Vapor intrusion source treatment
Vapor in a building comes from contaminated soil or groundwater below it. Nelson's work is treating that source: excavated soil through the mobile thermal fleet, or soil left in place with in-situ thermal treatment, followed by verification sampling against the applicable criteria. Building ventilation systems are designed and installed by mitigation specialists; Nelson works alongside them.
The problem
Vapor intrusion happens when volatile contaminants in soil or groundwater move up through the ground and into indoor air through cracks, joints and utility openings. Petroleum hydrocarbons and chlorinated solvents are the usual drivers.
A ventilation system under the slab controls what reaches indoor air while it keeps running. The contaminated soil underneath is still there, and so is the obligation to manage it. Treating that soil addresses the cause.
What Nelson does
Excavated soil: Nelson's mobile thermal fleet heats contaminated soil on site to drive off and destroy the hydrocarbons, so the soil can be reused or managed as clean fill where the criteria allow. Nelson has done this work on petroleum hydrocarbon sites for more than 30 years.
Soil left in place: where the source sits under or next to a building, or digging is impractical, in-situ thermal treatment heats the ground where it lies and captures the vapors for treatment above ground.
Every project closes on evidence. Treated soil is sampled and compared with the applicable provincial or state criteria, and those results support the file with the regulator.
Where it applies
Hydrocarbon soil is driving the vaporFuel, oil and other petroleum releases are the contamination Nelson has treated longest, through both the mobile thermal fleet and in-situ thermal treatment.
A site is being redevelopedRemoving the source before construction means the next owner does not inherit a system to run and a monitoring program to keep up.
A ventilation system is in place but the source remainsSource treatment can run alongside an existing system. Whether the system can later be scaled back is a decision made with the regulator on the verification data.
Excavation is limited by a building or utilitiesIn-situ thermal treatment reaches soil that cannot easily be dug out.
Chlorinated solvents are presentSites with chlorinated solvents are assessed case by case, with the treatment route chosen around the site conditions and applicable criteria.
Project evidence
Thermal soil remediationHow on-site thermal treatment works on hydrocarbon-impacted soil.
Technology selectionHow the remedy is chosen against site conditions, criteria and end state.
The Hub
The contaminant library sets out pathway behaviour, jurisdictional criteria and treatment routes for each family behind vapor intrusion.
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