CONVERTING BROWNFIELDS INTO “GREEN”
By Devin Rosnak
Posted April 26, 2018
Environmental remediation has become more and more commonplace in urban developments in recent years. Numerous government jurisdictions offer incentives to develop brownfields within transitioning former industrial areas. A brownfield is defined as a property that is suspected to have hazardous pollutants, chemicals or contaminants, which has prevented the property from being sold at market value for re-development. These lands are especially attractive because they are serviced with utilities and are typically situated close to developed areas; all of which increase the socio-economic value of the property. Or perhaps, the architecture of the industrial building is attractive for historical preservation and redevelopment as mixed-use commercial or residential use – those trendy high ceiling exposed brick loft apartments that are in such high demand!
Bottom line is, brownfields are big business, and the individuals purchasing these sites are well-versed in the environmental industry and are aware of the numerous options available to ‘clean’ these properties to be suitable for redevelopment. As such, the associated costs are factored into the negotiation of purchase or development of the property. If you do it right, you can turn a brownfield into some serious “green”!
So – what if you aren’t a guru of contaminated sites and brownfield redevelopment? What if you did not intend to purchase a contaminated site, or stumble upon an environmental issue as part of your redevelopment project? Maybe you are going for refinancing for a renovation to an industrial or commercial property, and the bank requests an environmental site assessment where you then find out you have some contamination issues. There are numerous cases where developers feel they have effectively delineated the property or identified environmental risk as part of the geotechnical investigation, however still come across contamination, an underground storage tank, or any other environmental surprises. When it comes to construction, surprises are sure to come up.
Many environmental issues can be dealt with simply and quickly through conventional means, such as a tank removal, ‘dig and dump’, or dewatering and disposal of impacted groundwater. But what if it’s not straightforward? What if your contamination is deep in soils that cannot be excavated easily? Or maybe the groundwater is causing the contaminant plume to migrate off-site, or it’s your neighbour that is impacting your land. Other common issues relate to impacts lying below the slab and footings of an existing structure that is being kept through redevelopment. What if it is too costly to remove a significant amount of overburden in order to get at a tiny seam of contaminated soil? There are other options to address or manage your environmental risk.
In some cases, a risk assessment can be done based on site use, and limiting exposure pathways to the occupants on-site. Perhaps a physical barrier below slab to eliminate vapour intrusion is enough to limit future risk. Emerging technologies in the industry have given property owners the option to deal with contamination in-situ. The Latin ‘in-situ’ simply translates to ‘in position’, or in its original place of origin. There are endless technologies, chemicals, and treatment methods for this work, such as: Bioremediation/Bioaugmentation, ISCR/ISCO, Phytoremediation, Thermal Desorption, Air Sparging, Subslab Vapour Mitigation, Reactive Barriers, and Filtration. For any successful remediation project, everyone involved must understand the Who, What, When, Where, and Why – this guides us to our choices on the How. It is vital that there is a full understanding of the environmental issue through an in-depth Phase I and II program. As with geotechnical investigations, a limited or incomplete environmental investigation leads to cost and schedule overruns, simply because there will be more surprises. Spending more time and money on a drilling investigation will pay off with a more detailed and accurate remedial plan. This is especially true of in-situ remediation projects.
Once we identify what the contaminants are, and where they are located, we can start the discussion surrounding how to implement our strategy – which is closely related to the when, or how long it will take to reach our objectives. As a very general example, a common approach to remediation of organic compounds would be through In-Situ Chemical Oxidation, or In-Situ Chemical Reduction (ISCO vs ISCR). The question is, what technology to select? Many factors need to be considered: Are we doing source removal or plume control? Is there free product? Are the soils tight or loose – which will impact the ability to target contaminants & relates to reaction time of the treatment process – especially with Chemical Oxidation. Are there breakdown or daughter products present? Is the subsurface environment aerobic or anaerobic? ISCR is typically used to target a wide variety of halogenated compounds, however, is not especially reactive towards hydrocarbons or BTEX contamination. If the subsurface is oxygen-rich, ISCO application would typically be employed. Conversely, if the environment is oxygen-depleted, the common approach would be an ISCR, or perhaps anaerobic bioremediation. In order to have a successful remediation program, there needs to be a clear understanding of the subsurface and environmental conditions on site. Some of the most notable and successful remedial projects have been those where the environmental contractor worked closely with the client, consultant and the project’s General Contractor early in the planning phase to develop a construction plan that is understood by all parties involved. This approach will ensure that you save more “green” and successfully remediate your brownfield development.
Devin Rosnak, Hon. B.Sc. is a Project Manager at Ground Force Environmental. He manages construction projects relating to brownfield development and contaminated site remediation. Devin can be contacted at [email protected]
Tags: Brownfield, Contaminants, Development, Environmental, In-Situ, Remediation