RCRA Assessment Plan for Single-Shell Tank Waste Management Area T

Horton, Duane G.

doi:10.2172/882973

Cited by 3 publications

(3 citation statements)

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“…The information given in this section is taken largely from Horton et al (2002) and is updated with more current groundwater data.…”

Section: Existing Groundwater Contaminationmentioning

confidence: 99%

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196, and RCRA Borehole 299-W11-39

Serne¹,

Bjornstad²,

Horton³

et al. 2008

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Executive SummaryThis report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.8, 4.28, and 4.52. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in September 2004.The overall goal of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities at Hanford. To meet this goal, CH2M HILL Hanford Group, Inc. tasked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediments from within Waste Management Area (WMA) T-TX-TY. This report is the second of two reports written to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from boreholes C4104 and C4105 in the T Tank Farm, and from borehole 299-W-11-39 installed northeast of the T Tank Farm. Finally, the measurements on sediments from borehole C4104 are compared with a nearby borehole drilled in 1993, 299-W10-196, through the tank T-106 leak plume.Sediments from borehole 299-W-11-39 were considered to be background uncontaminated sediments against which to compare contaminated sediments for the T tank farm characterization effort. However, during characterization of the sediments from 299-W11-39, numerous indications were found that suggest some nearsurface contamination may have occurred in the past such that the water extract information for sediments from 299-W11-39 may not represent natural background conditions. Therefore, most of the comparisons of the contaminated T tank farm boreholes to natural background conditions used the sediment characterization information from background borehole 299-W10-27, just northeast of the TX Tank Farm.This report also presents our interpretation of the data in the context of sediment types, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the T Tank Farm. The information presented in this report supports the T-TX-TY Waste Management Area field investigation report (a) in preparation by CH2M HILL Hanford Group, Inc. Sediment samples from the boreholes were analyzed and characterized in the laboratory for the following parameters: moisture content, gamma-emitting radionuclides, one-to-one water extracts (which provide soil pH, electrical conductivity, cation, trace metal, radionuclide and anion data), total carbon and inorganic carbon content, and 8 M nitric acid extracts (which provide a measure of the total leachable sediment content of contaminants). Key radiocontaminants, technetium-99, actinides, fission products (including strontium-90, europium radioisotopes, ruthenium and molybdenum), cobalt-60, and uranium, along with other trace metals were determined in acid and water...

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“…The information given in this section is taken largely from Horton et al (2002) and is updated with more current groundwater data.…”

Section: Existing Groundwater Contaminationmentioning

confidence: 99%

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196, and RCRA Borehole 299-W11-39

Serne¹,

Bjornstad²,

Horton³

et al. 2008

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“…The tritium plume passes underneath the WMA (Figure 4.6). Chou (1998, 2001) used tritium concentrations, plume distribution, and tritium/technetium-99 ratios to infer that the source of most of the tritium beneath the WMA is probably the upgradient 216-S-25 crib. The areal extent of the tritium plume is growing as evidenced by increasing concentrations in the furthest downgradient wells in the WMA S-SX monitoring network.…”

Section: Extent Of Contamination At Waste Management Area S-sx -Geogrmentioning

confidence: 99%

“…Most of the information in this section is taken from Dresel et al (2006), Serne et al (2004b), and Horton (2006).…”

Section: Groundwater Contamination Beneath Waste Management Area Tmentioning

confidence: 99%

Data Package for Past and Current Groundwater Flow and Contamination beneath Single-Shell Tank Waste Management Areas

Horton¹

2007

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Aquifer testing has shown that vertical hydraulic gradients exist in some wells in the 200 West Area. Vertical flow is upward in some places and downward in other places. The reason for the vertical flow is not known for certain. Nevertheless, vertical flow has important implications pertaining to (1) the representativeness of groundwater samples collected from monitoring wells and (2) the vertical distribution of contaminants in the aquifer.The major contaminants of concern in the groundwater below and locally adjacent to all single-shell tank waste management areas (WMAs) in 200 West Area are carbon tetrachloride, technetium-99, and nitrate. Chromium and tritium are contaminants present at WMAs T, TX-TY, and S-SX; iodine-129 is of concern at WMA TX-TY and fluoride is of concern at WMA T. The groundwater contaminants of concern below all single-shell tank WMAs in 200 East Area are nitrate, technetium-99, and tritium. Sulfate, uranium, cobalt-60, and cyanide are also of concern at WMA B-BX-BY, and cyanide is of concern at WMA C.Vertical concentration gradients are known to exist in the upper unconfined aquifer at several singleshell tank WMAs:• Around WMA T, maximum technetium-99 concentrations occur at the water table in some wells and 10 m below the water table in other wells east of the WMA.• Around WMA TX-TY, maximum concentrations of nitrate, technetium-99, and iodine-129 are within 1 m of the water table in the high concentration plume east of the WMA.• Around WMA S-SX, chromium, nitrate, and technetium-99 are present throughout the upper 23 m of the unconfined aquifer near the center of the plume south of the WMA. Technetium-99 and nitrate decrease rapidly with depth in the aquifer at a well near the northern edge of the plume.• Around WMA B-BX-BY, the concentration of tritium increases with increasing depth at one well. The concentrations of technetium-99 and nitrate are high in a zone at the base of the aquifer in another well at WMA B-BX-BY. ivThe vertical concentration gradients are probably a function of several characteristics including distance to source area, salinity of waste fluids, and vertical hydraulic flow in the wells.Comparing the nitrate, technetium-99, and chromium concentrations in groundwater with concentrations in pore water representing leaked tank fluids suggests that tank waste has influenced groundwater at WMA T and WMA S-SX. Similar comparisons at WMA TX-TY and WMA B-BX-BY do not show similarities between groundwater, pore water and estimated tank fluid composition.v

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Analysis of the Hydrologic Response Associated With Shutdown and Restart of the 200-ZP-1 WMA T Tank Farm Pump-and-Treat System

Spane¹

2008

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A number of programs have been implemented on the Hanford Site that use the pumping and treatment of contaminated groundwater as part of their remediation strategy. The implementation of remedial pump-and-treat systems results in hydraulic pressure responses both areally and vertically (i.e., with depth) within the pumped aquifer. The area within the aquifer affected by the pump-and-treat system (i.e., radius of influence) is commonly estimated based on detecting associated water-level responses within surrounding monitor wells. Natural external stresses, such as barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These temporal barometric effects may significantly mask water-level responses within more distant wells that are only slightly affected (≤0.10 m) by the treatment system. External stress effects, therefore, can lead to erroneous indications of the radius of influence of the imposed pump-and-treat remediation activities and can greatly diminish the ability to analyze the associated well responses for hydraulic property characterization. When these extraneous influences are significant, adjustments or removal of the barometric effects from the test-response record may be required for quantitative hydrologic assessment.This report examines possible hydrologic effects of pump-and-treat remediation actions and provides a detailed analysis of water-level measurements for selected 200-ZP-1 T Tank Farm pump-and-treat system monitor wells during a recent shutdown (May 1, 2008) and restart activity (June 4, 2008) involving extraction well 299-W11-46. Specifically, this report 1) applies to recently developed methods for removing barometric pressure fluctuations from well water-level measurements to enhance the detection of pump-and-treat system effects at selected monitor wells, 2) analyzes the barometric-corrected well water-level responses to determine large-scale hydraulic properties, and 3) assesses characteristics and conditions that influence hydrologic responses (both laterally and vertically) associated with pumpand-treat systems. In all, the 10 T Tank Farm wells monitored during this investigation provided results for six composite and individual interwell tests for unconfined aquifer characterization. These large-scale aquifer characterization results will be utilized for optimization and site selection of additional extraction wells within the WMA T Tank Farm pump-and-treat system. v v SummaryAs noted in a previous study by Spane and Thorne (2000), remedial pump-and-treat systems impose variable hydrologic pressure responses both areally and vertically (i.e., with depth) within the affected aquifer. The area within the aquifer influenced by the pump-and-treat system (i.e., radius of influence) is commonly determined by detecting associated water-level responses within surrounding monitor wells. These discernible hydrologic responses can also be analyzed, under favorable conditions, to provide estimates of aquifer hydraulic properties. T...

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RCRA Assessment Plan for Single-Shell Tank Waste Management Area T

Cited by 3 publications

References 50 publications

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196, and RCRA Borehole 299-W11-39

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196, and RCRA Borehole 299-W11-39

Data Package for Past and Current Groundwater Flow and Contamination beneath Single-Shell Tank Waste Management Areas

Analysis of the Hydrologic Response Associated With Shutdown and Restart of the 200-ZP-1 WMA T Tank Farm Pump-and-Treat System

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