Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


INEEL geoscientist to present NAPL contaminant modeling advance at AGU Meeting


DOE News Release Embargoed for release December 6, 2002 INEEL geoscientist to present NAPL contaminant modeling advance at AGU Meeting By modifying the mathematical theory describing the relationship between permeability, saturation, and pressure in a multiple fluid system, researchers can now more accurately predict the movement of non-aqueous phase liquid (NAPL) contaminants in the subsurface. New calculations account for residual NAPL that remains in the vadose zone-forming a long-term source for groundwater contamination, and also explain how part of this residue can be flushed into groundwater during rainstorms or flooding.

This research, funded through U.S. Department of Energy’s Idaho National Engineering and Environmental Laboratory’s Subsurface Science Initiative (SSI), supports the DOE’s mission in environmental science.

Hydrologist Robert Lenhard of the INEEL, has resolved a critical contamination modeling problem by refining current constitutive theory - theory describing relations among fluid relative permeabilities, saturations, and pressures. His new model predicts the distribution of residual NAPL based on the prior fluid wetting and drying cycles in the subsurface. Lenhard will present his work at the American Geophysical Union meeting in San Francisco, CA, on December 8, 2002 during the Hydrology session.

"If you run existing multiphase flow models long enough, the results show that NAPL will completely drain from a vadose zone, which is contrary to field and experimental observations" said Lenhard. Better constitutive theory is needed for developing accurate computer models. "The lack of well-founded constitutive theory may be the foremost element impeding the development of accurate predictive multiphase flow models," he adds.

Lenhard’s modeling advance represents a shift in researchers’ conceptual understanding of NAPL behavior by recognizing that some NAPL becomes immobilized in pore spaces or as thin films on soil solids. Nowadays, subsurface contamination by NAPLs is almost ubiquitous. As a result of DOE’s efforts to develop, test, manufacture, and maintain nuclear weapons for national security purposes, the DOE has very complex contamination problems with NAPLs that are denser than water. Additionally, an estimated 60 percent of Superfund (DOE, industrial and municipal) sites have NAPL contamination.

Lenhard and colleagues conducted pilot-scale (mesoscale) experiments in the laboratory to study how NAPLs behave under different conditions. NAPLs can move through the vadose zone as liquid, vapor, or carried along as dissolved droplets within a moving stream of water. His experiments indicate that residual NAPL will generate pulses of contamination during heavy rainstorms or flooding, especially at arid sites. A better understanding of how residual NAPLs contribute to contamination could influence environmental remediation choices.

Most NAPLs, such as fuels and degreasing solvents, are petroleum based. Predicting the movement of NAPLs in the subsurface is challenging because NAPLs can be either lighter or heavier than water and don’t mix with water. Light NAPLs accumulate above the water table, and can depress the water-saturated region. Heavy or dense NAPLs sink below the water table and are very difficult to locate and clean up.

In order to predict the subsurface movement of multiple fluids, it is very important to know how the fluids are distributed throughout the pore spaces. The sizes of the pores containing the fluids will affect how rapidly these fluids can move downward to groundwater. If the fluids contain compounds harmful to humans and the environment, then by knowing how fast and in what quantities these compounds will reach the groundwater, effective remediation strategies can be developed using computer modeling. Lenhard has spent much of his career developing new techniques for measuring subsurface NAPL behavior and developing mathematical models for describing multi-fluid flow constitutive theory, which is needed to predict the flow behavior of multiple fluids in porous media. He is a leader in multiphse flow constitutive theory and his models are used worldwide by many scientists to predict air-NAPL-water flow behavior.

Martinus Oostrum of the DOE’s Pacific Northwest National Laboratory, who has worked with Lenhard, plans to use Lenhard’s new methodology to enhance the accuracy of the STOMP model- a numerical computer program for predicting Subsurface Transport Over Multiple Phases (STOMP). It is expected that the improved computer model will be used to help address NAPL contamination at DOE sites. Lenhard is also interested in employing his constitutive models in other multiphase flow

Deborah Hill | INEEL
Further information:

More articles from Earth Sciences:

nachricht UCI and NASA document accelerated glacier melting in West Antarctica
26.10.2016 | University of California - Irvine

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>