Protocol for the Derivation of Environmental and Human ... - CCME

Section 6
Derivation of the Final Human Health Soil Quality
Guidelines
6.1 Agricultural Land Use
The preliminary human health soil quality guideline (PSQG HH ) is calculated using the equations in
Sections 5.1 or 5.2, depending on whether the contaminant is a threshold or non-threshold contaminant.
For agricultural land use, the check mechanisms for indirect exposure to soil contaminants via ingestion
of groundwater, infiltration of volatile compounds into indoor air, and ingestion of produce, meat, and
milk produced on-site are all calculated. If these modelling procedures indicate an unacceptable
exposure, the final SQG HH is set at the lowest value generated by the three check modelling procedures.
This ensures that the final SQG HH is protective of all these potential contaminant media transfer
pathways. If the check mechanisms indicate acceptable exposures, then the final SQG HH is set at the
level of PSQG HH .
6.2 Residential/Parkland and Commercial Land Uses
The preliminary human health soil quality guideline (PSQG HH ) is calculated using equations in Section
5.1 or 5.2, depending on whether the contaminant is a threshold or non-threshold contaminant. For
residential/parkland and commercial land uses, check mechanisms for indirect exposure to soil
contaminants via ingestion of groundwater, and infiltration of volatile contaminants into indoor air is
calculated. If these modelling procedures indicate an unacceptable exposure for the PSQG HH , then the
final SQG HH is set at the lower of the values generated by these two models. If the check mechanisms
indicate acceptable exposures, then the final SQG HH is set at the level of the PSQG HH .
For residential properties with backyard gardens, the check mechanisms for contamination of produce
grown on-site is calculated and presented in the contaminant assessment document for possible use as a
site-specific objective.
6.3 Industrial Land Use
The preliminary human health soil quality guideline (PSQG HH ) is calculated using equations in Section
5.1 or 5.2, depending on whether the contaminant is a threshold or non-threshold contaminant. As with
residential and commercial land use, the check mechanisms for indirect exposure via ingestion of
groundwater and infiltration of volatile contaminants into indoor air are applied to the industrial
PSQG HH . Where unacceptable exposures are found using these modelling procedures, the industrial
PSQG HH is set at the lower of the values generated by these check mechanisms. Where acceptable
exposures are found, the original PSQG HH is used. The procedure for checking off-site migration via
wind and water erosion from an industrial site to adjacent more sensitive land use is then applied as a
management adjustment factor to determine the final SQG HH .
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