Evaluation of Central Plateau Remediation Alternatives: Interim Status Report

Bagwell, Christopher E.; Lawter, Amanda R.; Cantrell, Kirk J.; Brown, Christopher F.

doi:10.2172/1489412

Cited by 1 publication

(1 citation statement)

References 27 publications

(46 reference statements)

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“…The use of gas-phase carbon amendments has been successfully demonstrated for degradation of perchlorate and nitrate in the vadose zone (Cai et al 2010). Preliminary laboratory testing (Bagwell et al 2018) has evaluated gas-phase bioremediation as an effective treatment to decrease the amount of nitrate present in the subsurface. If implemented to a theoretical nitrate plume below the IDF it could lead to a significant decrease in projected nitrate levels present in the subsurface.…”

Section: Line 18 -Gas Phase Bioremediationmentioning

confidence: 99%

Evaluation of Technologies for Enhancing Grout for Immobilizing Hanford Supplemental Low-Activity Waste (SLAW)

Skeen

Langston

McCabe

et al. 2020

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An expert panel consisting of the document authors was assembled by Washington River Protection Solutions, LLC (WRPS) and tasked with (1) identifying technical and regulatory limitations to treating and disposing of grouted low-activity waste (LAW), and (2) with identifying and evaluating a wide range of technical solutions to these limitations. The analysis included technologies to allow inventory management and/or improve retention of iodine, technetium, and nitrate either in the waste packages, or within the Integrated Disposal Facility (IDF), and, technologies to ensure regulated organics are below Resource Conservation and Recovery Act of 1976 (RCRA) Land Disposal Restriction (LDR) levels.The expert panel completed their analysis in three distinct phases. In Phase I, the team reviewed the chemical and physical characteristics of the most recent projected supplemental LAW (SLAW) feed vector along with disposal site waste acceptance criteria and the fiscal year 2019 results from Pacific Northwest National Laboratory that identified the level of improvement that would be needed to meet onsite disposal requirements in the IDF (Asmussen et al. 2019a). The two regulatory constraints targeted for technology solutions by the expert panel were (1) current estimates based on performance assessment fate-andtransport modeling indicate that if the entire quantity of LAW currently designated for supplemental treatment were solidified as a cementitious material, nitrate, 99-Tc, and 129-I could exceed groundwater standards after DOE's time of compliance (1,000 years) but within 10,000 years after IDF closure and (2) LAW may contain RCRA LDR organics at levels that require removal to meet LDR concentration-based limits. It should also be noted that the first issue is only applicable to on-site disposal, not offsite at WCS and is based on calculations that assume either a low-performing grout is used, or high-performance grout does not maintain its performance (SRNL-RP-2018-00687). Asmussen et al. (2019a) estimated that the inventory of grouted SLAW could meet IDF groundwater requirements if the release rate of nitrate, 99-Tc, and 129-I were reduced by a factor of approximately 3.2, 10, and 32, respectively versus baseline formulation performance.In Phase II, an extensive list of technologies and engineering approaches was identified and subjected to an initial assessment by the group. Current knowledge associated with technology maturation needs and constraints to implementation at Hanford were recorded in 13 distinct categories. In the final phase of the process (Phase III), the expert panel selected 7 of the 13 categories for qualitative rating and a series of meetings were held between the expert panel to discuss and rate each technology in each category. All ratings were developed by consensus. After the qualitative rating was complete, a numerical scoring criterion for each category was applied and a composite score for the individual technologies was calculated. An uncertainty score was also developed for each technolo...

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Section: Line 18 -Gas Phase Bioremediationmentioning

confidence: 99%