Environmental Research & Technology Division
Technology Development & Applications Group
Diffusion/Hydraulic Barriers Surrounding Buried Waste
Contaminated soils, buried waste and leaking underground storage
tanks (UST) pose a threat to the environment through contaminant transport. One of the
options for control of contaminant migration from buried waste sites is the construction of a
subsurface diffusion/hydraulic barrier that consists of a
wall of low permeability material. In the case of
underground storage tanks it has been proposed that an interim subterranean containment
barrier be placed around the tanks. This would minimize or prevent future contamination of
soil and groundwater in the event that further tank leakages occur before or during
remediation. Use of interim subterranean barriers can also provide sufficient time to evaluate
and select appropriate remediation alternatives. Portland cement grout curtains have been used
for barriers around waste sites. However, large castings of hydraulic cements invariably result
in cracking due to shrinkage and thermal stresses induced by the hydration reactions. For this
and other reasons improved, low permeability, high integrity materials are being investigated
through the Department of Energy's Office of Technology Development integrated
demonstrations and programs.
 Brookhaven National Laboratory (BNL) has
been involved in several tasks to develop, demonstrate and implement advanced polymer
materials for use in subsurface barriers throughout the DOE complex., The barrier material
must be compatible with soil and waste conditions encountered at the various Department of
Energy (DOE) facilities and have as low an effective diffusivity as is reasonably achievable to
minimize or inhibit transport of moisture and contaminants. The materials being investigated
were selected based on their applicability with conventional placement technologies (e.g., jet
grouting, permeation grouting, trenching) and chemical and physical properties including low
permeability to water, resistance to aggressive chemicals, radiation resistance and tolerance of
an elevated temperature environment. Binders investigated as barrier composites include
polyester styrenes, vinylester styrenes, high molecular weight acrylics, sulfur polymer cement,
polyacrylic acids, bitumen and a furfuryl alcohol based furan polymer.
This project is a multi-year program that initially investigated the
regulatory issues, assumptions, and drivers associated with the use of barriers and advanced
polymer systems around buried waste sites. This task was accomplished from November 1992
to February 1993 and resulted in the issuance of the report
"Regulatory Issues and
Assumptions Associated with Barriers in the Vadose Zone Surrounding Buried Waste".
Sample fabrication and performance testing were completed during
FY93-94. Laboratory testing was completed in FY 1994. Testing included compressive
strength, hydraulic conductivity, splitting tensilestrength, flexural strength 120-day solvent
(TCE) resistance, wet-dry cycling, 120-day acid resistance, rapid chloride diffusivity,
120-day base resistance, and 90-day water immersion. The polymer material has
proven to be durable and has performance values capable of meeting
the needs of subsurface barriers throughout the DOE complex. A final database of
formulations and performance characteristics were compiled in the report
"Laboratory
Evaluation of Performance and Durability of Polymer Grouts for Subsurface
Hydraulic/Diffusion Barriers".
BNL prepared a review of technologies that could be used for barrier
placement and integrity verification in the report
"Subsurface Barrier Verification
Technologies".
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Copyright © 1995 BNL/AUI
Last Modified: November 12, 2009
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Linda Satalino
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