Modelling of vapour intrusion into a building impacted by a fuel spill in Antarctica.

A new vapour intrusion contaminant transport model was designed specifically to allow an assessment of the impact of a hydrocarbon fuel spill on air quality in cold region buildings. The model is applied to a recent situation in Antarctica, where a diesel spill impacted the construction of a new building. For the first time, this model allows consideration of the diffusive resistance of different vapour barrier to the transport of hydrocarbons into the building and an assessment of the effectiveness of different products. Site specific indoor air criteria are derived. Five scenarios are modelled at field temperatures: (1) build on current contaminated site; (2) excavate contaminated soil, backfill with clean soil and assess impact of residual contamination; (3) excavate and backfill with remediated (biopile) soil; (4) backfill with remediated soil and assess impact of residual contamination; (5) backfill with remediated soil and assess impact of a potential future fuel spill. Two different vapour barriers, a co-extruded ethylene vinyl alcohol (EVOH) geomembrane (VB1) and a linear low-density (LLDPE) geomembrane (VB2), are investigated for each scenario and compared to a base case with no vapour barrier, providing quantifiable evidence of the benefit of installing an engineered vapour barrier Contaminant concentrations were below regulatory limits for Scenarios (2-5) with VB1 and air exchange in the building. For all scenarios, the EVOH geomembrane (VB1) was consistently superior at reducing vapour transport into the building indoor air space over the LLDPE geomembrane (VB2) and no vapour barrier. The risk mitigation measures developed for this contaminated Antarctic site may be relevant for other buildings in cold regions.

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