How is it determined what ground pollution is from 2012 and before…and what is from 2012 to the present?

When the facility was sold to PES in 2012, Sunoco had a good understanding of the nature and extent of contamination at the facility. After the sale of the property, if changes in the contaminant profile on-site occurred, or known spills happened, the resulting cleanup became PES’ responsibility. In some instances, new contamination co-exists with old contamination, and the responsibility is shared.

Similar to our understanding of LNAPL, multiple lines of data are used to help support our understanding of what’s historic and what’s more recent. Looking at stable isotope chemistry of different elements like carbon and hydrogen and looking at trends (how contaminant concentrations change through time) are examples of some of the tools that are planned to applied for the Site.