Using vertical conceptual site models and the USACE MEC risk matrices as tools to support decision-making for remedial investigation/feasibility study projects

Abstract

Recently, emphasis has been placed on the value of vertical conceptual site models (CSMs) as tools to support decision-making for Remedial Investigation/Feasibility Study (RI/FS) projects. Vertical CSMs are used to better show the connection between the following: the vertical distribution of munitions and explosives of concern (MEC) and munitions debris indicative of MEC found at a site; the depth to which these items could be reliably detected during a RI with the instruments used; and the confidence in the data to make decisions regarding risk, remedial alternative development and evaluation, and current and future site use. The presentation will provide an example of a vertical CSM, illustrate the steps needed to present information in this format, and discuss the information shown as it relates to risk, remedial alternatives, and current and reasonably anticipated site use. Additionally, a set of MEC risk matrices (Matrices 1 – 4) will be included to show the link between the vertical CSM and the United States Army Corps of Engineers (USACE) MEC risk methodology. The vertical CSM and MEC risk matrices developed for the Waugoshance Point Target Remedial Investigation/Feasibility Study (RI/FS) project will be used as the examples. Lessons learned/best practices in using vertical CSMs and the MEC risk matrices will be highlighted, including comments and suggestions received from USACE and project stakeholders on the Waugoshance Point Target RI/FS project.