In this issue of our newsletter, you will find updates on important news at the forefront of the environmental remediation industry.

Spring is traditionally a time of growth and renewal, a theme that is central to site remediation which is all about bringing contaminated land and water back to productive life. In our Spring 2017 issue of Remediation Pathways we pay homage to growth and renewal through:

  • Site remediation through natural attenuation processes
  • Introducing our new MNA focused service area SiREMNA
  • Celebrating 15 years of SiREM

Focus on Monitored Natural Attenuation

Monitored natural attenuation (MNA) is a site cleanup strategy that relies on contaminant removal via intrinsic natural processes that is far from a “do nothing” approach.  The “do” part requires confirmation of the remediation potential of these natural processes and continually assessing if they are sufficiently rapid to reach remedial goals.  MNA offers very real benefits, especially in an era of limited budgets, and is an important polishing phase for many sites following rapid contaminant removal by more aggressive remediation approaches.  Clemson University, Professor, Kevin Finneran emphasized the usefulness of MNA as a polishing approach in a recent SiREM webinar stating “MNA is a strategy for almost all chlorinated solvent sites in the end”.

Natural attenuation (NA) encompasses both biotic and abiotic processes, or both, in the case of biogeochemical reactions, where sulfate and iron reducing bacteria mediate chlorinated volatile organic compound (CVOC) destruction via iron minerals.  A recent review (He et al., 2016) on the impact of various forms of iron minerals on chlorinated solvents in aquifers indicated that for some contaminants (e.g., carbon tetrachloride), iron mediated abiotic reactions were more significant than biotic reactions.  The authors concluded that “abiotic reactions contribute significantly to natural attenuation processes”.  The type of iron also matters (see Minerals and MNA, this issue) – accordingly, characterization of iron minerals is one key to understanding NA potential.

To facilitate the characterization and quantification of natural attenuation processes, SiREM has introduced SiREMNA, a suite of tests for iron minerals, specialized geochemical parameters and microbiology, which provides a comprehensive overview of natural attenuation potential and progress.

This issue of Remediation Pathways focuses on technologies that are available to assist with MNA remedies including:

  • MNA and the Regulatory Environment
  • Minerals and MNA – Reduced Mineral Impact on Biogeochemical Reduction of Chlorinated Solvents
  • Case Study: Confirming Natural Attenuation Processes at a Coastal Site

The use of MNA on its own or in conjunction with enhanced remediation processes is enjoying growing acceptance in the regulatory community and by remediation practitioners based on improved understanding of the underlying processes.  Our mission is to assist with this growing understanding so we all can derive the benefits of MNA.

Your Partner in Remediation Success, SiREM

MNA and the Regulatory Environment

According to current regulations in the USA, at least two lines of evidence are required to support selection of monitored natural attenuation (MNA) as a site remedy (e.g., USEPA, 1998; 2012).



Minerals and MNA – Biogeochemical Reduction of Chlorinated Solvents

Reactive iron minerals are Fe(II)-containing solid phases are often present in anoxic subsurface environments and engineered systems designed for groundwater remediation.



Case Study: Confirming Natural Attenuation Processes at a Coastal Site

Past waste disposal practices at a California coastal site resulted in a groundwater plume containing CVOCs (mainly chlorinated ethenes [CEs] and 1,1-dichloroethane) migrating offshore towards a marine harbor.


SiREM Focus

In 2002, bioaugmentation for chlorinated solvent remediation was relatively new and still controversial in some circles, despite the publication of a watershed paper that demonstrated its in situ effectiveness (Major et al., 2000).



Conference Presentations

SiREM’s technologies are featured at leading recent and upcoming conferences including, Battelle Miami and ISMOS-6: