Demonstration of Steam Injection as an Enhanced Source Removal Technology for Aquifer Restoration
Technical rept. 1 Apr 95-31 Oct 97
APPLIED RESEARCH ASSOCIATES INC SOUTH ROYALTON VT NEW ENGLAND DIV
Pagination or Media Count:
Steam injection combined with groundwater pumping and soil vapor extraction was demonstrated at Operable Unit One OU-1, Hill AFB, Utah. The purposes of the research were to increase understanding of the technology and evaluate its effectiveness for cleanup of non-aqueous phase liquids NAPLs. The results will be included in an evaluation of various technologies for potential inclusion in the OU-1 Record of Decision. Applied Research Associates, Inc. and Praxis Environmental Technologies, Inc. teamed to conduct the experiments in a 3-by-5 meter cell enclosed by steel sheet-pile walls extending into a low permeability clay layer located about 9.1 meters 30 feet below ground surface. Constituents of the NAPL were primarily weathered fuels and oils with chlorinated solvents. Results of the steam injection test reveal very effective distillation of contaminants from the residual NAPL. Compounds of concern showed reductions in soil concentrations greater than 95 in steam-swept layers. The final groundwater concentrations in the test cell were close to cleanup levels with only two target compounds exceeding the drinking water standard. As predicted by theory, the heavy NAPL was not effectively mobilized by the steam because of its high viscosity and low residual saturation yet the low residual saturation allowed good contact between the steam and NAPL for distillation. Estimates of the masses removed based on extracted concentrations were consistent with mass changes in the cell based on soil concentrations. An estimated total of 55 liters 14.5 gallons of NAPL were removed from the cell. This study also employed an innovative technique known as a partitioning inter-well tracer test PITT to estimate the mass and spatial distribution of residual NAPL before and after the steam injection.
- Solid Wastes and Pollution and Control
- Water Pollution and Control