RELEASE NO. 00-65
|For Release: August 31, 2000|
TONS OF SEDIMENT REMOVED
NASA Langley Research Center in Hampton, Va., has completed the cleanup of a creek singled out as contaminated by the U.S. Environmental Protection Agency
The creek, which is a tributary of the Back River, had been contaminated by the release of PCBs (Polychlorinated Biphenyls) and PCTs (Polychlorinated Terphenyls) from the 1950s to the 1970s.
Before the cleanup technicians measured contamination levels in parts of Tabbs Creek as high as 2,260 parts per million. Now those levels register at less than five parts per million, well below what the EPA requires for the protection of human health and the environment.
"We worked hard to plan and execute this cleanup," said Greg Sullivan, Remedial Project Manager for the Office of Security and Environmental Management at NASA Langley. "We finished the project on time and substantially under budget." Originally estimated to cost nearly $8 million, the Tabbs Creek project was completed at a cost of $5.5 million.
NASA worked with the EPA and the Virginia Department of Environmental Quality to formulate the cleanup plan. "NASA has demonstrated its commitment to cleaning up Tabbs Creek, adhering to a carefully developed plan. From what we have seen, the results are excellent," said Stacie Driscoll, Hazardous Site Cleanup Division Project Manager for EPA Region III.
NASA hired Foster Wheeler Environmental Corporation, a nationwide environmental and remedial cleanup company that has worked with NASA Langley for nearly a decade, to do the dirty work.
The project presented some unique challenges. Crews had to remove contaminated mud while protecting existing wetlands. During excavation the wetlands were protected by a "silt curtain," a screened fabric that allowed water to pass through, but stopped sediment and suspended particles from flowing from one cell to another.
Excavated sediment was taken to a soil handling area, where it was dried and, when necessary, stabilized with quick lime. Approximately 9300 tons of sediment, with PCB/PCT contaminant levels below 50 parts per million, were taken to the Southeastern Public Service Authority Public Landfill in Suffolk, Va., and the Bethel Landfill in Hampton, Va. Another 2000 tons of sediment, with levels above 50 parts per million, were taken to the Chemical Waste Management Landfill in Model City, NY.
After the cleanup workers restored the wetlands. "We did more than remediation - we enhanced the site," said NASAs Sullivan. "The area is now completely green. The wetlands look better than ever."
Crews removed piles of concrete rubble and "undesirable vegetation" called phragmite, a tall swamp grass-like plant that has grown unchecked in many areas of the country. In addition, workers lowered the elevation in a three-and-a-half acre area of the wetlands to encourage the movement of more salt water, which discourages phragmite growth. They also planted shrubs and seeded uplands.
Since 1992, hundreds of samples of sediment, surface water and animal tissue have been taken from Tabbs Creek. During the cleanup process, technicians removed 190 "pre-remedial" samples of sediment to further refine the excavation limits. Another 200 "confirmatory samples" were also taken to ensure that the contaminants had been reduced to required cleanup levels. Now that the cleanup is over, the creek and wetlands will be monitored on a regular basis. Samples from fish, crabs and other indigenous animals will be taken every six months.
Foster Wheeler has issued a draft final report documenting the work done and has sent it to NASA Langley for review. Langley expects the EPA will okay the cleanups completion by early September.
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