Dip Tank Site Investigations and Risk-Based Closure
Hot Springs, Arkansas
FTN was retained by a wood products company to assess the nature and extent of soil and groundwater impacts related to the former use of dip tanks to treat wood products with pentachlorophenol (PCP). Former dip tank sites were assessed at three facilities located in Arkansas and Oklahoma. FTN used rapid site assessment techniques to confirm impacts followed by performance of subsurface drilling programs that included soil sampling and installation of groundwater monitoring well networks at all three sites. This phase of the project included analysis of aquifer tests and acquisition and analysis of other data (e.g., geotechnical), to support decision-making. The next phase of the project consisted of completing human health and ecological risk assessments, which concluded the potential for human exposure to PCP to be within the theoretical lifetime cancer risks considered acceptable by the USEPA. Furthermore, no potential or actual receptors were identified at or near these mill sites.
The risk-based remedial option selected for two of the three dip tank sites was monitored natural attenuation (MNA). The third site is located in a Wellhead Protection Area, therefore, source reduction via pump and treat and MNA were selected as the site remedy. These sites are currently being monitored for a period of 5 years, after which contaminant plumes will be evaluated to determine if controlled migration is occurring. Typical deliverables that were prepared in support of the project included Work Plans, Data Management Plans, Heath and Safety Plans, Quality Assurance Project Plans, Sampling and Analysis Plans, detailed status reports and project schedules, Site Investigation Reports, Human Health and Ecological Risk Assessment reports, Remedial Alternatives Evaluations, Remedial Action Plans, and cost estimates.