Groundwater Conditions at Single-Shell Tank Waste Management Area TX-TY (January 1998 through December 2001)

Horton, Duane G.

doi:10.2172/15010061

Cited by 5 publications

(12 citation statements)

References 18 publications

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“…That value is from the screened, top 8 meters of the aquifer and is about 1,180,000 pCi/L, which is a reasonable mean of the concentrations in the upper 8 meters of well 299-W14-11. These data contradict the earlier interpretation using data from well pair 299-W14-13 and 299-W14-12 that tritium was evenly distributed throughout the aquifer (Horton 2002). Table 2.9.…”

Section: Groundwater Contaminationcontrasting

confidence: 77%

“…That sample represented a mean technetium-99 concentration from the upper, screened 10 meters of the aquifer. The conclusion was that technetium-99 existed at the top of the aquifer at about 6,000 pCi/L and the concentration decreased deeper in the aquifer (Horton 2002;Serne et al 2004). The 2,500 pCi/L technetium-99 value from well 299-W14-13 is a mixture of relatively high concentration technetium-99 near the water table with more dilute groundwater from deeper in the aquifer.…”

Section: 35mentioning

confidence: 98%

“…Most of the information presented in this section is from Horton et al (2002), Hartman et al ( , 2005, and Serne et al (2004).…”

Section: Groundwater Contaminationmentioning

confidence: 99%

“…The technetium-99 concentrations in wells 299-W14-12 and 299-W14-13 have been used to presume a technetium-99 concentration gradient in the upper part of the aquifer (Horton 2002;Serne et al 2004). The concentration of technetium-99 in the last sample from well 299-W14-12 was ~6,000 pCi/L.…”

Section: 35mentioning

confidence: 99%

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RCRA Assessment Plan for Single-Shell Tank Waste Management Area TX-TY

Horton¹

2007

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(2) information from routine quarterly groundwater monitoring during the last five years. Also, this plan describes activities for continuing the groundwater assessment at WMA TX-TY.This plan describes the data quality objectives (DQO) process used to guide information gathering to further the assessment at WMA TX-TY. The general approach of the assessment is to (1) determine what effects the newly expanded 200-ZP-1 pump-and-treat operation will have on the monitoring being done at the WMA, (2) improve our understanding of the lateral and vertical distributions of contaminants and their relationship to potential sources within the study boundary, and (3) continue routine quarterly groundwater sampling and analysis to comply with RCRA regulatory requirements.This assessment plan includes a sampling and analysis plan (Appendix A) consisting of a field sampling plan and a quality assurance project plan. The sampling and analysis plan is used as the principal controlling document to conduct the work identified by the data quality assessment process.v Acronyms

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Section: Groundwater Contaminationcontrasting

confidence: 77%

Section: 35mentioning

confidence: 98%

“…Most of the information presented in this section is from Horton et al (2002), Hartman et al ( , 2005, and Serne et al (2004).…”

Section: Groundwater Contaminationmentioning

confidence: 99%

Section: 35mentioning

confidence: 99%

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RCRA Assessment Plan for Single-Shell Tank Waste Management Area TX-TY

Horton¹

2007

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“…Previous indications of vertical concentration gradients include depth-discrete sampling of wells 299-W14-14 Hodges 1999), 299-W14-19, and299-W15-44 (Horton 2003), comparisons of groundwater chemistry in older wells with their adjacent replacement wells (Horton 2002), and depth profiles of specific conductance in the screened interval of existing wells (Serne et al 2004a). These recent studies provided new insights into the occurrence and nature of groundwater contamination in the WMA TX-TY area.…”

Section: Extent Of Contamination At Waste Management Area Tx-ty -Deptmentioning

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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RCRA Groundwater Quality Assessment Report for Single-Shell Tank Waste Management Area TX-TY (January 1998 through December 2001)

Horton¹

2002

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Waste Management Area (WMA) TX-TY at the Hanford Site contains the TX and TY single-shell tank farms and their auxiliary equipment. These tank farms, located in the northern portion of the 200 West Area, include 24 single-shell carbon steel tanks constructed in the 1940s and early 1950s. During operations, tanks received mixed waste from plants that processed spent reactor fuel to recover plutonium as part of Hanford's defense mission. The tank farms ceased active operations in 1980 but are currently storing waste and are currently regulated as Resource Conservation and Recovery Act (RCRA) Interim Status Facilities. Waste Management Area TX-TY was placed in RCRA Groundwater Quality Assessment in 1993 and has remained in that status because of indications that dangerous-waste contaminants from within the area may be entering groundwater. The water table is declining and groundwater flow directions are changing in the vicinity of WMA TX-TY. These changes are a result of the cessation of effluent discharge to ground in 1995 and the initiation of a major pump-and-treat operation in 1998. To meet the changing groundwater monitoring needs, twelve new RCRA monitoring wells have been constructed since 1997 and two others are in the planning stage. Monitoring at WMA TX-TY indicates that the dangerous-waste constituent chromium occurs above the drinking water maximum contaminant level at one well east of the WMA. Although the nearest potential source for the chromium is the WMA and the chromium is attributed to the WMA, the high concentrations of chromium appear to be deeper in the aquifer than the maximum concentrations of nonregulated technetium-99, which is most likely from WMA TX-TY. Chromium contamination is located on the downgradient (east) side of the WMA and is currently migrating to the southeast. The dangerous-waste constituent carbon tetrachloride is also present at WMA TX-TY. The carbon tetrachloride is from a well document, upgradient source associated with the Plutonium Finishing Plant. Data gathered during drilling indicates that the carbon tetrachloride is distributed relatively deep in the upper part of the aquifer at WMA TX-TY.

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Groundwater Conditions at Single-Shell Tank Waste Management Area TX-TY (January 1998 through December 2001)

Cited by 5 publications

References 18 publications

RCRA Assessment Plan for Single-Shell Tank Waste Management Area TX-TY

RCRA Assessment Plan for Single-Shell Tank Waste Management Area TX-TY

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

RCRA Groundwater Quality Assessment Report for Single-Shell Tank Waste Management Area TX-TY (January 1998 through December 2001)

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