evenly throughout

the deposit (because of the natural variations in the host 

rock properties), the extraction process cannot be assumed 

to remove all of the uranium; in fact, it does not. The 

restoration process likewise cannot be assumed to fully 

restore the porosity and permeability characteristics of 

the host rock to the exact conditions that existed before 

the ISR operations began. These changes in hydrologic 

properties in the host rock during extraction and 

restoration processes can have the net effect of altering 

flow paths within the deposit on a local level. Such 

largely unavoidable, incomplete restoration efforts may 

result in pockets of slowly leaching contaminants that may 

migrate out of the production zone over time.

In the absence of explicit regulatory language 

addressing ISR facilities, NRC and its Agreement States 

have used guidance and license conditions to implement many 

aspects of groundwater protection programs, including the 

selection of restoration goals and post-restoration 

monitoring. Based upon the information that we have 

reviewed,23 we believe an even more rigorous approach is 

 

23 For example, Hall, Susan (2009). “Groundwater Restoration at Uranium 

In-Situ Recovery Mines, South Texas Coastal Plain.” U.S. Geological 

Survey.
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warranted for (a) determining background groundwater 

concentrations, which are necessary to establish 

appropriate restoration goals, (b) establishing restoration 

goals, and (c) demonstrating the continued stability of 

groundwater after restoration. In addition, prolonged

stability monitoring is needed to provide the necessary 

level of confidence that groundwater quality will not 

degrade over time or promote contaminant migration in the 

future. 

We recognize that it is difficult to reach a 

definitive conclusion regarding the frequency and extent to 

which long-term contamination has been or is likely to be a 

problem at ISR sites, because post-restorationlong-term

stability monitoring typically occurs for only a relatively 

short timeframe, a few years at most; nevertheless, we 

believe the available information supports our concerns in 

this matter. Because the lixiviant used during operations 

oxidizes not just the uranium but the entire production 

zone, the effect from adding reducing agents to restore the 

wellfield may just be temporary. If these reducing agents 

migrate out of the production zone, re-oxidation of the 

uranium in the “restored” wellfield may occur. This is

especially likely if the natural reducing agents originally 

present in the production zone (i.e., organic materials and 

Commented [UEUoC13]: Change made per interagency 

review.
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iron sulfide minerals) were sufficiently depleted during 

ISR operations. To determine if re-mobilization of 

constituents precipitated by the restoration process will 

occur, longer -term monitoring of the site is warranted.

We are aware of the potential for geochemical 

conditions in the restored wellfield to alter over time. 

The ISR process can cause a loss of the chemically reducing 

potential in the ore zone. Over time, as oxidizing 

groundwater makes its way into the abandoned wellfield, reoxidation could occur. Given the slow groundwater travel

times in these deposits, it would take even longer time for 

the degraded water to make its way to water supply wells 

downgradient of the production zone aquifer and be detected 

there. Therefore, when we speak of long-term alteration of 

the groundwater, we imply timeframes of decades (or longer)

rather than a few years.

2. What analysis has EPA done to support the proposal?

There is only very limited information in the open 

literature24 on the stability of a restored wellfield after 

ISR operations have ended. Typically, post-restoration 

monitoring concludes and license termination proceeds 

 

24 Borch, T., N. Roche and T.E. Johnson (2012), “Determination of 

Contaminant Levels and Remediation Efficacy in Groundwater at a Former 

In Situ Recovery Uranium Mine.” Journal of Environmental Monitoring, 

14:1814-1823.
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within a matter of several years after the restoration 

phase ends. The behavior of the restored wellfield in the 

long-term, i.e., decades or longer after the ISR operations

end, has not been examined. The potential for remobilization of the contaminants is possible and this 

concern is the impetus for proposing longer postrestoration monitoring periods.

We have assessed exposure scenarios and exposure 

pathways for potentially hazardous constituents (mainly 

radionuclides) and found that migration of contaminants 

within the ore-bearing aquifer and slow movement of 

contaminants into upper aquifers through discontinuities or 

disruptions (e.g., abandoned boreholes) and other possible 

failure scenarios (leaks, spills, etc.) have the potential 

to result in significant exposures to individuals outside 

the production areas.25 These assessments suggest that a 

robust regulatory approach is advisable in order to prevent 

various failure scenarios that may occur during and after 

ISR operations, and to mitigate the potential adverse 

effects of any such failures.

In examining the technical literature pertaining to 

ISR operations, we have found that some modeling studies 

 

25 EPA (2012), “GroundwaterGround Water Modeling Studies at In Situ 

Leaching Facilities and Evaluation of Doses and Risks to Off-Site 

Receptors from Contaminated GroundwaterGround Water.”
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indicate that the uranium recovery operations can result in

the development of relatively slowerslow groundwater 

pathways through the wellfield, as well as the persistence 

of injected lixiviant within the production zone. These 

results suggest that the typically short post-remediation 

monitoring periods prior to license terminations may fail 

to detect subsequent contaminant migration out of the 

wellfield along these slow transport paths. We are 

proposing stability monitoring periods longer than the 

current practice and requirements to address these 

situations. Statistical analyses of well water chemistry 

data over a relatively short time (a year or two) alone 

does not in itself demonstrate that slow pathways are 

absent or that the groundwater will remain in a chemically 

reduced state over the long term. We believe that only a 

combination of longer stability monitoring and geochemical 

modeling using site-specific data can provide confidence 

that the ISR site poses no long-term hazards, and we are 

proposing such provisions today.

We have also examined various statistical approaches 

that might be suitable for evaluating long-term groundwater 

stability.26 We gave special attention to the data 

 

26 EPA (2014), “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”

Commented [UEUoC14]: Change made per interagency 

review.

Commented [UEUoC15]: Changes made per interagency 

review.
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requirements for data to be usedutilized in deciding,

withachieving a given level of statistical confidence, that 

would indicate stability was achieved over a specified 

period of time. While we do not recommend any specific 

statistical method be applied universally to all ISR 

situations (because the hydrogeology and geochemistry of 

ISR sites are not uniform by nature and because there is 

more than one statistical method that can be used), we do 

believe that the method(s) chosen must be justified by the 

quality and quantity of the field data collected. Linear 

regression techniques are typically used to examine time 

series measurements (concentrations of groundwater 

constituents measured over time intervals) for the presence 

of trends in the data (i.e., to determine if the data show 

increases or decreases in the measured concentrations over 

time). While this type of analysis is relatively simple and 

can be used for quick screening to identify the presence of 

strong linear trends, it is often not sufficiently rigorous 

when used with field data because of significant 

limitations on the data sets. For linear regression 

assessments, the data must have a normal distribution and 

constant variance (two requirements that are difficult to 

demonstrate with field data). The data must have few or no 

values below the analytical detection limits for the 
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measured parameter, and minimal outliers in the data or 

cyclical patterns (e.g., no detectable seasonality in the 

case of shallow aquifers). Field data rarely meet these 

conditions. Parametric and nonparametric techniques are 

more rigorous than simple linear regression but also have 

specific data demands. Parametric statistical tests require 

more complete data sets but require less data overall to 

reach the same statistical confidence levels as nonparametric tests, which are more tolerant of data 

shortcomings such as missing data in a series of 

measurements. Less than perfect data sets are common in 

field efforts, making non-parametric techniques potentially 

more useful in practice. These methods are extensively 

assessed in the background information document.27 The EPA 

document, “Statistical Analysis of Groundwater Monitoring 

Data at RCRA Facilities – Unified Guidance” (2009), offers 

appropriate guidance on the level of confidence to be 

attained for demonstrating stability before regulatory 

decisions are made to terminate the operating license and 

release the wellfield for other uses. For RCRA monitoring 

results, where the intent is to ensure contaminants do not 

migrate out of the unitarea and into the uppermost 

 

27 Ibid.

Commented [UEUoC16]: Changes made per interagency 

review.
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aquifersurrounding potable groundwater sources, a 

confidence level of 95 percent is expected to support a 

regulatory action to terminate the permit.28 We believe an 

equivalent degree of confidence in the long-term stability 

of a restored ISR wellfield is appropriate.

3. What came out of the Advisory from EPA’s Science 

Advisory Board?

In early 2011, we approached EPA’s Science Advisory 

Board (SAB)29 to obtain advice regarding the complex 

scientific and technical issues related to groundwater 

protection at ISR sites. The SAB is an independent advisory 

body established by Congress in 1978 with a broad mandate 

to advise the Agency on technical matters. The SAB 

typically interacts with EPA programs through one of the 

following processes: (1) a consultation, which is a 

conceptual evaluation at the early stages of an action; (2) 

an advisory, which is typically a more detailed evaluation 

to address specific technical issues during development of 

a rule or technical guidance; or (3) a review, which is a 

detailed evaluation of a completed action to determine how 

the Agency incorporated science into its decision-making. 

The SAB will often conduct a review of an action on which 

 

28 40 CFR 264.97 (h) & (i).

29 http://yosemite.epa.gov/sab/sabpeople.nsf/WebCommittees/BOARD
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it had previously weighed in through a consultation or 

advisory.

We sought an advisory with the Radiation Advisory 

Committee (RAC), which is the committee of the SAB 

specializing in radiation issues. For purposes of this 

advisory, the RAC was augmented with several additional 

experts with specialized knowledge of geochemistry or 

hydrogeology pertinent to ISR.

We prepared a report outlining the technical issues 

involved in groundwater protection during the life cycle of 

an ISR facility30 and requested that the RAC comment on the 

following:

1) The technical areas described in the report and 

their relative importance for designing and implementing a 

groundwater monitoring network;

2) The proposed approaches for characterizing 

background (baseline) groundwater chemical conditions in 

the pre-operational phase and proposed approaches for 

determining the duration of such monitoring to establish 

background (baseline) conditions;

3) The approaches considered for monitoring in the 

long-term stability phase and the approaches considered for 

 

30 EPA 402/D-14-001 “(2011), “Draft Technical Report on Considerations 

Related to Post-Closure Monitoring of Uranium In-Situ Leach/In-Situ 

Recovery (ISL/ISR) Sites,” Environmental Protection Agency, 2014..”
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determining when groundwater chemistry has reached a 

“stable” level; and

4) Suitable statistical techniques that would be 

applicable for use with uranium ISR applications 

(particularly for the areas in items 2 and 3 above), as 

well as the subsequent data requirements for their use.

Public meetings/teleconferences of the advisory 

committee were held from July 12, 2011 through December 21, 

2011, and included a two-day meeting in July 2011 with 

presentations by EPA management and staff, discussions with 

the RAC members, comments from members of the public, and 

initial reporting assignments for the RAC. NRC staff also 

attended the meetings and provided valuable input for the 

committee.

The RAC submitted its final report on February 17, 

2012.31 EPA responded to each recommendation and updated its 

draft report as part of the technical background 

information document for this proposal.32 Among the more 

prominent RAC recommendations are the following: 

 Identify indicators, both chemical and radioactive, 

for establishing conditions pre- and post-

 

31 All information related to the advisory is located at 

http://yosemite.epa.gov/sab/sabproduct.nsf/c91996cd39a82f64852574240069

0127/0314cef928df63cc8525775200482fa3!OpenDocument

32 EPA (2014), “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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operationally, not limited to those with regulatory 

limits, but also including non-hazardous 

constituents that can affect the behavior of, or 

serve as surrogates for, constituents of interest;

 Devote at least as much effort to defining 

background groundwater conditions as to postoperational trend monitoring;

 Consider challenging and fluctuating ambient 

circumstances in background characterization;

 Build in flexibility to modify the design and 

implementation of monitoring programs as new 

information becomes available;

 Carefully qualify the meaning of “return to 

preoperational groundwater quality”;

 Match sampling frequency and duration to information 

needs for hydrogeologic model confirmation;

 Present a survey of methods to determine sufficient 

well number and density; and 

 Select statistical evaluation approach in terms of 

strengths and weaknesses to suit questions to be 

answered.

We believe today’s proposal appropriately addresses 

these issues and incorporates the advice of the RAC.
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4. What efforts has the Nuclear Regulatory Commission

taken recently?

NRC regulates uranium mills and mill tailings in 

accordance with Appendix A to 10 CFR part 40.33 Appendix A

incorporates EPA’s 40 CFR part 192 standards. NRC has 

developed guidance related to ISR activities34 and has 

implemented facility requirements through license 

conditions. Agreement States regulating ISR facilities have 

taken a similar approach.

In recent years, NRC has recognized the desirability 

of ISR-specific regulations. NRC has been concerned with

the potential for duplicative or conflicting groundwater 

protection requirements at ISR sites where NRC implements 

UMTRCA requirements but the EPA, or a state with primary 

enforcement responsibility (“primacy”), also regulates the 

injection associated with ISR through its Underground 

Injection Control (UIC) authorities, which are derived from 

EPA under the Safe Drinking Water Act (see Section II.F.1 

of this document). In 2003, NRC staff recommended that NRC 

 

33 “Criteria Relating to the Operation of Uranium Mills and the 

Disposition of Tailings or Wastes Produced by the Extraction or 

Concentration of Source Material From Ores Processed Primarily for 

Their Source Material Content.” 10 CFR part 40 more broadly covers 

“Domestic Licensing of Source Material.”

34 For example, see NRC (2003). “Standard Review Plan for In Situ Leach 

Uranium Extraction License Applications (NUREG-1569).” Available at 

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1569/.
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enter into a MemorandumMemoranda of Understanding (MOU) 

with the affected states (at the time, Wyoming and 

Nebraska) to defer active regulation of groundwater to the 

states.35 This recommendation was approved by the 

Commission.

Upon further investigation, however, NRC staff 

reported to the Commission that “the Nebraska and Wyoming 

groundwater protection programs were found to be not 

equivalent to the NRC’s groundwater protection program.” 

Specifically, both states required restoration of 

groundwater to “a quality of use” consistent “with the uses 

for which [it] was suitable prior to” the ISR operation, 

rather than to levels consistent with NRC and EPA 

restoration standards under UMTRCA.36

After considering this information, the Commission 

determined in 2006 that the appropriate action was 

“initiation of a rulemaking effort specifically tailored to 

groundwater protection programs at in situ leach (ISL) 

uranium recovery facilities.” Further, the Commission 

directed that “[t]he staff should focus on eliminating dual 

 

35 NRC (2003). “Options and Recommendations for NRC Deferring Active 

Regulation of Ground-Water Protection at In Situ Leach Uranium 

Extraction Facilities.” SECY-03-0186.

36 NRC (2006). “Status of the Development of Memoranda of Understanding 

with Nebraska and Wyoming, Regarding the Regulation of Groundwater 

Protection at Their In Situ Leach Uranium Recovery Facilities.” SECY05-0123.
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regulation by the NRC and EPA of groundwater protection. 

The NRC should retain its jurisdiction over the wellfield 

and groundwater under its Atomic Energy Act authority, but 

should defer active regulation of groundwater protection 

programs to the EPA or the EPA-authorized state through 

EPA’s underground injection-control permit program.”37

EPA disagreed with the approach recommended by the 

Commission. EPA has always held the position that UMTRCA is 

the controlling legal authority for protection of 

groundwater and NRC is obligated to implement the 40 CFR 

part 192 standards to carry out that function at ISR sites. 

Reliance on the requirements of the UIC program alone would 

not adequately address groundwater protection at ISR 

facilities, given that the purpose of the UIC program is to 

prevent endangerment of underground sources of drinking 

water (USDWs), not to address restoration of groundwater. 

Moreover, if the groundwater is not considered a USDW, as 

is typically the case at ISR sites, it is not protected 

under the Safe Drinking Water Act (SDWA). Reliance on the 

UIC program alone would also likely lead to inconsistent 

levels of protection since states can implement more 

stringent requirements than the national UIC requirements

 

37 NRC (2006). “Regulation of Groundwater Protection at In Situ Leach 

Uranium Extraction Facilities.” Staff Requirements – COMJSM-06-0001.
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and, as NRC discovered, states with authority to implement 

the UIC program may not have groundwater protection 

requirements consistent with those that have been applied 

to conventional mills. EPA decided to address groundwater 

protection at ISR facilities by amending its UMTRCA 

standards, as we are proposing to do today. The Commission 

subsequently decided that the NRC rulemaking should be 

deferred until EPA’s revised standards are final.38

F. What other EPA statutes and regulations are relevant?

There are several other EPA environmental statutes and 

regulations that are relevantapplicable to ISR facilities

and operations. The Safe Drinking Water Act, Clean Water 

Act, Clean Air Act and Resource Conservation and Recovery 

Act are all detailed below. It should be noted that UMTRCA 

requires us to establish protections consistent with the 

requirements of the Resource Conservation and Recovery Act.

1. Safe Drinking Water Act (SDWA)

The Safe Drinking Water Act (42 U.S.C. 300f et seq., 

1974) is the main federal law that addresses drinking 

water. Under the SDWA, EPA sets health-based standards for 

drinking water to protect against naturally occurring and 

anthropogenic contaminants that may be found in drinking 

 

38 NRC (2011). “NRC Regulatory Agenda: Semiannual Report, July -

December 2010.” NUREG-0936; Vol. 29, No. 2.

Commented [UEUoC17]: Change made per interagency 

review.
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water.39 EPA and states work together to implement those 

standards at public water systems.40 Implementing 

regulations in 40 CFR part 141 include the establishment of 

national primary drinking water standards. 

The SDWA also addresses sources of drinking water, 

including underground sources, which may be used by public 

water systems or private well owners. As required by the 

SDWA, EPA established regulations for UIC programs to 

prevent underground injection that endangers drinking water 

sources.41 Under this program, the Agency has a permit 

system to prevent endangerment of USDWs. It prohibits any 

injection activity that allows the movement of fluid 

containing any contaminant into underground sources of 

 

39 After reviewing health effects studies, EPA sets a Maximum Contaminant Level Goal (MCLG), the 

maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the 

health of persons would occur, and which allows an adequate margin of safety. MCLGs are nonenforceable public health goals. Since MCLGs consider only public health and not the limits of detection 

and treatment technology, sometimes they are set at a level which water systems cannot meet. When 

determining an MCLG, EPA considers the risk to sensitive subpopulations (infants, children, the elderly, 

and those with compromised immune systems) of experiencing a variety of adverse health effects. Once 

the MCLG is determined, EPA sets an enforceable standard. In most cases, the standard is a Maximum 

Contaminant Level (MCL), the maximum permissible level of a contaminant in water which is delivered to 

any user of a public water system. The MCL is set as close to the MCLG as feasible. EPA must determine 

the feasible MCL or treatment technique which the Safe Drinking Water Act defines as the level that may 

be achieved with the use of the best available technology, treatment techniques, and other means which 

EPA finds are available (after examination for efficiency under field conditions, not solely under laboratory 

conditions), taking cost into consideration. 

40 SDWA does not regulate private wells that serve fewer than 25 

individuals or have fewer than 15 service connections.

41 SDWA Section 1421(c)(2)(C)(2) states: “Underground injection 

endangers drinking water sources if such injection may result in the 

presence in underground water which supplies or can reasonably be 

expected to supply any public water system of any contaminant, and if 

the presence of such contaminant may result in such system’s not 

complying with any national primary drinking water regulation or may 

otherwise adversely affect the health of persons.” 42 U.S.C. 300

h300h(d)(2).

Commented [UEUoC18]: Change made per interagency 

review.
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drinking water if the presence of that contaminant may 

cause a violation of any primary drinking water regulation 

or otherwise adversely affect the health of persons. EPA’s

UIC regulations, including permit requirements, are found 

at 40 CFR parts 144-148. They address construction, 

operation, monitoring, reporting, and plugging and 

abandonment of injection wells to prevent the movement of 

fluids into any USDW.42

EPA’s UIC regulations for Class III wells protect 

USDWs by prohibiting the movement of any contaminant into 

the underground source of drinking water (e.g., injection 

of fluids or release or migration of naturally occurring 

contaminants into an underground source of drinking water). 

A USDW is defined in EPA regulations as any aquifer or its 

portion (a)(1) which supplies a public water system or (2) 

which contains a sufficient quantity of groundwater to 

supply a public water system; and (i) currently supplies 

drinking water for human consumption; or (ii) contains 

fewer than 10,000 mg/l total dissolved solids; and (b) 

which is not an exempted aquifer. The receiving aquifer 

must not meet the definition of a USDW. An aquifer or a 

portion of an aquifer may be exempted from the protections 

 

42 EPA defines six classes of underground injection well. Uranium insitu recovery operations are permitted as Class III wells. 40 CFR 

146.5(c)(2).
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afforded USDWs if (a) it does not currently serve as a 

source of drinking water and (b) it cannot now and will not 

in the future serve as a source of drinking water because 

one of four specified conditions is met,43 or the total 

dissolved solids content of the groundwater is more than 

3,000 mg/l and less than 10,000 mg/l and it is not 

reasonably expected to supply a public water system. 

The construction of a Class III injection well at an 

ISR facility requires a UIC permit be obtained. Currently, 

ISR facilities are injecting lixiviant and extracting 

uranium from within exempted aquifers. If an underground 

injection well is used for injection into an exempted 

aquifer or a portion of an exempted aquifer, it is still 

regulated to protect the non-exempt portions of the USDW 

and other nearby USDWs. The scope of coverage of an aquifer 

exemption request is typically the portion of the USDW 

affected by the activity. It is possible that future ISR 

facilities will inject lixiviant and extract uranium from 

ore deposits that are within poorer quality aquifers that 

do not meet the definition of USDW; although an aquifer 

exemption would not be necessary in such a case, an UIC

permit would still be required.

 

43 The presence of minerals or hydrocarbons that are, or are expected to 

be, commercially producible, is one of these specified conditions; this 

would likely be the situation at a proposed ISR site. 40 CFR 146.4.
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EPA has established minimum requirements for states or 

tribes to obtain authority to implement the UIC program.44

To obtain “primacy” to implement the UIC program for Class 

III wells, states or tribes must adopt and submit to EPA 

for approval, UIC Class III injection well requirements 

that are at least as stringent as EPA’s minimum 

requirements. The state or tribe may establish and 

implement requirements more stringent than the EPA UIC 

regulations, but not less stringent than the minimum 

federal requirements. Further, primacy states have the 

authority to identify and propose aquifers for exemption as 

part of their initial UIC program submission, or subsequent 

to program approval; however, these proposed exemptions 

generally must be affirmatively approved by the EPA.45

Aquifer exemptions have been a source of confusion 

regarding the applicability of our UMTRCA standards, which 

we hope to clarify today in this rule. There are limited 

UIC requirements relating to restoration of the exempted 

portion of the aquifer;46 furthermore, an aquifer exemption 

does not eliminate the need to comply with the requirements 

of UMTRCA. The aquifer exemption provides relief from 

certain UIC requirements under the SDWA, thereby allowing

 

44 40 CFR part 145, “State UIC Program Requirements.”

45 40 CFR 144.7(b)(2) & (3).

46 40 CFR 146.10(a)(4).
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injection into aquifers that would otherwise meet the 

definition of a USDW. The part 192 standards, however, are 

promulgated under a different statute. Therefore, an

aquifer exemption under the SDWA does not relieve the 

licenseeowner/operator of the obligation to remediate 

environmental contamination resulting from activities 

regulated under UMTRCA. Today’s proposal clarifies that EPA 

standards issued pursuant to UMTRCA do apply within the 

exempted portion of the aquifer.

2. Clean Water Act (CWA)

The Clean Water Act (33 U.S.C. §1251 et seq., 1972) 

requires the establishment of water quality standards for, 

and regulation of pollutant discharges into, waters of the 

United States. The CWA’s definition of “pollutant” includes 

radioactive materials, 33 U.S.C. § 1362(6); EPA’s 

regulations at 40 C.F.R. § 122.2 define the term 

“pollutant” to include radioactive materials “except those 

regulated under the Atomic Energy Act of 1954, as amended 

(42 U.S.C. 2011 et seq.)....” Radioactive materials covered 

by the AEA are those encompassed in its definitions of 

source, byproduct, and special nuclear materials. See 42 

U.S.C. § 2014. The radioactive materials EPA may regulate 

under the CWA “are those not encompassed in the definition 

of source, byproduct or special nuclear materials as 

Commented [UEUoC19]: Change made per interagency 

review.
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defined by the [AEA] and regulated pursuant to that Act.” 

See Train v. Colorado Public Interest Research Group, Inc., 

426 U.S. 1, 11 (1976). Under the CWA, EPA has implemented 

pollution control programs, such as setting technologybased wastewater discharge limitations and standards for 

various industries. Subpart C of 40 CFR part 440 provides 

technology-based effluent limitations guidelines and 

standards applicable to discharges from mills atfrom which 

uranium, radium and vanadium are extracted. Permits for 

discharges to surface waters must include applicable 

technology-based limits, as well as any more stringent 

water quality-based effluent limits necessary to achieve 

water quality standards established under Section 303 of 

the CWA, including state narrative criteria for water 

quality.

3. Clean Air Act (CAA)

EPA regulates radionuclide emissions through its 

authority under the CAA, 42 U.S.C. 7401 et seq. The Agency 

has promulgated regulations for controlling radon emissions 

from operating uranium byproduct materials impoundments 

located at uranium recovery facilities, including ISR 

sites, at 40 CFR part 61, Subpart W.

4. Resource Conservation and Recovery Act (RCRA)
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The Resource Conservation and Recovery Act (42 U.S.C. 

§6901 et seq.) was passed in 1976 as an amendment to the 

Solid Waste Disposal Act of 1965, to ensure that solid 

wastes are managed in an environmentally sound manner. RCRA 

gives EPA the authority to control hazardous waste from 

“cradle-to-grave.” This includes the generation, 

transportation, treatment, storage, and disposal of 

hazardous waste (Subtitle C). RCRA also set forth a 

framework for the management of non-hazardous solid wastes 

(Subtitle D). RCRA has been further amended to extend its 

application; for example, the 1986 amendments to RCRA 

enabled EPA to address environmental problems that could 

result from underground tanks storing petroleum and other 

hazardous substances.

UMTRCA requires that generally applicable standards 

promulgated under its authority by EPA for non-radiological 

hazards be consistent with the standards issued under 

Subtitle C of the Solid Waste Disposal Act (now RCRA) that 

are applicable to those same hazards. The most appropriate 

RCRA regulations that bear on the ISR process are contained 

in 40 CFR part 264.47 These regulations deal with 

functionally relevant issues such as requirements for: the 

 

47 “Standards for Owners and Operators of Hazardous Waste Treatment, 

Storage, and Disposal Facilities.”
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siting, design and operation of impoundments; monitoring 

groundwater around land-based storage and disposal 

facilities; detecting contaminant releases and conducting 

subsequent corrective actions; and establishing the 

duration of compliance monitoring periods. These 

requirements are easily applied to conventional mill 

tailings impoundments, which are to be constructed to RCRA 

standards, although they are expected to remain under 

institutional control for much longer periods.48 Similarly, 

we believe many of the requirements and concepts should be

applicable to the long-term behavior of an ISR site after 

uranium extraction has ceased and the operators have made 

efforts to restore the wellfield to conditions that existed 

before the uranium recovery operation began. Conceptually,

at that stage there is similarity between a closed 

hazardous waste disposal facility and a restored ISR 

wellfield in the sense that both strive to avoid off-site 

migration of contaminants. The intent of the groundwater 

monitoring efforts at these two types of facilities share 

the common objective of verifying that containment of 

contaminants meets expectations. The location of compliance 

point(s) for monitoring data collection, performance 

 

48 These requirements also apply to any uranium byproduct impoundments 

(i.e., ponds) that are removed at the end of licensed operations.
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measures for assessing compliance with regulatory 

requirements, duration of the monitoring program and the 

extent of data necessary for regulatory decision-making are 

areas that we believe can be adapted to better fit the 

unique aspects of the ISR application. These subjects are 

discussed in the next section.

III. Summary of Today’s Proposal

Today’s proposal is limited to the following items. 

First, we are proposing new standards to explicitly address 

groundwater protection at uranium ISR facilities. Second, 

we are proposing to amend existing provisions only as 

necessary to address a judicial decision, an outdated 

reference and known typographical and grammatical errors.

At this time, we request public comment only on these 

proposed standards and amendments. We are not requesting, 

and will not respond to, public comments related to any 

other provisions since they are beyond the scope of today’s 

proposal. The rationale for these elements of our proposal 

is discussed in Section IV of this document.

A. Proposed standards (Subpart F)

1. Proposal of a new subpart – Subpart F-Public 

Health, Safety and Environmental Protection Standards for 

Byproduct Materials Produced by Uranium In-situ Recovery.
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A new subpart F is being proposed that would set 

standards that would apply to uranium ISR facilities only.

2. Addition of a new section on applicability – § 

192.50 Applicability.

We are proposing applicability language under subpart 

F that specifies the subpart will apply to the management 

of uranium byproduct materials during and following the 

processing of uranium ores using ISR methods.

3. Addition of a new section containing definitions -

§ 192.51 Definitions and cross-references.

To help ensure consistency with subparts A, B, C, D 

and E, all terms in the proposed subpart shall carry the 

same meaning as previously defined, unless otherwise 

specified. To help ensure clarity, the new subpart will 

contain numerous definitions specific to ISR. The following 

terms are defined:

Terminology

Adjacent Aquifer

Alternate Concentration Limit (ACL)

Aquifer

Background

Constituent

Exceedance

Excursion

Excursion Monitoring Well

Exempted Aquifer

Extraction Well
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Indicator Parameter

Injection Well

In-Situ Recovery (ISR)

Listed Constituent

Lixiviant

Long-Term Stability Phase

Maximum Constituent Concentration

Maximum Contaminant Level (MCL)

Monitoring Wells

Operational Phase

Overlying Aquifer

Point(s) of Compliance

Point(s) of Exposure

Preoperational Monitoring

Production Zone

Restoration (Act of)

Restoration Goal

Restoration Phase

Site

Stability Phase

Underlying Aquifer

Upper Control Limit (UCL)

Uranium Recovery Facility

Wellfield

4. Addition of a new section detailing standards - § 

192.52 Standards.

In the new subpart, EPA proposes to specify the 

minimum 13 constituents for which groundwater protection 

standards must be met. The list includes the following: 

arsenic, barium, cadmium, chromium, lead, mercury, 
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selenium, silver, nitrate (as N), molybdenum, combined 

radium-226 and radium-228, uranium (total), and gross 

alpha-particle activity (excluding radon and uranium). See 

section II.F.1 of the preamble and footnote for background.

After groundwater restoration, the concentration of each 

listed constituent within the exempted aquifer of an ISR 

wellfield must remain at or below the most protective 

standards under the SDWA (40 CFR 141.61, 141.62, 141.66, 

141.80 and 143.3), values from RCRA standards (40 CFR 

264.94), or Table 1 to subpart A of part 192, except in

cases where the measured preoperational background 

concentration is higher than the most stringent value in 

the applicable regulations. In such cases, the measured 

background concentration will serve as the restoration 

goal. The proposed language allows for the regulatory 

agency to set groundwater protection standards for 

additional constituents as necessary, consistent with site 

conditions.

The new subpart also describes the process for 

requesting and approving alternate concentration limits 

(ACLs) after restoration has taken place. 

5. Addition of a new section discussing monitoring 

requirements - § 192.53 Monitoring programs.
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In addition to the constituents to be monitored at ISR 

facilities, the new subpart also details the specific 

requirements of monitoring programs to be conducted during 

the preoperational, operational, restoration, stability and 

long-term stability phases.

6. Addition of a new section establishing requirements 

for corrective actions - § 192.54 Corrective action 

program.

Should an excursion be detected or the proposed 

groundwater standards be exceeded at the excursion 

monitoring wells or long-term stability compliance wells at 

any licensed ISR site, we propose to require that a 

corrective action program be put into place as soon as is 

practicable and no later than 90 days after an excursion or 

an exceedance is discovered. Similar to the approach taken 

in subpart D, we propose that the corrective action program 

put into place meet the specifications of § 264.100.

7. Addition of a new section detailing the effective 

date of the new subpart - § 192.55 – Effective date

We are proposing that the rule go into effect 60 days 

after it is promulgated in the Federal Register, the legal
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minimum amount of time between promulgation of the new 

subpart and its effective date.49

B. Other proposed amendments

1. Revision to Subpart C – Implementation

In an effort to address an outdated reference, EPA 

proposes to remove mention of the Grand Junction Remedial 

Action Criteria (10 CFR 712); the criteria were removed 

from the CFR between 1981 and 1982. In addition, EPA 

proposes to delete language citing certain remedial options 

that “may provide reasonable assurance of” radon decay 

product concentration reductions. The final report for the 

Grand Junction Remedial Action Program, issued in 1989,

stated that the methods were not effective over the long 

term.

2. Revision to Subpart D – Standards for the 

Management of Uranium Byproduct Materials 

EPA proposes to amend the heading of Subpart D. The 

proposed amendment will remove an inaccurate citation of 

EPA’s authority. In order to correct certain typographical 

and grammatical errors that have been identified in Subpart 

D since promulgation, EPA proposes the following technical 

corrections:

 

49 See 42 U.S.C. 2022(c)(3).
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Section Proposed technical correction and 

reason

§ 192.31(a) Replace “Uranium Mill Tailings 

Rediation Control Act” with 

“Uranium Mill Tailings Radiation 

Control Act” to correct a 

typographical error

§ 192.31(f) Replace “pile containing uranium by 

product materials” with “pile 

containing uranium byproduct 

materials” to correct a 

typographical error

§ 192.32(a)(2)(v) Replace “laser fusion, of soils, 

etc.” with “laser fusion of soils, 

etc.” to correct a grammatical 

error

EPA is also proposing to modify § 192.32(a)(2)(v) in 

order to delete the NRC requirement to obtain concurrence 

from EPA before NRC may approve an alternate requirement or 

proposal under AEA section 84(c).50 This portion of § 

192.32(a)(2)(v) was effectively struck down by the Tenth 

Circuit Court of Appeals in Environmental Defense Fund vs. 

U.S. Nuclear Regulatory Commission, 866 F.2d 1263 (10th Cir. 

1989).

IV. What is the Rationale for Today’s Proposal?

Groundwater is one of our nation’s most precious 

resources. A significant portion of the U.S. population 

draws on groundwater for its potable water supply. In 

 

50 See 42 U.S.C. § 2114(c).
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addition to serving as a source of drinking water, people 

use groundwater for irrigation, stock watering, food 

preparation, personal health and hygiene, and various 

industrial processes. When that water is radioactively 

contaminated, each of those uses becomes a radiation 

exposure pathway for people. Groundwater contamination is 

also of concern to us because of potential adverse impacts 

upon ecosystems, particularly sensitive or endangered 

ecosystems. For these reasons, it is a resource that needs 

protection.

A number of federal and state laws have been passed 

through the years to protect drinking water. At the federal 

level, the SDWA (discussed in detail in Section II.F.1) 

establishes the basic framework for protecting the drinking 

water used by public water systems in the United States. 

This law contains requirements for ensuring the safety of 

the nation’s public drinking water supplies. At the state 

level, many similar drinking water and water use laws have 

been passed.

Groundwater is also a valuable and dwindling resource, 

particularly in western states where most ISR activities 

are anticipated. EPA views protecting groundwater as a 

fundamental part of its mission. Particularly in cases 

where groundwater is directly threatened by an activity, as 
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it is by the ISR technology, EPA believes it has a special 

duty to ensure that the authority of all applicable federal 

statutes (e.g., UMTRCA and the SDWA) are used to help 

protect the groundwater and that appropriate standards to 

protect public health, safety and the environment are 

developed and implemented. 

We anticipate the objection that the presence of 

uranium deposits typically results in groundwater of poor 

quality, and not a pristine source of drinking water. We 

recognize that this is often the case, and that the volume 

of water affected by the mineralized zone may be 

significant. We do not, however, see this as a reason to 

allow this groundwater to be further degraded. The 

increasing scarcity of groundwater is leading some 

communities to consider using sources of water that 

previously would have been considered non-potable, using 

advanced treatment to make it suitable for livestock or 

human consumption. Since such advanced treatment may not be 

economically feasible for some communities, it is all the 

more important to prevent, as much as reasonably possible, 

additional degradation of the groundwater. 

A guiding philosophy in radioactive waste management, 

as well as waste disposal in general, has been to avoid 

imposing burdens on future generations for clean-up efforts 
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as a result of management approaches that are reasonably 

anticipated towould knowingly result in pollution in the 

future. Adhering to the concept of sustainability, we 

should not knowingly impose undue burdens on future 

generations that we ourselves are not willing to assume. 

Imposing performance requirements that avoid polluting 

resources that reasonably could be used in the future, 

therefore, is a more appropriate choice than imposing 

clean-up burdens on future generations. ISR facilities use 

significant volumes of water during both operations and 

restoration. We believe it is reasonable to make every 

effort to ensure that ISR activities leave groundwater in 

no worse condition than pre-ISR operational 

statusoperations.

A. How Does Today’s Proposal Relate to Existing 40 CFR Part 

192?

In 1983, EPA promulgated regulations at 40 CFR part 

192 in response to the statutory requirements of UMTRCA. At 

the time, uranium recovery from ore was done almost 

exclusively by conventional milling processes, where at 

most a few pounds of uranium were recovered for each ton of 

ore mined and processed. The wastes from the milling 

process (the tailings and raffinates, i.e., uranium 

byproduct materials) were disposed of in large piles on the 
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surface at mill sites, posing contamination risks to

surface water, groundwater, and soils, both on and off 

site. Liquid wastes were often discharged into rivers. 

Contaminants of concern consisted primarily of 

radionuclides and non-radioactive metals, radon gas and 

organics. Concerns that these tailings piles would be a 

continuing source of radiation exposure and environmental 

contamination unless properly reclaimed and managed were

the driving force behind the passage of UMTRCA. The 

statute’s intent was to contain tailings in engineered 

impoundments to prevent the further dispersion and misuse 

of the material. This measure would also protect 

uncontaminated aquifers from becoming contaminated by the 

uranium mill tailings impoundments and prevent radon 

emissions through performance specifications for radon 

barriers (covers). Because the major environmental risk at 

that time was perceived to come from the conventional 

uranium mill tailings, which already existed in large 

volumes, other uranium recovery technologies, including 

ISR, received little attention.

As stated earlier, ISR has surpassed conventional 

milling as the dominant form of uranium extraction in the 

United States and is expected to predominate in the future. 

The ISR process presents different environmental concerns 
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from conventional milling. ISR does not generate large 

volumes of solid waste materials or require permanent 

tailings impoundments. The ISR process does, however, 

directly alter groundwater chemistry, posing the challenge 

of groundwater restoration and long-term subsurface 

geochemical stabilization after the ISR operational phase

ends. With ISR, the “milling” of uranium ore is performed 

within the ore zone aquifer by injection of lixiviants. As 

stated earlier, the lixiviants can also liberate other 

elements, particularly metals that are often found colocated with uranium deposits. Their migration outside the 

production zone can potentially contaminate surrounding 

aquifers. Furthermore, when processing of the ore zone is 

no longer economically viable, ISR operators can release 

the site for future use, either by selling the land or

returning the property to the original owner. The operators 

are required to restore the aquifer to its original 

geochemical conditions, to the extent possible, and to show 

some level of stability in the geochemistry of the 

production zone before terminating the license and making 

the site available for other uses. Whereas conventional 

mill tailings piles are under perpetual institutional 

control, current NRC regulations allow for ISR sites to 
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terminate their licenses, essentially ending regulatory 

oversight of the site. 

Today, EPA is reaffirming that ISR facilities are 

subject to the 40 CFR part 192 requirements. We seek to 

provide clear direction on how to monitor groundwater in 

and around the production zone during all phases of the ISR 

facility’s lifecycle, and how to demonstrate geochemical 

stability at these sites.

We believe there has been some uncertainty about how 

to apply the current standards, which are more targeted to 

conventional mills, to ISR sites. In addition, there has 

been confusion about applicability of UMTRCA restoration 

requirements at aquifers that have been exempted from the 

standards of the SDWA. With the prospect of additional ISR 

facilities beginning operations, we believe it is necessary 

to clarify these issues. Therefore, we are proposing 

additional groundwater protection provisions to 40 CFR part 

192 that are specific to uranium ISR facilities and 

consistent with the SDWA and RCRA. We believe these 

provisions are necessary to ensure that ISR sites are not 

released from regulatory control until it can be reasonably 

demonstrated that groundwater will not degrade over time. 

Specifically, we are proposing provisions that will 

result in long lasting protection of surrounding aquifers. 
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The provisions specify how to determine preoperational 

background conditions that will be used to set appropriate 

restoration goals, applicable standards and alternate 

concentration limits. We are also proposing specifications 

for long-term groundwater stability monitoring and a 

corrective action program that is triggered if 

excursions/exceedances do occur. We view these as the key 

elements in ensuring that ISR sites do not become a source 

of continuing or widespread contamination after the ISR 

operation is terminated. 

Sufficient data must be collected to characterize the 

conditions existing within and outside the proposed 

production zone to set appropriate groundwater protection 

standards (i.e., restoration goals) that account for the 

variability in geochemistry frequently encountered in 

mineralized regions. Subsequent to the end of uranium 

production, the regulator must ensure that alternate 

standards are approved only after restoration has been 

attempted and it is clearly demonstrated that the initial 

groundwater protection standard(s) cannot be achieved, or 

once achieved, cannot be maintained. Such approval should 

take place only after the operator has made reasonable and 

satisfactory efforts to achieve and maintain the initial 

standard(s) and fully considered a number of factors. 
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Whether the initial goals are met or alternate 

concentration limits are approved, conditions must be shown 

to be stable and groundwater quality must not degrade over 

time, as is possible when: lingering amounts of lixiviant 

solution remain in isolated pockets within the wellfield;

reducing conditions are not fully reestablished; and/or the 

long-term stability monitoring period is too short compared 

to the time it takes for groundwater to move through the 

aquifer. Therefore, the operator must monitor groundwater

at the site for a sufficiently long period after 

restoration is complete and use sufficient statistically 

significant results to provide a reasonable demonstration 

that long-term stability has been achieved. This 

demonstration can include geochemical modeling to confirm 

the persistence of stability of the groundwater chemistry.

Geochemical modeling can provideprovides a defensible 

demonstration of an aquifer’s natural capacity to maintain 

stability, which statistics alone cannot provide. Although

the selection and application of geochemical models will be 

on a site-specific basis, geochemical models that have been 

used to predict the fate and transport of uranium at ISR 

facilities include PHT3D, PHREEQC, and PHAST.

We intend for today’s proposal to eliminate any

confusion about the relationship of the aquifer exemption 

Commented [UEUoC20]: Change made per interagency 

review.

Commented [UEUoC21]: Change made per interagency 

review.
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process to restoration requirements at ISR sites. We 

further recognize that the application of the existing 

standards in 40 CFR part 192 to ISR sites is not as 

straightforward as it could be. Nevertheless, we believe 

there is sufficient information available to indicate that 

practices related to groundwater protection at ISR 

facilities have not been sufficiently rigorous to provide 

confidence either that groundwater is being restored

appropriately or that such restoration will persist into 

the reasonably foreseeable future.51,52,53 We believe today’s 

proposal addresses these issues in a manner that is both 

logical and implementable;54 we solicit comment on our view

of the current situation and the overall approach of our 

proposal. 

B. What groundwater protection standards are we proposing 

for ISR facilities?

 

51 Hall, Susan (2009). “Groundwater Restoration at Uranium In-Situ 

Recovery Mines, South Texas Coastal Plain.” U.S. Geological Survey. 

52 Darling, Bruce (2008). “Report on Findings Related to the Restoration 

of Groundwater at In-Situ Uranium Mines in South Texas.” Southwest 

Groundwater Consulting, LLC.

53 Fettus, G. and M.G. McKinzie (2012). “Nuclear Fuel’s Dirty 

Beginnings: Environmental Damage and Public Health Risks from Uranium 

Mining in the American West.” Natural Resources Defense Council.

54 It should be noted that we are not proposing to establish specific

requirements related to the technical aspects of groundwater 

restoration (i.e., what methods to use for restoration or which

statistical methods to use for assessing temporal stability of the 

groundwater chemical state).
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We are proposing today to establish groundwater 

protection standards consistent with those applied to 

conventional mills in 40 CFR part 192, subpart D. That is, 

the licenseeowner/operator will use as the applicable 

standard during restoration and long-term stability 

monitoring either (1) the background concentrations of 

groundwater constituents measured prior to the start of the 

ISR operational phase; or (2) a specified regulatory level, 

whichever is higher. In certain circumstances, the 

licenseeowner/operator may request that the regulatory 

agency approve an alternate concentration limit.

1. Generally applicable groundwater standards

We emphasize again that the groundwater protection 

standards currently found in 40 CFR part 192 apply to ISR 

sites. These standards address both radiological and nonradiological constituents. The standards applicable to nonradiological constituents adopted the requirements for 

groundwater monitoring at RCRA hazardous waste sites.55

These generally applicable standards were originally based 

upon EPA’s 1976 Maximum Contaminant Levels (MCLs) in 

drinking water (40 CFR part 141).56 See section II.F.1 of 

 

55 40 CFR 264.94, Table 1.

56 47 FR 32285, July 26, 1982. The use of MCLs as standards for 

groundwater protection anticipated the Agency’s Ground WaterGroundwater

Protection Strategy, first developed in 1984 and updated in 1991. Under 

the Strategy, MCLs provide a benchmark for groundwater protection. 

Commented [UEUoC22]: Change made per interagency 

review.
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the preamble and footnote for background. EPA further 

specified radiological and non-radiological constituents of 

concern at mill tailings sites. Following the same 

approach, we are proposing today to specify, as Table 1 to 

subpart F, the constituents that must be monitored at ISR 

sites, as appropriate. The required constituents mirror 

those included in Table 1 to subpart A of 40 CFR part 192, 

with the exception of the six pesticides.57

We are not proposing to establish new numerical 

standards in the rule. EPA’s preferred option for carrying 

over and updating the groundwater protection standards in 

the new ISR-specific subpart F is to incorporate, by 

reference, the most protective standards issued under the 

SDWA (40 CFR 141.61, 141.62, 141.66, 141.80 and 143.3),

values from RCRA standards (40 CFR 264.94), and the maximum 

constituent concentrations found in Table 1 to subpart A of 

40 CFR part 192. By incorporating these standards by 

reference, the new subpart F would automatically update if 

those concentration values changechanged in the standards 

under SDWA or RCRA and thereby, be self-implementing. Upon 

promulgation, licenseesowner/operators currently in 

 

Contamination of groundwater above MCLs is viewed as a failure of 

pollution prevention.

57 Endrin, lindane, methoxychlor, toxaphene, 2,4-D, and 2,4,5-TP Silvex. 

These constituents are unlikely to be present at ISR sites.
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restoration, stability monitoring or long-term monitoring 

at a given wellfield at a licensed facility would continue 

to be held to the standard(s) in place at the time of 

licensing for those given wellfield(s), unless the 

regulatory agency determines otherwise. Operating 

wellfields, new wellfields and expansions of wellfields 

would be required to meet the newly promulgated standards.

This option would make the groundwater protection standards 

under the proposed subpart consistent with all relevant

current and future standards under SDWA and RCRA. We 

believe that this approach will more effectively keep the 

groundwater protection standards current with the Agency’s 

policies while providing for regulatory certainty. The 

standards in the existing portion of 40 CFR part 192 are 

outdated for arsenic and uranium, both of which have had 

new MCLs established since the year 2000.58 Today’s proposal 

would update the standards for arsenic and uranium as they 

apply to ISR facilities. Should the Agency propose to 

update its MCLs or RCRA standards at some point in the 

future, stakeholders will have the opportunity to comment 

on the potential impacts to ISR activities. 

 

58 66 FR 6976, January 22, 2001; and 65 FR 76708, December 7, 2000, 

respectively.

Commented [UEUoC23]: Change made per interagency 

review.
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We are also considering the alternative approach of 

placing a static table of restoration goals in the new 

subpart F. The table would list the 13 required 

constituents for which groundwater protection standards 

must be met, and also provide the specific numeric 

concentration value associated with each constituent. If 

this option is promulgated in the final rule, the standards 

would not automatically update with any future changes to 

standards under the SDWA or RCRA but would remain static.

Under this approach, the Agency would initiate future

changes to standards through a notice-and-comment 

rulemaking specifically for 40 CFR part 192.

In order for an ISR operation to proceed, a UIC permit 

is required and typically, an aquifer exemption is needed 

as well. The exemption effectively removes from the 

protection of the SDWA, an aquifer or portion of an aquifer 

that would otherwise meet the definition of an underground 

source of drinking water. The wellfield used by the ISR 

operation to extract the uranium deposit may constitute 

only a portion of the overall exempted area. As noted in 

Section II.E.1 of this document, there is no similar

exemption for the aquifer from the requirements of UMTRCA, 

nor does UMTRCA contemplate such a concept. We emphasize 

again that the SDWA-based aquifer exemption does not 
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relieve the operator of an ISR facility of the obligation 

to remediate environmental contamination resulting from 

activities regulated under UMTRCA, both within and outside 

the exempted portion of the aquifer.

2. Alternate concentration limits (ACLs)

Consistent with RCRA, EPA currently allows the use of 

ACLs if the operator is unable to restore groundwater to 

either preoperational background conditions/concentration 

levels or the applicable restoration goals. Today we 

propose to clarify the requirements for requesting and 

granting ACLs in the production zone, after restoration 

efforts have taken place. While the 19 criteria to be 

considered in granting ACLs are spelled out for Title II 

sites in 40 CFR 192.32(a)(2)(iv) through incorporation of 

40 CFR 264.94(b), they have not always been implemented as 

intended.59,60 In the past, NRC and Agreement States have 

issued secondary class-of-use restoration goals at ISR 

sites, but these goals were typically less restrictive than 

meeting background concentration levels.61 NRC no longer 

 

59 These criteria are also reproduced for Title I sites in 40 CFR 

192.02(c)(3)(ii).

60 EPA (1987). “Alternate Concentration Limit Guidance, Interim Final,” 

provides guidance to RCRA facility permit applicants and writers 

concerning the establishment of RCRA Alternate Concentration Limits. 

The guidance lists 19 factors, or criteria, that are used to evaluate 

ACL requests.

61 “Class of use” designates the potential uses of groundwater based on 

its quality. For example, groundwater that is not suitable for human 
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recognizes class-of-use as an appropriate standard for 

restoration of groundwater at uranium ISR facilities;62

secondary class-of-use restoration goals are inconsistent 

with the requirements of 40 CFR part 192 and 10 CFR part 

40, Appendix A. There is evidence that relaxed restoration 

standards have been granted in Agreement States,63 and some 

instances where ACLs have been identified and approved by 

the regulator before restoration efforts have been 

initiated and/or completed.64,65 We believe these situations

can result in insufficient protection of groundwater; in 

particular, we believe it only is appropriate to establish 

restoration goals based on a thorough characterization of 

the preoperational environment and not to approve ACLs 

unless it has proven impracticable to achieve or maintain 

the initial restoration goals or return to background 

conditions after restoration. With this proposal, we 

specify the conditions that must be met prior to requesting 

 

consumption may be designated for livestock. Class of use typically 

encompasses a range of constituent concentration values.

62 NRC (2009). “Uranium Recovery Policy Regarding: (1) The process for 

scheduling licensing reviews of applications for new uranium recovery 

facilities and (2) the restoration of groundwater at licensed uranium 

in situ recovery facilities.” NRC Regulatory Issue Summary 2009-05.

63 Darling, Bruce (2008). “Report on Findings Related to the Restoration 

of Groundwater at In-Situ Uranium Mines in South Texas.” Southwest 

Groundwater Consulting, LLC.

64 Hall, Susan (2009). “Groundwater Restoration at Uranium In-Situ 

Recovery Mines, South Texas Coastal Plain.” U.S. Geological Survey.

65 Fettus, G. and M.G. McKinzie (2012). “Nuclear Fuel’s Dirty 

Beginnings: Environmental Damage and Public Health Risks from Uranium 

Mining in the American West.” Natural Resources Defense Council.
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an ACL and emphasize the factors that must be considered in 

establishing and approving ACLs. These factors specify 

that, if ACLs are deemed necessary or appropriate after all 

best practicable restoration activities have been 

completed, they must not pose a substantial present or 

potential hazard to human health or the environment.66 ACLs

can be established for carcinogens and/or non-carcinogens. 

When considering the potential for health risks caused by 

human exposure to known or suspected carcinogens, ACLs 

should, where practicable, be established at concentration 

levels that represent a cumulative excess lifetime risk to 

an average individual at no greater than 10-4 (one chance in 

ten thousand).

The regulatory agency may face situations in which the 

operator will request ACLs. If after extensive effort the 

operator determines that the initial restoration goals for 

one or more constituents cannot be achieved as required in 

 

66 “[A] licensee may propose alternatives to specific requirements 

adopted and enforced by the Commission under this chapter. Such 

alternative proposals may take into account local or regional 

conditions, including geology, topography, hydrology and meteorology. 

The Commission may treat such alternatives as satisfying Commission 

requirements if the Commission determines that such alternatives will 

achieve a level of stabilization and containment of the sites 

concerned, and a level of protection for public health, safety, and the 

environment from radiological and nonradiological hazards associated 

with such sites, which is equivalent to, to the extent practicable, or 

more stringent than the level which would be achieved by standards and 

requirements adopted and enforced by the Commission for the same 

purpose and any final standards promulgated by the Administrator of the 

Environmental Protection Agency in accordance with section 2022 of this 

title.” 42 U.S.C. 2114(c), emphasis added.

Commented [UEUoC24]: Change made per interagency 

review.
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the license, the operator may request and the regulatory 

agency may approve the levels that have been achieved as 

provisional ACLs and determine that restoration is complete

(i.e., that there is no statistically significant trend in 

the concentrations of regulated species over time). Then, 

the operator may request and the regulatory agency may 

approve final ACLs if post-restoration monitoring indicates

three consecutive years of stability at the 95 percent 

confidence level. The approval of final ACLs, however, 

would not by itself satisfy the requirements for long-term

stability monitoring.

In the second case, after restoration is complete, the 

operator may find that post-restoration monitoring detects 

increases in the concentration of one or more constituents

of concern. Depending on the statistical significance of 

the increase, the regulatory agency may determine that 

further attempts at restoration or corrective action are 

needed. If the situation persists after such action is 

taken, the regulatory agency may choose to wait and see if 

the increase levels off (i.e., stabilizes). If 

stabilization does occur, the operator may request and the 

regulatory agency may approve final ACLs if postrestoration monitoring indicates three consecutive years of 

stability at the 95 percent confidence level. 
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An additional consideration is the potential effect of 

ACLs on groundwater downgradient of the wellfield. The 

granting of ACLs could be viewed as inconsistent with the 

purpose of groundwater restoration, which is to prevent 

contamination of groundwater resources beyond the 

production zone. However, NRC has in recent years adopted 

an approach defining the “point of exposure” as the aquifer 

exemption boundary, where the initial restoration goal must 

be met. We propose to adopt a similar approach today.67 This 

will ensure that the non-endangerment condition of the UIC 

permit will be sustained. We believe the decision to grant 

an ACL is among the most important that the regulatory 

agency can make. We believe our proposal appropriately 

clarifies the situations in which ACLs can be considered 

and emphasizes the factors that must be considered, thereby 

making the overall process more rigorous. However, we also 

recognize that the regulatory agency may need to spend 

additional effort to evaluate the full record of activities 

at the site in order to determine whether an ACL is 

 

67 EPA guidance on application of ACLs under RCRA makes a similar 

distinction between the “point of compliance” and the “point of 

exposure,” emphasizing that in granting ACLs, 1) groundwater plumes 

should not increase in size or concentration above allowable health or 

environmental exposure levels; 2) increased property holdings should 

not be used to allow a greater ACL; and 3) ACLs should not be 

established so as to contaminate off-site groundwater above allowable 

health or environmental exposure levels. See 

http://www.epa.gov/wastes/hazard/correctiveaction/resources/guidance/gw

/acl.htm.
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appropriate, and at what level. Because the long-term 

protectiveness of this decision may not be fully understood 

until well after site activities conclude and the license 

is terminated, we encourage the regulatory agency to inform 

and seek input from the affected public when ACLs are being 

considered. We believe this request would constitute a 

license amendment significant enough to warrant an 

opportunity for public comment, if not public hearings.

C. Adequate characterization of groundwater prior to 

uranium recovery

To design and operate an ISR facility, the chemical 

composition and hydrology of the groundwater in and around 

the ore body must first be rigorously characterized. 

Defining the configuration of the ore zone and designing 

the production zone for uranium recovery requires detailed 

subsurface information obtained from geophysical 

investigations, including but not limited to logs and 

cores.68 In addition, the groundwater in the production zone 

is also characterized to determine the proposed chemical 

composition of the lixiviant and to determine background 

groundwater chemistry by which to set restoration goals for 

the post-production phase of the ISR operation (, i.e., the 

 

68 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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efforts to return the groundwater chemical conditions in 

the production zone to those that existed prior to the 

uranium recovery efforts).. The preoperational chemical 

composition of the groundwater in the production zone is 

called “baseline” in practice within the ISR industry and 

by NRC. In EPA documents and regulations the term 

“background” is used to indicate the original state of 

groundwater before activities take place that may introduce 

contamination into the groundwater, such as leakage of 

contaminants from a surface or near-surface waste disposal 

cell or an underground source of contamination such as 

leaking storage tanks or disposal wells.69

For the ISR method, there are a number of 

“backgrounds” involved, the most important being the 

preoperational background within the portion of the ore 

zone where uranium production will take place (i.e., the 

production zone). Knowledge of this background is necessary 

to design the leaching process and set restoration goals –

two very important steps in the ISR operation. “Background” 

groundwater composition data are also needed in portions of 

the aquifer surrounding the wellfield and in overlying and 

 

69 For example, owners and operators of hazardous waste facilities are 

required to have a monitoring system that can “represent the quality of 

background water that has not been affected by leakage from a regulated 

unit.” 40 CFR 264.97(a)(1).
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underlying aquifers that may have communication with the 

uranium ore-bearing aquifer to determine whether excursions 

occur during operations, and to determine whether seasonal 

variations in groundwater chemistry are occurring in 

shallow aquifers. Background data are also needed for 

geochemical modeling of the groundwater in the production 

zone and downgradient to support assessments of the natural 

capacity of the restored production area and downgradient 

portion of the exempted aquifer to maintain long-term 

stability of the restored wellfield. 

There are spatial and temporal designations for the 

various “backgrounds” measured in relation to an ISR 

operation. For instance, preoperational background is 

determined above, below, around and within the wellfield in 

the exempted aquifer. The preoperational background 

downgradient of the wellfield and in aquifers above and 

below the production zone are needed to detect any

excursions that may occur during the ISR operational phase

or restoration phase. The uses of the various “backgrounds” 

are described in the technical background information 

document supporting this rulemaking.70

 

70 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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NRC requires establishment of background at uranium 

recovery sites in its regulations at 10 CFR part 40, 

Appendix A, Criterion 7;71 most of the implementing 

requirements are found in guidance and license conditions. 

Today’s proposal includes provisions to ensure that 

operators adequately characterize preoperational conditions 

inside and outside the wellfield. This characterization is 

necessary to establish appropriately protective restoration 

goals that are representative of the wellfield, accounting 

for natural variability. There is evidence that regulators 

and operators have at times used high-end values to 

represent the overall wellfield or have used a generalized 

“class-of-use” for the groundwater to set restoration 

goals.72 We do not believe this is appropriate, as we 

explain below.

Today’s proposal also specifies that the 

preoperational groundwater monitoring program must account 

for the effects of well installation and development on the 

 

71 “At least one full year prior to any major site construction, a 

preoperational monitoring program must be conducted to provide complete 

baseline data on a milling site and its environs. Throughout the 

construction and operating phases of the mill, an operational 

monitoring program must be conducted to measure or evaluate compliance 

with applicable standards and regulations; to evaluate performance of 

control systems and procedures; to evaluate environmental impacts of 

operation; and to detect potential long-term effects.”

72 12. NRC (20062005). “Status of the Development of Memoranda of 

Understanding with Nebraska and Wyoming, Regarding the Regulation of 

Groundwater Protection at Their In Situ Leach Uranium Recovery 

Facilities.” SECY-05-0123.
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groundwater characteristics. The physical act of 

penetrating the aquifer to install the well can cause 

localized changes in constituent concentrations or chemical 

parameters, which can lead to a misleading picture of 

background conditions. This can, in turn, result in 

selection of artificially high restoration goals. It is 

important that the operator allow a sufficient interval of 

time between well installation and sampling to allow 

localized disturbances to dissipate and ensure that 

background conditions are accurately characterized. We are 

interested in stakeholder views on this point.

1. Establishing restoration goals

The successful protection of groundwater at ISR sites 

begins with the selection of rigorous and appropriate 

restoration goals. As described in Section III.B of this 

preamble, restoration goals will be established as the 

preoperational background concentration or as a specified 

regulatory level for that constituent, whichever is higher.

This is more complicated than it might seem. ISR 

wellfields may cover areas of 10 acres or more, and the 

presence of mineralized zones often means that there is 

significant variability within the proposed production 

area. As a result, background concentrations in one area of 

the wellfield may diverge significantly from those measured 

Commented [UEUoC25]: Deleted following sentence due to 

repetitive nature of request for comments. 
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elsewhere. The question, then, is whether it is possible to 

select a single level that is representative of the entire 

wellfield and, if not, how measurements should be 

evaluated.

We stated previously that we do not believe it is 

appropriate to select among high-end measurements as 

representative values for restoration. It might be argued, 

however, that restoring a given well to its preoperational 

values would be an indication that restoration would be 

equally successful in the rest of the wellfield. This might 

be the case at sites where remediation of groundwater is 

focused on removing a contaminant that has been introduced 

from outside the system; however, we question the general 

application of this assumption at ISR sites. As discussed 

earlier, the initial deposition (precipitation) of uranium 

mineralization is uneven and alters the porosity and

permeability of the host rock. The extraction and 

restoration processes at ISR sites are imperfect and 

further alter the distribution of the uranium in the 

deposit. Flow paths and velocities in local areas are 

altered as a result of changes in porosity and permeability 

that occur from the removal of material from pore spaces 

and later re-precipitation. It is possible that areas of 

heavy and lighter mineralization or groundwater 
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concentrations can change from the distribution existing 

before uranium recovery to that after restoration,

reflecting the degree to which the oxidizing and reducing 

agents contact the mineralization. As a result of these 

changes, “hot spots” may be found at wells that initially 

registered lower constituent concentration measurements, 

and vice versa.

Because of the site-specific nature of this 

variability, we are proposing today that operators utilize 

background measurements from across the wellfield, combined 

with appropriate statistical techniques, to determine 

restoration goals. As appropriate, goals may be developed 

for individual wells, groups of wells, or the entire 

wellfield. The point(s) of compliance for restoration will 

be determined by the operator and regulatory agency after a 

thorough technical evaluation of the operator’s geophysical 

investigation.

D. Excursions

During the operational and restoration phases at an

ISR wellfield, it is possible that lixiviant or byproduct

fluids can escape the capture zones of the extraction wells 

and move toward the monitoring well ring surrounding the 

production zone. The placement of the injection and 

extraction wells, combined with their relative pumping 
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rates, are designed to prevent such movement,73 but 

heterogeneities in the aquifer characteristics and 

difficulties in maintaining perfect performance of the 

wellfield can lead to lateral excursions as well as 

excursions into overlying and underlying aquifers (i.e., 

vertical excursions). Detecting these excursions is a prime 

focus of regulatory attention. Indicators of excursions 

(e.g., increases in concentrations of certain indicator 

parameters, such as, but not limited to, chloride ion 

concentrations above the preoperational background) are 

typically defined in the license conditions, as are 

requirements for reporting excursions to the regulatory 

authorities and corrective action requirements once an 

excursion is detected. The excursion monitoring wells are

positioned far enough away from the injection and 

extraction wells so as to not be affected by the production 

processes, but close enough to detect excursions in a 

timely manner. The spacing of wells within the monitoring 

ring must prevent contaminants from passing between the 

wells. The excursion monitoring wells should also be far 

enough from the aquifer exemption boundary to ensure that 

any necessary corrective action can be taken before a USDW 

 

73 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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is adversely impacted. We have seen instances where the 

outer monitoring ring is essentially coincident with the 

boundary of the exempted aquifer. We do not believe this 

practice is appropriate. While it may allow the operator to 

limit the amount of land dedicated to the ISR facility, it 

provides little margin for error in preventing contaminants 

from reaching protected aquifers (i.e., USDWs), and may 

hamper corrective actions should they be needed. 

Today we are proposing to adopt a definition of 

“excursion” consistent with that used by NRC in license 

conditions. Under this definition, an excursion is 

identified when two or more indicator parameters are 

measured at levels exceeding their upper control limits 

(essentially, background levels) at perimeter monitoring 

wells or in monitoring wells in overlying or underlying 

aquifers. Thus, an excursion can take place vertically 

between aquifers as well as horizontally within the aquifer 

from which uranium is being extracted.

This approach differs somewhat from that taken under 

RCRA to detect releases of hazardous constituents, so it is 

important that we distinguish between the two approaches 

and explain why our proposed approach is more suitable in 

the ISR context and consistent with law.
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Monitoring under RCRA is conducted to detect any 

evidence that an engineered hazardous waste unit (e.g., a 

landfill or impoundment) has failed. To that end, the 

detection monitoring program includes not only indicator 

parameters that might signal a change in groundwater 

chemistry or quality, but also hazardous constituents 

contained in the waste unit.74 The statistically significant 

detection of any monitored parameter or constituent 

triggers further investigation and potentially corrective 

action. Because the engineered unit has been introduced 

into the environment and the monitoring takes place at the 

edge of the unit, it is unlikely that a detection can be 

attributed to the natural variability in the groundwater at 

the site. Detection of a single parameter or constituent 

appropriately triggers action in this case because, in 

addition to remediating groundwater, the failure of the 

unit itself must be addressed to prevent further releases.

By contrast, at an ISR site all constituents that may 

be “released” are part of the natural setting, and their 

presence in groundwater may vary over time. Only the 

lixiviant is introduced from outside the natural system. 

Therefore, the “indicator parameters” are typically those 

 

74 See 40 CFR 264.98.
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that most reflect the lixiviant properties. For example, 

chloride is often incorporated into the lixiviant as a 

tracer; similarly, because the lixiviant mobilizes uranium 

by increasing alkalinity, a significant increase in 

alkalinity at excursion monitoring wells may signal that 

lixiviant has escaped the production zone extraction wells. 

Because the lixiviant typically moves more rapidly than the 

mineral constituents, increases in the properties 

associated with the lixiviant will most likely be detected 

well before the other constituents reach the excursion 

monitoring wells. The presence of these parameters in the 

natural groundwater accounts for the reliance on detecting 

two such parameters at levels above their upper control 

limits to signal an excursion, rather than only one.

We believe this approach to defining excursions (i.e., 

relying on two indicator parameters) is reasonable and has 

been shown to be workable in practice. We are also 

proposing to define “upper control limit” consistent with 

NRC’s use of the term. The “upper control limit” defines 

the level of an indicator parameter that, when two of which 

are detected at excursion monitoring wells, would signal an 

excursion; as described above, indicator parameters will 

typically be identified in the facility license. 
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It is important that the upper control limits be set 

appropriately to account for both background levels of 

indicator parameters and the characteristics of the 

lixiviant. We agree with NRC that “upper control limit 

concentrations of the chosen excursion indicators should be 

set high enough that false positives (false alarms from 

natural fluctuations in water chemistry) are not a frequent 

problem, but not so high that significant groundwater 

quality degradation could occur by the time an excursion is 

identified.”75 We have heard some concerns that upper 

control limits have in some cases been established at 

levels that would be unlikely to be exceeded under any 

conditions, thereby eliminating the possibility of 

detecting an excursion altogether. Such a situation must be 

avoided.

Upper control limits can be calculated using various 

statistical techniques, but are often derived by adding a 

multiple of the standard deviation to the mean of a 

distribution. Although it does not employ this term, EPA’s 

Unified Guidance76 covers methods that can be used to 

develop control limits or prediction limits, which serve a 

 

75 See NRC (2003). “Standard Review Plan for In Situ Leach Uranium 

Extraction License Applications.” NUREG-1569, page 5-40.

76 EPA (2009). “Statistical Analysis of Groundwater Monitoring Data at 

RCRA Facilities – Unified Guidance.”

Commented [UEUoC26]: Changes made per interagency 

review.
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similar function. NRC staff describes its current view of 

acceptable practice in NUREG-156977: “The staff has decided 

that in areas with good water quality (total dissolved 

solids less than 500 mg/l), setting the upper control limit 

at a value of 5 standard deviations above the mean of the 

measured [background] concentrations is an acceptable 

approach.”78

The potential for excursions may also be a factor in 

the facility’s decision to stop operations and enter the 

restoration phase. In some cases, conventional mills may 

enter a standby period, in which they stop processing ore 

with the intent to resume operations at some point in the 

future (the price of uranium is often the decisive factor 

in these decisions). In some cases, mills have remained on 

standby for years at a time. For an ISR facility, however, 

such a “standby” period is inappropriate because the 

migration of constituents mobilized by the prior injection 

of lixiviant continues even if the decision is made to stop 

extracting uranium. Excursions beyond the production zone

are more likely to occur if the gradient within the 

wellfield is not maintained. In our view, stopping the 

 

77 NRC (2003). “Standard Review Plan for In Situ Leach Uranium 

Extraction License Applications.” NUREG-1569.

78 Ibid, page 5-41.
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extraction cycle must be interpreted as an end to the 

operational phase and should trigger initiation of the 

restoration phase. We are interested in stakeholder views 

on this interpretation.

E. Long-term stability monitoring

Perhaps the most significant aspect of today’s 

proposal involves the actions to be taken by the operator 

after groundwater restoration is complete. If insufficient 

monitoring is conducted, either in duration, frequency, or 

in the number of wells used to sample the wellfield, it is 

very possible to reach premature conclusions of stability. 

In such cases, residual lixiviant or localized areas within 

the production zone that have not stabilized may cause 

continued mobilization of uranium and other constituents 

after monitoring is terminated, potentially leading to 

contamination downgradient or beyond the boundary of the 

exempted aquifer. Today’s proposal contains provisions 

related both to the duration of the monitoring and to the 

sufficiency of the data necessary to determine that 

stability has been achieved.

After the ISR operational phase ends, the altered

chemical state has to be returned to the preoperational 

conditions, to the extent possible, so that uranium and 

other contaminants do not migrate outside the wellfield. 
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Treatments to re-establish chemically reducing conditions 

(which greatly reduce the uranium concentration in the ore 

zone groundwater) can restore groundwater constituents to 

preoperational background levels to a large extent, 

although experience has shown that restoration of all 

constituents to the preoperational background level is 

seldom 100 percent successful.79 In addition, the chemically 

reducing conditions initially present, and the mechanisms 

that maintained these conditions originally, may not be 

restored sufficiently to persist over the long-term. Reoxidation of treated groundwater-host rock systems in other 

situations has been observed, and post-restoration 

monitoring at ISR locations has historically been 

relatively short, typically six months to periods of no 

more than a few years. A slow re-oxidation process with the 

resulting potential for enhanced migration of uranium and 

other contaminants may not be detected during a relatively 

short post-restoration monitoring period. Such an event 

could occur if the oxidizing agents in the lixiviant

significantly removed the reducing agents originally 

present in the ore zone (e.g., organic material and iron 

sulfide minerals) that were responsible for sequestering 

 

79 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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the uranium to form the ore deposit in the first place. 

Over time, naturally oxygenated waters entering the ore 

zone from up gradient could re-oxidize the uranium removed 

from solution during the restoration process, mobilizing it 

once again and transporting it downgradient beyond the 

wellfield. To determine whether a trend of increased

concentrations is occurring, it is necessary to monitor 

over long periods of time and use statistical techniques to 

analyze the data. This is particularly important if the 

trend in increased concentrations is relatively slow and 

the natural variability in the well samples is relatively 

high. These difficulties point to the need for longer postrestoration monitoring periods than historically performed.

However, as discussed earlier, the choice of appropriate 

statistical techniques to determine the presence or absence 

of trends in monitoring data can be complicated by 

shortcomings in the monitoring database, such as missing 

measurements, “nondetects,” analytical errors and other 

causes that are difficult to avoid in practice for long 

timeframe monitoring efforts.80 We have considered several 

options for the length of the long-term stability

monitoring period as described below.

 

80 Ibid.
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1. Thirty-year long-term stability monitoring period, 

with provisions for shortening that time period

The initial part of our proposal for long-term 

stability monitoring addresses the duration of monitoring. 

Specifically, we are proposing that a facility must

demonstrate three consecutive years of stability monitoring 

and then maintain long-term stability monitoring for an 

additional period of 30 years; this timeframe can be 

shortened by demonstrating long-term geochemical stability 

through modeling, as described below. In determining the 

appropriate length of long-term stability monitoring to 

provide confidence that the restored wellfield conditions 

will remain stable over time, and considering our statutory 

direction for consistency with RCRA requirements, we find 

that some direction can indeed be found in the RCRA 

regulatory framework. For RCRA hazardous waste disposal 

facilities, a post-closure monitoring period of thirty 

years is required before permit termination can occur.81

Since an engineered RCRA disposal facility for the 

containment of chemically hazardous waste is similar in 

concept to relying upon a chemically treated ISR wellfield 

to contain the potential spread of contaminants, we believe 

 

81 See 40 CFR 264.117(a)(1).
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it is reasonable to conclude that a thirty-year long-term 

stability monitoring period for ISR activities is a 

consistent application of RCRA requirements. We have 

examined various statistical techniques for determining the 

presence or absence of trends in monitoring data, under 

assumed levels of natural variability and extent of 

trending, and concluded that, under reasonable values for 

these variables, a thirty-year monitoring period is a 

reasonable length of time to detect upward trends in 

constituent concentrations.82

We recognize that a thirty-year monitoring period 

would be significantly longer than current practice and 

that stability may be achieved in a shorter timeframe. 

Therefore, we are also proposing a provision that would 

allow the regulatory agency to shorten the monitoring 

period83 if the operator can both demonstrate geochemical 

stability through monitoring and support a conclusion of 

long-term stability through geochemical modeling. We 

believe that modeling, which can provide confidence that a 

 

82 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”

83 This decision authority is also present in RCRA regulations: “... any 

time during the post-closure period for a particular unit, the Regional 

Administrator may...shorten the post-closure care period applicable to 

the hazardous waste management unit...if he finds that the reduced period 

is sufficient to protect human health and the environment...” 40 CFR 

264.117(a)(2).
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geochemical environmentmechanism exists to prevent uranium 

and other constituents from re-mobilizing, is an important 

element of any decision to shorten the monitoring period. 

Further, we believe this provision will encourage operators 

to expend more effort in preoperational site 

characterization, which will improve their modeling 

efforts.84

We are proposing that three consecutive years of 

stability be demonstrated through monitoring as a 

prerequisite before the modeling would be considered as 

justification for reducing the monitoring period. The 

three-year stability demonstration begins when sufficient 

monitoring data have been collected to allow a showing of 

statistical significance at a specified level of 

confidence. This three-year demonstration period has its 

roots in the RCRA framework, where it is a metric for the 

success of corrective action after groundwater 

contamination has been detected.85 We also see this 

 

84 The Agency recently took a similar approach in defining the postinjection monitoring timeframe applicable to Class VI wells used for 

carbon dioxide geologic sequestration. Owners or operators of Class VI 

injection wells are required to monitor for at least 50 years after the 

cessation of injection, unless an alternative timeframe is approved. 

Further, the monitoring period can be shortened if it can be 

demonstrated, based on monitoring and other site-specific data, that 

the project no longer poses an endangerment to USDWs. See 40 CFR 

146.93(b).

85 “If the owner or operator is engaged in a corrective action program 

at the end of the compliance period specified in paragraph (a) of this 

section, the compliance period is extended until the owner or operator 

Commented [UEUoC27]: Change made per interagency 

review.
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situation as analogous to the restoration of the ISR 

wellfield. Stability would be demonstrated statistically at 

the 95 percent confidence level, which we believe will help 

to ensure that operators collect data of sufficient 

quantity to support regulatory judgments. Stability would 

be demonstrated using statistical tests with sufficient 

power to detect trends with a false negative rate no higher 

than 5 percent. We believe this will ensure that operators 

collect data of sufficient quantity and quality with 

adequate power to support regulatory judgments.and quality 

to support regulatory judgments. As noted in Section II.E.2 

of this document, a 95 percent confidence threshold can 

also be found in the RCRA monitoring program. 

2. What other options did EPA consider for the longterm stability monitoring period?

In addition to the option described above, EPA 

considered two alternatives related to the duration of 

long-term stability monitoring. We are interested in 

receiving comments and data on all three options described.

 

can demonstrate that the ground-water protection standard of §264.92 

has not been exceeded for a period of three consecutive years.” 40 CFR 

26.96(c). “The owner or operator may terminate corrective action 

measures taken beyond the period equal to the active life of the waste 

management area (including the closure period) if he can demonstrate, 

based on data from the ground-water monitoring program under paragraph 

(d) of this section, that the ground-water protection standard of 

§264.92 has not been exceeded for three consecutive years.” 40 CFR 

264.100(f).

Commented [UEUoC28]: Change made per interagency 

review.
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a. Required thirty-year long-term stability monitoring 

period 

The second option we considered also relies on the 

RCRA regulatory framework. In this alternative, no 

provision for shortening the long-term stability monitoring 

time frame is permitted; thirty years of groundwater 

monitoring is required. This alternative provides a 

significant increase in the monitoring period over current 

industry practice, and the extended time would provide 

added confidence that the restored wellfield chemistry is 

remaining stable through this period of time. Thirty years 

of consistent statistical performance (i.e., no upward 

trending) would provide strong support for concluding that 

groundwater systems will remain in a chemically reduced 

state over time. If upward trending of contaminant 

concentrations was observed during the monitoring period 

under this approach, the operator would be required to 

perform additional corrective action, after which the 

monitoring period would begin again. We ultimately decided 

not to pursue this option because it does not sufficiently 

recognize the site-specific aspects of aquifer restoration 

or give operators the incentive to reach license 

termination sooner by conducting geochemical modeling. 

b. Narrative standard with no fixed monitoring period
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We also considered the option of a performance-based 

standard without explicitly calling for a long-term

monitoring period. We considered requiring that two 

conditions be met (i.e., return of the physical hydrologic 

system to a condition similar to the preoperational flow 

regime and stability of the geochemical environment) before 

license termination. To meet the first condition, return of 

the physical hydrologic system, no significant residual 

influences from the injection-extraction restoration cycle

could remain after restoration. This would include 

conditions such as hydraulic head and flow direction. 

Depending on the site, this would likely take many months

and perhaps a year or more. To meet the second condition, 

stability of the geochemical environment, the operator 

would have to show that the groundwater chemistry is 

statistically stable at a 95 percent confidence level for a

duration of time sufficient to account for site conditions. 

These site conditions would include such things as 

variability of constituents in the wellfield, groundwater 

velocity, constituent travel times and any seasonal 

influences. We expect it to take at least several years to 

collect data sufficient to achieve the 95 percent 

confidence level. With this approach, the regulatory agency 

would have maximum flexibility in determining whether to 
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establish general requirements or approach each site on an 

individual basis.

Ultimately, we decided against this approach for

several reasons. Statistical analyses alone, without the 

added requirement of long-term monitoring or the option of 

geochemical modeling, would provide no assurance that 

groundwater systems will remain in a chemically reduced 

state over a longer time frame than that used for data 

collection. Furthermore, this option does not incorporate 

RCRA’s thirty-year post-closure period. As previously 

stated, UMTRCA requires that generally applicable standards 

promulgated under its authority by EPA for non-radiological 

hazards be consistent with the standards issued under 

Subtitle C of RCRA. Based on these two reasons, we feel 

that this approach has greater potential for premature 

termination of the license. Furthermore, ambiguity in the 

narrative nature of such standards has the potential to

provoke litigation and make implementation difficult.

3. How will groundwater stability be determined?

The success of a groundwater restoration effort will 

be measured ultimately not only by whether the restoration 

goals are achieved, but also by whether those levels can 

persist and the geochemistry of the groundwater remain 

stable in the long term. The primary intent of the 
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restoration effort is to return the chemical condition of 

the groundwater in the production zone to the state that 

existed prior to the initiation of the ISR operations; 

restoring the hydrologic regime is also important. The 

persistence in time (i.e., stability) of the chemical 

condition developed during restoration is the ultimate 

measure of success for the aquifer restoration effort. We 

define stability as the state in which the concentrations 

of the constituents in the groundwater remain relatively 

constant over time, with no significant upward trending. 

The key factor in determining stability, then, is 

developing a meaningful measure by which to determine 

whether trending is occurring. Such a measure must address 

the sufficiency of the data collected, both over time and 

in its spatial distribution within the wellfield. We 

discussed the proposed monitoring timeframes in the 

previous section. The remainder of this section describes 

how we propose to determine whether groundwater chemistry

is stable and where we propose to apply this method.

a. What do we propose for determining stability? 

There are some similarities between a hazardous waste 

land disposal situation and an ISR operation that allow us 

to draw on the RCRA experience for developing standards. 

Both the RCRA disposal technology and the post-operation 
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aquifer restoration efforts for an ISR operation are 

intended to prevent contaminants from migrating in the 

environment. However, there are some differences that apply 

to developing ISR standards. An ISR production zone differs 

from a hazardous waste disposal situation in that the 

contaminants of potential concern (largely uranium and 

radium) were present at significant levels entrained within 

the host rock of the aquifer before ISR operations began 

and will still be present, to some extent, in the 

groundwater after the aquifer restoration effort has ended; 

the process will not completely remove them. The 

concentrations of contaminants of potential concern are 

subject to natural temporal variations both before and 

after ISR operations, and this variability must be taken 

into consideration in setting standards for judging the 

adequacy of aquifer restoration. Because of this natural 

variability, repeated sampling of the post-restoration 

groundwater must be done to judge the adequacy of the 

restoration process. To assess when the chemical condition 

in the wellfield groundwater has become stable, statistical 

measures and analyses are necessary for examining temporal 

variations in the water composition data collected over a 

period of time. Today we are proposing to establish a 

statistical level of confidence as the standard for
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determining stability of post-restoration groundwater. We 

believe this is a relatively simple and straightforward way 

to represent the level of rigor we believe is necessary to 

conclude that concentrations of important constituents in 

the groundwater are not increasing significantly over time.

Determining when groundwater compositions have 

achieved temporal stability will be a site-specific 

decision, dependent on the natural variability at the site, 

which is in turn dependent on many site-specific factors 

(e.g., spatial variations in uranium mineral distribution 

within the aquifer, variations in other chemical 

constituents that affect uranium dissolution), the 

frequency of sample collection, and the magnitude of any 

trends in composition that may be present relative to the 

magnitude of natural variability. Chapter 7 of the 

technical background information document supporting this 

rulemaking discusses these aspects of stability monitoring 

in much greater detail and illustrates the relationships 

between sampling frequency and data trends with time.86

Because of the site-specific interplay between the 

variables that affect stability, we are not proposing to 

specify what statistical methods the operator should use to 

 

86 EPA (2014). “Considerations Related to Post Closure Monitoring of 

Uranium In-Situ Leach/In-Situ Recovery Sites.”
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make this determination. There are a variety of methods 

available that could prove appropriate given the specific 

conditions at each site. These would include both 

parametric and non-parametric methods. We recommend that 

readers consult EPA’s “Statistical Analysis of Groundwater 

Monitoring Data at RCRA Facilities – Unified Guidance” 

(2009), which provides exhaustive discussion of methods 

that have been considered for use in the RCRA program. 

Further discussion of statistical methods for determining 

trends in groundwater data may also be found in EPA’s 

technical background information document, which was 

prepared to support this proposal.87 We emphasize that the 

choice of statistical method must be based on the quantity 

and quality of the available data and must be justified 

accordingly to the implementing regulatory agency.

The intent of the statistical analysis of groundwater 

monitoring data is to avoid a situation where a wellfield 

that is unstable is judged to have reached temporal and 

spatial stability. An appropriate statistical analysis will 

help to ensure that the regulatory decision reflects a high 

degree of confidence in the interpretation of the 

monitoring data. We are proposing that a statistical 

 

87 Ibid.
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confidence level of upper 95 percent confidence limit be 

used to determine stability over time. This level of 

confidence is often used in regulatory applications, 

including in the RCRA groundwater monitoring framework.88 We 

believe that an equivalent level of confidence, and its 

implications for sampling and analysis of groundwater 

composition data, is appropriate for consistency with RCRA 

approaches and requirements and the statutory direction 

applicable to this rulemaking. We believe a confidence 

level of this rigor will make it necessary for operators to 

collect an appropriate amount of data that clearly 

demonstrates that the restored ISR aquifer is geochemically 

stable and that UMTRCA requirements have been met. The 

frequency of sampling that will provide meaningful data 

must be determined from site-specific conditions, such as 

groundwater flow rates. Another consideration is that 

stability sampling may be misleading if the operator has 

not allowed sufficient time for the natural system to 

recover to the point where the injection-extraction cycle 

is no longer influencing groundwater flow parameters in the 

wellfield, particularly in the immediate area around the 

monitoring wells.

 

88 See 40 CFR 264.97 (h) & (i).
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b. Where will the determination of stability be made?

We have noted that a restored ISR wellfield 

essentially functions as a RCRA hazardous waste management 

unit. In this sense, when restoration is completed 

successfully, and the chemistry of the groundwater has been 

returned to a reducing environment, the uranium and other 

constituents that were mobilized are essentially “locked 

in” to the subsurface, as are hazardous constituents that 

are contained by RCRA engineered units. Following this 

reasoning, it might be considered appropriate for the outer 

boundary of the restored ISR wellfield to be designated as 

the point of compliance with the groundwater standards. 

However, we are not proposing to take this approach.

Today we are proposing that each well within the 

wellfield be considered for use as a point of compliance 

for purposes of determining stability after restoration is 

determined to be complete (note that today’s proposal does 

not address the point of compliance for the regulatory 

agency’s determination that restoration is complete, which 

may be a more complicated matter). We believe that this is 

appropriate given the size of some wellfields (on the order 

of hundreds of acres) and the significant variability that 

is typically present in the mineralized zone. We believe 

such an approach will more readily inform both the operator 
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and regulatory agency of localized trending, which may then 

be remedied as appropriate. If the licenseeowner/operator

is able to demonstrate that a particular well is 

sufficiently representative of groundwater conditions in a

larger area, the regulatory agency may approve the use of 

one well to demonstrate stability in the area covered by a 

larger number of wells. 

F. Institutional control

Institutional controls are intended to maintain longterm cognizance of the nature and location of particular 

activities that were done at a specific site, in this case 

the location of the uranium ore zone exploited by an ISR 

process. Institutional controls can prevent inadvertent 

intrusions or adverse consequences for future use of the

site. Institutional controls are commonly described as 

active or passive. Active controls are measures such as 

guards and fences posted around a site. Passive controls 

could be the erection of signs or placards at a site.

We are not proposing to establish institutional controls 

for ISR facilities. Active maintenance of the site will 

cease with the termination of the license, which will occur 

when the regulatory agency determines that all license 

conditions have been met. In this sense, we do not view the 

long-term stability monitoring period as an institutional 
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control following the ISR restoration phase; rather, we 

view it as a period of active surveillance to determine the 

long-term success of the restoration effort.

Nor are we proposing to establish passive controls, 

either at the site or in documents such as local land 

records. Requirements for survey plats or other records to 

be maintained would be consistent with RCRA requirements 

for hazardous waste facilities; however, these typically 

apply when waste management units remain at the site and 

are intended to restrict disturbance of the site.89 Though 

we are not proposing that such records be established for 

ISR sites, we strongly encourage NRC and Agreement States 

to include such provisions in ISR licenses since ISR sites 

will not be restricted from sale or further development.

Such provisions could simply inform the subsequent owner of 

the previous ISR, groundwater restoration activities and 

aquifer exemption on the property.

G. Other proposed amendments

EPA has identified several non-ISR related provisions 

within 40 CFR part 192 that should be updated and amended. 

The issues that we propose to address today include:

 

89 See 40 CFR 264.116 and 264.119.
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 Amending § 192.32 to address a ruling of the Tenth 

Circuit Court of Appeals; 

 Deleting reference to Grand Junction Remedial Action 

Criteria (10 CFR 712) at § 192.20(b)(3) since the 

criteria have been removed from the Code of Federal 

Regulations (CFR); and

 Correcting minor typographical and grammatical errors 

found in § 192.31 and in § 192.32.

1. Judicial decisions

Section 192.32 has been affected by a ruling from the 

Tenth Circuit Court of Appeals. Under § 192.32(a)(2)(v), 

NRC was required to obtain EPA concurrence for approval of 

ACLs in groundwater restoration. This provision was 

effectively struck down by the Tenth Circuit Court of 

Appeals in Environmental Defense Fund v. U.S. Nuclear 

Regulatory Commission, 866 F.2d 1263, 1268-1269 (10th Cir. 

1989), when the Court ruled that NRC has authority under 

AEA section 84(c) to independently make these site-specific 

ACL determinations, and that NRC has no duty to obtain this 

EPA concurrence. Therefore, today we are proposing to 

revise 40 CFR 192.32(a)(2)(v) by deleting this EPA 

concurrence requirement.

2. Miscellaneous updates and corrections
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EPA is proposing an amendment to address an area of 

part 192 where reference is made to another environmental 

regulation that has since been removed from the CFR. EPA is 

also proposing several technical corrections to address 

known typographical and grammatical errors.

a. Outdated cross-reference

Section 192.20(b)(3) refers to criteria that no longer 

exist in the CFR. Because of this, EPA is proposing to 

eliminate reference to the Grand Junction Remedial Action 

Criteria, which once existed at 10 CFR part 712. 

In addition, language in § 192.20(b)(3) cites methods 

that did not prove effective during the Grand Junction 

Remedial Action Program.90 The final report for the program 

clearly states that filtration (by high efficiency filters 

or by electrostatic precipitators) and sealants (mainly 

epoxy-based resins) were not effective over the long term, 

and were not recommended as remedial options for radon 

mitigation.91 EPA proposes to eliminate the language 

referencing sealants and filtration.

b. Technical corrections

 

90 In 1972, Public Law 92-314 created the Grand Junction Remedial Action 

Program to reduce radiation exposures inside structures affected by 

uranium tailings. The U.S. Surgeon General published cleanup guidelines 

for the voluntary project.

91 Colorado Department of Health (1989). “Final Report on the Grand 

Junction Remedial Action Program.”
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Since promulgation of 40 CFR part 192, several 

typographical and grammatical errors have been identified. 

Today, EPA is proposing amendments in § 192.31(a), § 

192.31(f) and § 192.32(a)(2)(v) to address these technical 

errors (e.g., spelling mistakes, misplaced comma).

V. Summary of Environmental, Cost and Economic Impacts

A. What are the impacts to groundwater?

EPA has conducted a qualitative assessment of the 

benefits of the proposed rule and the expected effects on 

human and environmental health.92 The rule would require 

thorough characterization of background groundwater 

conditions within the ore zone and surrounding aquifers, 

and would put in place an automatic updating feature so 

that the requirements affecting ISR operations are always 

consistent with requirements of the SDWA and the RCRA. The 

proposed rule would also require a longer period of 

monitoring, 30 years, to ensure that conditions in the 

exempted aquifer had been restored, achieved steady-state 

and remain stable. Further, EPA allows facilities to use 

geochemical modeling to demonstrate that groundwater 

conditions will remain stable, and thereby reduce the 

 

92 See EPA (20142013). “Economic Analysis: Proposed Revisions to the 

Health and Environmental Protection Standards for Uranium and Thorium 

Mill Tailings Rule (40 CFR Part 192).” This document can be found in 

the docket for today’s proposed rule. (Docket EPA-HQ-OAR-2012-0788).
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duration of stability monitoring to less than 30 years. 

These provisions help to ensure that, after the ISR 

operation’s license is terminated and the site is closed, 

groundwater conditions do not deteriorate. Since a closed 

ISR facility has no regulatory oversight, EPA expects that 

the improved monitoring program being proposed will reduce 

the risk of contaminating valuable groundwater resources, 

thus also reducing unintended exposure of human and 

ecological receptors to radiological and non-radiological 

constituents in groundwater. To the extent that such 

exposures are reduced, associated human health risks such 

as cancer may also be reduced. 

Groundwater is a valuable resource, particularly in 

the Western United States where uranium ISR is most common. 

Although EPA is unable to quantify the value of the 

groundwater resources that would be protected by the 

proposed rule, EPA nevertheless believes that the 

groundwater resources are likely to become more valuable 

over time. Reducing the risk of contamination of 

groundwater also protects surface water bodies to which 

affected aquifers discharge. If groundwater near an ISR 

facility were to become contaminated due to re-mobilization 

of uranium and other constituents, it might be many years 

before the contamination was discovered, especially under 
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current practice where stability monitoring only lasts a 

year or two. Benefits associated with protecting other 

potential services provided by groundwater are also 

expected.93

B. What are the benefits of avoiding impacts to 

groundwater?

In order to illustrate the potential benefits of 

avoiding impacts to groundwater, EPA estimated the costs of 

corrective action that would be required if uranium and 

other constituents remobilized in groundwater over time,

resulting in contamination.94 By preventing groundwater 

contamination (or causing it to be discovered sooner), the 

proposed rule reduces the corrective action costs incurred 

to remediate the contamination. Based on groundwater 

contamination simulations (using a model facility approach 

under varying assumptions), the cost of remediation would 

far exceed the costs of complying with the proposed rule, 

both on an annual and total basis. Using a hydrological 

model, EPA estimated that cleaning up the plume of 

 

93 See Committee on Valuing Ground Water, National Research Council 

(1997), “Valuing Ground Water: Economic Concepts and Approaches,” which 

discusses both the extraction value (e.g., value of groundwater used 

for drinking water, industrial water supply, and agriculture) and the 

value of in situ services (e.g., buffer against periodic shortages in 

surface water supplies, protect water quality by maintaining the 

capacity to dilute and assimilate groundwater contaminants, etc.).

94 See EPA (20142013). “Economic Analysis: Proposed Revisions to the 

Health and Environmental Protection Standards for Uranium and Thorium 

Mill Tailings Rule (40 CFR Part 192).”
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contamination could require 100 years of pump and treat 

remediation. In addition, if contamination were detected 

after decommissioning of a site, it is possible that the 

costs of remediation would be borne by the taxpayer or by 

the owner of the property, rather than by the uranium 

company responsible. Because we cannot anticipate how many 

ISR operations might experience deteriorating groundwater 

conditions after decommissioning or how long it would be 

before the contamination would be detected, EPA was unable 

to estimate potential avoided costs of remediation on a 

national scale. However, EPA believes they could be 

substantial.

C. What are the cost impacts?

Using information about the uranium extraction 

industry and estimated incremental costs that would result 

from the rule as proposed today, EPA examined the economic 

impacts that may result from the revisions to 40 CFR part 

192.95

EPA’s study estimates that affected ISR operators 

would incur costs to comply with the proposed rule, which 

would require comprehensive pre-operational 

characterization of the site (including characterization of 

 

95 EPA (20142013). “Economic Analysis: Proposed Revisions to the Health 

and Environmental Protection Standards for Uranium and Thorium Mill 

Tailings Rule (40 CFR Part 192).”

Commented [UEUoC29]: Change made per interagency 

review.
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geochemical conditions downgradient of the production 

zone), careful monitoring during the operation, restoration 

of groundwater quality, at least three years of stability 

monitoring, and 30 years of long-term stability monitoring, 

with the potential to shorten the duration based on 

modeling and monitoring of downgradient geochemical 

conditions. Using existing ISR operations as models for ISR 

operations that would be affected by the rule, projecting 

that 20152014 ISR uranium production will be 9.58.2 million 

pounds, and using average estimated costs of complying with 

the proposed rule, EPA estimates that the proposed rule 

would increase the average cost of uranium production at 

ISR facilities by approximately $1.5049 per pound of 

uranium (2.9%), and that annual costs incurred by 

individual ISR facilities would vary from $304245,000 to 

$9.59 million, depending on the scale of the ISR facility. 

Nationally, EPA estimates that the incremental total annual 

cost of the proposed rule would be approximately $13.512.2

million. Discounted at 7%, the estimated present value of 

the stream of national costs would be approximately $181264

million. Discounted at 3%, the estimated present value of 

national costs would be approximately $290164 million.

EPA estimated the impact of the proposed rule on the 

market for uranium using a simplified model of the U.S. 

Commented [UEUoC30]: Numbers updated per interagency 

review.
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market for uranium in 20152014. The partial equilibrium 

model estimated market impacts and revealed: (a) changes in 

the quantity of uranium purchased by U.S. civilian owners 

and operators of nuclear power plants, (b) changes in the 

domestic sales of uranium and imports, and (c) changes in 

the market price for uranium. EPA found that overall, the 

market quantity of uranium purchased for use in electric 

generation would decline by less than 0.1% and the market 

price would increase by approximately 0.4%. Domestic ISR 

facilities would decrease their production by approximately 

3.8%, and imports of uranium would increase by less than 

1%. Because the cost of uranium is a very small share of 

the cost of electricity, EPA estimates that the cost of 

generating electricity would increase by less than 0.1%.

Although the national total annual cost of the proposed 

rule (approximately $13.512.2 million, based on average 

costs) is well below the $100 million threshold that is one 

of the criteria used to identify a significant regulatory 

action, the industry has only a small number of companies 

operating a small number of ISR operations. EPA used 

existing ISR operations and the companies that own them as 

models for the types of facilities and companies that would 

potentially be affected by the proposed rule. EPA thus 

estimated that individual ISR facilities couldwould incur 
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annual costs of compliance between $304245,000 and $9.59

million, depending on the characteristics of the ISR 

facility and the costing assumptions used.96 For small firms 

owning ISR facilities, EPA’s analysis estimates cost-tosales ratios of 0.61% to 1.70%. Because costs are generally 

less than 2% of company sales, EPA estimates that 

compliance costs would not cause a significant impact.

Further, EPA estimates that and because only a few small 

businesses (ten or fewer, based on current information) 

would be affected by the proposed rule at a given time. 

Thus, EPA concludes that the rule would not have a 

significant impact on a substantial number of small 

entities.

VI. Statutory and Executive Orders Review

A. Executive Order 12866: Regulatory Planning and Review 

and Executive Order 13563: Improving Regulation and 

Regulatory Review

 

96 See sensitivity analysis results in Table D-1 of EPA (20142013). 

“Economic Analysis: Proposed Revisions to the Health and Environmental 

Protection Standards for Uranium and Thorium Mill Tailings Rule (40 CFR 

Part 192).” The $245,000 compliance estimate was based on the smallest 

wellfield acreage (210 acres) and the lowest costing scenario. The $9.9 

million compliance estimate was based on the greatest wellfield acreage 

(6,582 acres) and the highest costing scenario. The total estimated 

wellfield acreage for most ISR operations is under 500 acres (see Table 

3-7 of EPA EA(2014(2013). “Economic Analysis: Proposed Revisions to the 

Health and Environmental Protection Standards for Uranium and Thorium 

Mill Tailings Rule (40 CFR Part 192).” 
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Under Executive Order 12866 (58 FR 51735, October 4, 

1993), this action is a "significant regulatory action.”

The Executive Order defines “significant regulatory action”

as one that is likely to result in a rule that may “raise 

novel legal or policy issues arising out of legal mandates, 

the President’s priorities, or the principles set forth in 

the Executive Order.”

Accordingly, EPA submitted this action to the Office 

of Management and Budget (OMB) for review under Executive 

Orders 12866 and 13563 (76 FR 3821, January 21, 2011) and 

any changes made in response to OMB recommendations have 

been documented in the docket for this action.

B. Paperwork Reduction Act 

This action does not impose an information collection 

burden under the provisions of the Paperwork Reduction Act, 

44 U.S.C. 3501 et seq.; no reporting requirements are 

imposed on affected facilities by this rule. This rule will 

not in-and-of itself create any new information collection 

requirements that require approval of the OMB.

Burden means the total time, effort, or financial 

resources expended by persons to generate, maintain, 

retain, or disclose or provide information to or for a 

Federal agency. This includes the time needed to review 

instructions; develop, acquire, install, and utilize 
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technology and systems for the purposes of collecting, 

validating, and verifying information, processing and 

maintaining information, and disclosing and providing 

information; adjust the existing ways to comply with any 

previously applicable instructions and requirements; train 

personnel to be able to respond to a collection of 

information; search data sources; complete and review the 

collection of information; and transmit or otherwise 

disclose the information.

An agency may not conduct or sponsor, and a person is 

not required to respond to, a collection of information 

unless it displays a currently valid OMB control number. 

The OMB control numbers for EPA’s regulations in 40 CFR are 

listed in 40 CFR part 9.

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) generally 

requires an agency to prepare a regulatory flexibility 

analysis of any rule subject to notice and comment 

rulemaking requirements under the Administrative Procedure 

Act or any other statute unless the agency certifies that 

the rule will not have a significant economic impact on a 

substantial number of small entities. Small entities 

include small businesses, small organizations, and small 

governmental jurisdictions.
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For purposes of assessing the impacts of today's rule 

on small entities, small entity is defined as: (1) a small 

business whose company has less than 500 employees and is

primarily engaged in leaching or beneficiation of uranium, 

radium or vanadium ores as defined by NAIC code 212291; (2) 

a small governmental jurisdiction that is a government of a 

city, county, town, school district or special district 

with a population of less than 50,000; and (3) a small 

organization that is any not-for-profit enterprise which is 

independently owned and operated and is not dominant in its 

field. Of these three categories, only small businesses are 

potentially affected by the proposed rule; no small 

organizations or small governmental entities have been 

identified that would be impacted by the proposed revisions 

to part 192.

This proposed rule is estimated to impact 

approximately 1819 uranium recovery facilities that are 

currently operating or may operate in the near future. The 

1819 uranium recovery facilities are owned by 10 firms, of 

which eight are believed to be small. 

The proposed revisions to 40 CFR part 192 would apply 

to the six ISRsfive currently operating in 2013. TheseISRs. 

The operating ISRs are as follows: (1) Crow Butte 

(Nebraska) and (2) Smith Ranch-Highland (Wyoming), owned by 
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Cameco Resources; (3) Alta Mesa (Texas), owned by Mestena 

Uranium, LLC; (4) Willow Creek (Wyoming), owned by Uranium 

One, Inc.;(.; and (5) Hobson-La Palangana (Texas), owned by 

Uranium Energy Corp.; and(6) Lost Creek(Wyoming), owned by 

Ur-Energy Inc.. Using the fewer than 500 employees’ 

criterion Mestena Uranium, LLC, Ur-Energy, Inc., and 

Uranium Energy Corp. qualify as small businesses, while 

Cameco Resources and Uranium One, Inc. are both large 

businesses.

In addition to the six ISRsfive operating in 2013, 

anISRs, three additional ISR hasISRs have been licensed, 

all in the state of Wyoming: . These are: (1) Lost Creek, 

owned by Ur-Energy Inc.; (2) Moore Ranch, owned by Uranium 

One, Inc.; and (3) Nichols Ranch, owned by UranerzUranez

Uranium Corp. UranerzOf these three companies, both UrEnergy Inc. and Uranez Uranium Corp. qualifiesqualify as 

small businessbusinesses.

Eleven other ISRs are at some stage ofhave been 

proposed for licensing or permitting, or are undergoing 

restoration.. These include: (1) Dewey-Burdock in South 

Dakota and (2) Centennial in Colorado, both owned by 

Powertech Uranium Corp.;(2)Moore Ranch in Wyoming, owned by 

Uranium One, Inc.; .; in Texas, (3) Kingsville Dome, (4) 

Los Finados, (5) Rosita, and (56) Vasquez, all in Texas and
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owned by Uranium Resources Inc.; (67) Crownpoint and (7) in 

New Mexico, owned by Uranium Resources Inc., (8) Church 

Rock, both in New Mexico and , owned by Uranium Resources 

Inc.,;(8Strathmore Minerals; (9) Ross in Wyoming, owned by 

Strata Energy, Inc., (910) Goliad in Texas, owned by 

Uranium Energy Corp.; (10and (11) Antelope-Jab in Wyoming, 

owned by Uranium One, Inc., and (11) Reno Creek in Wyoming, 

owned by Bayswater E&P. All of these companies, except for 

Uranium One, Inc., are small businesses.

To evaluate the significance of the economic impacts 

of the proposed revisions to 40 CFR part 192, EPA estimated 

the costs that would be incurred by existing facilities, 

based on their estimated production and EPA’s estimated 

cost per pound of U3O8. 

Of the 1819 ISR facilities identified above, 1314 are 

owned by a total of eight small businesses; the other five

are owned by two large businesses. EPA’s economic impact 

analysis estimated that for the threetwo small firms 

currently operating ISR facilities, costs of the proposed 

rule would range frombe at most 0.6% to 1.73% of estimated 

company sales, depending on operating revenues for one 

small business, and at most 1% of estimated operating 

revenues (if the costing assumptioncompanies’ ISR 

facilities were operating) for the other small business, if 
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the highest cost assumptions were used. Because the costs 

are generally estimated to be less than 2% of salesBased on 

EPA’s criteria for significance, impacts for these firms 

would not be significant. In addition, fewer than 10 small 

firms are likely to be affected by the proposed rule at any 

time, so the number of firms potentially incurring costs to 

comply with the rule is not a substantial number. Thus, EPA 

concludes that the proposed rule would not result in a 

significant impact to a substantial number of small 

entities.

No small organizations or small governmental entities 

have been identified that would be impacted by the proposed 

revisions to 40 CFR part 192. We continue to be interested 

in the potential impacts of the proposed rule on small 

entities and welcome comments on issues related to such 

impacts.

After considering the economic impacts of this 

proposed rule on small entities, I certify that this action 

will not have a significant economic impact on a 

substantial number of small entities.

D. Unfunded Mandates Reform Act

This rule does not contain a Federal mandate that may 

result in expenditures of $100 million or more for State, 

local and Tribal governments, in the aggregate, or the 
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private sector in any one year. Using the sixfive existing

ISR operations operating in 2013 as examples of typical ISR 

facilities, EPA estimates that total annual costs of 

complying with the rule for sixfive such ISR facilities, 

would berange from $10.6 million to $13.57 million. The 

proposed rule imposes no enforceable duties on any State, 

local or Tribal governments or the private sector. Thus, 

this rule is not subject to the requirements of sections 

202 or 205 of UMRA.

This rule is also not subject to the requirements of 

section 203 of UMRA because it contains no regulatory 

requirements or obligations that might significantly or 

uniquely affect small governments; the rule does not 

contain requirements that apply to such governments nor 

does it impose obligations upon them.

E. Executive Order 13132: Federalism

This proposed rule does not have federalism 

implications. It will not have substantial direct effects 

on the States, on the relationship between the national 

government and the States, or on the distribution of power 

and responsibilities among the various levels of 

government, as specified in Executive Order 13132. None of 

the facilities subject to this action are owned and 

operated by State governments, and nothing in the proposed 
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rule will supersede State regulations. Thus, Executive 

Order 13132 does not apply to this proposed rule.

EPA recognizes that Agreement States will have a 

substantial interest in this rule revision since they have 

primary responsibility for implementation of 40 CFR part 

192 standards. In the spirit of Executive Order 13132 and 

consistent with EPA policy to promote communications 

between EPA and State and local governments, EPA 

specifically solicits comment on this proposed rule from 

State and local officials.

F. Executive Order 13175: Consultation and Coordination 

with Indian Tribal Governments

This action does not have tribal implications, as 

specified in Executive Order 13175 (65 FR 67249, November 

9, 2000). The action imposes requirements on 

licenseesowners and operators of ISR facilities and not 

tribal governments. Although Executive Order 13175 does not 

apply to this action, EPA sought opportunities to provide 

information to tribes and tribal representatives during the 

review of 40 CFR part 192. EPA specifically solicits 

additional comment on this proposed action from tribal 

officials.

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks
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EPA interprets Executive OrderEO 13045 (62 FR 

19885, April 23, 1997) as applying to those regulatory 

actions that concern health or safety risks, such that 

the analysis required under section 5-501 of the Order 

has the potential to influence the regulation. Because 

this action addresses environmental standards intended 

to mitigate health or safety risks, it is subject to 

Executive Order 13045. We evaluated several regulatory 

strategies for assuring groundwater restoration and 

stability at ISR facilities and selected the option 

providing most assurance that groundwater systems will 

remain in a chemically reduced state, thereby limiting 

contamination of groundwater. The proposed rule is 

expected to reduce children’s risk of exposure to 

contaminated groundwater by improving monitoring to 

detect and correct contamination.

H. Executive Order 13211: Actions Concerning Regulations 

That Significantly Affect Energy Supply, Distribution or 

Use

This action is not a “significant energy action” as 

defined in Executive Order 13211 (66 FR 28355, May 22, 

2001), because it is not likely to have a significant 

adverse effect on the supply, distribution, or use of 

energy. This proposed rule will not adversely directly 
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affect productivity, competition, or prices in the energy 

sector.

I. National Technology Transfer and Advancement Act

Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (“NTTAA”), Public Law No. 104-113, 

12(d) (15 U.S.C. 272 note) directs EPA to use voluntary 

consensus standards in its regulatory activities unless to 

do so would be inconsistent with applicable law or 

otherwise impractical. Voluntary consensus standards are 

technical standards (e.g., materials specifications, test 

methods, sampling procedures, and business practices) that 

are developed or adopted by voluntary consensus standards 

bodies. NTTAA directs EPA to provide Congress, through OMB, 

explanations when the Agency decides not to use available 

and applicable voluntary consensus standards.

 This proposed rulemaking does not involve technical 

standards of the type indicated in NTTAA. Therefore, EPA is 

not considering the use of any voluntary consensus 

standards. 

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and LowIncome Populations
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Executive Order 12898 (59 FR 7629, Feb. 16, 1994)

establishes federal executive policy on environmental 

justice. Its main provision directs federal agencies, to 

the greatest extent practicable and permitted by law, to 

make environmental justice part of their mission by 

identifying and addressing, as appropriate, 

disproportionately high and adverse human health or 

environmental effects of their programs, policies, and 

activities on minority populations and low-income 

populations in the United States. 

EPA has determined that this proposed rule will not 

have disproportionately high and adverse human health or 

environmental effects on minority or low-income populations 

because it increases the level of environmental protection 

for all affected populations without having any 

disproportionately high and adverse human health or 

environmental effects on any population, including any 

minority or low-income population. This proposed rule 

addresses groundwater restoration, monitoring and 

protection of surrounding aquifers and thus decreases the 

potential groundwater contamination to which all affected 

populations are exposed. Thus, the proposed rule is 

projected to have positive, not adverse impacts on human 

health and the environment.
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Health and Environmental Protection Standards for Uranium 

and Thorium Mill Tailings and Uranium In-Situ Recovery

Page 148 of 177

List of Subjects in 40 CFR Part 192

Environmental protection, Hazardous substances, Radiation 

protection, Radioactive materials, Reclamation, Uranium,

Waste treatment and disposal, Water resources

_________________________

Dated:

_________________________ 

Gina McCarthy,

Administrator.
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For the reasons stated in the preamble, the Environmental 

Protection Agency proposes to amend title 40, Chapter I of 

the Code of Federal Regulations as follows:

PART 192—-[AMENDED]

1. The authority citation for 40 CFR part 192 continues to 

read as follows:

Authority: Sec. 275 of the Atomic Energy Act of 1954, 42 

U.S.C. 2022, as added by the Uranium Mill Tailings 

Radiation Control Act of 1978, Pub. L. 95-604, as amended.

2. Section 192.20 is amended by revising paragraph (b)(3)as 

follows:

Subpart C-[Amended]

§ 192.20 Guidance for implementation.

* * * * *

(b) * * *

(3) Compliance with § 192.12(b) may be demonstrated by 

methods that the Department of Energy has approved for use 

or methods that the implementing agencies determine are 

adequate. Residual radioactive materials should be removed 

from buildings exceeding 0.03 WL so that future replacement 

buildings will not pose a hazard [unless removal is not 

practical-see § 192.21(c)]. However, ventilation devices 

and other radon mitigation methods recommended by EPA may 

provide reasonable assurance of reductions from 0.03 WL to 
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below 0.02 WL. In unusual cases, indoor radiation may 

exceed the levels specified in § 192.12(b) due to sources 

other than residual radioactive materials. Remedial actions 

are not required in order to comply with the standard when 

there is reasonable assurance that residual radioactive 

materials are not the cause of such an excess. 

* * * * * 

3. Section 192.31 is amended by:

a. Revising paragraph (a).

b. Revising paragraph (f).

c. Revising the second sentence of paragraph (m).

Subpart D-[Amended]

4. The heading for Subpart D is amended by revising the 

language to read as follows:

Subpart D – Standards for the Management of Uranium 

Byproduct Materials

* * * * * 

§ 192.31 Definitions and cross-references.

(a) Unless otherwise indicated in this subpart, all 

terms shall have the same meaning as in Title II of the 

Uranium Mill Tailings Radiation Control Act of 1978, 

subparts A and B of this part, or parts 190, 260, 261, and 

264 of this chapter. For the purposes of this subpart, the 

terms “waste,” “hazardous waste,” and related terms, as 
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used in parts 260, 261, and 264 of this chapter, shall 

apply to byproduct material.

* * * * * 

(f) Disposal area means the region within the 

perimeter of an impoundment or pile containing uranium 

byproduct materials to which the post-closure requirements 

of § 192.32(b)(1) of this subpart apply.

* * * * * 

(m) Available technology * * * This term shall not 

be construed to include extraordinary measures or 

techniques that would impose costs that are grossly 

excessive as measured by practice within the industry or 

one that is reasonably analogous (such as, by way of 

illustration only, unreasonable overtime, staffing or 

transportation requirements, etc., considering normal 

practice in the industry; laser fusion of soils, etc.), 

provided there is reasonable progress toward emplacement of 

a permanent radon barrier.

* * *

* * * * * 

5. Section 192.32 is amended by revising paragraph 

(a)(2)(v) as follows:

§ 192.32 Standards

* * * * *
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(a) * * *

(2) * * *

(v) The functions and responsibilities designated in

part 264 of this chapter as those of the “Regional 

Administrator” with respect to “facility permits” shall be 

carried out by the regulatory agency.

* * * * *

6. 40 CFR part 192 is amended by adding subpart F to read

as follows:

Subpart F- Public Health, Safety and Environmental 

Protection Standards for Byproduct Materials Produced by 

Uranium In-situ Recovery

Sec.

192.50 Applicability.

192.51 Definitions and cross-references.

192.52 Standards.

192.53 Monitoring programs.

192.54 Corrective action program.

192.55 Effective date.

Subpart F-Public Health, Safety and Environmental 

Protection Standards for Byproduct Materials Produced by 

Uranium In-situ Recovery

§ 192.50 Applicability.
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This subpart applies to the management of uranium 

byproduct materials prior to, during and following the

processing of uranium ores utilizing uranium in-situ 

recovery methods, and to the restoration of groundwater at

such sites. Unless otherwise specified, all wellfields 

shall comply with this subpart as of the effective date of 

this rule.

§ 192.51 Definitions and cross-references.

(a) Unless otherwise indicated in this subpart, all 

terms shall have the same meaning as in Title II of the 

Uranium Mill Tailings Radiation Control Act of 1978, 

subparts A, B, and D of this part, or parts 190, 260, 261, 

and 264 of this chapter. 

(b) Adjacent Aquifer. An aquifer or portion of an 

aquifer that shares a border or end point with the exempted 

aquifer or the exempted portion of an aquifer.

(c) Alternate Concentration Limit (ACL). Concentration 

limit approved by the regulatory agency for a groundwater 

constituent that has not been restored to its restoration 

goal after best practicable restoration activities have 

been completed following the process prescribed in 40 CFR 

192.52(c)(2)thru 192.52(c)(5).

(d) Aquifer. A geological “formation,” group of 

formations, or part of a formation that is capable of 
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yielding a significant amount of water to a well or spring.

See 40 CFR 144.3.

(e) Background. The condition of groundwater, 

including the radiological and non-radiological constituent

concentrations, in the exempted aquifer, adjacent aquifers, 

and in both overlying and underlying aquifers, prior to the 

beginning of ISR operations. 

(f) Constituent. A detectable component within the 

groundwater.

(g) Exceedance. An exceedance has occurred when, 

during stability or long-term stability monitoring, a

groundwater protection standard is exceeded at any point of 

compliance well.

(h) Excursion. The movement of fluids containing 

uranium byproduct materials from an ISR production zone

into surrounding groundwater. An excursion is considered to 

have occurred when, during operational or restoration phase

monitoring, any two indicator parameters (e.g., chloride, 

conductivity, total alkalinity) exceed their respective 

upper control limits in any overlying, underlying, or 

perimeter monitoring well. Horizontal excursions refer to 

the lateral movement of the water, while vertical 

excursions indicate movement of water through aquitards 

above or below the production zone aquifer.
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(i) Excursion Monitoring Wells. Wells located around 

the perimeter of the production zone (horizontal excursion 

wells) and in overlying and underlying aquifers (vertical 

excursion wells), which are used to detect any excursions 

from the production zone. Excursion monitoring wells can 

serve as the “point(s) of compliance” during all phases of 

ISR.

(j) Exempted Aquifer. An “aquifer,” or its portion,

that meets the criteria of “underground source of drinking 

water” in 40 CFR 144.3, but which has been exempted 

according to the procedures in 40 CFR 144.7. See 40 CFR 

144.3.

(k) Extraction Well. Well used to extract uranium 

enriched solutions from the ore-bearing aquifer; also known 

as a “Production Well.” Extraction and injection wells may 

be converted from one use to the other.

(l) Indicator Parameter. A constituent, such as 

chloride, conductivity, or total alkalinity, whose “upper 

control limit” is used to identify an excursion. Indicator 

parameters are not contaminants, but relate to geochemical 

conditions in groundwater.

(m) Injection Well. A well into which fluids are being 

injected. See 40 CFR 144.3.
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(n) In-Situ Recovery (ISR). A method of extraction by 

which uranium is leached from underground ore bodies by the 

introduction of a solvent solution, called a lixiviant, 

through injection wells drilled into the ore body. The 

process does not require the extraction of ore from the 

ground. The lixiviant is injected, passes through the ore 

body, mobilizes the uranium, and the uranium-bearing 

solution is pumped to the surface from extraction wells. 

The pregnant leach solution is processed to extract the 

uranium.

(o) Listed Constituent. One of the thirteen 

groundwater constituents specified in Table 1 to subpart F 

of part 192.

(p) Lixiviant. A liquid medium used to recover uranium 

from underground ore bodies through in-situ recovery. This 

liquid medium typically contains native groundwater and an

added oxidant, such as oxygen and/or hydrogen peroxide, as 

well as sodium carbonate/bicarbonate or carbon dioxide. The 

lixiviant is introduced through injection wells into the 

ore body to mobilize the uranium. The resulting solution is 

then pumped via extraction wells to the surface, where the 

uranium is recovered from the solution for further 

processing, after which the lixiviant may be re-injected.
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(q) Long-Term Stability Phase. The period after the 

groundwater protection standards have been met and 

stability has been demonstrated according to 192.53(d), as 

determined by the regulatory agency.

(r) Maximum Constituent Concentration. The maximum 

permissible level of a constituent in groundwater, as 

specified in Table 1 to subpart A of part 192.

(s) Maximum Contaminant Level (MCL). The maximum 

permissible level of a contaminant in water which is 

delivered to any user of a public water system. See 40 CFR 

141.2.

(t) Monitoring Wells. Wells used to obtain groundwater 

levels and water samples for the purpose of determining the 

hydrologic regime and the amounts, types, and distribution 

of constituents in the groundwater. Wells are located in 

the production zone, around the perimeter of the production 

zone (horizontal excursion monitoring wells), and in 

overlying and underlying aquifers (vertical excursion 

monitoring wells). 

(u) Operational Phase. The time period during which 

uranium extraction by in-situ recovery occurs. Operations 

begin when injection of lixiviant starts. Operations end 

when the operator permanently ceases injection of lixiviant
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and recovery of uranium-bearing solution for processing 

purposes.

(v) Overlying Aquifer. An aquifer that is immediately 

vertically shallower (i.e., directly above) than the 

production zone aquifer.

(w) Point(s) of Compliance. Site-specific location(s)

where groundwater protection standards must be met. During 

all phases of ISR, excursion monitoring wells can serve as 

the points of compliance; during the restoration, stability

and long-term stability phases, points of compliance may

also include monitoring, injection and extraction wells in 

the production zone, as determined by the regulatory 

agency.

(x) Point(s) of Exposure. Intersection of a vertical 

plane with the boundary of the exempted aquifer.

(y) Preoperational Monitoring. Measurement of 

groundwater conditions in the production zone, and in the 

groundwater up and down gradient from the production zone, 

as well as in overlying and underlying aquifers, prior to 

the operational phase.

(z) Production Zone. The portion of the aquifer in 

which ISR activities occur. The production zone lies within 

the wellfield.
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(aa) Restoration (Act of). The process of returning 

groundwater quality to preoperational conditions for the 

purpose of achieving restoration goal values for identified 

constituents.

(bb) Restoration Goal. A concentration limit for an 

identified constituent in groundwater after restoration has 

occurred. The limit is obtained from the most protective 

regulatory standards in 40 CFR 141.62, 141.66, 141.80, 

143.3, 264.94, and Table 1 to subpart A of this part, and 

from preoperational background levels in the wellfield, 

whichever is higher.

(cc) Restoration Phase. The period immediately after 

lixiviant injection permanently ceases, during which 

restoration activities occur.

(dd) Site. The land or water area where any facility 

or activity is physically located or conducted, including 

adjacent land used in connection with the facility or 

activity. See 40 CFR 144.3.

(ee) Stability Phase. The period after the restoration 

phase when groundwater protection standards are met and 

monitored to test for temporal stability.

(ff) Underlying Aquifer. An aquifer that is 

immediately vertically deeper (i.e., directly below) than 

the production zone aquifer.
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(gg) Upper Control Limit (UCL). Preoperational

concentrations of indicator parameters in horizontal and 

vertical excursion monitoring wells, as determined by the 

regulatory agency and contained in the license.

(hh) Uranium Recovery Facility. A facility licensed to 

process uranium ores for the purpose of recovering uranium 

and to manage uranium byproduct materials that result from 

during and following the processing of uranium ores. Common 

names for these facilities include, but are not limited to, 

the following: a conventional uranium mill, an in-situ 

recovery (or leach) facility, and a heap leach facility or 

pile.

(ii) Wellfield. The area of an ISR operation that 

encompasses the array of injection, extraction, and 

monitoring wells, ancillary equipment and interconnected 

piping employed in the uranium in-situ recovery process.

The area of the wellfield exceeds that of the production 

zone.

§ 192.52 Standards.

(a) Except for those wellfields currently in and 

remaining in restoration, stability monitoring or long-term 

monitoring at a licensed facility, all operating 

wellfields, new wellfields and expansions of wellfields 

Commented [UEUoC31]: Changes made per interagency 

review.
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shall comply with § 192.52(c)as of the effective date of 

this rule.

(b) Surface and subsurface standards. (1) Surface

impoundments associated with ISR activities shall conform 

to the standards of § 192.32 of this part. 

(2) Disposal of solid uranium byproduct materials 

produced by ISR activities shall conform to the standards 

in § 192.32 of this part.

(c) Groundwater protection standards. (1) Restoration 

goals shall be determined for each of the constituents 

listed in Table 1 to subpart F that is identified in the 

groundwater. Following restoration activities in the 

production zone, and prior to license termination, the 

concentration of a listed constituent in the groundwater 

within the production zone, as determined by the regulatory 

agency, must not exceed the higher of the following values:

(i) The background level of that constituent in the 

groundwater, as determined by preoperational monitoring 

conducted under § 192.53(a) of this subpart; or

(ii) The lowest concentration listed in 40 CFR 141.61, 

141.62, 141.66, 141.80, 143.3, 264.94, or Table 1 to 

subpart A of this part for that constituent.

(iii) When considering the potential for health risks 

caused by human exposure to known or suspected carcinogens 
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not listed in Table 1 to subpart F that are designated for 

monitoring by the regulatory agency, the restoration goal 

above the background level should be established at 40 CFR 

part 141, 143 or 264 concentration levels, if such values 

exist. For constituents that are not found in 40 CFR part 

141, 143 or 264, the restoration goal above the background 

level should be established at concentration levels which 

represent a cumulative excess lifetime risk no greater than 

10-4 to an average individual.

(2) The regulatory agency may establish provisional 

alternate concentration limits within the production zone

provided that all of the following conditions are met:

(i) After all best practicable active restoration 

activities have been completed in accordance with the 

permit, the regulatory agency determines that 

concentrations for one or more constituents cannot be 

restored to restoration goals; and

(ii) the constituent(s) will not pose a substantial 

present or potential hazard to human health or the 

environment as long as the proposed alternate concentration 

limit(s) is not exceeded; and

(iii) in all cases, the restoration goals, as 

determined under paragraph (c)(1) of this section, are 

satisfied at all points of exposure.
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(3) the regulatory agency may approve final alternate 

concentration limits provided that the following conditions 

are met:

(i) the licenseeowner/operator has demonstrated 

groundwater stability at 95 percent confidence for three 

consecutive years (i.e., no increasing trend in 

concentration levels as identified by appropriate 

statistical techniques) of groundwater concentrations for 

the listed constituents before entering the long-term 

stability monitoring phase; and

(ii) the constituent(s) will not pose a substantial 

present or potential hazard to human health or the 

environment as long as the proposed alternate concentration 

limit(s) is not exceeded.

(4) In deciding whether to approve a provisional or a 

final alternate concentration limit, the regulatory agency 

shall consider, at a minimum, the following factors:

(iA) Potential adverse effects on groundwater quality, 

considering:

(A1) The physical and chemical characteristics of 

constituents in the groundwater at the site, including 

their potential for migration;

(B2) The hydrogeological characteristics (e.g.,

groundwater velocity) of the site and surrounding land;
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(C3) The quantity of groundwater and the direction of 

groundwater flow;

(D4) The proximity and withdrawal rates of local 

groundwater users;

(E5) The current and anticipated future uses of 

groundwater in the region surrounding the site;

(F6) The existing quality of groundwater, including 

other sources of contamination and their cumulative impact 

on groundwater quality;

(G7) The potential for health risks caused by human 

exposure to constituents;

(H8) The potential damage to wildlife, crops, 

vegetation, and physical structures caused by exposure to 

constituents; and

(I9) The persistence and permanence of the potential 

adverse effects.

(iiB) Potential adverse effects on hydraulicallyconnected surface-water quality, considering:

(A1) The volume and physical and chemical 

characteristics of the groundwater at the site; 

(B2) The hydrogeological characteristics of the site 

and surrounding land;

(C3) The quantity and quality of groundwater, and the 

direction of groundwater flow;
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(D4) The patterns of rainfall in the region;

(E5) The proximity of the site to surface waters;

(F6) The current and future uses of surface waters in 

the region surrounding the site and any water quality 

standards established for those surface waters;

(G7) The existing quality of hydraulically-connected 

surface water, including other sources of contamination and 

their cumulative impact on surface water quality;

(H8) The potential for health risks caused by human 

exposure to constituents;

(I9) The potential damage to wildlife, crops, 

vegetation, and physical structures caused by exposure to 

constituents; and

(J10) The persistence and permanence of the potential 

adverse effects.

(iiiC) The presence of any underground source of 

drinking water as defined under § 144.3 of this chapter and 

any exempted aquifer identified under § 144.7 of this 

chapter.

(5) When considering the potential for health risks 

caused by human exposure to known or suspected carcinogens, 

alternate concentration limits pursuant to paragraphs

192.52(c)(2) and 192.52(c)(3) should be established at 

concentration levels which represent a cumulative excess 
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lifetime risk no greater than 10-4, at a point of exposure, 

to an average individual.

TABLE 1 TO SUBPART F – MAXIMUM CONCENTRATION OF 

CONSTITUENTS

FOR GROUNDWATER PROTECTION AT ISR FACILITY SITES

Constituent Maximum Concentration

Arsenic 

Barium 

Cadmium 

Chromium 

Lead 

Mercury 

Selenium 

Silver 

Nitrate (as N) 

Molybdenum 

Radium-226 and 

 radium-228 (combined) 

Uranium (uranium-234, 

 uranium-235 and 

 uranium-238 combined) 

Gross alpha particle 

 activity (excluding 

 radon and uranium) 

The restoration goal is the 

primary or secondary MCL listed 

in 40 CFR 141.61, 141.62, 

141.66, 141.80, and 143.3, the 

maximum concentration of 

hazardous constituents for 

groundwater protection under 

264.94, or the maximum 

constituent concentration 

specified in Table 1 to Subpart 

A of this Part, whichever value 

is most stringent. 

Where a background 

concentration is determined to 

be higher than the most 

stringent value in the 

applicable regulations, the 

background concentration will 

serve as the restoration goal. 

§ 192.53 Monitoring programs.

Licensees Owners and operators subject to this subpart 

must conduct a groundwater monitoring program, subject to 

approval by the regulatory agency, at prospective and 

licensed ISR sites and environs. This program shall address 
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all phases of the site’s activities and must be conducted 

as follows:

(a) Preoperational phase monitoring. (1) A sufficient 

number of wells, at appropriate locations and depths, shall 

be installed in such a manner as to yield representative 

samples in order to define the groundwater flow regime and 

measure preoperational conditions and water quality for use 

in statistical tests during licensing, operations, 

restoration, stability and long-term stability.

(2) All monitoring wells must be cased in a manner 

that maintains the integrity of the monitoring-well bore 

hole. This casing must be screened or perforated and packed 

with gravel or sand, where necessary, to enable collection

of groundwater samples. The annular space (i.e., the space 

between the bore hole and well casing) above the sampling 

depth must be sealed to prevent contamination of samples 

and the groundwater.

(3) The preoperational background monitoring effort 

shall include immediately overlying aquifers, immediately 

underlying aquifers, and background monitoring inside and 

outside of the exempted aquifer, including both the up and 

downgradient areas outside of the production zone.

(4) During the monitoring effort, relevant data

documenting geology, hydrology and geochemistry for 

Commented [UEUoC32]: Change made per interagency 

review.
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radiological and non-radiological constituents shall be 

collected, both in the production zone and in surrounding 

areas that may be affected by the ISR operations.

(i) The monitoring effort shall be of sufficient 

duration of no less than one year and of sufficient scope 

to adequately characterize temporal and spatial variations 

in groundwater, and to account for impacts of well 

installation and development on background concentrations 

of constituents and values of indicator parameters, where 

applicable.

(ii) Preoperational monitoring shall be focused on 

determining background concentrations of constituents and 

indicator parameters in the following locations: 

(A(1) point of compliance wells within the proposed 

production zone;

(B(2) point of compliance wells immediately overlying 

and immediately underlying aquifers;

(C(3) point of compliance wells outside the production 

zone;

(D(4) point of compliance wells within the exempted 

aquifer; and 

(E(5) point of compliance wells in upgradient and 

downgradient non-exempt portions of the adjacent aquifer.
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(iii) The licenseeowner/operator shall employ 

appropriate statistical techniques to analyze background 

concentrations measured in individual wells within the 

proposed production zone for the purpose of determining 

restoration goals for groundwater restoration and long-term

stability monitoring under § 192.52(c)(1) of this subpart. 

As determined by the licenseeowner/operator and approved by 

the regulatory agency, background concentration limits may 

be representative of individual wells, multiple wells, or 

all wells within the proposed production zone. 

(iv) Radiological and non-radiological constituents to 

be monitored during the preoperational phase of an ISR 

facility shall include:

(A) all constituents listed in Table 1 to this 

subpart;

(B) constituents and parameters necessary for 

geochemical calculations of groundwater chemistry and to 

model site performance in order to demonstrate that a 

stable groundwater chemistry state, as approved by the 

regulatory agency, has been achieved through restoration

and is likely to persist in the long term; and

(C) any additional constituents or parameters required 

by the regulatory agency, including metals potentially 

mobilized by the recovery process.
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(b) Operational phase monitoring. (1) Indicator 

parameters, as established by the regulatory agency, shall 

be monitored in horizontal and vertical excursion 

monitoring wells determined by the regulatory agency 

throughout the operational phase of ISR activities.

(2) If an excursion is detected, as determined by the 

regulatory agency and as evidenced by indicator parameters 

exceeding established upper control limits, all 

constituents listed in Table 1 of this subpart shall be 

monitored as part of the corrective action program set 

forth in § 192.54 of this subpart until the excursion is 

controlled.

(c) Restoration phase monitoring. (1) All constituents 

listed in Table 1 of this subpart and otherwise specified 

by the regulatory agency shall be monitored during active 

restoration; sampling should occur no less frequently than 

quarterly, or other time interval specified by the 

regulatory agency.

(2) Indicator parameters, as established by the 

regulatory agency, shall be monitored in horizontal and 

vertical excursion monitoring wells determined by the 

regulatory agency throughout the restoration phase of ISR 

activities.
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(3) If an excursion is detected, as determined by the 

regulatory agency and as evidenced by indicator parameters 

exceeding established upper control limits, all 

constituents listed in Table 1 of this subpart shall be 

monitored as part of the corrective action program set 

forth in § 192.54 of this subpart until the excursion is 

controlled.

(d) Stability phase monitoring. (1) The constituents 

to be monitored throughout the stability phase of an ISR 

facility in points of compliance wells in the production 

zone, as determined by the regulatory agency, shall 

include:

(i) all constituents listed in Table 1 of this 

subpart; 

(ii) any additional constituents required by the 

regulatory agency, such as:

(A) constituents and parameters necessary for 

geochemical calculations of the groundwater chemistry in 

order to demonstrate that a stable groundwater chemistry 

has been achieved and is likely to persist in the longterm;

(B) components of the lixiviant fluids injected during 

uranium recovery and any fluids injected during 

restoration; or 
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(C) metals potentially mobilized by the uranium 

recovery process.

(2) Through field measurements using the monitoring 

network established to meet the requirements of § 192.53(a)

of this section, observations and calculations, and 

applying appropriate statistical techniques, the 

licenseeowner/operator shall demonstrate that aquifer 

conditions within the production zone are stable.

(i) Stability shall be demonstrated for three 

consecutive years at a 95 percent confidence interval, 

measured from the time at which sufficient data to 

determine statistical significance has been collected, and 

based on sampling no less frequently than quarterly.

(ii) Individual wells within the production zone can 

be the point of compliance for the purpose of assessing 

stability, as approved by the regulatory agency.

(iii) If the licenseeowner/operator finds that the 

stability of groundwater meeting the concentration limits 

determined in § 192.52(c)(1) of this subpart cannot be 

demonstrated for three consecutive years for one or more 

constituents, the regulatory agency may:

(A) require the licenseeowner/operator to resume 

active restoration efforts; or
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(B) depending on the significance of the departure 

from the groundwater protection standards determined in § 

192.52(c)(1) of this subpart, approve a provisional

alternate concentration limit according to the requirements 

of § 192.52(c)(2) of this subpart. Once stability has been 

documented for three consecutive years, the regulatory 

agency may approve a final alternate concentration limit 

according to the requirements of § 192.52(C)(3) of this 

subpart. 

(3) If an exceedance occurs, as determined by the 

regulatory agency and as evidenced by exceeding groundwater 

protection standards in 192.52(c) at point of compliance 

wells, all constituents listed in Table 1 of this subpart 

shall be monitored as part of the corrective action program 

set forth in § 192.54 of this subpart until the exceedance

is controlled.

(e) Long-term stability phase monitoring. (1) Through 

field measurements utilizing the monitoring network 

established to meet the requirements of § 192.53(a) of this 

section, observations and calculations, and applying 

appropriate statistical techniques, the 

licenseeowner/operator shall demonstrate that postrestoration aquifer conditions within the production zone 

remain stable and continue to show compliance with 
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groundwater protection standards established under §

192.52(c) of this subpart.

(i) Stability and groundwater protection compliance 

shall be demonstrated based on sampling no less frequently

than quarterly, or other time interval approved by the 

regulatory agency.

(ii) Specific, individual wells within the production 

zone and approved by the regulatory agency shall be the 

points of compliance for the purpose of assessing stability

and groundwater protection compliance, as approved by the 

regulatory agency. 

(iii) Long-term stability monitoring shall be 

conducted for a period of 30 years. The regulatory agency 

may shorten the long-term stability monitoring period if, 

after stability is documented for a period of three 

consecutive years as described under § 192.53(d), the 

licenseeowner/operator demonstrates through geochemical 

modeling of the site that the subsurface conditions within 

the production zone will remain stable into the future. In 

evaluating such modeling, the regulatory agency must 

determine that there is a reasonable assuranceexpectation

that restoration goals will continue to be met and that

subsurface conditions in the future will not cause the remobilization of uranium, radium or other constituents into 

Commented [UEUoC33]: Change made per interagency 

review.
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the groundwater and their migration beyond the boundaries 

of the production zone.

(2) If one or more monitored groundwater constituents 

in a point of compliance well within the wellfield exceeds 

a groundwater protection standard as defined in 192.52(c), 

or one or more monitored constituents in a point of 

compliance well within the wellfield show statistically 

significant increasing trends that would threaten 

groundwater quality if left unabated, then the 

licenseeowner/operator must submit a report to the 

regulatory agency within 60 days describing the 

circumstances and the corrective actions to be taken. All 

constituents listed in Table 1 to this subpart shall be 

monitored as part of the corrective action program set 

forth in § 192.54 of this part.

§ 192.54 Corrective action program.

(a) A corrective action program shall be developed by 

the licenseeowner/operator and approved by the regulatory 

agency for each ISR site at the time of licensing. The plan 

shall address a range of possible excursion and exceedance

scenarios (e.g., minor to catastrophic) and list options 

for corrective action. If an excursion is detected at a 

licensed facility at any time during the ISR operational 

phase or restoration phase, or an exceedance is detected 

Commented [UEUoC34]: Change made per interagency 

review.
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during the stability or long-term stability phase, 

applicable portions of the corrective action program shall 

be implemented as soon as is practicable, and in no event 

later than ninety (90) days after such an occurrence. With 

the objective of returning constituent concentration levels 

in groundwater to the restoration goals within the 

production zone and the maximum contaminant level in 

adjacent aquifers, the corrective action program shall:

(1) address removing constituents at the point of 

compliance or treating them in place; and 

(2) address removing or treating in place any 

constituents that exceed groundwater protection standards 

between the point of compliance and the point of exposure.

(b) The licenseeowner/operator shall continue 

corrective action measures to the extent necessary to 

achieve and maintain compliance with the groundwater 

protection standards in § 192.52(c) of this subpart. The 

regulatory agency will determine when the 

licenseeowner/operator may terminate corrective action 

measures based on data from the groundwater monitoring 

program and other information that provides reasonable 

assurance that the groundwater protection standards in § 

192.52(c) will not be exceeded.
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(c) After the corrective action program has been 

terminated, the licenseeowner/operator must establish and 

implement a groundwater monitoring program to demonstrate 

the effectiveness of the corrective action program in 

stabilizing the concentrations of constituents in the 

groundwater. The monitoring program shall continue for a 

period of not less than 3 years and be based on the 

requirements specified in § 192.53(d) and 192.53(e). 

§ 192.55 Effective date.

Subpart F shall be effective on [INSERT DATE 60 DAYS 

AFTER DATE OF PUBLICATION OF FINAL RULE IN FEDERAL 

REGISTER].