Wednesday, April 15, 2020


Just to be clear they may be the initial polluters having left behind heavy metals, petroleum hydrocarbons and volatile organic compounds (solvents) in the soil and groundwater. Of course I also expect they were significant air polluters in their day as well. That said it is my understanding that the City of Guelph have owned the site since 1997. So who do you think is responsible today for health effects that have originated on this site? Also keep in mind that there are other former, and maybe even possibly current, industries nearby. Two that I have an interest in would be Hart Chemical and Huntsman Corp.

Perhaps the City of Guelph thought they were doing the right thing back in 1997 when they purchased a highly contaminated site. Afterall two former owners, after IMICO, did not seem to get much positive press in regards to their cleanup efforts. That would be John Long followed by Mr. Tucker and Mr. Baldasaro of the Church of the Universe. If memory serves me correctly those latter two gentlemen were better known for their lifestyles possibly including marijuana and nudity.

So how bad has the pollution been from the former IMICO site? From my reading of a number of reports I would suggest that there is/was free phase LNAPL (light non aqueous phase liquid) as well as likely free phase DNAPL (dense non aqueous phase liquid) left behind on the site. The LNAPL would be the petroleum hydrocarbons (PHC) floating on top of the water table found at monitoring well OW23S in the south-east corner of the IMICO site. There is a reference to LNAPLS in the April 2014 Phase Two Environmental Site Assessment (page 6-7) as well as a concentration of the PHC F3 fraction of 508,000 parts per billion (ppb). There is another reference to a concentration of the F3 fraction of the petroleum hydrocarbons in April 2007 at 730,000 ppb. These are astronomically high concentrations and clearly represent floating petroleum hydrocarbons on the surface of the water table. As the water table (shallow groundwater) flows southwards towards the Eramosa River these LNAPLS flow along with it. The release of vapours into the soil from this floating liquid is almost unavoidable.

As serious and unhealthy as petroleum hydrocarbon vapours are, DNAPL chemicals which include chlorinated solvents generally are more toxic. These solvents include trichloroethylene (TCE), trichloroethane (TCA), tetrachloroethylene (PCE), and the breakdown products from them such as dichloroethylene (DCE), vinyl chloride (VC), and dichloroethane (DCA). TCE is especially known as highly toxic with a huge host of human health problems associated with exposure to its fumes. Its breakdown product, vinyl chloride (VC) is yet even more toxic to human beings.

I believe that LNAPLS may contain DNAPL chemicals in a mixture with the petroleum hydrocarbons. Similarly DNAPL mixtures may contain some lighter compounds mixed in with them. Hence it is possible to have TCE, VC, DCE etc. being released as a vapour into residential basements either from the LNAPLS floating on top of the water table or even possibly from the deeper DNAPL mixture. While LNAPLS move along with the flow of groundwater, the DNAPL mixture generally flows via gravity and possibly with some kind of pressure from an ongoing release behind it. That said a DNAPL mixture could have moved offsite decades ago and currently be immobile in the subsurface slowly releasing both dissolved contaminants into groundwater as well as vapours which move upwards towards the surface. While to date I have not found TCE concentrations in groundwater nearly as high as PHC concentrations, that is to be expected. The solubility of TCE in groundwater, especially in a mixture with so many other compounds (PHC, TCA, PCE, DCE, DCA etc) is much lower than the components of petroleum hydrocarbons. Most DNAPL chemicals inherently have relatively low solubilites in water although higher solubilities when mixed with some other solvents.

It is an outrage that the City of Guelph had not removed the obvious LNAPL mixture a long time ago. The deeper DNAPLS would have been more difficult to find yet was any attempt made to do so? All in all the nearby residents may have paid a terrible price for this apparent relaxed attitude towards toxic sub-surface contamination.

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