Our clients are typically seeking to characterize and/or remediate in-place or contain surface and subsurface zones where soil, sediment, soil gas, groundwater and/or bedrock have been impacted by human activities. Remediation and containment actions often involve engineered contaminant mass destruction or transformation to reduce mobility, physical hazards, and/or toxicity to human and ecological receptors. Sometimes the containment source or hot spots is the focus of aggressive treatment. In other cases, treatment or containment is sought for greater diffuse plume, and sometimes the entire “plume” consisting of the source and diffuse plume must be treated or otherwise managed aggressively or passively. A wide range of options are available for potential application at a specific site but only a small subset will offer attractive balance of treatment/containment effectiveness and cost. More often than not those approaches that are based on in-place or in-situ treatment, such as those listed below, will offer the attractive balance. In all cases, an effective understanding of subsurface conditions is critical.
Technologies that are in the forefront of the transformation of the remediation industry are the technologies that InfraSUR knows:
- Advanced Hydraulic and Biogeochemical Characterization
- In Situ Chemical Oxidation (ISCO) – specifically involving the following four key technologies:
- Catalyzed Hydrogen Peroxide advanced oxidation process (AOP)
- Activated Persulfate AOP
- Permanganate chemical oxidation
- Ozone chemical oxidation
- In Situ Chemical Reduction and In Situ Biogeochemical Transformation – specifically the following two technologies:
- Biogeochemical Reductive Dehalogenation and Metals Stabilization (BiRDS)
- Zero Valent Iron
- In-Situ Bio-Oxidation and In Situ Bio-Reductive Dechlorination – the following three:
- Aerobic
- Anaerobic Oxidative
- Anaerobic Reductive
The above technologies can be effective in low to moderate mass density environments where aqueous phase mass destruction or removal is rate limiting but may not be as effective when LNAPL or DNAPL and/or high sorbed organic mass is present and rate limiting.
Proper selection and application of technology for making the contaminant mass available for direct treatment, whether abiotic or biotic or both, can be critical to success. Thermal or chemical approaches to transferring NAPL and/or sorbed mass to the aqueous phase are available. InfraSUR has applied its experience with chemical and thermal tools for enhanced containment mass transfer, recovery, and in-situ destruction to advancing remedial goals and objectives.
Physical mixing can be effective in encouraging containment mass to become more available to chemical and biological attack. Often two or more modalities are applied e.g., physical mixing with surfactant or heat addition. A range of chemicals can be used to gain access to sorbed or NAPL mass and the chemical category simply referred to as “surfactant”, is the most relevant and popular for solubilizing and in some cases mobilizing NAPL. This is important considering the fact that, when NAPL is present, typically the vast majority of the contaminant mass that exists is present as NAPL.
Subsurface fracturing, shear thinning polymers, and other tools can be used in a variety of ways to improve remedial efficiency and in some cases offer critical path functionality.