Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

INEEL geoscientist to present NAPL contaminant modeling advance at AGU Meeting

09.12.2002


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:
http://www.inel.gov

More articles from Earth Sciences:

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>