Geochemistry of Samples from Borehole C3177(299-E24-21)

Abstract

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

Kd Values for Agricultural and Surface Soils for Use in Hanford Site Farm, Residential, and River Shoreline Scenarios

“…2 The data in Patton and Crecelius (2001) show total organic carbon contents for sediments along the Columbia River banks at three sloughs range from <0.5 to 1.5% by weight and that the silt and clay content is generally <10% by weight. These particle-size values are similar to agricultural soils expected at the Hanford Site in the future and not much different from the existing sediments in burial grounds at present and Horton et al (2003). The observed organic carbon content in the sloughs is somewhat greater than subsurface sediments near burial grounds that generally have organic carbon at or less than 0.1%.…”

Limited Field Investigation Report for Uranium Contamination in the 300 Area, 300-FF-5 Operable Unit, Hanford Site, Washington

“…Overall, these moisture results reveal reasonable vadose moisture levels, averaging between 4.7 to 5.4 wt.%, which would be expected for this type of Hanford formation gravel-dominated environment (Horton et al 2003;Serne et al 2002). The core liners from below the water table often showed moisture contents below values expected for fully saturated sediments, which reflects moisture loss out of the bottom of the splitspoon core sampler while traveling back up the casing.…”

Sorption and transport behavior of radionuclides in the proposed low-level radioactive waste disposal facility at the Hanford site, Washington

“…The following characterization data for this sediment sample were determined and reported by Horton et al [14]. The sediment consists of a mixture of gravel, sand, silt, and clay, but sand-sized particles are dominant, while a small portion of silt-and clay-sized particles are present.…”