Maps produced from a JPL-developed airborne sensor are cutting costs and helping to speed the hazardous waste clean-up at a Superfund site in Leadville, Colo.
Several federal agencies, including the Bureau of Reclamation, the Environmental Protection Agency and the U.S. Geological Survey (USGS), are using the maps to find sources of acid mine drainage and heavy-metal contamination at the California Gulch Superfund Site. The contamination is the result of more than 130 years of historic mining activities associated with the Leadville Mining District, according to Felix W. Cook Sr., director of the Technical Service Center at the Bureau of Reclamation in Denver.
The maps were produced by the USGS using data from NASA's Airborne Visible and Infra-Red Imaging Spectrometer (AVIRIS), which was developed and is managed by the Jet Propulsion Laboratory. The AVIRIS instrument flies aboard a NASA ER-2 airplane, which is a U2 spy plane that has been modified for civillian use.
While being carried 20 kilometers (12 miles) above sea level at speed of 730 kilometers per hour (450 mph), the instrument can take approximately 7,000 measurements per second. Earth scientists use AVIRIS to make measurements related to global climate change research in geology, oceanography, snow hydrology and cloud and atmospheric studies.
"This technique of imaging spectroscopy represents a fundamental new way of doing remote-sensing. We are measuring in detail how light is absorbed or reflected by various materials on the Earth's surface and that gives us an accurate picture of what those materials on the ground are made of. Once we know where the materials are, we can begin to make decisions based on those maps," said Robert Green, the AVIRIS experiment scientist at JPL.
"The imaging spectroscopy mineral mapping has allowed us to identify potential contaminating sources as small as individual mine dumps for evaluation," said Cook. "Based on our recent experience, Reclamation anticipates that the future for hazardous clean-up at many locations, especially large sites, throughout the United States should use AVIRIS to produce relatively inexpensive site thematic maps to aid in remediation."
An analysis program that recognizes the spectral signature of the contaminants on the ground has been developed by the USGS to construct the mineral map from the AVIRIS data. "AVIRIS data are like a treasure chest of scripts in an unknown language -- totally unreadable to the untrained observer," said Gregg Swayze, a geophysicist at the USGS. "The imaging analysis program is like a Rosetta stone, a key to that language, by which the AVIRIS data can be interpreted and profited from."
The mineral maps have helped officials save roughly $500,000 and about a year's time in identifying the areas that need attention.
"NASA's AVIRIS program has, therefore, enabled more money to be used for actually cleaning up the hazardous mine waste materials currently contaminating this site," Cook said. "In addition, the speed with which the AVIRIS data can be processed, mapped, and integrated into our system has enabled us to complete the site data development and analysis process about a year ahead of schedule, saving additional money and time."
Reclamation officials believe the AVIRIS data mineral mapping could be used for site investigations on many of the hazardous waste sites now included on the Environmental Protection Agency's National Priorities List.
The AVIRIS program is managed by JPL for NASA's Office of Mission to Planet Earth, Washington, D.C. The Mission to Planet Earth is a long-term, coordinated program to study the Earth's air, water, land and life as a global environmental system.
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