Characterization of Vadose Zone Sediment: Borehole 41-09-39 in the S-SX Waste Management Area

Serne, R. Jeffrey ; Last, George V. ; Schaef, Herbert T. ; Lanigan, David C. ; Lindenmeier, Clark W. ; Ainsworth, Calvin C. ; Clayton, Ray E. ; Legore, Virginia L. ; O' ; Hara, Matthew J. ; Brown, Christopher F. ; Orr, Robert D. ; Kutnyakov, Igor V. ; Wilson, Teresa C. ; Wagnon, Kenneth B. ; Williams, Bruce A. ; Burke, Deborah Sd

Pacific Northwest National Laboratory (U.S.)

关键词: Geochemistry;    Radioactive Waste Storage;    Sediments;    Mineralogy;    Storage Facilities;   

DOI  :  10.2172/15001171
RP-ID  :  PNNL-13757-3
RP-ID  :  AC05-76RL01830
RP-ID  :  15001171

美国|英语

来源: UNT Digital Library

【 摘 要 】

The geology under the SX Tank Farm forms the framework through which the contaminants move and provides the basis with which to interpret and extrapolate the physical and geochemical properties that control the migration and distribution of contaminants. Of particular interest are the interrelationships between the coarser and finer-grained facies and the degree of contrast in their physical and geochemical properties. The vertical distribution of cesium-137, based on borehole gamma logging and the laboratory analysis of the sediment at borehole 41-09-39, suggest that much of the tank fluid that leaked from tanks SX-108, SX-109, SX-111, and SX-112 traveled within the coarse-grained Hanford formation H1 unit that is found between 67 and 88 feet below ground surface (bgs) at borehole 41-09-39. It is difficult to differentiate the known moisture content relationship with particle size (finer-grained material retains higher moisture contents) from excess moisture from leaked fluid. Thus, moisture content distribution did not give us a clear indication of the vertical extent of the plume. However, moisture content does help identify intervals that have been impacted by drilling operations. The pH values are not nearly as high as would be expected for tank liquor completely saturating sediment. Therefore, it would appear that the significant pH reactions occur from the tank bottoms at ~55 feet to a maximum of 90 feet bgs for sediment surrounding the tanks. We have identified common ion exchange and heterogeneous (solid phase-liquid solute) redox reactions as two mechanisms that are influencing the distribution of contaminants in the vadose zone sediment within the zone impacted by tank liquor. We did not observe significant indications of pH alteration of the sediment mineralogy or porosity but we did observe slightly elevated pH values between 55 to 90 feet bgs.