Research Areas
Subsurface Contaminant Fate and Transport
PNNL is engaged in studies that describe how contaminants move in the Earth's material that is near, but not exposed to, the surface of the ground. That region just below the surface, but above the water table, is of interest to PNNL staff because we realize that trapping contaminants before they reach groundwater is of immeasurable value to our client's cleanup progress.
Analysis of Geologic Media and Water Samples
Mineralogy, water chemistry, pH and oxidation-reduction conditions are some of the most important factors affecting the migration of radionuclides and other hazardous contaminants in soils and subsurface geologic systems. PNNL can provide the facilities, instrumentation and established procedures to perform radionuclide and hazardous chemical assays. We also perform a variety of physical and chemical analyses of contaminated soil and water samples, solid waste forms and uncontaminated geologic media under the highest levels of quality assurance and control.
Laboratory Measurement and Analysis of Contaminant Retardation
The batch equilibration and flow-through (or column) methods are the two most common laboratory techniques used to measure partition coefficient values. PNNL's capabilities include having all the necessary facilities, equipment, analytical capabilities and staff experience to conduct both of these measurements on radionuclides and other hazardous contaminants. PNNL also has the capabilities to measure contaminant retardation with flow-through columns operating at unsaturated water conditions. The column pressurized unsaturated flow apparatus is designed to 1) vary the volumetric water content from saturation down to 20% of saturation, 2) minimize the flow rate to increase liquid residence time and 3) operate at a maximum temperature of 90°C.
PNNL's capabilities also include state-of-the-art instrumentation for obtaining high-resolution, two-dimensional computer tomographic images of columns of soil or other geologic media.
Laboratory Measurement of Contaminant Release from Solidified Waste Forms
PNNL's staff have extensive research experience in testing the long-term release of contaminants from solid wastes of all compositions. Testing methodologies that may suffice for waste classification requirements include the strictly empirical EPA's Method 1311 "Toxic Characteristic Leach Procedure (TCLP);" Method 1312 "Synthetic Precipitation Leaching Procedure;" Method 1320 "Multiple Extraction Procedure;" comparable ASTM leach protocols such as D3987 "Standard Test Method for Shake Extraction of Solid Waste with Water," D4793 "Standard Test Method for Sequential Batch Extraction of Waste with Water;" D4874 "Standard Test Method for Single Batch Extraction Method for Wastes," D5284 "Standard Test Method for Sequential Batch Extraction of Waste with Acidic Extraction Fluid," D5744 "Standard Test Method for Accelerated Weathering of Solid Materials Using a Modified Humidity Cell" and D6234 "Standard Test Method for Shake Extraction of Mining Waste by the Synthetic Precipitation Leaching Procedure;" as well as the American Nuclear Society's ANS 16.1 intermittent Solution Replacement Test Procedure or ASTM C1308 "Standard Test Method for Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program to Model Diffusive, Fractional Leaching from Cylindrical Waste Forms." However, it is PNNL's belief that these empirical test protocols are deficient for predicting the long-term risks of disposal of nuclear and hazardous industrial wastes in geologic media. More site-specific leach testing that incorporates site geochemical and geohydrological aspects are recommended.
Laboratory Measurement of Contaminant Adsorption onto Sediments
PNNL's staff have extensive research experience in testing the adsorption tendencies of contaminants interacting with native soils, sediments and rocks under both water-saturated and unsaturated conditions. Testing methodologie such as the ASTM D4319 "Standard Test Method for Distribution Ratios by the Short-Term Batch Method" and ASTM D4646 "Standard Test Method for the 24-h Batch Type Measurement of Contaminant Sorption by Soils and Sediments" as well as flow-through column tests are used to determine both adsorption/distribution ratios and desorption/distribution ratios.
Point of Contact: R Jeffrey Serne
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