Enhanced vapor extraction system and method of in-situ remediation of a contaminated soil zone

摘要

This invention is an enhanced vapor extraction system and method for in-situ remediation of soils contaminated with volatile organic compounds, weathered organic compounds and residual organics. The system consists of air influx wells installed around the periphery of the contaminated zone, an air extraction well installed within the contaminated soil zone and a vacuum pump or suction blower pulling on the extraction well and creating an air circulation which flows from the influx wells through the pore spaces of the contaminated soil to the extraction well. The shear action of the flowing air strips the contaminants from the soil surfaces and pore spaces and entrains them into the air stream for later disposal. The improvement consists of increasing the air velocity through the system to increase shear action and so the rate of contaminant removal. This is done without added vacuum pump or suction blower capacity, but by tapering the air influx wells from a maximum flow cross-sectional area at ground level to a minimum flow area at the depth of the contaminated soil. The maximum air velocity is obtained at the minimum flow area. The taper may be gradual (conical with tubular wells) or stepwise (a series of straight tubes of diminishing cross-sections). The net benefit is an increase in the stripping rate of the contaminants and a reduction in operating time and cost for a given remediation task, with only minor structural changes.