Reduce Natural and Artificial Recharge
Infiltration of water to the vadose zone provides the driving force for downward migration of contaminants
in the vadose zone at the Hanford Site. Water in the vadose zone may come from such things as natural
precipitation, wastewater disposed to cribs, leaks from tanks, leaking water lines, septic tanks, or
drain fields.
Efforts to reduce recharge started in earnest in 1987, as plans were developed to discontinue disposal
of liquid waste streams to the soil. Over the next two years, the number of liquid waste streams was
drastically reduced, and waste streams containing radioactive contaminants were routed through the 200
Area treatment facility in compliance with the Tri-Party Agreement milestone M-17. These actions
have eliminated the disposal of unpermitted wastewater on the Central Plateau. The focus of baseline
and accelerated actions are on eliminating the inadvertent and natural recharge to further protect
Hanford's groundwater.
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Actions to reduce natural and artificial recharge were completed during fiscal year
2001 for 200 West Area tank farms. Actions for 200 East Area tank farms were completed
in 2002. The installation of prototype surface barriers to stabilize tank farm
surfaces is being considered for 2004.
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In 1998, DOE's Office of River Protection initiated a program to reduce natural and artificial recharge
in and around tank farms to reduce the potential for contaminants in the vadose zone to be carried to
groundwater. The program has four major components:
Design and construct surface water run-on control measures upgradient of single-shell tank farms Abandon leaking pressurized water lines adjacent to single-shell tank farms Upgrade monitoring drywells at single-shell tanks to include leak tight caps Install surface cover for stabilization purposes
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