If production closes and facilities such as mines, mills, and refineries reach the end of their operational life, efforts will focus on reinstating conditions that resemble those preceding production, to the extent that is reasonable. In the past, out of various reasons, such post-operational remediation was sometimes not [successfully] undertaken and left legacy sites behind.
A fundamental requirement in this process is the
decommissioning
of facilities. Moreover, if radionuclides inadvertently spread into the environment during previous operations, it may also be necessary to conduct remediation of sites that have become contaminated. Preferential then would be the removal of contaminants, or, should that not be reasonably possible, their containment or immobilization.
The thresholds for intervention are informed by international radiological standards—such as those established by the International Commission on Radiological Protection (ICRP)—and corresponding national regulations. However, the criteria for cleanup and definitions of the end state typically rely on national regulations, when such regulations are applicable. It is essential to engage in early discussions with relevant authorities and
stakeholders regarding all remediation measures.
A core aspect of this process is the evaluation of the post-operational environmental impact, which begins with a thorough radiological and radioecological
survey of the site
to ascertain the level of contamination and to identify if remediation is necessary. This evaluation may be based on a review of historical and operational data, will incorporate an analysis of monitoring data related to environmental media (achieved on-foot, or automated by car or drone), up to sampling and laboratory testing. If necessary, numerical modeling of the migration of contaminants can also be utilized to enhance this assessment.
To maximize efficiency in the remediation efforts, it is advisable to follow a structured approach consisting of three distinct phases:
(1) The primary goal is to confirm that a site is free from contamination, enabling its release from regulatory oversight (typically at relatively low costs). Ideally, this verification could be achieved after the initial qualitative screening phase,
(2) However, if it is determined that contamination levels exceed acceptable thresholds, adjustments need to be made during the second quantitative phase e.g. to enhance the sampling density and improve validity and to spatially localize any contamination,
(3) This will be followed by targeted remediation measures in the third phase.
The nature and extent of the identified contamination, alongside regulatory guidelines, safety standards, potential reuse options, and considerations of efficiency and cost, will determine the specific remediation technologies to be applied. Various advanced technologies are generally available, including:
- Soil water extraction
- Bio- or phytoremediation
- Pump and treat
- Soil washing
- Conveyor belt monitoring/separation
For contamination confinement, options such as seal walls can be employed, while treatment of seepage or Acid Mine Drainage may involve passive methods like Permeable Reactive Barriers or Constructed Wetlands.
In the end a state of passive safety should be achieved, i.e. no need for any active measure or maintenance in the longer term. GeoEnergy Consult is committed to tailoring solutions to meet the unique challenges of each client's site or even developing new approaches as needed.
The remediation process can generate Naturally Occurring Radioactive Material (NORM), which needs to be
managed
appropriately. This waste can arise from the excavation of contaminated soil or from treatment aimed at separating radionuclides during soil cleaning efforts. In cases where the waste activity and volume are relatively low, on-site disposal may be feasible. If activity levels or volume increase, off-site disposal of the generated waste might be required.
Post-remediation monitoring might be essential to verify the efficiency of the remediation measures. Typically a prolonged institutional control period follows.
If you have any specific question, feel free to
contact us.
