Over the past 25 years, there have been a considerable number of environmental innovations in environmental site remediation. These progressive changes are reflected in the adaptations of applicable regulatory standards and industry best practices. What was once deemed acceptable procedure at the turn of the century is not necessarily in the best interests of the planet.
Environmental awareness around the critical issue of sustainability is a game changer when it comes to remedial amendments. The evolution of science and technology has also played a crucial role in treatment options and significantly altered the industry landscape. Here is a closer look at some of the most important innovations in the field of environmental remediation.
Increased Environmental Awareness
For many years, environmental contamination was a nonissue in our society. An “out of sight = out of mind” mentality led to standard practices like back door dumping and uncontrolled landfills. In the face of environmental disasters, this attitude has gradually changed over time. Current site remediation regulations are designed to protect the environment and members of the community as much as possible.
In Ontario, site remediation rules are governed by O.Reg.153/04. This guiding legislation was first introduced in 2004 (and amended in 2011) to outline the proper procedures for environmental assessment, cleanup of brownfield sites, and the filing of a Record of Site Condition (RSC). Risk Assessment (RA) and protection from environmental liability are also addressed in the document. Through the implementation of O.Reg.153/04, environmental sustainability remains top of mind for both site owners and remediation specialists.
In-Situ Treatments vs. “Dig & Dump” and “Pump & Treat”
Traditional site remediation involved moving contaminated soils off-site or pumping contaminated groundwater out to be treated and disposed off-site. These methods of removing contamination from a site are also known as “dig & dump” and “pump and treat”.
Dig and dump was carried out by excavating contaminated soil and dumping it off-site, regardless of the actual contaminant. There were several different options for disposal, including lake filling sites, contaminated soil landfills, municipal landfills, or hazardous waste landfills. The drawback to digging and dumping is that it simply shifts the problem elsewhere and is much less cost and energy efficient than more modern treatment options.
Pump and treat was carried out by pumping contaminated groundwater out of a well or system of wells and treating the pumped water prior to disposal. As pump and treat projects continued far beyond projected timelines, the science demonstrated that a phenomenon known as “back-diffusion” was keeping the groundwater contaminated. Essentially, as contaminated groundwater was pumped out, fresh groundwater replaced it and became contaminated by the chemicals still absorbed in the soil, which diffused back into the fresh groundwater, contaminating an otherwise clean source of water. This process has since been modeled and it is now known that it has the potential to keep contaminant levels elevated for many decades and even many centuries at some sites.
While “dig & dump” and “pump and treat” are still used today when necessary, in-situ treatments have become far more common. The term “in-situ” means “on-site” or “in position.” Advancements in in-situ technologies and increased understanding of this remedial option have led to more frequent use. These technologies include In-Situ Chemical Oxidation (ISCO), In-Situ Chemical Reduction (ISCR), and In-Situ Biodegradation (Aerobic and Anaerobic), among others. The advancement of these technologies has also allowed for improved bedrock remediation.
In addition, many advancements have been made in understanding the relationship between risk and appropriate remedial action. In general throughout Canada and the United States, Risk Assessment (RA) as a method to understand risks associated with contamination and then designing remediation to mitigate risk rather than cleaning up sites to an otherwise unnecessarily stringent criteria has become more and more accepted by governing bodies and financial institutions.
Advanced Science and Technology
From in-situ strategies to digital cartography, advancements in science and technology have revolutionized the way site remediation is done. Notable advancements include:
High-Resolution Site Characterization (HRSC)
In order to better understand subsurface conditions, HRSC tools were developed by environmental consultants and contractors. These innovative techniques are part of an overall strategy aimed at increasing the speed and efficiency of site cleanup. With an increased understanding of subsurface contamination, HRSC enables a more precise and targeted approach to site remediation. This approach reduces the risk of potential harm to the environment and surrounding communities.
Carbon-Based Injectables (CBIs)
CBIs were first introduced in Canada back in 2015 and are considered a breakthrough in terms of in-situ technology! Simply put, CBIs use Activated Carbon (AC) to treat chlorinated solvents and petroleum hydrocarbons in groundwater. This top-grade remedial amendment is known for its speed and efficiency. Another great advantage of using CBIs is that permanent results can be achieved through a single injection, saving both time and money. With CBIs becoming more widely available in Canada, the projected timeline for site remediation projects will be expedited, and the overall costs significantly reduced.
Bioremediation
Initially, bioremediation was generally considered to be a “black box” where some contaminants were observed to naturally degrade in certain circumstances. In the past, bioremediation was often referred to as a “polishing technique”, meaning it could be employed after the main remediation effort in order to finish off the last small portion of surviving contaminants. Currently, microbial consortia have been isolated for specific classes of contaminants, even those that are highly recalcitrant, and may be injected into the midst of contaminated soils and groundwater to directly target degradation of the target contaminants, and is now often used as a primary remedial strategy. Studies have consistently demonstrated that remediation projects which properly incorporate bioremediation can avoid the dreaded back diffusion and achieve much longer and more permanent remedial success.
Remedial Amendment Chemistry
Options for remediation in terms of the chemicals and compounds that are available to treat contamination have increased steadily over the last 25 years. As the science has progressed, compounds have simultaneously become more reactive, long-lasting, easy to use, and more compatible with other compounds. Deeper insights into the interactions between the remedial amendments, underlying geochemistry, and the role of microorganisms have and continue to build the efficacy of remedial amendments to new heights.
Geographic Information Systems (GIS)
Geographic Information Systems (GIS) is a computerized software designed to interpret spatial data within hours. The information can then be displayed in different formats, including high-resolution maps, charts, and reports. Given the speed, accuracy, and quality of the results, it has quickly become an invaluable tool in environmental remediation. Not only does GIS software provide a visual representation for clients, it also allows professionals to communicate data in ‘real-time.’ This increased understanding and collaboration makes it easier to move forward with the right Remedial Action Plan (RAP) for the site.
Improved Contaminant Consideration
Historically, metal contamination in soil was the primary focus of site remediation and it was only addressed through excavation. Fast forward 25 years and hundreds of different contaminants are now considered – even those in ultra-low concentrations. A deeper understanding of the subsurface and the process of contaminant migration has led to better treatments and better outcomes.
The Takeaway
The field of site remediation has changed dramatically over the past 25 years due to several environmental innovations. While the basic premise remains the same, how information is obtained and processed continues to evolve at a rapid pace. Increased environmental awareness, advanced technologies, and improved remedial amendments have all contributed to this amazing evolution. What comes next will all depend on future advancements and the ongoing commitment to environmental sustainability and innovation.
English