Date of Award

12-2006

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Environmental Engineering and Science

Advisor

Falta, Ronald W

Abstract

Steam flooding is an aggressive remediation technology for removing volatile organic chemical (VOC) sources that slowly dissolve into passing groundwater. Plume concentrations can be reduced, accelerating cleanup, and decreasing plume management costs. Steam injected in wells surrounding the source spreads outward and develops into a front that drives contamination to a system of groundwater pumping wells in the saturated zone and soil vapor extraction wells in the vadose zone. The process can be modeled with the non-isothermal multi-phase flow simulator T2VOC to include operation designs and factors at individual sites.
A pilot field-scale test at the Savannah River Site (SRS) solvent storage tank area (SST) performed in 2000 to 2001 demonstrated the feasibility of steam flooding and modeling in the sediments at SRS for the upcoming M-Area settling basin flood. The comparison of actual and simulated heating patterns of the SST flood confirm that numerical simulation is a viable tool for designing, planning, and evaluating steam floods.
Steam movement in the subsurface is governed primarily by soil heterogeneity and gravity. Steam is buoyant in groundwater and tends to migrate upward unless injected below a continuous confining layer. Extraction rates (pumping and vacuums) typical of steam flooding are generally low compared to steam injection rates and pressures, and have limited influence over the lateral growth of the steam zone. Steam
can be controlled with air injection wells that limit steam migration away from the target, preventing mobilization of contamination outside the steam injection pattern and preventing steam from migrating to undesirable areas. The concept was proven with sand tank experiments and by a flood at a Hill Air Force Base demonstration site in 1997 (Stewart et al., 1998). Models of the planned steam flood of the M-Area settling basin incorporate design configurations with and without air control. Simulations show that the method can be used to keep steam from escaping to the surface for floods of shallow targets in un-stratified sediments. Configurations can be designed that balance vertical control, improve heat spread in the target zone, and minimize heat loss.

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