The Role of Historical Operations Information for Supporting Remedial Investigation Work at the Former Harshaw Chemical Site

摘要

In the early stages of hazardous, toxic, and radioactive waste (HTRW) site investigations, basic record searches are performed to help direct the agencies investigating contaminated sites to areas of concern and to identify contaminants of interest (COI). Plans developed on the basis of this preliminary research alone are often incomplete and result in unexpected discoveries either while in the field investigating the site or after the reports have been written. Many of the sites investigated under the Formerly Utilized Sites Remedial Action Program (FUSRAP) have complex histories that are slowly uncovered over the life of the project. Because of programmatic constraints, nuances of these sites are often discovered late in their programs and result in increased expenditures in order to fully characterize the site, perform a robust feasibility study, and recommend appropriate alternatives for remediation. By identifying resources for public records, classified records, historic aerial photographs, and other sources of site-specific historical information, a process can be established to optimize the collection of information and to develop efficient and complete project plans. In many cases, interviews with past site employees are very useful tools. In combining what is found in the records, observed on historic aerial photographs, and heard from former employees and family members, teams investigating these sites can begin to compile sound and more complete conceptual site models (CSM(s). The former Harshaw Chemical Site (HCS) illustrates this discovery process. HCS is part of FUSRAP. Preliminary investigations by the U.S. Department of Energy (DOE) in the 1970s provided an initial CSM of activities that had taken place that may have resulted in contamination. The remedial investigation (RI) conducted by the U.S. Army Corps of Engineers (USACE) was designed around this CSM. The RI work, however, identified a number of site conditions that were unexpected, including new potential COI associated with recycled uranium and contaminant locations that were inconsistent with the original CSM. As part of an RI Addendum effort, the USACE reconsidered its understanding of HCS historical activities. This effort included an intensive review of available historical aerial photography, an in-depth Potentially Responsible Parties (PRP) investigation, additional analysis of the production processes in place at HCS, and targeted supplemental data collection. The result of this effort was a revised CSM that included a number of previously unidentified potential COI and a much clearer understanding of the processes and resulting waste streams potentially associated with environmental contamination. Because of their complex and often poorly documented operational histories, unexpected discoveries will always be a part of investigating sites such as HCS. Taking advantage of available resources and expending funds for thorough historical research early in the life of a project will help to reduce the chances for expensive field remobilizations and significant schedule delays. A complete and accurate site history also allows for more efficient long-term technical and budgetary planning, thus eliminating many obstacles associated with the ultimate disposition of HTRW sites.