Remedial Investigation - Find, Define, Refine

by David Warwick, Vice President
Aug 4, 2015

Remedial cover

When you read the terms "remedial investigation" or "environmental investigation" do you know what they mean? I use them in my daily work. In my experience, though, these words often elicit a second look followed by "What?" Remedial investigations do not grab media attention as do grand scale cleanups such as Superfund sites, oil spills, or landfills, but prior to cleanup of these sites significant remedial investigation was conducted.

Remedial investigation is a term used to generically describe the evaluation, characterization, definition, and identification of cleanup alternatives of areas contaminated with hazardous substances such as petroleum, industrial solvents, metals, etc. It is the foundation of a successful cleanup of environmental contamination.

So what is remedial investigation? At the recent joint conference of the American Institute of Professional Geologists and the Remediation and Redevelopment Division of the MDEQ, keynote speaker Daniel T. Rodgers simply defined remedial investigation as find, define, refine.

I'll explain: Oddly, we sometimes become aware that a hazardous substance was released into the environment even before we know where it was released. So the first goal of remedial investigation is to find the release or problem. We ask lots of questions about the history of a site, building construction, and site infrastructure such as storm drains, sewers, process pits, foundation footings, so that we can understand its previous uses. This information leads us to the chemicals that might have been used "in other words, so we know what to look for. Then by having an idea of where those chemicals were used on the site, we know where to look for them. Knowing the infrastructure also helps us know where and how the chemicals might be moving. Once we understand where to look for contamination, we look into, over, around, and under various natural media to find it.

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Once found, we now must define the extent or the boundaries of the contamination and also define the characteristics of the media in which we are working. This can be complex since chemicals move differently in different media. Some move faster or slower, some disperse more readily or dissolve, some volatilize and some transform into other chemicals. We also need to know what type of media the contaminants are moving through, such as sand, silts, clay, rock or mixtures thereof. The same contaminants will move differently through these various materials, so it is imperative that we obtain a clear picture of the natural environment and all of its complexities. We do this by physically sampling the natural media; be it soil, groundwater, surface water, air, etc. Today there are many proven methods of collecting samples, and each media presents its unique challenges. The idea is to collect a sample that is representative of the area from which the sample was collected. By collecting numerous representative samples, one can begin to build a picture of what the contaminants have done, where they have gone, where they are going and who or what they are going to affect.

Lastly, yet no less important, is to refine the information. Refining our investigation is where we begin to identify potential cleanup approaches. During the find and define stages, we build a picture of the problem "referred to as a Conceptual Site Model. As new data is collected, we update or refine the model. Often gaps in data are identified that if filled, may enhance the model and lead to better understanding of the site and cleanup options.

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Refinement may take many forms, such as additional sample collection, additional historical research, computer dispersion modeling, and/or seasonal and temporal variation assessment. These and other tools when strategically employed will lead to better-informed cleanup decisions and ultimately shorter cleanup timeframes.

Spending the time and effort to find, define and refine will lead to better outcomes. Fewer surprises will arise once the cleanup has started. Time and effort do equate to dollars in the short term; however, new methodologies recently highlighted at the AIPG-MDEQ conference are available that allow for quick assessment while still providing the level of remedial investigation detail necessary to make sound cleanup decisions. That, in combination with recent regulatory reform, agency cooperation and creativity, remedial investigations and cleanup will continue to reduce effectively hazards in our environment and continue to protect human health and the environment.

My colleague and fellow geologist Derrick Lingle is preparing a technical white paper that describes some of the sampling methodologies that we use to find, define and refine remedial investigation. We will share the white paper in our next blog. If you have further questions, don t hesitate to reach out to me directly at 269.342.1100 or by email.

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remedial investigation  environmental investigation  find  define  refine  contamination  environmental cleanup 

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