Pressure extraction process for removing soil and groundwater contaminants

DETAILED DESCRIPTION The present invention is a more effective process for removal, including extraction and degradation, of underground contaminants from a soil area that includes a subsurface groundwater unit and a vadose zone above the groundwater unit.
The present invention comprises providing a well that extends downwardly from grade surface to below the groundwater surface, the well including an exterior pipe with fluid permeable openings therein at a lower portion that extends below the normal groundwater surface; providing an interior pipe inside the exterior pipe, the interior pipe having an inlet opening at a lower end below the normal groundwater surface; introducing gas in the exterior pipe, at a pressure that is sufficient to create a gas communication between the exterior and interior pipes through the inlet at the lower end of the interior pipe; maintaining a gas flow downwardly at a non-vacuum pressure in the exterior pipe and then upwardly in the interior pipe such that gas is not withdrawn from the vadose zone into the exterior pipe; and maintaining a gas pressure differential between the exterior and interior pipes that induces groundwater to flow into the exterior pipe adjacent the lower end of the interior pipe and thereafter be extracted by the gas flowing into the interior pipe.
After an initial extraction of high-concentration contaminants with a gas flow at a pressure as low as atmospheric pressure, pressure is increased in the exterior pipe.
The pressurized gas introduced into the well flows outwardly into the unsaturated soil and causes the soil to be permeated with oxygen-containing gas.
The pressurized gas also augments the effect of groundwater removal in depressing the groundwater surface for a wide area around the well, creating a larger unsaturated zone or vadose zone for volatilization and also creating a downwardly sloping groundwater surface leading toward the lower portion of the well.
Liquid contaminants thus flow toward the well under the influence of gravity