The two north lagoons at LANSCE are the second phase of the Environmental Restoration (ER) Project's work, designed to remove the legacy sludge and clay liner that contain low-level radioisotopes at unacceptable levels.
The contaminants of concern include cobalt-60, cesium-134, and sodium-22 while an organic contaminant of concern includes polychlorinated biphenyls.
Last year the ER project successfully removed 160 cubic yards of contaminated sludge and 60 cubic yards of liner from the south lagoon which had a capacity of 2.6 million gallons.
The two northern lagoons were constructed in 1969 to collect sanitary, radioactive and industrial wastewater from various LANSCE activities as well as septic tank sludge from other Lab activities. They operated until 1993 at which time TA-53 was connected to the TA-46 sanitary wastewater system consolidation.
After characterization data was collected and evaluated from the north lagoons a preliminary risk assessment was performed. "The results revealed that concentrations of the radio nuclides and carcinogenic chemicals within the dried sludge and clay liner surpassed the target amounts. In a risk management decision, the Department of Energy and Lab ER personnel decided to move forward with an accelerated action to remove the contaminated material.
"The decision to do a cleanup was made instead of performing additional assessments to see if the material could be left in place, " said Gabriela Lopez-Escobedo, team leader for the cleanup.
Approximately 2300 cubic yards of sludge and clay liner will be removed from both lagoons over a four-week period in April and May. The fieldwork will be done by a team comprised of Los Alamos Technical Associates, Philip Environmental Services and Science Applications International Corporation.
Because of the presence of radioactive elements, worker safety will be a major emphasis. A stringent safety plan has been developed that includes:
- Those who work inside the lagoon must wear two layers of personal protective equipment, or PPE, such as anti-contamination suits, gloves, booties and hoods.
- Workers will wear respirators initially for protection against the possibility of contaminated dust.
- Workers will wear passive and real-time electronic dosimeters.
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The team sets maximum individual and maximum team cumulative dose limits to limit any exposure.
Dosimeters sound an alarm if an individual receives an unacceptable potential exposure that exceeds safety standards.
When the sludge is scooped from the lagoon it is loaded into roll-off containers that each hold about sixteen cubic yards. The containers are then cleaned at a contamination reduction area after they are filled, then shipped to the Area-G landfill at TA-54. Heavy equipment used in the cleanup also is decontaminated.
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