[en] The primary objective of the Phase I dense non-aqueous phase liquid (DNAPL) characterization discussed in this document was to assess the status of DNAPL beneath A/M-Area at the Savannah River Site (SRS). The initial characterization phase consisted of: (1) geological data collection to more precisely define the controlling geologic features, and (2) physical/chemical measurements in existing wells. Additionally, background and historical information from the unit (e.g., operating history and detailed vadose zone characterization studies) were examined, with particular attention to implications for DNAPL occurrence and distribution. Use of minimally invasive technologies was the prime focus for Phase 1

[en] Fifty years ago, the Savannah River Site (SRS) was built to produce nuclear materials. These operations impacted air, soil, groundwater, ecology and the local environment. Throughout its history, SRS has addressed these contamination issues directly and has maintained a strong commitment to environmental stewardship. The site boasts many environmental firsts. Notably, SRS was the first major DOE facility to perform a baseline ecological assessment. This pioneering effort, by Ruth Patrick and the Philadelphia Academy of Sciences, was performed during SRS planning and construction in the early 1950's. This unique early example sets the stage for subsequent efforts. Since that time, the scientists and engineers at SRS have proactively identified environmental problems as they occurred and have skillfully developed elegant and efficient solutions

[en] A workshop to identify the scientific issues associated with contamination in riparian, fluvial, and hyporheic systems was held in March 2003 at the Savannah River Site (SRS). The workshop examined the general scientific remediation challenges and research opportunities in such systems and on Tims Branch - Steed Pond, a specific uranium- and heavy-metal-contaminated riparian system at SRS. A diverse group of scientists representing a wide range of scientific disciplines came from academia, national laboratories, and research centers to develop recommendations for future ERSD research opportunities. There was agreement among the workshop participants that riparian, fluvial, and hyporheic systems represent a unique opportunity to advance science and to enable progress on DOE's environmental cleanup of contaminated sites. The participants at this workshop documented both the critical need and the great promise for research on hydrological and biogeochemical processes controlling contaminant transport and fate in contaminated surface and near-surface systems. The approach of the workshop was to assess the Tims Branch - Steed Pond system at the SRS as an appropriate site to identify research needs that support potential remediation strategies

[en] The Subsurface Contaminants Focus Area (SCFA) is supported by a lead laboratory consisting of technical representatives from DOE laboratories across the country. This broadly representative scientific group has developed and implemented a process to define Technical Targets to assist the SCFA in strategic planning and in managing their environmental research and development portfolio. At an initial meeting in Golden Colorado, an initial set of Technical Targets was identified using a rapid consensus based technical triage process. Thirteen Technical Targets were identified and described. Vital scientific and technical objectives were generated for each target. The targets generally fall into one of the following five strategic investment categories: Enhancing Environmental Stewardship, Eliminating Contaminant Sources, Isolating Contaminants, Controlling Contaminant Plumes, Enabling DOEs CleanUp Efforts. The resulting targets and the detail they comprise on what is, and what is not, needed to meet Environmental Management needs provide a comprehensive technically-based framework to assist in prioritizing future work and in managing the SCFA program

[en] The Department of Energy is sponsoring an initiative to facilitate efficient, effective and responsible use of Monitored Natural Attenuation (MNA) and Enhanced Passive Remediation(EPR) for chlorinated solvents. This Office of Environmental Management Alternative Project, focuses on providing scientific and policy support for MNA/EPR. A broadly representative working group of scientists supports the project along with partnerships with regulatory organizations such as the Interstate Technology Regulatory Council and the Environmental Protection Agency. The initial product of the technical working group was a summary report that articulated the conceptual approach and central scientific tenants of the project, and that identified a prioritized listing of technical targets for field research. This report documented the process in which: (1) scientific ground rules were developed, (2) lines of inquiry were identified and then critically evaluated, (3) promising applied research topics were highlighted in the various lines of inquiry, and (4) these were discussed and prioritized. The summary report will serve as a resource to guide management and decision making throughout the period of the subject MNA/EPR Alternative Project. To support and more fully document the information presented in the summary report, we are publishing a series of supplemental documents that present the full texts from the technical analyses within the various lines of inquiry. The following report - documenting our Historical and Retrospective Survey of Monitored Natural Attenuation - is one of those supplemental documents

[en] Data collected during the first stage of a Savannah River Technology Center (SRTC) Strategic Research and Development Project confirmed the efficacy of chemical reduction and air stripping/sparging as an ultralow level mercury treatment concept for waters containing Hg(II). The process consists of dosing the water with low levels of stannous chloride to convert the mercury to Hg. This form of mercury can easily be removed from the water by air stripping or sparging. Samples of Savannah River Site (SRS) groundwater containing approximately 130 ng/L of total mercury (as Hg(II)) were used for the study. In undosed samples, sparging removed 0 percent of the initial mercury. In the dosed samples, all of the removals were greater than 94 percent, except in one water type at one dose. This sample, which was saturated with dissolved oxygen, showed a 63 percent reduction in mercury following treatment at the lowest dose. Following dosing at minimally effective levels and sparging, treated water contained less than 10 ng/L total mercury. In general, the data indicate that the reduction of mercury is highly favored and that stannous chloride reagent efficiently targets the Hg(II) contaminant in the presence of competing reactions. Based on the results, the authors estimated that the costs of implementing and operating an ultralow level mercury treatment process based on chemical reduction and stripping/sparging are 10 percent to 20 percent of traditional treatment technologies

[en] The overall objective of this work is to develop a reasonable and cost-effective approach to meet the emerging mercury standards, especially for high volume outfalls with concentrations below the drinking water standard

[en] Mercury analyses associated with the A-01 Outfall have highlighted the importance of developing an understanding of mercury in the Savannah River Site groundwater system and associated surface water streams. This activity is critical based upon the fact that the EPA Ambient Water Quality Criteria (AWQC) for this constituent is 0.012mg/L, a level that is well below conventional detection limits of 0.1 to 0.2 mg/L. A first step in this process is obtained by utilizing the existing investment in groundwater mercury concentrations (20,242 records) maintained in the SRS geographical information management system (GIMS) database. Careful use of these data provides a technically defensible initial estimate for total recoverable mercury in background and contaminated SRS wells

[en] Several technologies for clean up of solvents such as trichloroethylene, from groundwater were examined to determine the most reasonable strategy for the southern Sector in A/M Area of Savannah River Site. The most promising options identified were: pump and treat technology, airlift recirculation technology, and bioremediation technology. These options range from baseline/traditional methods to more innovative technologies. The traditional methods would be straightforward to implement, while the innovative methods have the potential to improve efficiency and reduce long term costs

[en] The Environmental Sciences Section (ESS) established a quarterly monitoring program of the Fourmile Branch (FMB) seepline down gradient from the F- and H-Area seepage basins. The program surveys and tracks changes in tritium, specific conductivity, and pH for the seepline water. Measurements from the sixth quarterly survey (September 1993) showed higher tritium and conductivity measurements and higher pH values (pH 5--6) than measurements from previous studies. Increased tritium concentrations and conductivity values, as compared to previous surveys, were attributed to decreased rainfall prior to the sampling event. However, overall results of the tritium survey and stream monitoring data (Looney et al., 1993) suggest that the tritium plume is flushing from the FMB system