Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

Abstract

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).

U–Sr isotopic speedometer: Fluid flow and chemical weathering rates in aquifers

“…The gravel-dominated HFGD unit is the coarsest in composition, ranging from 63.2% gravel and 36% sand, to 3% gravel and 92% sand at the contact with the finer-grained lower HFSD2 unit (94-98% sand). The silt and clay contents were highest in the Cold Creek units (38.6%), whereas the Ringold Formation is predominantly sand and silt (Serne et al, 2002).…”

“…Borehole 299-W22-48 (71.6 m) was drilled in the 200 West area in order to characterize the back- ground geochemistry and the geology of the area proximal to contaminated zones. The volumetric water content (h) and corresponding lithology (measured by Serne et al (2002)) are shown in Fig. 2.…”

“…The sediments are predominantly composed of quartz, plagioclase, alkali feldspar, and minor accessory minerals such as biotite, calcite, and clays (Serne et al, 2002;Maher et al, 2003). The most notably different layer is the lower Cold Creek unit (CCUc-f(calc)), which has a high calcite content (40%).…”

“…The grain size distributions were also measured as part of the initial core characterization and are tabulated in Serne et al (2002). The upper HFSD1 facies of the Hanford Formation is composed predominantly of sand ($90%) and inter-bedded silt and clay layers ($8%) with slightly higher water contents (Table 1, Fig.…”

“…After heating for 48 h on a hot plate, the solution was evaporated to dryness and re-dissolved in 1.5 N HNO 3 prior to the chemical separations. (Bulk sediment U concentrations were also measured by XRF methods in Serne et al (2002), and were generally below the detection limit of 6 ppm). Different methods of sample pre-treatment were considered in order to ensure that secondary minerals were removed prior to digestion of the sediment for U isotopic analysis.…”