What We Are Doing
Vadose Zone
The WRPS Tank Farms Vadose Zone Project was established to understand the contamination in the soil beneath Hanford’s underground waste storage tanks so action can be taken to protect public health and the environment. The storage tanks hold 53 million gallons of radioactive and chemical waste. The soil contamination is the result of earlier leaks from as many as 67 older single-shell tanks, as well as discharges to the soil from past site operations. The project focuses on contaminants in the vadose zone, which is the area of soil between the ground’s surface and the water table. Information gained from the project will be integrated with data from other groundwater/vadose projects at the site, providing greater understanding of the site’s subsurface contamination.
Major activities are Planning, Characterization, Inventory of Released Materials, Risk Assessments, and Interim Measures.
Overview of Phase 1: RCRA Facility Investigation Report for Hanford Single-Shell Tank Waste Management Areas (DOE/ORP-2008-01, Rev. 1). This very large report, organized in 3 tiers (or volumes) describes the activities of the Program for its first 10 years. Tier 1 is oriented toward the general public. Tier 2 provides technical information, while Tier 3 contains key documents issued by the Program or that are needed by the Program.
These documents describe what and how we will perform the Phase 2 activities.
Phase 2 RCRA Facility Investigation/Corrective Measures Study Master Work Plan for Single-Shell Tank Waste Management Areas (RPP-PLAN-37243)
RCRA Facility Investigation/Corrective Measures Study Work Plan for Waste Management Area C. RPP-PLAN-39114
Science Road Map For Phase 2 of the Tank Farm Vadose Zone Program (RPP-PLAN-38191)
These documents describe the results of the Phase 2 characterization activities including Surface Geophysical Exploration (SGE), direct push logging and sampling, and gamma logging.
Surface Geophysical Exploration (SGE): This volumetric technique analyzes the vadose zone for changes in electrical resistivity, which because of the high salt content of much of the released tank waste, indicates potentially contaminated areas. Results since the publication of the RFI Report can be found in:
Surface Geophysical Exploration of UPR 200-E-81 near the C Tank Farm (RPP-RPT-41236)
Surface Geophysical Exploration of the S and SX Tank Farms at the Hanford Site (RPP-RPT-38322)
Surface Geophysical Exploration of the TX and TY Tank Farms at the Hanford Site (RPP-RPT-38320)
Direct Push Logging and Sampling: Direct push technology (pushing rods into the ground) can allow gamma and moisture logging and the acquisition of samples that can be analyzed in the laboratory. Reports since the publication of the RFI Report can be found in:
Completion Report for TY Single-Shell Tanks Direct Push Barrier Investigation, RPP-RPT-41100
Summary of Direct Push Exploration at 241-C-152 Diversion Box In 241-C Tank Farm, RPP-32130
Completion Report for U Tank Farm Hydraulic Rotary Hammer Direct Push Drilling, Probe Installation and Sampling, RPP-35968
Characterization of Vadose Zone Sediments Below the C Tank Farm: Borehole C4297 and RCRA Borehole 299-E27-22, PNNL-15503 Rev. 1
Characterization of Vadose Zone Sediments from C Waste Management Area: Investigation of the C-152 Transfer Line Leak, PNNL-15617 Rev. 1
Gamma Logging: Gamma-emitting radionuclides can be detected by their radiation. Each of the drywells in the tank farms has been logged. Please see the web site Tank Farm Borehole Geophysical Logging Data for the results.
These documents describe the process and the results for estimating the inventory of released tank farm releases to the soil. Earlier efforts are described in the RFI.
Process to Assess Tank Farm Leaks in Support of Retrieval and Closure Planning (RPP-32681)
Hanford A and AX-Farm Leak Assessments Report: 241-A-103, 241-A-104, 241-A-105, 241 AX-102, 241-AX-104 and Unplanned Waste Releases (RPP-ENV-37956)
Tank Farm Vadose Zone Contamination Volume Estimates, RPP-23405, Rev. 3
These documents estimate future impacts from tank farm releases. Field-specific risk assessments are included in Field Investigation Reports, which are included in the RFI.
Initial Single-Shell Tank System Performance Assessment (DOE/ORP-2005-001)
The U.S. Department of Energy and the Washington State Depart of Ecology are hosting a series of working sessions designed to create a performance assessment for Waste Management Area C. More information can be obtained from the Office of River Protection web site.
These documents describe the planning, design, construction, and monitoring of interim measures to reduce the impact of tank farm releases. Previous interim measures to date are described in the RFI.
T Tank Farm Interim Surface Barrier Demonstration—Vadose Zone Monitoring FY07 Report, PNNL-17306
T Tank Farm Interim Surface Barrier Demonstration - Vadose Zone Monitoring FY08 Report, PNNL-18803
241-TY Tank Farm Interim Surface Barrier Monitoring Plan (RPP-PLAN-36705)
Tank Farm Interim Surface Barrier Materials and Runoff Alternatives Study (RPP-RPT-38323)
Criteria for Prioritizing Hanford Site Tank Farm Interim Surface Barriers and for Evaluating Their Performance (RPP-ENV-41309)
