The textbook approach to new or legacy spills is to ensure that you have a vertical and horizontal delineation of the pollutants. This understanding of how deep and wide your pollutant has travelled is essential before you can begin any remediation, restoration, or reclamation process. The rationale for this approach is that we should not begin a remediation process until we have enough information to ensure that it can be successful. Thus, we carefully assess a site, set data quality objectives, and carefully plan out the goal of a remediation program.
But, this practical, reasonable, and defensible approach has failed us.
Traditional delineation doesn’t work
Since the 1980’s, there have been efforts to remediate high and low priority sites.
Despite these efforts, ~20 million polluted sites worldwide contribute to ~2 million deaths each year through soil and water pollution[i]. The world’s ~20 million sites contain 84 Gm3 of contaminated soil. The carbon cost of cleaning these sites is 177 billion tonnes of CO2-equivalents, five times what the entire globe emits each year. Collectively, contaminated sites represent $12 trillion CAD in environmental liability, and costs to the global economy are between $0.2 and $1.1 trillion USD per year (0.25 to 1.89% global GDP)[ii]. Despite the urgent need to reduce the economic and health effects of contaminated sites, current technologies are not up to the task. Within Canada, only 4% of the remediation market is being addressed, similar to the 5% observed in Europe[iii]. These low rates of market activity will, in the worst case lead to a doubling of contaminated sites over the next decadeii, or best case, merely equal the rate of new site pollution[iv].
The question is why?
How do we explain this?
One option is say it’s due to incompetence. It could be that, given great information, remediation teams are either too incompetent or do not care enough to clean up a site. I know that this is untrue.
It could be that our science is inadequate. Unlikely. Even the ‘forever’ chemicals like PFAS have remediation solutions now. Despite this, even hydrocarbon sites, whose solution to remediation was outlined in the 1940’s (i.e. add fertilizer and electron acceptors), persist.
Why then, does the number of contaminated sites continue to increase yearly?
One simple phrase explains it: polluted soils are a global problem, with a local solution.
Effective remediation relies on immediate feedback from IoT sensors
I have helped clean sites worldwide, and every site was the same. And every remediation solution was different. Thus, what remediation teams need is feedback. Immediate feedback on how the pollutants is responding to remediation efforts.
Remediation teams know this. That’s why they measure groundwater intensely. However, as I mentioned before, soil is 70 times more pollutant than water. Groundwater provides a bright, clear picture of risk, but for remediation, groundwater sees remediation through a glass, darkly.
What does all this focus on delineation do to remediation systems? It delays their implementation. And every month you delay, the pollutant travels, increasing groundwater risk and increasing liability as soil volumes increase daily. To obtain delineation, we often miss a deployment season or watch as our pollutant migrates further and further away from the source.
Before IoT sensors, to delineate, one had to plan an intrusive investigation. Such investigations were expensive, and thus, sample sizes would be highly constrained. At the end of delineation, operators and remediation teams might have an estimate of where the plume is, but not an accurate portrayal of the plume dynamics. Once delineated, a supplemental investigation is often ordered to identify plume dynamics. Only when that is complete, will a team consider remediation. But… consider that all this expense and time typically yields only 10 to 15 tablespoons of soil and borehole logs to build a remediation program upon.
Imagine a different way of doing this. Rapidly install an IoT-based sensor on the day you collect groundwater. If you are installing groundwater monitoring wells, install 5 wells representing your best estimate of the upgrade, downgradient, source and the 1000 ppm isocline. Collect groundwater samples and immediately install a remote, real-time sensor. Such sensors collect 48 measurements a day of pollutants and degradation activity. By the time your laboratory samples return, you will likely have ~2000 measurements of plume dynamics. And if your well is in the wrong location, you can simply move your sensor.
A few weeks go by, while you and your team design, decide and deploy an easy remediation system. Perhaps a simple recovery system, a peroxide trip, or an easy air sparger. Now, you’ve collected additional ~4000 measurements to feed into your groundwater model. Within a month, you’ll know your groundwater plume dynamics (i.e., risk) and have an idea of how quickly soil liability is changing. Imagine how much more fun this would be. You could reduce your risk and increase your visibility of the processes. And perhaps, make a dent in the world’s contaminated site register, reducing it to 19,999,999.
[i] Landrigan, P. J.; Fuller, R.; Acosta, N. J. R.; Adeyi, O.; Arnold, R.; Basu, N.; Balde, A. B.; Bertollini, R.; Bose-O’Reilly, S.; Boufford, J. I.; Breysse, P. N.; Chiles, T.; Mahidol, C.; Coll-Seck, A. M.; Cropper, M. L.; Fobil, J.; Fuster, V.; Greenstone, M.; Haines, A.; Hanrahan, D.; Hunter, D.; Khare, M.; Krupnick, A.; Lanphear, B.; Lohani, B.; Martin, K.; Mathiasen, K. V.; McTeer, M. A.; Murray, C. J. L.; Ndahimananjara, J. D.; Perera, F.; Potocnik, J.; Preker, A. S.; Ramesh, J.; Rockstrom, J.; Salinas, C.; Samson, L. D.; Sandilya, K.; Sly, P. D.; Smith, K. R.; Steiner, A.; Stewart, R. B.; Suk, W. A.; van Schayck, O. C. P.; Yadama, G. N.; Yumkella, K.; Zhong, M., The Lancet Commission on pollution and health. Lancet 2018, 391, (10119), 462-512.
[ii] Carre, F.; Caudeville, J.; Bonnard, R.; Bert, V.; Boucard, P.; Ramel, M., Soil Contamination and Human Health: A Major Challenge for Global Soil Security. Global Soil Security 2017, 275-295.
[iii] Panagos, P.; Van Liedekerke, M.; Yigini, Y.; Montanarella, L., Contaminated Sites in Eu ropes: Review of the Current Situation Based on Data Collected through a European Network. Journal of Environmental and Public Health 2013, Article ID 158764.
[iv] Horta, A.; Malone, B.; Stockmann, U.; Minasny, B.; Bishop, T. F. A.; McBratney, A. B.; Pallasser, R.; Pozza, L., Potential of integrated field spectroscopy and spatial analysis for enhanced assessment of soil contamination: A prospective review. Geoderma 2015, 241, 180-209.