Abstract: A system, method and apparatus for monitoring the subsurface at facilities for the presence of volatile organic compounds (VOCs). A surface penetration is made in a facility surface providing access to the subsurface soil beneath the facility. A soil probe is placed in communication with the soil beneath the facility surface and used to withdraw samples of soil gas from the pore space within the soil. The soil probe includes a monitoring port configured to seal the surface penetration and minimize the movement of undesirable materials between the facility and the subsurface via the monitoring port. The soil probe has an end filter in communication with the subsurface under the facility. The monitoring port is coupled to a sampling pump used to withdraw the soil gas sample. Soil gas samples are periodically obtained and analyzed for the presence of VOCs.