Estimation of operation time for soil vapor extraction systems

Abstract

Since the inception of Soil Vapor Extraction (SVE) as a viable contaminated soil restoration strategy, operators of these systems have struggled with determining the best date to terminate operation of their systems. Using principles of soil-gas flow and mass transport through unsaturated soils, stochastic hydrogeology, uncertainty analysis, and a cost/risk decision model, a procedure that can determine the appropriate time to discontinue operation of SVE systems was developed. Modeling of physical characteristics and determination of mass removal of a SVE system was accomplished using statistical realizations of permeability (uncertainty model) and a 2D advective-dispersive finite element vapor transport program (VapourT). The results from subsequent Monte Carlo analysis of the mass removal simulations are then subjected to a cost/risk analysis (decision model) to determine the appropriate termination time for the system based on costs and the probability that the system will fail to reach the regulatory standard. The decision model provides information on the cost benefits associated with either the continued operation of a SVE system, or its replacement with a more economically feasible remediation system. The intention of this research is to validate a framework for the estimation of termination time for the operational phase of a selected soil vapor extraction system.