PAHs or Polyaromatic Hydrocarbons can also be solids at ambient temperatures but just like dioxins and DDT cab be readily dissolved in solvents including DNAPL solvents. The former Uniroyal site was blessed with many PAHs which among other locations ended up in the Canagagigue Creek sediments, creekbank soils, fish etc. Hence they have also migrated into groundwater beneath the Uniroyal site and most likely onwards from there into Elmira's groundwater long before the company allegedly fully slammed the gate shut via Pump & Treat (hydraulic containment) in 1992/93.
Further studies of steam flushing have confirmed the early positive results in removing/dissolving the higher solubility compounds in DNAPLS such as chlorobenzene and other solvents but there are later "tailing" effects or dramatic slowdowns in the removal of these relatively higher solubility compounds compared to more recalcitrant to steam flushing and dissolution; dioxins, DDT and PAHs.
It is not just DNAPL that can infiltrate into low permeability zones. Dissolved contaminants in aquifers at the interface between aquifers and aquitards can diffuse from the higher concentration aquifer into the lower to zero contaminant concentration aquitard over time. This diffusion can be a few inches deep or even a few feet into the aquitard. After many years of pump & treat for example as the aquifer concentrations of contaminants decrease significantly then the contaminants held in the aquitards can back diffuse into the aquifers.
The 1% rule referencing a DNAPL chemical's dissolved concentration in an aquifer indicating likely nearby free phase DNAPL must be viewed in the context of all contaminants dissolved in the aquifer including non DNAPL contaminants. Hence for example five contaminants (4 chlorinated solvents & toluene (non DNAPL)) each having a concentration less than 1% of their Solubility can have their cumulative mole fractions sum higher than 1% providing evidence of possible DNAPL presence nearby (Raoult's Law). The cumulative mole fraction is each compound's concentration in groundwater divided by its' Solubility (i.e. Ci/Si) and then added together. In the example by Bernard Kueper Queen's University Kingston and Kathryn Davies U.S. EPA, Region 3 in their EPA Ground Water Issue titled "Assessment and Delineation of DNAPL Source Zones at Hazardous Waste Sites" these five compounds mole fractions (Ci/Si) total .034 or 3.4% , well in excess of the 1% criteria.
So apologies fir getting a little technical there but how are we to interpret this information? Firstly any honest evaluation of even a fraction of the multitude (hundreds approx.) of dissolved Uniroyal Chemical contaminants compared to their Solubility in water would show the high probability of DNAPLS nearby. Secondly the single minded focus on NDMA/Chlorobenzene and later Ammonia has been simply a distraction from the even worse contaminants and by no means am I deprecating NDMA's toxicity. I'm referring to dioxins, DDT and PCBs. Possibly on Monday we'll discuss the PCBs further. Thirdly we are seeing exactly how difficult it would be to fully remediate the Elmira Aquifers honestly and transparently. Any idjit can lie and say they are doing it but it takes truly inspired prevaricators to hold to the same lie after thirty years and failure.