Critical Thinking in Phase I ESAs
A good Phase I Environmental Site Assessment (ESA) combines raw data and observations with appropriate analysis and interpretation. Therefore, in order for the ESA report to meet its goals, the environmental professional (EP) conducting the Phase I ESA must not only conduct accurate historical and regulatory research, but should also use critical thinking skills to make sense of the data and draw appropriate conclusions.
EPs, put your thinking caps on!
How an EP interprets data determines the results and validity of a Phase I ESA report. An EP should assess all aspects of a site – including but not limited to the site history, regulatory documentation, interviews and the site’s geology and hydrogeology – to be able to properly assess the site as a whole. When one or more of these areas is not thoroughly researched, the analysis of the data can be skewed by the EPs personal knowledge or experience. This can result in wrong conclusions, or unnecessary additional work.
An Interesting Case Study
At a conference I recently attended, an interesting case study was presented which nicely illustrates my point. A Phase II Subsurface Investigation was conducted at a site that resulted in its inclusion on the EPA’s National Priorities List (NPL) because of extensive pesticide and herbicide contamination. A nearby former pesticide manufacturing facility was quickly identified as the obvious responsible party to be held liable for the clean-up.
However, review of the analytical data didn’t support the hypothesis that the facility was indeed the source of the contamination. Additional sampling showed that the concentration of contamination wasn’t actually greater at the site of the former pesticide manufacturer. Instead there were “pockets” of hot spots scattered throughout the area that couldn’t easily be attributed to the identified source.
So, further analysis was required. Closer review of the historical Sanborn records and historical aerial photographs identified a second suspected source that clearly did support the identification of the hot spots: former orchards! In addition, it was also revealed that some of the samples were taken from locations adjacent to residential building foundations that were treated with a known pesticide, which also accounted for a portion of the skewed results.
While this case study deals with actions taken most likely after the Phase I ESA was completed, it appears that if the site history and geography had been properly analyzed a different hypothesis may have been achieved. It’s easy for an EP to rely on the obvious or personal knowledge and experience when forming conclusions. While experience does factor into ESA reporting, sometimes it’s important for the EP to take a step back and objectively re-examine the data.
The value of objective analysis
Critical thinking in Phase I ESAs requires the EP to identify and report all potential sources of contamination whether it is identified in historical research, regulatory research or interviews. The conclusion formed in the Phase I ESA may be the basis for conducting a Phase II ESA at the subject property, so it’s crucial that the EP collects representative samples, reviews all of the data, weighs the significances, and resists the temptation to form a conclusion prior to proper examination.
EP’s should base their recommendation only on critical analysis of evidence in front of them, not on their personal experience, knowledge or presumptions.
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