Crosshole shear-wave seismic monitoring of an in situ air stripping waste remediation process
Crosshole shear-wave seismic surveys have been used to monitor the distribution of injected air in the subsurface during an in situ air stripping waste remediation project at the Savannah River site in South Carolina. To remove the contaminant, in this case TCE`s from a leaking sewer line, two horizontal wells were drilled at depths of 20 m and 52 m. Air was pumped into the lower well and a vacuum was applied to the upper well to extract the injected air. As the air passed through the subsurface, TCE`s were dissolved into the gas and brought out the extraction well. Monitoring of the air injection by crosshole shear wave seismics is feasible due to the changes in soil saturation during injection resulting in a corresponding change in seismic velocities. Using a downhole shear-wave source and clamped downhole receiver, two sets of shear-wave data were taken. The first data were taken before the start of air injection, and the second taken during. The difference in travel times between the two data sets were tomographically inverted to obtain velocity differences. Velocity changes ranging up to 3% were mapped corresponding to saturation changes up to 24%. The distribution of these changes shows a desaturation around the position of the injection well with a plume extending in the direction of the extraction well. Layers with higher clay content show distinctively less change in saturation than the regions with higher sand content.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10125877
- Report Number(s):
- SAND-91-2742; ON: DE92008974
- Resource Relation:
- Other Information: PBD: Feb 1992
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
WELLS
SEISMIC SURVEYS
AIR INFILTRATION
MONITORING
ORGANIC CHLORINE COMPOUNDS
REMOVAL
SEISMIC DETECTION
REMEDIAL ACTION
SAVANNAH RIVER PLANT
EXTRACTION
SEISMIC S WAVES
SOILS
SEISMIC DETECTORS
SOIL-STRUCTURE INTERACTIONS
SATURATION
MATHEMATICAL MODELS
CONTAMINATION
TOMOGRAPHY
VELOCITY
540250
540220
580000
054000
SITE RESOURCE AND USE STUDIES
CHEMICALS MONITORING AND TRANSPORT
GEOSCIENCES
HEALTH AND SAFETY