Table 2.1. Stratigraphy of the Vadose Zone Beneath the SX Tank Farm. Stratigraphic Symbol (a) Formation Facies/Subunit Description Genesis Holocene/Fill NA Backfill Poorly sorted gravel to medium sands and silt derived from the Hanford formation (Price and Fecht, 1976a) Anthropogenic Unit H1a-gravelly sand Upper coarse-grained sequence equilvalent to Johnson et al.'s (1999) "Hanford Gravel Unit B" and Sobczyk's (2000) "Hanford Unit B" H1a Unit H1a-slightly silty sand Upper fine sand and silt sequence. Equivalent to "Hanford silty sand" of Sobcyzk (2000) H1 Unit H1 Lower coarse-grained sequence equivalent to "Gravel Unit A" described by Johnson et al. (1999) and "Hanford Unit A" described by Sobcyzk (2000).
This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4. 8, 4.28,4.43, and 4.59. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in April 2004.The overall goal 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 at Hanford. To meet this goal, CH2M HILL Hanford Group, Inc. tasked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediments from within Waste Management Area (WMA) T-TX-TY. This report is the first of two reports written 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 boreholes C3830, C3831, and C3832 in the TX Tank Farm, and from borehole 299-W-10-27 installed northeast of the TY Tank Farm.
This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. 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.
Executive SummaryThis report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.8, 4.28, and 4.52. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in September 2004.The overall goal 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 at Hanford. To meet this goal, CH2M HILL Hanford Group, Inc. tasked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediments from within Waste Management Area (WMA) T-TX-TY. This report is the second of two reports written 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 boreholes C4104 and C4105 in the T Tank Farm, and from borehole 299-W-11-39 installed northeast of the T Tank Farm. Finally, the measurements on sediments from borehole C4104 are compared with a nearby borehole drilled in 1993, 299-W10-196, through the tank T-106 leak plume.Sediments from borehole 299-W-11-39 were considered to be background uncontaminated sediments against which to compare contaminated sediments for the T tank farm characterization effort. However, during characterization of the sediments from 299-W11-39, numerous indications were found that suggest some nearsurface contamination may have occurred in the past such that the water extract information for sediments from 299-W11-39 may not represent natural background conditions. Therefore, most of the comparisons of the contaminated T tank farm boreholes to natural background conditions used the sediment characterization information from background borehole 299-W10-27, just northeast of the TX Tank Farm.This report also presents our interpretation of the data in the context of sediment types, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the T Tank Farm. The information presented in this report supports the T-TX-TY Waste Management Area field investigation report (a) in preparation by CH2M HILL Hanford Group, Inc. Sediment samples from the boreholes were analyzed and characterized in the laboratory for the following parameters: moisture content, gamma-emitting radionuclides, one-to-one water extracts (which provide soil pH, electrical conductivity, cation, trace metal, radionuclide and anion data), total carbon and inorganic carbon content, and 8 M nitric acid extracts (which provide a measure of the total leachable sediment content of contaminants). Key radiocontaminants, technetium-99, actinides, fission products (including strontium-90, europium radioisotopes, ruthenium and molybdenum), cobalt-60, and uranium, along with other trace metals were determined in acid and water...
CH2M HILL Hanford, Inc., drilled the second borehole C3177 for the Immobilized Low-Activity Waste (ILAW) disposal site in 2001. The borehole is located just south of Fourth Street in the middle of the 200 East Area and in the northeast corner of the ILAW disposal site. Vadose zone samples from that borehole were characterized by scientists from Pacific Northwest National Laboratory. The information from this characterization will be used to augment data previously collected to support future performance assessments of the ILAW facility. The physical and geochemical properties were determined for six large composite samples and six discrete depth samples from the second ILAW borehole C3177. The composite samples were made so that large volumes of well characterized material can be used in future geochemical studies. These studies may help determine interactions between Hanford formation sediment and contaminants that may leach from the glass waste forms scheduled to be disposed in the ILAW facility. All samples were analyzed for particle-size distribution, moisture content, whole sediment chemical composition, carbon content, surface area, mineralogy, pH, electrical conductivity, alkalinity, and the major and trace metal and anion concentrations of 1:1 sediment to water extracts. This investigation determined that all composite samples are sand or gravelly sand. The moisture content ranges from 1.7 to 5.3 wt. %. The bulk chemistry and mineralogy of the samples are typical of the Hanford formation sand-dominated sequence. Likewise, the chemical characteristics of the 1:1 water extracts are similar to extracts from other samples of the Hanford formation sand-dominated sequence from other boreholes. The water extracts (and by inference the natural vadose zone pore water) from borehole C3177 are dominated by calcium, bicarbonate (from alkalinity), magnesium, sodium, and sulfate. No information was found by this characterization effort that would invalidate any of the data used in the 2001 performance assessment (Mann et al. 2001) of the overall performance of the ILAW facility. v
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