Analysis of sequential ex-situ remediation of an encapsulated contaminated soil pile

For many years, efforts have concentrated on in-situ soil remediation techniques because excavation and re-disposal costs have hindered the development of ex-situ remediation. However, ex-situ remediation has valid applications. This is particularly true for small sites contaminated from sources such as underground storage tank leaks, surface spills, or Brownfields. When properly designed and monitored, ex-situ remediation can yield superior results because any in-situ treatment process can also be applied ex-situ under more carefully controlled conditions. The purpose of this paper is to describe a remediation analysis tool that will allow engineers to consider a sequence of conventional remedial actions applied ex-situ, under controlled conditions to an encapsulated contaminated soil pile. The analysis tool is designed to use a backbone simulation engine that can interface with a large set of remediation processes such as bio-venting, soil washing, bioremediation, vapor extraction, and thermal enhancement. The simulation engine defines the structure of the problem by simulating the geometry of the soil pile, inlets and outlets, now models, etc. This paper describes the geometric framework of the ex-situ remediation environment, and the gas and liquid flow models. The remediation process subprograms which implement individual remediation treatments are also discussed. The goal of the analysis tool is to provide user-friendly support which will allow engineers to test alternative treatment sequences and identify the most desirable sequence to achieve remediation goals at lower cost and higher efficiency.