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Low-level Waste Safely Dispositioned Under Runoff Cover at SRS

April 26, 2011 - 12:00pm

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The liner installer heat-welds a sand anchor closed. The sand anchors are installed under the liner and across the length of the slit trench to keep the liner in place and minimize the effects of wind lift.

The liner installer heat-welds a sand anchor closed. The sand anchors are installed under the liner and across the length of the slit trench to keep the liner in place and minimize the effects of wind lift.

A view of the Slit Trenches 1-4 operational cover in E Area.

A view of the Slit Trenches 1-4 operational cover in E Area.

The liner installer heat-welds a sand anchor closed. The sand anchors are installed under the liner and across the length of the slit trench to keep the liner in place and minimize the effects of wind lift.
A view of the Slit Trenches 1-4 operational cover in E Area.

AIKEN, S.C. – A $3.5-million American Recovery and Reinvestment Act project at the Savannah River Site (SRS) has placed an operational stormwater runoff cover over the 625,000-square-foot area comprising E-Area Low-Level Waste (LLW) Facility Slit Trench Disposal Units 1-4. The cover was installed as an interim remedial action and will enhance the protection of human health and the environment.

"The operational cover ensures our compliance with requirements to protect the environment and the public, and adheres to our agreements with the regulatory agencies," said Dr. David Moody, manager, U.S. Department of Energy (DOE)-Savannah River Operations Office.

Typically, the slit trench disposal units are below-grade earthen disposal units that are used to dispose of low-level radioactive waste such as construction debris, concrete from reactor demolition and clean-up from jobs involving legacy waste at SRS.

The newly installed operational stormwater runoff cover is a 30-millimeter-thick impermeable geomembrane, made of a polypropylene base material with ultraviolet protective additives. The material has a high-tear and puncture value, which significantly reduces the amount of rainwater that filters through the ground, reaching the low-level waste, thus enhancing the protection of the groundwater. Walkways span across the cover to allow quarterly access to lysimeters and monitoring wells that are part of the environmental monitoring program for the E-Area LLW Facility. A 2,800-foot-long by 9-foot-wide concrete channel anchors the outer edge of the cover and directs rainwater runoff to two stormwater outfalls.

The cover was put in place in early March as an interim measure through a Recovery Act contract awarded to Panegea-Brinkman of St. Louis, Mo. The company hired two subtier contractors and 25 members of local unions to perform the work and rented equipment from local suppliers.

Operations continue at the E-Area LLW Facility to accept low-level radioactive waste from cleanup activities and operations at SRS. The Site has eight slit trench disposal units; five of these have operational covers. SRS will determine at a later date how many additional slit trenches will be built.

“As other slit trench disposal units become operationally filled, similar stormwater runoff covers will be put into place to enhance protection and adhere to the agreements with the regulatory agencies,” explained John Gilmour, director of Solid Waste Management, Savannah River Nuclear Solutions (SRNS). “Final closure of the slit trench disposal units will take place at a later date with the final closure of the entire E-Area LLW Facility.”

“The recent completion of the runoff cover system for Slit Trenches 1-4 is an important milestone at the E-Area Low-Level Waste Facility and for the Recovery Act,” said Paul Hunt, vice president of the Recovery Act portfolio for SRNS. “With the operational cover in place and quarterly monitoring, we are assured that the lowlevel waste is in safe final disposition.”

Additional information on the Department of Energy’s Office of Environmental Management and the Savannah River Site can be found at
http://www.em.doe.gov or http://www.srs.gov. For more information about the SRS Recovery Act Project, visit www.srs.gov/recovery.

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