Remediation is the glory work of the brownfield industry. In my opinion, this is when environmental consultants shine and can show their true colors. Who’s got the guts to face this site, immerse themselves in the all the data, and come up with the best game plan to clean this thing up? Some of these remedial plans and projects take years to implement…some of them take a few days to complete. Some plans are as simple as taking a truck load of dirt to the local landfill, and some are so beautifully complicated that its nearly impossible to understand what’s going on, but both have the same end goal and both work…the property gets cleaned up.
The face of remediation has changed significantly over the past 20 years or so. From the legacy sites I’ve been involved in and from the historical reports I’ve read, there is certainly a developing change in the remedial strategies being used. Historically remedial activities would have either consisted of the traditional dig and dump strategy or else the implementation of mitigation measures such as encapsulation or capping (which really isn’t remediation its more like hiding the contamination on site in order to protect people from it). These traditional methods still exist and are widely used today but now we are seeing such a wider variety of engineering solutions that can support these projects and get the job done at a lower cost or shorter timeframe. (Now that I think of it, the “History of Remediation” would be a great blog post for the future…if anyone has any cool stories out there about historical remediations they encountered send me an email I’d love to hear them email@example.com)
…So to keep with the theme of the two previous posts regarding the evolution of a Phased Environmental Site Assessment (ESA), I introduce to you the final chapter called “Remediation” aka the “Phase Three ESA”.
In a very short recap:
- The Phase One ESA has been done and areas of concern have been identified;
- The Phase Two ESA has been done and contamination has been found; and
- Then its time for the Phase Three ESA, remediate the property and bring the contaminant concentrations below the allowable limits.
Before starting there is a need to develop a remediation plan which will be designed to meet the client’s needs and wants. Do they care how much its going to cost? Do they need it cleaned up right away? Many things to consider…I prefer, and I think most people would agree with me, simplicity in designing these projects is the key to success as well as to avoid the burden of unnecessary costs and duration.
Similar to the Phase Two ESA process, a Remediation starts with a good game plan detailing how its going to be completed. I like to refer to this as the Remedial Action Plan (RAP). The RAP cannot be completed until a thorough evaluation of the property’s geophysical and contaminant characteristics has been completed. The two work so dynamically together that without completing this evaluation your RAP will be truly limited in its full potential of performance, and may not even be successful. The following are a few examples of remediation strategies that are often considered when designing the RAP:
- Soil excavation and disposal/treatment (ex-situ)
- Chemical Oxidation (in-situ, also referred to as ISCO)
- Soil Vapor Extraction
- Pump and Treat
- Air Sparging
- Permeable Reactive Barriers
- Thermal Treatment
Some of these examples are much more widely used than others and each of their viabilities are completely dependent on the individual site characteristics, the type of contamination and how its reacting in the subsurface. For more information on these strategies, I recommend you visit my favorite environmental website called CLU-IN, sponsored by the United States Environmental Protection Agency (http://clu-in.org/).
Once the best strategy(ies) have been determined, a sampling or confirmation program has to be designed. This confirmation program is used to monitor the effectiveness of the remediation and ensures that the vertical and lateral extents of the contaminants are cleaned up. For some examples of sampling plans and confirmation program design (in Ontario) check out the Ministry of Environment and Climate Change document titled “Guidance and Sampling and Analytical Methods for use at Contaminated Sites in Ontario” (https://archive.org/details/guidanceonsampli00ontauoft).
When the contractor implementing the RAP commences there is usually a role for a consultant to be on-site at this time to monitor and document the process as third party verification. The consultant will be implementing the confirmation program by collecting samples and directing the work. As confirmatory data validates that the remediation work is complete, the construction activities come to an end…the dust settles and things are put back together. In most cases a formal remediation report is prepared by the consultant that documents everything that was completed and the results of the confirmation program. When complete and done correctly you are left with a piece of land free of any environmental liabilities…a ‘clean’ site.
Some people might be asking why do we even need to remediate? I ask why wouldn’t we want to? Notwithstanding the most important reason (i.e., to protect our health and environment), we recycle everything else in our lives from coke bottles to newspapers, why not recycle our land? I can accept that pollution happens…unfortunately that seems to be part of business, whether by human error or negligence. What I can’t accept is businesses not cleaning up their mess and abandoning their brownfield properties for years to come, letting our future generations be the ones left to clean them up.