VAPOR INTRUSION INVESTIGATION
WET supported a vapor intrusion evaluation and acceptable building use for a proposed office space located in Kalispell, Montana. The commercial building was located adjacent to a former gas station where leaking underground storage tanks were located that leached petroleum products into the soil and groundwater that migrated toward the commercial building. The client had concerns regarding the potential for chemicals to enter the indoor air of the commercial building and approached WET to investigate. WET performed an initial round of indoor air monitoring for petroleum hydrocarbons following Montana Department of Environmental Quality (DEQ) vapor intrusion guidance to evaluate whether chemicals in the groundwater were volatilizing into the commercial building air at levels that could cause health effects for future building occupants. Following the initial air monitoring, WET provided recommendations to the owner to improve the efficiency of the existing vapor extraction system as well as building ventilation. Following these improvements, WET performed a second round of monitoring to verify the changes were effective in reducing the concentrations of petroleum hydrocarbons detected in the air and to ensure the levels observed were safe for future workers in the building.