02-31007. National Nuclear Security Administration, Office of Los Alamos Site Operations; Notice of Floodplain Involvement for the Proposed Installation of a Permeable Reactive Barrier Within Mortandad Canyon at Los Alamos National Laboratory, Los ...

AGENCY:

Department of Energy, National Nuclear Security Administration, Los Alamos Site Office.

ACTION:

Notice of floodplain involvement.

SUMMARY:

The Department of Energy (DOE), National Nuclear Security Administration (NNSA) Office of Los Alamos Site Operations plans to construct a multiple permeable reactive barrier within Mortandad Canyon at Los Alamos National Laboratory (LANL). The permeable reactive barrier (PRB) would be located within a floodplain area for the purpose of reducing the contaminant load within shallow groundwater. The PRB would be operated for about five years as a site-specific technology demonstration project. The site chosen for the PRB is in the central portion of LANL. In accordance with 10 CFR part 1022, DOE has prepared a floodplain/wetland assessment and will perform this proposed action in a manner so as to avoid or minimize potential harm to or within the affected floodplain.

DATES:

Comments are due to the address below no later than December 24, 2002.

ADDRESSES:

Written comments should be addressed to: Elizabeth Withers, Department of Energy, National Nuclear Security Administration, Office of Los Alamos Site Operations, 528 35th Street, Los Alamos, NM 87544, or submit them to the Mail Room at the above address between the hours of 8 a.m. and 4:30 p.m., Monday through Friday. Written comments may also be sent electronically to: [e-mail] or by facsimile to [phone].

FOR FURTHER INFORMATION CONTACT:

Everett Trollinger, Department of Energy, National Nuclear Security Administration, Office of Los Alamos Site Operations, 528 35th Street, Los Alamos, NM 87544. Telephone [phone], facsimile [phone].

For Further Information on General DOE Floodplain Environmental Review Requirements, contact: Carol M. Borgstrom, Director, Office of NEPA Policy and Compliance, EH-42, Department of Energy, 1000 Independence Avenue, SW., Washington, DC 20585-0119. Telephone [phone] or [phone], facsimile [phone].

SUPPLEMENTARY INFORMATION:

In November 2002, NNSA considered a proposal for constructing a PRB system at a narrow constriction in Mortandad Canyon within LANL where contaminated groundwater is confined to a small cross-section of alluvial materials. The entire PRB structure would extend about 120 feet from side-wall to side-wall within the canyon bottom. The PRB would consist of a “funnel and gate” system to direct contaminated groundwater into a centrally-located gate area of reactive materials. The impermeable funnel would be constructed of sheet piling driven to a depth of approximately 27 feet on either side of the canyon. The permeable gate would contain multiple buried cells of selected media designed to react with and reduce the concentration of contaminants in groundwater passing through the gate. The PRB would be left in place for about five years and its function would be monitored through a system of shallow monitoring wells that would be installed at the same time the PRB was constructed. Construction of the PRB and associated monitoring wells will commence in 2003 and be completed in less than 6 months.

In accordance with DOE regulations for compliance with floodplain and wetlands environmental review requirements (10 CFR part 1022), NNSA has prepared a floodplain/wetland assessment for this action, which is available by contacting Elizabeth Withers at the previously identified addresses, phone and facsimile numbers. The floodplain/wetland assessment is available for review at the DOE Reading Room at the Los Alamos Outreach Center, 1619 Central Avenue, Los Alamos, NM 878544; and the DOE Reading Room at the Zimmerman Library, University of New Mexico, Albuquerque, NM 87131. The NNSA will publish a floodplain statement of findings for this project in the Federal Register no sooner than December 24, 2002.

Issued in Los Alamos on November 26, 2002.

Ralph E. Erickson,

Director, U.S. Department of Energy, National Nuclear Security Administration, Office of Los Alamos Site Operations.