Soil Vapor Intrusion Mitigation

The phrase “soil vapor intrusion” refers to the process by which vapors migrate from a subsurface source, through soil and into the indoor air of a building where exposure is possible. Soil vapor, also referred to as soil gas, is the air found in the pore spaces between soil particles. After the contaminant partitions from the source and into “vapor” it travels through the pore spaces of vadose or unsaturated soil via diffusion or advection. If the vapor migrates into the radius of influence of an existing building, then typical building pressure differentials related to heating or cooling systems can draw the vapors into or below the structure where they can accumulate. In order to properly evaluate the soil vapor intrusion pathway, Aztech uses the recommended multiple lines of evidence approach where samples are collected from soil vapor, sub‐slab vapor, indoor air, outdoor air, groundwater and soil. Aztech geologists are fully versed and experienced in collecting these samples in accordance with pertinent state and federal protocols and regulations. All soil vapor and/or air sampling is done using summa canisters set to specific sampling durations. The sampling durations are dependent on site conditions. After the samples are collected they are sent to a certified laboratory for analyses.