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 Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>