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Emulsified Zero-Valent Iron
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Field Demonstration
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Emulsified Zero-Valent Iron (EZVI) was demonstrated as part of the EPA's Superfund Innovative Technology Evaluation (SITE) Program. The purpose of this demonstration was to evaluate the technical performance and verify the cost of EZVI when applied to dense non-aqueous phase liquids (DNAPLs) in the saturated zone.
The objectives for the SITE demonstration included the following:
- Determine the changes in total trichloroethylene (TCE) and DNAPL mass
- Determine the change in flux of TCE to groundwater from DNAPL source areas
- Determine the changes in aquifer quality due to the applied treatment
- Determine the fate of TCE
- Verify the operating requirements and cost of the technology
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Figure 1: Engineering
Support Building (ESB) at LC34
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Kennedy Space Center's Launch Complex 34, or LC34, was chosen as the location for the SITE demonstration (See Figure 1). Between 1960 to 1968, LC34 was used for NASA's Saturn rocket program. Chlorinated solvents, including TCE, were used to clean rocket engines both inside and outside of the Engineering Support Building (ESB) at the site. As a result, groundwater at LC34 became contaminated with DNAPLs.
Pre-demonstration groundwater and soil sampling events were performed at LC34 to characterize the hydrology and extent of contamination. The pilot test area (PTA) at the site is 9.6 by 15 feet in area with a target depth interval for treatment from 14 to 24 feet below ground surface (Figures 2 and 3). Water levels at the site are approximately 5 feet below ground surface with a relatively flat gradient. TCE mass estimates were based on the pre-demonstration soil sampling events (Figure 4).
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Figure 2: Layout of EZVI Plot at LC34
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Low-flow groundwater samples were taken from the performance monitoring wells. These samples were analyzed for volatile organic compounds
(VOCs), as well as inorganics, alkalinity, biochemical oxygen demand (BOD), and total organic carbon (TOC).
Soil cores were extracted from the subsurface at the site in continuous sections. Soil samples were then collected along the entire length of the cores in two-foot intervals. Collecting large quantities of soil along the entire length of the cores was advantageous because the resulting data provided an understanding of the continuous VOC distribution with depth.
Soil samples were placed directly into pre-weighed, methanol-filled bottles to minimize VOC loss. On-site methanol extraction was then performed to recover VOCs from the soil. Finally, methanol extracts were sent to an off-site analytical laboratory for VOC analysis.
Preliminary test results are presented in the Table below.
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Figure 3: EZVI
Plot at LC34
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Figure 4: TCE Distribution Before Treatment in the EZVI Plot
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