Remediation activities are undertaken to improve environmental conditions. That's obvious. But what "environment" is being considered when deciding how to improve conditions? At a larger scale, it's becoming apparent that some of the remediation efforts expected from and undertaken by the environmental industry have adverse impacts beyond the site boundaries. Those impacts are often not well understood nor are they always considered when contemplating remedial action.
Clearly, proper remediation of a site results in an improvement in local conditions. But what is happening off site? All remediation activities have some impacts: the installation of in situ remediation systems disrupts the surface of the site and may disturb neighbours; operation and maintenance of remediation systems consume electricity, natural gas, propane, maintenance chemicals, etc.; noise or odours affect neighbours during operation of remediation systems; surface disruption, traffic, noise and dust occur during excavation activities; safety and environmental issues arise from hundreds of additional hours of truckers on highways hauling contaminated soil; additional wear and tear takes place on roadways due to thousands of tonnes of soil being trucked back and forth; fuel consumption and associated greenhouse gases rise due to excavator and truck operation; landfills (a non-renewable resource) are loaded with soil; greenfields are stripped back to obtain clean backfill material; and additional costs are incurred by future development on top of backfilled soil.
This is just a partial list of "adverse impacts" that may be realized for active remediation projects. Knowing all this, the question has to be asked -- are these efforts sustainable?
If they're not sustainable -- and I feel they often are not -- then what can be done to take what we know and build a more sustainable approach to remediation?
We begin by taking a risk management or risk assessment approach to the situation, with reduction being a key target. Risk-based approaches may allow you to select measures to reduce the amount of active remediation required and allow you to develop cleanup criteria that realistically protect the necessary receptors, but do not force overly conservative actions. Therefore, the amount of work required can be reduced as well as the impacts associated with that work while, at the same time, achieving the remediation goals of protecting human health and the environment. In some instances, site-specific risk assessment can even achieve project closure without having to undertake any active remediation, which avoids those impacts identified above.
It stands to follow that after reducing the amount of effort required to meet that remediation end point, the remaining measures to be undertaken now need to work more efficiently. At this time, this effort requires some innovative thinking. You may be required to excavate a site, but this doesn't mean you need to haul the soil to the landfill if it can be treated onsite. If you can't treat it onsite, perhaps offsite treatment is possible so that you can re-use the treated soil as backfill. For in situ work, remediation systems should be designed so that you can modify as many aspects of injection or extraction as possible to always keep the energy directed toward the wells or treatment areas that will yield the greatest results at that time.
Currently, the regulatory models used to assess risks from contamination generally allow for a certain amount of flexibility or site-specific modification, which can help remediate a site more efficiently and with less overall environmental impact. However, many stakeholders (e.g., municipal authorities, lending institutions, etc.) aren't comfortable with the concept of leaving any contamination exceeding generic criteria on-site, regardless of how well managed it may be. It's easier to take all the contamination away and call the site clean, but we have to accept that the contamination has been moved elsewhere and we should be asking ourselves, "At what cost?" The analogy of a splinter in your finger comes to mind. If you have removed the splinter, you've been successful. But how you went about removing the splinter (amputating your finger vs. a small incision) makes a big difference!
By educating stakeholders about the difference between active remediation and risk management options and by un der standing the long-term benefits of using the reduction and efficiency efforts outlined above, we will begin to move toward a more sustainable approach to environmental remediation.
In short, I look at more widely accepted risk management as the next layer of the onion; our next step on the path of continuous improvement. We have learned to do active remediation well and have seen some excellent results through these methods. Because of these successes, we are now in a place to ask how current processes can be improved to make these methods even better, to make them sustainable, and to see the results of an even stronger model of environmental remediation.
Gary Millard, P.Geo., is an Environmental Geologist with Shell Canada Products in Calgary, Alberta. Contact Gary at firstname.lastname@example.org