Refined conceptual model for the Volatile Organic Compounds-Arid Integrated Demonstration and 200 West Area Carbon Tetrachloride Expedited Response Action

Last, George V; Rohay, V.J.

doi:10.2172/10151709

Cited by 21 publications

(38 citation statements)

References 9 publications

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“…Each of the sedimentary sequences overlying the Saddle Mountains Formation can be further subdivided into a number of lithofacies or subunits. Table 3.3 (modified from Oostrom et al 2004 andRohay 1993) illustrates the dominant grain size, calcium carbonate content, and gross gamma activity for the principal sedimentary sequences and lithofacies overlying the basalt bedrock.…”

Section: Geologic Framework Beneath the 216-z-1a And 216-z-18 Facilitiesmentioning

confidence: 99%

“…For each simulation, the maximum DNAPL penetration depth was recorded. 1966, 1968, 1970, 1974, 1984, and 1993 reflect the change in disposal location within the 216-Z-1A site as the DNAPL body is getting larger in a southerly direction with time. In 1970, DNAPL has moved into the Lower Sand unit but not yet into the CCU.…”

Section: Undocumented Discharge Simulationsmentioning

confidence: 99%

“…After 1974 no aqueous phase or DNAPL were disposed at either site. The CT gas concentrations in 1970, 1974, 1984, and 1993, respectively. The figures show that the gas plume grows rapidly and spreads out over the lowerpermeability CCU and later in time over the water table.…”

Section: Undocumented Discharge Simulationsmentioning

confidence: 99%

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Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-18 Crib and 216-Z-1A Tile Field at the Hanford Site: Multifluid Flow Simulations and Conceptual Model Update

Oostrom¹,

Rockhold²,

Thorne³

et al. 2006

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Three-dimensional modeling was conducted with layered models to further develop the conceptual model of CT distribution in the vertical and lateral direction beneath the 216-Z-1A tile field and 216-Z-18 cribs and to investigate the effects of soil vapor extraction (SVE). Base case and sensitivity analysis simulations considered migration of dense, nonaqueous phase liquid (DNAPL) consisting of CT and co-disposed organics in the subsurface beneath the two disposal sites as a function of the properties and distribution of subsurface sediments and of the properties and disposal history of the waste. Simulations of CT migration were conducted using the Subsurface Transport Over Multiple Phases (STOMP) simulator.Simulation results support a conceptual model for CT distribution where CT in the DNAPL phase is expected to have migrated primarily in a vertical direction below the disposal trench. None of the simulations predicted that CT in the DNAPL phase would move across the water table below the 216-Z-18 site. Movement of CT in the DNAPL phase across the water table below the 216-Z-1A site was only predicted in simulations with smaller disposal areas and larger volumes, compared to the base case simulation, and in isotropic porous media. Because uncertainties in disposal area and volume exist, movement of CT in the DNAPL phase across the water table in the subsurface below the 216-Z-1A site should be considered as a possibility. However, even if DNAPL moved across the water table in the past, there may not currently be a DNAPL phase in the groundwater beneath the 216-Z-1A site because of dissolution. Results also show that the Hanford 1a geologic unit, located just beneath the 216-Z-1A and 216-Z18 disposal areas, retains more CT DNAPL within the vadose zone during infiltration and redistribution than other hydrologic units. During simulated SVE operations, CT in this unit remained in the subsurface while DNAPL in other layers was effectively removed. Additional characterization of the Hanford 1a unit below the two disposal sites would provide valuable information about the quantity of DNAPL phase CT remaining in the vadose zone. A significant amount of the disposed CT DNAPL may have partitioned to the vapor phase and subsequently into water and sorbed phases. As for the 216-Z-9 site, it is predicted that any continued migration of CT from the vadose zone to the groundwater is likely to occur through interaction of vapor phase CT with the groundwater and not through continued DNAPL migration. The results indicated that SVE appears to be an effective technology for vadose zone remediation, but additional effort is needed to improve simulation of the SVE process through an enhanced understanding of rate-limited volatilization. A total of 34 three-dimensional simulations have been conducted based on a layered EarthVision™ geologic model, which is an interpretation of available geologic data. These simulations consist of one base case simulation and 33 sensitivity analysis simulations. These simulations examined the infilt...

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Section: Geologic Framework Beneath the 216-z-1a And 216-z-18 Facilitiesmentioning

confidence: 99%

Section: Undocumented Discharge Simulationsmentioning

confidence: 99%

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Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-18 Crib and 216-Z-1A Tile Field at the Hanford Site: Multifluid Flow Simulations and Conceptual Model Update

Oostrom¹,

Rockhold²,

Thorne³

et al. 2006

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“…Rohay et al (1994) speculated that groundwater in this perched horizon was of recent origin, based on infiltration calculations by Wright et al (1994). Last and Rohay (1993) predicted, based on modeling of the 216-2-21 Pond discharges, that infiltrating moisture from past-practice facilities in this area would spread a maximum of -62 m (203 ft).…”

Section: -3mentioning

confidence: 99%

Potential effects of low-volume effluent discharges on past-practice vadose zone contamination

Barnett¹

1996

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“…We also created two binary mixtures (MIX5 and MIX6) to investigate the effects of lard oil (LO) and dibutyl-butyl phosphonate (DBBP) on carbon tetrachloride (CT) separately. The compounds used to create MIX1-4 are based on reports that list major NAPL (Rohay et al, 1994) and wastewater (Last and Rohay, 1993) components at the Hanford site. The major NAPL components of all mixtures (including two binary mixtures) are listed in Table 2; the major wastewater components are listed in Table 3.…”

mentioning

confidence: 99%

Influence of Wetting and Mass Transfer Properties of Organic Chemical Mixtures in Vadose Zone Materials on Groundwater Contamination by Nonaqueous Phase Liquids

Werth¹,

Valocchi²

2011

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Objectives:Previous studies have found that organic acids, organic bases, and detergent-like chemicals change surface wettability. The wastewater and NAPL mixtures discharged at the Hanford site contain such chemicals, and their proportions likely change over time due to reaction-facilitated aging. The specific objectives of this work were to 1) determine the effect of organic chemical mixtures on surface wettability, 2) determine the effect of organic chemical mixtures on CCl4 volatilization rates from NAPL, and 3) accurately determine the migration, entrapment, and volatilization of organic chemical mixtures. Tasks:Five tasks were proposed to achieve the project objectives. These are to 1) prepare representative batches of fresh and aged NAPL-wastewater mixtures, 2) to measure interfacial tension, contact angle, and capillary pressure-saturation profiles for the same mixtures, 3) to measure interphase mass transfer rates for the same mixtures using micromodels, 4) to measure multiphase flow and interphase mass transfer in large flow cell experiments, all using the same mixtures, and 5) to modify the multiphase flow simulator STOMP in order to account for updated P-S and interphase mass transfer relationships, and to simulate the impact of CCl4 in the vadoze zone on groundwater contamination.

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Refined conceptual model for the Volatile Organic Compounds-Arid Integrated Demonstration and 200 West Area Carbon Tetrachloride Expedited Response Action

Cited by 21 publications

References 9 publications

Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-18 Crib and 216-Z-1A Tile Field at the Hanford Site: Multifluid Flow Simulations and Conceptual Model Update

Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-18 Crib and 216-Z-1A Tile Field at the Hanford Site: Multifluid Flow Simulations and Conceptual Model Update

Potential effects of low-volume effluent discharges on past-practice vadose zone contamination

Influence of Wetting and Mass Transfer Properties of Organic Chemical Mixtures in Vadose Zone Materials on Groundwater Contamination by Nonaqueous Phase Liquids

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