Experimental investigation of LNAPL transport in the vadose zone: Comparison with the hydrocarbon spill screening model

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:569947

Simpson, M M ^[1]; Willson, C S ^[2]; Weaver, J W ^[3]; Charbeneau, R J ^[4]

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1. Roy F. Weston, Inc., Austin, TX (United States)
2. Univ. of North Carolina, Chapel Hill, NC (United States)
3. Environmental Protection Agency, Athens, GA (United States)
4. Univ. of Texas, Austin, TX (United States)

The Hydrocarbon Spill Screening Model (HSSM), released in April 1994 by the United States Environmental Protection Agency (USEPA) in conjunction with the University of Texas at Austin (UT Austin), simulates subsurface releases of petroleum hydrocarbons, or light nonaqueous phase liquids (LNAPLs). HSSM simulates petroleum hydrocarbon constituent concentrations at downgradient receptor locations and estimates the effects of groundwater velocities, hydrocarbon loadings, chemical and porous media properties, etc. on contaminant transport and downgradient concentrations. The hydrocarbon release is conceptualized as consisting of vertical LNAPL migration through the vadose zone, formation and radial spreading of the oil lens through the capillary fringe, and transport of a chemical constituent within the aquifer. Separate component models within HSSM address each of these processes. Two-dimensional (2-D) multi-phase flow experiments were conducted to investigate hydrocarbon flow in the vadose zone and support work on the development of Version 2.0 of HSSM. The experiments physically modeled vertical transport of the hydrocarbon from near the surface to the capillary fringe and lateral spreading of the hydrocarbon lens through the capillary fringe. Comparisons between the Kinematic Oily Pollutant Transport (KOPT) model, the vadose zone component of HSSM, and observations from the 2-D experiments indicate that the one-dimensional (1-D) assumption used in the KOPT derivation is conservative. For comparison with the laboratory experiments, a 2-D analogue of the radial flow, capillary fringe portion of HSSM was derived so that the dimensionality of the experiments matched that of the model. The significance of vertical permeability heterogeneities on hydrocarbon vadose zone transport and the effect of water table elevation fluctuations on oil lens development and trapping of free product in the saturated zone were investigated in the 2-D experiments as well.

• OSTI ID: 569947
• Report Number(s): CONF-971116--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
99 GENERAL AND MISCELLANEOUS
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
FLOW MODELS
GROUND WATER
H CODES
HYDROCARBONS
K CODES
NONAQUEOUS SOLVENTS
REMEDIAL ACTION