Soil Vapor Extraction Systems
Sub-Slab Depressurization Systems
Soil Venting
Methane Venting 
Radon Mitigation Systems

These 5 names are for similar systems to remove gases and chemical vapors from the soil to prevent harm. Soil Vapor Extration Systems(SVES) are used to remove volatile chemicals from the soils, usually when the chemicals are in the soils above the water table.  Wells are installed and screened above the water table and the screens are placed in the level of  contamination. The wells are piped together and the pipes go to a blower or fan to pull the vapors out of the ground.  If needed the exhaust from the fan can be treated with carbon to collect the chemical vapors. For an example of this, please look at another page of this website: The Perc Plume .

If the gases in the soil are under a house or building, we can install a sub-slab depressurization system.  This is similiar to the SVES, but we do not need deep wells, we only want to pull the vapors out from under the house so that the vapors do not go into the house. For this application we do not need deep wells, we are not trying to remove the source- we are only trying to remove the vapors under the house, to protect the house.

A hole is made in the basement floor, and a shallow hole is dug in the soil under the floor. A pipe is installed in the hole, the rest of the hole is filled with gravel and then cemented over.  The pipe goes to a blower and the exhaust from the blower goes to the outside air. When the fan is turned on, the vapors under the house are pulled into the pipe, through the blower and then up and out above the house.  This type of system is also used to protect a house from naturally occuring radon gas.

  Soil venting systems are also used on and near landfills to protect buildings from methane gas.  Methane is an explosive gas that is produced from the decomposition of garbage or paper or wood.  Sometimes buildings are built on or near old landfills and soil venting is needed. 

Closed landfills that are capped also need venting to release the methane gas.  Sometimes there is enough methane gas to run a generator that will produce electricty- the venting system can be piped to the generator.