Kingston Ash Release
Groundwater Monitoring & Modeling
Last Updated September 2, 2011
Groundwater monitoring related to the ash recovery project began in June 2009, with twenty-seven sampling locations in and around the dredge cell (6 pre-existing wells, 3 new permanent wells, 6 new temporary wells and 12 geoprobe borings). All samples have met drinking water standards, except for the first two taken at one of the newly installed wells. Those two samples had elevated arsenic levels, along with elevated levels of suspended particulates. Subsequent results from this same well routinely met drinking water standards.
TVA gathered additional groundwater and subsurface information to incorporate into a computer model. The model was used to calculate future groundwater conditions and whether ash-related materials will flow, via groundwater, into the Emory River after cleanup and site closure. Types of information used by the model and the results it produces include the following:
Depths of soil, ash, and bedrock
Chemical interactions of ash-related materials with soil, ash, and bedrock
Concentrations of ash-related materials in groundwater
Groundwater flow patterns
Groundwater flow rates
Concentrations of ash-related materials where groundwater and river water meet, also called mixing zones
The model also accounts for the effects of a flexible membrane liner cap to decrease the amount of precipitation that enters the dredge cell. The computer model results will be analyzed and compiled into a groundwater modeling report. Once that report is completed, it will be made available online.
The model predictions will be used in a Baseline Ecological Risk Assessment (BERA), as part of the Engineering Evaluation/Cost Analysis (EE/CA) for the river system. The EE/CA will evaluate if any risk remains to human health and the environment after the site has been restored and present alternatives for further restoration of the river, if needed.
Tables 1 and 2 summarize water quality data for permanent and temporary groundwater wells, respectively. For a detailed description of the field and quality control procedures, see the Technical Memorandum.