US Department of Energy

 

Date of this Version

2-2002

Citation

CH2M Hill Hanford Group, Inc., and the U.S. Department of Energy, February 2002

Abstract

The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples.

Intact cores from two “clean” RCRA boreholes (299-W22-48 and 299-W22-50) near the SX Tank Farm and four, large-quantity grab samples from outcrop sediment on the Hanford Site were sampled to better understand the fate of contaminants in the vadose zone beneath underground storage tanks at the Hanford Site. Borehole and outcrop samples analyzed for this report are located outside the tank farms, and therefore may be considered standard or background samples from which to compare contaminated sediments within the tank farms themselves. This report presents our interpretation of the physical, chemical, and mineralogical properties of the uncontaminated vadose zone sediments, and variations in the vertical distribution of these properties. The information presented in this report is intended to support preparation of the S-SX field investigation report(a) prepared by CH2M HILL Hanford Group, Inc. as well as future remediation actions at the S-SX Tank Farm.

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. For the two boreholes, lithologic sections were constructed using detailed geologic descriptions and geophysical logs. In some cases the results of laboratory analyses (e.g., particle-size distribution, moisture, calcium carbonate content) helped to refine the resulting stratigraphic and lithologic interpretations.