Map showing uranium concentrations in the western southwestern and northeastern continental USA.

Defending Limits on Uranium Mining Contaminants in Groundwater


Rollback of Contamination Limits in Groundwater  from Uranium Mining

What’s at Risk, How to Comment and Talking Points

The Trump Administration wants to roll back groundwater protection standards regulating the amount of radiation contamination that uranium mines are allowed to release during extraction operations.  The current regulation is aimed at preventing contamination of downgradient groundwater used for drinking water. Radionuclide contamination of downgradient drinking water aquifers has been documented at a number of uranium mines in recent years. The Pruitt EPA is “re-proposing” the rule, and the revised rule significantly weakens the groundwater standards.

Deadline for Public Comment on Rollback Proposal:  October 16, 2017

Docket # EPA-HQ-OAR-2012-0788 and FRL-9958-12-OAR

Docket information @ 

Submit comments @ 


The US currently imports more than 85% of the uranium used for power production. Uranium mining is likely to increase over the next decade in response to a renewed interest in nuclear energy in the United States, Asia, Europe, Africa and South America. Globally, there are currently 439 operating reactor units, 36 under construction, 93 in planning and 218 proposed (Yancey, 2008). Within the United States there are 104 operating nuclear reactors which produce about 19% of the US electricity (2007). More than 4000 mines have a history of uranium production in the United States, almost all of these in the western US (Yancey, 2008).    The western United States was the world’s leading producer of uranium during the previous uranium booms in the 1950s and 1970s. The Organisation for Economic Co-operation and Development estimates that the US has about 377,000 tons of uranium reserves – about 6 % of the world’s supply. 

In many deposits, uranium can be recovered by in-situ recovery (ISR) also referred to as in-situ leaching. ISR involves the injection of an oxygenated solution (lixiviant) into ground water which flows through the uranium deposit. Uranium is dissolved into the ground water/ lixiviant solution which is then recovered by extraction wells. The uranium is removed from the “pregnant”solution via ion exchange and processed into yellow cake, a uranium concentrate. The uranium depleted water is then refortified with the lixiviant and re-circulated through the deposit for continued recovery.

Diagram showing injection of chemicals into deep geologic formations and pumpback of the uranium-containing slurry to the surface.

How in-situ leaching works at uranium mines

The percentage of total global uranium production from ISR mines has increased from 16% in 2000 to 47% in 2013.  ISR production in the USA began in Wyoming in 1960s (experimental) and the first commercial mine opened in 1974. Since then more than 30 ISR uranium mines have been permitted. Most currently operating ISR mines in USA began in 1990s and are located in South Dakota, Nebraska, Wyoming, New Mexico and Texas Total annual production typically under 1000 tons. Currently more than 12 ISR facilities are operating in the USA.

The Nuclear Regulatory Commission (NRC) regulates ISR operations. In contrast, conventional uranium mining is regulated by the OSM and individual State mine permitting agencies. The distinction is that NRC is responsible for regulating uranium recovery operations when the ore is processed and chemically treated. This happens in a uranium mill (ore processed from conventional open pit and underground mines) or during in-situ leaching. Therefore the NRC regulates ISR operations, uranium mills and disposal of solid and liquid waste from uranium recovery operations. The NRC has established a process where states can become Agreement States and implement NRC regulations for ISR facilities.  Texas, Colorado and Utah have primacy. NRC regulated ISR facilities in Wyoming, Nebraska and South Dakota.

Contamination Issues from Uranium In-situ Leaching Operations

There are two major environmental issues specific to in-situ uranium mining:

1. Excursions – Roll-front uranium ore bodies often occur with sandstone formations which are typically fresh water aquifers and are protected under the Safe Drinking Water Act. The part of the aquifer that hosts the ore body is typically exempted from protection thru the Underground Injection Control regulations. Excursions occur when uranium bearing fluids (lixiviant and groundwater containing uranium) move beyond the mined portion of the ore body and into adjacent un-impacted groundwater. Mining operations are designed to minimize excursions and to mitigate excursions when they happen. Though excursions do happen at numerous ISR facilities, the groundwater contamination is usually local – but can be serious.

2. A more serious issue is the failure to meet post-closure groundwater restoration goals. Groundwater restoration is required by NRC regulations even though an aquifer is exempted from protection through a UIC permit. At ISR facilities, impacted groundwater (regulated constituents) must be restored to baseline quality, applicable State groundwater quality standards or alternative concentration standards (ACLs). Various treatment methodologies are utilized by the industry. Post mining GW monitoring is required to demonstrate compliance and “stabilization.” At many ISR facilities restoration standards for a small group of parameters (mainly metals, including uranium and radium) are too often not achieved after initial restoration efforts. Metals are mobilized by in-situ recovery and can reach dissolved concentrations that exceed applicable groundwater protection standards;  restoration methods (including active treatment) have not been as effective as necessary to prevent exceedance of standards. This commonly results in the approval of alternative concentration limits for the problematic metals. Once ACLs are approved, the risk of contaminated groundwater migrating down-gradient beyond the aquifer exemption boundary into a drinking water aquifer ( USDW) is increased and – in fact – has happened.


In January 2015, the Obama EPA proposed new Health and Environmental Protection Standards under the Uranium Mill Tailings Radiation Control Act (UMTRCA).1 The proposed standards were aimed at improving ground water protection at uranium mines using in-situ recovery facilities).

As most uranium ore in the USA is now mined using in-situ leaching methods it is critically important to restore impacted groundwater to acceptable standards. The 2015 rule was important in that was aimed at preventing contamination of downgradient groundwater used for drinking water. Radionuclide contamination of downgradient drinking water aquifers (USDWs) has been documented at a number of in-situ uranium mines in recent years. The Pruitt EPA is “re-proposing” the rule and the revised rule significantly weakens the groundwater protection regulations established by the January 2015 rule.

The new standards proposed by the Obama EPA in 2015 included the following key provisions:

  1. Requirements for consistent characterization of baseline water quality. Selection of background concentration values are often too subjective and determined with too little data.
  2. Requirements to meet restoration goals for 13 specific constituents (arsenic, barium, cadmium, chromium, lead, selenium, ,NO3, radium, total uranium, gross alpha radioactivity, mercury, silver and molybdenum).                      
  3. Applicable standards for regulated contaminants will be the most protective from from the three statutes that set standards for drinking water.2  If standards are already exceeded before operations begin, alternative concentration limits are established.
  4. Requirements for long-term (30 years) stability monitoring UNLESS
    1. Monitoring data demonstrate restoration to standards
    2. Statistical analyses demonstrates stability for 3 consecutive years
    3. Geochemical modeling indicates stability and no re-mobilization


First, explain why you’re commenting on this proposed withdrawal – why it matters to you.

If you have relevant expertise, say so. You don’t have to be an expert to make a valid and valuable comment, but if you do have expertise, share your knowledge.

If you have information relevant to the rule (for example, news articles about events in your community or anecdotal information showing how the public is impacted) include that information and highlight it.

Be constructive and civil. Don’t write a lot if less will do. 


1. Reducing groundwater monitoring requirements following mine closure from 30 years to 6 years will allow contamination to continue with no responsible party to monitor or remediate the contamination.

2. Mining companies should be held to clear drinking water protection standards, even when requesting an alternative concentration limit. The proposed “best practicable active restoration” test is vague, leading to extensive agency time evaluating proposals with inconsistent outcomes. 

3. It is critical to establish a scientifically adequate baseline characterization before mining activities begin. At a minimum, baseline characterization should include one full year of monitoring to account for seasonal variation. The proposed rule would allow for monitoring of less than one year- a blatant attempt to reduce monitoring costs for the industry at the expense of public health.

4. Well construction standards are vague, with no related guidance on sampling methods. Clear standards should be established to support adequate baseline characterization. 

5. The 2015 proposal requires operational and post-closure monitoring inside and outside of the aquifer affected by uranium in-situ mining. This monitoring is critical to ensure that down-gradient drinking water aquifers are not contaminated by mining activities, and should be retained. 

6. The rule should retain require that the list of 13 specific contaminants identified in the 2015 proposal be met during restoration. 

7. The re-proposed rule improperly extends the time period for facilities to take corrective action when operations have resulted in contamination to the aquifer, putting drinking water aquifers at further risk.

8. The re-proposed rule eliminates the requirements for public participation when setting alternative concentration limits. Public participation in rulemaking – including alternative concentration limits – is a fundamental right and must be retained.


EPA will accept written comments on the proposals until October 16, 2017.  To submit online comments for the proposal, click on the following links and then click on the “comment now” button.

Submit comments @ 

If you wish to submit comments by mail, fax, or other means see directions at 

Comments should be identified by the following Docket ID: EPA-HQ-OAR-2012-0788


140 CFR part 192

2 Safe Drinking Water Act, Resource Concentration and Recovery Act, Uranium Mill Tailings Control and Reclamation Act


Electronic link to proposed rule

In-situ Leach Uranium Mining


1. The Trump re-proposal significantly weakens the protections in the 2015 proposed rule. The re-proposed rule reduces the post closure monitoring requirements from 30 years to a total of 6 years (three years for “initial” stability monitoring and 3 additional years for “long-term” stability monitoring). Given the commonly occurring failure to achieve initial restoration goals, utilizing the current approaches to restoration, and subsequent reliance on ACLs, it is clear that at many ISR mines water quality stability may not be achieved for many years. it is irresponsible to allow the use of groundwater fate and transport models to “demonstrate” stability in lieu of empirical monitoring data. At a minimum quarterly monitoring should be required after the six year period.

2. Prior to requesting an ACL the mining company must use “best practicable active restoration.”  However there is no definition or explanation as to what this means. Also under the re-proposed rule the “regulatory agency would consider a list of factors when considering setting an ACL ( the list is included in Section II A. 2 of the FR notice). The list is long and exhaustive and, while including critical factors, will require a significant effort by the regulatory agency and is likely to be incomplete with no consistent approach.

3. Duration of pre-operational monitoring and changes to well completion requirements: the changes in the re-proposed rule would significantly weaken the  requirements aimed at assuring that an adequate baseline characterization is completed. Adequate establishment of baseline is a problem. The re-proposed rule allows for baseline monitoring to occur for less than a year in areas where “temporal variations are not expected to occur”. This does not conform with hydrologic reality – even confined aquifers have seasonal variability regarding recharge, potentiometric surface levels and water chemistry. It seems perfectly reasonable to require at least one full year of baseline data to establish that there is “no seasonal variation”. This is just an attempt to reduce monitoring costs for the industry.

4. The re-proposed rule states that “EPA believes that sufficient monitoring should completed to ensure that all perturbations associated with well construction are resolved prior to establishing background concentrations” and “EPA requires the sampling frequency to be sufficient to ensure statistically valid background levels are not influenced by well construction.” The well construction problems refer to the introduction of oxygen (which helps mobilize uranium) during monitoring well construction. This proposed revision introduces too much vagueness and provides no guidance on how to conduct sampling to “ensure statistically valid background levels are not influenced by well construction.”  This will be a complicated procedure and will rely far too much on the discretion of State agency staff. The end result will be a less rigorous determination of baseline water quality conditions which will impact the establishment of post-closure restoration standards.

5. The re-proposed rule eliminates the requirement to do operational and post-closure monitoring both inside and outside the boundaries of the exempted aquifer. However, the re-proposed rule is very unclear as to where post- closure compliance monitoring should occur. The proposed change in definition of point of exposure, in combination with what is likely to be an increase in ACL requests, certainly increases the risk of post-closure down-gradient groundwater contamination.

6. The re-proposed rule will eliminate the requirement to monitor and establish standards for all constituents listed in Table 1 of 40 CFR part 192, subpart F. Instead facilities would only be required to monitor and establish standards for the listed constituents that are present or could be affected by the ISR operation.  What is meant by “identified as present or affected by operations in the groundwater”? No guidance or definition.

7. The re-proposed rule establishes a corrective action approach to deal with exceedances in standards during operation (excursions) and post-closure restoration and stability. It further extends the time frame for implementing corrective action. Given the fact that once an excursion has been detected, groundwater outside the production zone has already been impacted, this provision allows for too much time to meet standards and will result in a higher risk to down-gradient groundwater.

8. This re-proposed rule does not require a public participation process in the request/ agency approval process for ACLs. This is a serious omission -given the current use of ACLs and the expected increase in ACL requests. The NRC was considering a requirement that all ALCs must be approved by the NRC, which would trigger a public participation process. It is unknown if this is true.

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