A Study of Soil Remediation by Vapor Extraction System and Air Sparging

Abstract

Soil remediation by heated soil vapor extraction system and air sparging is a new technology developed by Advanced Remedial Technology, Inc. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. The process developed by Advanced Remedial Technology, consists of a heater/boiler that pump and circulates hot oil through a one-inch pipeline that is enclosed in a six-inch pipe. This six-inch pipe is vertically installed within the contaminated soil up to a certain depth and is welded at the bottom and capped at the top. Pea gravel or fine sand fills the six-inch pipe and thus acts as a heat transfer medium. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. Soil vapor extraction cannot remove contaminants in the saturated zone of the soil that lies below the water table. In that case air sparging may be used. In air sparging system air is pumped into the saturated zone to help flush the contaminants up into the unsaturated zone where the contaminants is removed by SVE well. In our present study we concentrated on modeling one Heated Soil Vapor Extraction System with air sparging and predicting the behavior of different chemicals in the saturated and unsaturated zone of the soil. This analysis uses the species transport and discrete phase modeling to predict the behavior of different chemicals when it is heated and driven out by the sucking well.