Investigation of Accelerated Casing Corrosion in Two Wells at Waste Management Area A-AX

摘要

The sidewall core samples from well 299-E24-19, which were comprised of a mixture of bentonite and silt lens material, had an average porewater chloride concentration of 376 mg/L. The sidewall core samples collected from well 299-E25-46 had calculated porewater chloride concentrations ranging from 1,200 to more than 10,000 mg/L. Clearly, the sidewall core samples tested were capable of generating porewaters with sufficient chloride concentrations to cause corrosion of the stainless steel well casing. Furthermore, analysis of the sidewall core samples yielded a clear relationship between chloride concentration and well casing corrosion. This report contains all the geochemical and selected physical characterization data collected on archived vadose zone sediment recovered during the early 1990s installation of four RCRA monitoring wells: 299-E24-19, 299-E24-20, 299-E24-22, and 299-E25-46, sidewall core samples collected during the decommissioning (in 2004) of wells 299-E24-19 and 299-E25-46, splitspoon core samples collected during the installation (in 2004) of two RCRA monitoring wells: 299-E24-33 and 299-E25-95, a sample of Wyoming bentonite, as well as a perched water sample collected during the installation of well 299-E24-33. Laboratory tests were conducted to characterize the sediment and to identify water-leachable constituents. Testing consisted primarily of 1:1 sediment:water extractions, which were used to calculate the elemental concentrations of water soluble constituents in the solid and to estimate in-situ porewater chloride concentrations. Additionally, 8M nitric acid extractions and X-ray diffraction analysis of the solids were used to provide a measure of the total leachable sediment content of constituents and to search for the formation of new crystalline phases that may have formed during the corrosion process, respectively.