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

Abstract

SummaryThis report provides best estimate K d values and a minimum and maximum range of K d values to be used for agricultural soils and Columbia River bank sediments that exist today or would exist in the future when portions of the Hanford Site are released for farming, residential, and recreational use after the U.S. Department of Energy (DOE) completes clean up of defense waste on the site. The K d values should be used to determine the fate and transport rates of contaminants and their availability for plant and animal uptake in selected non-groundwater scenarios included in Hanford Site environmental impact statements, risk assessments and specific facility performance assessments.This report describes scenarios such as a small farm where drilling of a well inadvertently goes through buried waste and brings waste to the surface, allowing the tailings to become available for direct human exposure or incorporation into garden crops and farm animals used for food by the farm family. The K d values recommended in this report can also be used to calculate sediment-water partitioning factors used to predict plant and animal uptake from interaction with the contaminated soil.The values recommended herein should not be used to predict exposure to contaminants in drinking water or from water used for irrigation. For the waterborne scenarios, K d values recommended in Last et al. (2004) and Krupka et al. (2004) should be used because they better predict the distribution and mobility of contaminants in water.Other non-groundwater scenarios include (1) recreational or native American use of the Columbia River bank that exposes humans to contaminants adsorbed to the river bank sediments, (2) contaminants transferred from sediments to plants or animals that reside along the Columbia River bank, and (3) any other scenario that requires estimation of soil-to-plant or soil-to-animal transfer parameters that are often calculated based on soil K d values.For these non-groundwater exposure scenarios, choosing a larger K d value from available values will be "conservative" in the sense that large K d values keep the contaminant available longer (retains more contaminants in the soils) such that exposure to humans or incorporation into animals and plants is maximized. Therefore, the K d values in this report are slightly biased to keep the contaminants near the ground surface for longer time periods. Upon exposure to water or by direct contact, the contaminated near-surface soils allow more opportunity for direct exposure and incorporation into plant matter and animals.The following contaminants of concern were the focus of the search: americium,

Sensitivity Analysis of Contaminant Transport from Vadose Zone Sources to Groundwater

“…Figure 4.8 show observed concentrations over time for , respectively, at the selected monitoring wells, and simulation results for cases in which K d values were varied for the three subunits of the Hanford fm (H1, H2, and H3). The ranges used for the K d values are based on Serne (2007). The hydraulic properties were held constant for these simulation cases at the baseline values.…”

“…The lower end of the K d range is typical of what is expected for native Hanford sediments that have very low organic matter content. The upper end may be more representative of values that might develop if the liquid wastes contained dissolved organic matter that sorbs with contaminants and binds with the sediment, or if Hanford sediments were used for future agricultural purposes (Serne 2007). A value of K d = 0 cm 3 /g provides the closest correspondence to measured Tc-99 concentrations for the majority of the selected groundwater monitoring wells.…”

Geochemical association of Pu and Am in selected host-phases of contaminated soils from the UK and their susceptibility to chemical and microbiological leaching

“…Despite the low Kd values of Pu in soils and sediments (McCubbin et al, 2004;Serne, 2007), the potential remobilization of small quantities of the actinide is still a concern (Kersting et al, 1999;Santschi and Roberts, 2002;Xu et al, 2014). Previous work by the current authors has demonstrated that negligible Pu present in environmental contaminated soils (from the AWE Aldermaston site) is released into solution (<0.01%) under induced-reducing conditions, suggesting that little Pu is mobilized despite the inferred dissolution of oxide minerals and presence of microorganisms linked to Pu reduction (Kimber et al, 2012).…”

Groundwater contaminant plume maps and volumes, 100-K and 100-N Areas, Hanford Site, Washington

“…Nitrate has low sorption characteristics so it flows with the other groundwater (Serne, 2007) but it can readily change chemical form; so nitrate is not considered a conservative constituent in groundwater.…”