This discussion is relation to the parameters for chemical analysis and common exceedances found for each parameter.
The majority of environmental investigations I have carried out require one or more of the following five (5) main parameters for chemical analysis:
1) Petroleum Hydrocarbons (PHCs)
PHCs are essentially your gasoline, diesel and heating fuel projects from spills, leaks and long term release into the soil and groundwater. This parameter is broken down into four (4) main fractions denoted as F1, F2, F3 and F4. Each fraction represents a specific chain length of carbons as follows:
There will be instances when heating fuel is the source and lighter fraction such as F2 may be identified in the chemical analysis. This may be attributed to the heavier fractions breaking down. This may be an indicator of how long this parameter has been impacting this area.
PHCs are usually analyzed with Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) which are part of the Volatile Organic Compounds (VOCs) found with gasoline and diesel.
2) Volatile Organic Compounds (VOCs)
VOCs are a great way to find out if chlorinated solvents have been released in the soil and groundwater. Chlorinated solvents could originate from dry cleaning facilities and heavy industrial processes that either required them as part of the operation and/or as a cleaning agent (i.e. degreaser).
Chlorinated solvents are Dense Non-Aqueous Phase Liquids (DNAPLs) as opposed to gasoline which is a Light Non-Aqueous Phase Liquids (LNAPLs). This makes sampling for Chlorinated solvents different and more difficult than the LNAPLs. This will be further discussed in another article.
Sampling for VOCs is different than sampling for the other parameters. Currently in Ontario, 5g soil samples are placed into 40 ml vials with a pre-weighed amount of methanol. The methanol acts as a preservative to mitigate VOCs from being lost during transportation. It is common to take two (2) to three (3) vials from each sampling location. The 5g sample is measured from various devices, but I tend to use Terra Core® Samplers.
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| Terra Core® Samplers |
Groundwater samples for VOCs require three (3) 40 ml vials to be filled to the top with no air bubbles. The preservative used for groundwater samples submitted for VOC analysis is either NaHSO4 or HCl. These samples have a short holding time of 14 days.
3) Polycyclic Aromatic Hydrocarbons (PAHs)
PAHs are typically found in the burning of coal, oil, gasoline, trash or wood. I have encountered PAHs in creosote treated wood (often black wood) that was found mixed with some soils. PAHs can be found from locations such as near railway tracks or known locations where PAHs were used. They are not very mobile and have a low solubility to water.
4) Polychlorinated Biphenyls (PCBs)
PCBs are starting to get rarer to find in Toronto due to their mission to rid themselves of PCB transformers. It may still be found in soil from past industrial operations that have used them.
5) Metals and Inorganics (M&I)
Surprisingly, this parameter provides the most headache for consultants. When applying for a Record of Site Condition (RSC) we need to watch out for the pH the soil has been registered with because it may be classified as a sensitive site. In addition, it is getting harder and harder to find sites that can meet the Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR) requirements due to close proximity to roads that may use road salts. The use of Calcium Chloride as road salts may alter pH in soil as well.
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