Soil vapor investigations provide a rapid and cost effective way to collect information at sites potentially impacted by volatile organic compounds (VOCs), like chlorinated and fuel hydrocarbons, or by methane and hydrogen sulfide. The data can be used to identify contaminant sources, determine their distribution, and estimate indoor air risk.

Intrusion of subsurface vapors into buildings can cause an unacceptable risk to the occupants. VOCs in the subsurface, whether in soil or groundwater, can migrate upward through the soil and enter into buildings. Regulators routinely require human health risks be evaluated, including this pathway, before site closure.

EnvApps follows all appropriate soil vapor survey protocols for the location of the project, including those of the California Department of Toxic Substance Control (DTSC) and the Los Angeles Regional Water Quality Control Board. Samples are analyzed onsite using U.S. Environmental Protection Agency Method 8260B, with duplicate samples analyzed offsite using U.S. EPA Method TO-15.

Following sample collection, risk is evaluated using fate and transport models to predict indoor air concentrations from vapor intrusion. Indoor air sampling is conducted, if necessary.

EXAMPLE PROJECTS:

  • Installed 18 permanent, multi-stage, soil vapor probes on- and offsite of an abandoned dry cleaners for the DTSC. Project was complicated due to the presence of an unexpected shallow perched water zone. EnvApps conducted indoor air evaluations for three of the 23 compounds encountered in the soil gas, as well as two compounds encounter in the water.
  • On Tuesday afternoon, a long-term client called, saying that one of a package of properties he was considering (an either take or none proposal) may have had a dry cleaners on it. EnvApps mobilized, determined the former location of the cleaners, conducted a soil vapor survey that Thursday, provided him the report on Monday (without having to work on it over the weekend), and the $14 million deal closed the following week.
  • For a property transaction, EnvApps conducted a soil vapor survey to see if impact from former occupants or an nearby Superfund site was present. No impact was found.
  • Installed 150-foot deep, multi-stage probe for methane monitoring within a landfill.