Development of Recommendations and Methods to Support Assessment of Soil VentingPerformance and Closure

摘要

Soil venting, which includes gas extraction and/or gas injection, is the primarymethod used in the United States to remove volatile organic compounds (VOCs) from unsaturated subsurface porous media. The widespread use of venting is due to its above ground simplicity of operation and proven ability to remove contaminant mass inexpensively relative to competing technologies. However, there is little consistency in assessment of performance of the technology in U.S. EPA or State regulatory programs. Design, monitoring, and closure schemes are typically based on empirical methods with little consideration given to fundamental physical, chemical, and biological processes controlling mass removal during venting operation. This results in the technology not being utilized to its fullest potential, nor its limitations being well understood. The purpose of this document was to improve the current state of the art and state of the science of soil venting application. This purpose was accomplished by attainment of three specific objectives. The first objective was to develop a regulatory approach to assess closure including measures to ensure consistency in ground-water and vadose zone remediation. The second objective was to provide comprehensive and detailed literature reviews on gas flow and vapor transport. These reviews formed the basis of recommendations and methods to improve venting design and monitoring. The third objective was to perform research to improve various aspects of venting application.