Carol A. Eddy-Dilek

Recent Advances in Characterization of Vadose Zone Dense Non-Aqueous Phase Liquids (DNAPL) in Heterogeneous Media

One of the most important technological developments for characterization of unconsolidated sediments in the past 20 years is the direct-push method for accessing and probing the subsurface. The cone penetrometer and related direct-push technologies, such as the Geoprobe, have increasingly been used for geologic and chemical characterization at sites throughout the United States and abroad. In addition to its standard suite of sensors (i.e., tip pressure, sleeve friction, and capillary pressure) to determine soil type, the cone penetrometer has been used with innovative sensors and samplers to perform contaminated site assessments and has also been used to install wells, sampling points, and geophysical tools and arrays. By integrating geologic information from the standard cone penetrometer sensor with the depth-discrete chemical and physical information obtained from innovative cone penetrometer-based samplers and sensors, an accurate, rapid, and cost-effective characterization can be accomplished. Cone penetrometer tests provide quality, high-resolution data. The tests are minimally invasive, rapid, and produce a minimum of investigation-derived waste. These attributes are critical to investigative and cleanup operations at large hazardous waste sites with heterogeneous sediments.

In Situ Monitoring of Groundwater Contamination Using the Kalman Filter

This study presents a Kalman filter-based framework to establish a real-time in situ monitoring system for groundwater contamination based on in situ measurable water quality variables, such as specific conductance (SC) and pH. First, this framework uses principal component analysis (PCA) to identify correlations between the contaminant concentrations of interest and in situ measurable variables. It then applies the Kalman filter to estimate contaminant concentrations continuously and in real-time by coupling data-driven concentration-decay models with the previously identified data correlations. We demonstrate our approach with historical groundwater data from the Savannah River Site F-Area: We use SC and pH data to estimate tritium and uranium concentrations over time. Results show that the developed method can estimate these contaminant concentrations based on in situ measurable variables. The estimates remain reliable with less frequent or no direct measurements of the contaminant concentrations, while capturing the dynamics of short- and long-term contaminant concentration changes. In addition, we show that data mining, such as PCA, is useful to understand correlations in groundwater data and to design long-term monitoring systems. The developed in situ monitoring methodology is expected to improve long-term groundwater monitoring by continuously confirming the contaminant plumes stability and by providing an early warning system for unexpected changes in the plumes migration.

Technical assistance to Ohio closure sites; Recommendations toaddress contaminated soils, concrete, and corrective action managementunit/groundwater contamination at Ashtabula, Ohio

The Ashtabula Environmental Management Project (AEMP) at Department of Energy-Ohio (DOE-OH) requested technical assistance from the EM-50 Lead Lab to aid in defining new cost and time effective approaches in the following problem areas: soils, concrete, and groundwater/Corrective Action Management Unit (CAMU) at RMIES in Ashtabula, Ohio. Attachment 1 provides the site request for assistance. The technical assistance team assembled for this request is provided in Attachment 2. These individuals reviewed key site information prior to convening with DOE and contractor personnel (RMIES and Earthline) for a three-and-a-half-day meeting to better understand baseline technologies, limitations, and site-specific issues. After listening to presentations about the nature and extent of known contamination, the team broke out into several groups to brainstorm ideas and develop viable solutions. This executive summary details unresolved issues requiring management attention as well as recommendations to address soils, concrete, and groundwater/CAMU. It also provides a summary of additional technical assistance that could be provided to the site. More details are presented in the body of this report.