The 13th International Conference on Environmental ... - Events

Abstracts
stability, set times, heat generation and interactions with materials within the structure. <strong>The</strong> large size and configuration
of the facility necessitates that grout must be pumped from the exterior to the spaces to be filled, which requires that the
material must retain a high degree of flowability to move through piping without clogging while achieving the required
leveling properties at the pour site. Set times and curing properties must be controlled to meet operations schedules,
while not generating sufficient heat to compromise the properties of the fill material.
<strong>The</strong> properties of residual materials can result in additional requirements for grout formulations. If significant
quantities of aluminum are present in the facility, common formulations of highly alkaline grouts may not be appropriate
because of the potential for hydrogen generation with the resultant risks. <strong>The</strong> SRS is developing specialized inorganic
grout formulations that are designed to address this potential problem. One circum-neutral chemical grout formulation
identified for initial consideration did not possess the proper chemical characteristics having exceptionally short set times
and high heat of hydration. Research efforts are directed toward developing formulations that can meet operational
requirements for chemical compatibility, extended set times and reduced heat generation.
SESSION R1: Environmental Impacts
1) 40298 – Main Results of A Remediation of Uranium- and CHC-Contaminated Groundwater
Jörg Wörner, Sonja Margraf, Walter Hackel, RD-Hanau (Germany)
<strong>The</strong> ground-water of a former research- and production site for various nuclear fuel-elements has been remediated
for the last 8 years taking place after an intensive soilremediation by large-scale drilling and additional soil-exchange
within the saturated zone. <strong>The</strong> remediation-activities were improved successfully by several measures of which one was
the increase of the plant’s throughput and another the setting of additional remediation-wells at selected places. This
procedure is mainly based on the regular observation of the remaining contaminants’ concentrations in the ground-water
and the aquifer’s specific lithography. <strong>The</strong> cleaning process was adopted for a second installation which was taken in
operation last November. Both installations’ experience will be presented by which about 450.000 m³ ground-water will
have been extracted by midyear. <strong>The</strong> area affected by the contaminants has been downsized by the remediation which is
manifested by the results of the monthly monitoring. <strong>The</strong> conventionally set target-values have not yet been reached, but
the progress will offer the chance to release the remediation out of the rules of the German Atomic Law by the year 2013.
Details in the ground-water’s Uranium-nuclide composition allow the attribution of the ground-water to two main plumes
associated to different former production-activities. Blending of the two plumes with respect to their specific
Uranium-nuclide composition caused by the chosen pump-regime has been observed and is meanwhile a helpful means
for reaching the set aims on a planned time-scale. Figures for the totally extracted amounts of Uranium and CHC
(chlorinated hydrocarbons) will be presented which are increasing actually for both contaminants as result of setting
additional remediation-wells close to the still- observable contamination-centres. Completely remediated areas are
observed on the other hand where intensive pumping was executed from the very beginning of the remediation-activities.
<strong>The</strong>se observations give data to estimate the residual amounts of ground-water which have to be treated in the future. <strong>The</strong>
decrease of the Uranium-contamination is observed as a function of the extracted amount of ground-water whereas the
CHC-contamination has decreased irregularly due to the fact of its dependence of the pump-regime and the
remediation-wells’ different distances to the former handling locations. <strong>The</strong> CHC-compound-spectrum shows natural
attenuation effects in the close down-stream area which can be helpful after achievement of the remediation’s
target-value for the Uranium and possible finalizing of a continuous pumping procedure. As detailed results were
published in two former ICEM-papers [1,2] this paper will highlight main results and discuss taken measures to finalize
the remediation-activities within the next 3 to 4 years. [1] ICEM07-7270 Remediation of a Uranium-contamination in
groundwater, [2] ICEM09-16244 Remediation of Uranium- and CHC-contaminated groundwater on a former nuclear
fuel-element production site.
2) 40267 – Biogeochemical Gradients, Waste Site Evolution, and Implications for Sustained Metal and
Radionuclide Attenuation in Complex Subsurface Environments
Karen Skulbal, Justin Marble, Kurt D. Gerdes, US DOE (USA);
Miles Denham, Karen Vangelas, Savannah River National Laboratory (USA)
<strong>The</strong> U.S. Department of Energy (DOE) Office of Technology Innovation and Development sponsors applied
research to improve the understanding of metal and radionuclide behavior in soil, sediment, and groundwater.
DOE-supported researchers are developing advanced site characterization and simulation capabilities, as well as novel
remediation tools and technologies to control contaminants over long time frames in highly complex subsurface
environments. Natural and enhanced attenuation strategies are being studied in the context of subsurface biogeochemical
gradients, such as variations in pH and redox potential. <strong>The</strong>se gradients are spatially and temporally dynamic and can
strongly influence metal and radionuclide migration, speciation, and reactivity. Knowledge of gradient evolution is
essential for site evaluation, initial remedy selection, and technology transitioning to sustainable, low-energy remediation
approaches such as monitored natural attenuation. Research activities in this area will be discussed using case studies
from DOE sites. One case study focuses on a former disposal area at the Savannah River Site (SRS) in Aiken, South
Carolina. Unlined seepage basins at the site received approximately seven billion liters of acidic, aqueous, low-level
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