Environmentally Sustainable ESG

The summary

  • In-situ remediation is 100 times less carbon-intensive than ex-situ remediation. 
  • Transportation costs account for 45% to 70% of emissions associated with traditional remediation. 
  • Excavation accounts for 20% to 45% of emissions.  
  • Motor vehicle crashes are the second leading cause of workplace deaths. 

An In-Situ Remediation Solution Improves ESG by Reducing GHG emissions

Much like medical doctors, soil doctors do not like to use cures that are worse than the disease. Examples of such soil ‘cures’ are incineration or immobilization. If the soil is unable to support life after being ‘cured’, then the ‘cure’ is more of a curse really.  

What goes for the soil, goes for the world. The world’s 20 million contaminated sites contain 84 billion m3 of contaminated soil. That’s nearly 34 million Olympic-sized swimming pools worth! The carbon cost of cleaning these sites by ex-situ means is 177 billion tonnes of CO2-equivalents or five times what the entire globe emits each year. This means, we should be actively thinking about the ESG metrics of our contaminated site management programs. 

Without a doubt, in-situ approaches and monitoring programs dramatically reduce the carbon footprint of contaminated site management. Individual emissions estimates* of ex-situ remediation ranged from 711 kg to 7,590 kg CO2 eq per m3. Or more generally, a meta-study of 63 case studies of hydrocarbons found that in-situ remediation technologies were 100 times less carbon-intensive (64 kg CO2 eq per m3) than ex-situ techniques (2,083 kg CO2 eq per m3).  

Based on these dry statistics alone, it is clear that excavation should be a method of last resort. 

*Amponsah, N. Y.; Wang, J. Y.; Zhao, L., A review of life cycle greenhouse gas (GHG) emissions of commonly used ex-situ soil treatment technologies. Journal of Cleaner Production 2018, 186, 514-525.

Amponsah, N. Y.; Wang, J. Y.; Zhao, L., Environmental Profile of Two Soil Remediation Options – A Case Study in Northern Alberta. Journal of Environmental Accounting and Management 2017, 5, (2), 117-131.

Ladotte, M.; Deschenes, L.; Samson, R., Selection of a remediation scenario for a diesel-contaminated site using LCA. International Journal of Life Cycle Assessment 2007, 12, (4), 239-251.

In-Situ Based Remediation Solutions Improve ESG by Reducing Workplace Deaths 

In-situ methods have other benefits that are often overlooked.  

First, transportation and excavation account for most ex-situ emissions (45%-70% and 20%-45% of emissions, respectively). In other words, ex-situ remediation involves a lot of driving and moving large machinery around. The leading cause of workplace deaths is transportation, accounting for a whopping 37% of all workplace deaths. Even worse news for ex-situ remediation is that transportation on gravel roads is three times more likely to cause injuries and fatalities than on paved roads. Combined, this means that one of the highest workplace risks a company can undertake is likely linked to ex-situ remediation. 

Second, ex-situ remediation has acute impacts on the surrounding communities. Having grown up in a rural area, I can tell you that having rocks spit out of a dump truck into your windshield, or worse hitting a pile of soil that has fallen out of a truck on the highway, are scary experiences that I am glad to have survived (cars and motorcycles were not so lucky).  

An In-Situ Remediation Solution is the Cheapest Option 

At this point, you are likely asking, surely companies are doing ex-situ because it is cheaper, right?  

Typically not.  

Excavation followed by landfarming is typically around $40 per m3 treated, whereas bioremediation is $34 per m3. Other ex-situ options like soil washing run up to $187 per m3 (think dig, pump, and treat) or incineration can run to a whopping $1,047 per m3. I would note that these values are lower than those typically reported in the literature, but I used them because they are all from the same meta-analysis. In essence, in-situ remediation is around 15% cheaper than ex-situ*. 

So why do companies do ex-situ?  

Well, that has to do with financial and legal risk. Our regulatory frameworks only resolve a liability when a site is certified as clean. Excavation can clean a site over the course of two months, whereas in-situ methods take three to five years. Combine that with the dreaded fiscal discount rate and a smart Chief Financial Officer will always punt a solution down the road until they are forced to clean up. When it comes to the environment, our accounting system is definitely the grasshopper in Aesop’s fable, highlighting the perils of improvidence.  

In-situ technologies can also expose a company to legal risks. If other stakeholders want things cleaned up quicker or basically disagree with the results, they can force an owner to make a clean site cleaner and basically chew up all of the savings that in-situ provides via legal bills. 

The challenge that we face as a society is how we can create a remediation technology platform that optimizes ESG metrics while minimizing financial and legal risk. It’s a tough solution but given the existential risk posed by meeting a dump truck head-on (still thinking of my poor cars and motorcycles of my younger years), and/or planetary extinction. I think we owe it to our children to come up with a solution.

*Gurdon, L., Esmahi, L., Amponsah, N.Y. et al. Life cycle cost analysis of contaminated site remediation using information technology tools. Environ Dev Sustain23, 10173–10193 (2021). https://doi.org/10.1007/s10668-020-01052-x