Application of a Simple Decision Model for Soil Vapor Extraction System Operation

Abstract

AbstractOver the past several decades, soil vapor extraction (SVE) systems have successfully reduced the mass of volatile organic compounds in contaminated soils at many sites. However, predicting when operation of these systems should end once mass removal rates decline and become asymptotic to some low value is still a difficult task. To help make this decision, a simple decision model has been derived from a more rigorous cost‐risk‐based objective function that requires extensive Monte Carlo analyses. Use of the simple model to make a decision on continued operation does not require the same extensive modeling effort. Yet, use of the model does require the contaminant removal rate to be asymptotic to some low value indicating that the removal process has become dominated by diffusion from relatively low permeable soil. At this stage of the removal process, the SVE system should be replaced with an alternative approach if the cost of this alternative approach is less than the capital cost of continued SVE system operation. Applicability of the simple model is discussed through a comparison of the results predicted by the simple model for an operating SVE system to the rigorous results determined with the objective function. Results from this study show that under most conditions the simple model can be used to make a decision of whether a SVE system should continue to operate.