Results of Tritium Tracking and Groundwater Monitoring at the Hanford Site 200 ARea State-Approved Land Disposal Site--Fiscal Year 2002

Barnett, D. Brent; Rieger, J.T.

doi:10.2172/897389

Cited by 3 publications

(7 citation statements)

References 7 publications

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“…Currently, 200-West Area groundwater contaminant plume maps are generated based on data collected from wells screened only within the upper one-fourth of the unconfined aquifer. Confirmation of contaminants located deeper than this shallow monitoring network within the suprabasalt aquifer system have been documented in Williams (1995), Swanson et al (1999), Barnett (2000), and Johnson et al (2001). Artificially induced vertical hydraulic heads within the uppermost-unconfined aquifer are implied as the mechanism to explain the presence of contaminants detected deep within the suprabasalt aquifers.…”

Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 65%

“…The last remaining effluent disposal site, SALDS, is located north of 200-West Area where the Unit 8 (Ringold Formation lower mud unit) is absent, and the uppermost-unconfined aquifer flows within the Ringold Unit 5. Recent hydrochemistry indicates that wastewater discharge to the SALDS does not significantly impact water quality of the uppermost-unconfined aquifer within the 200-West Area (Barnett 2000), but downgradient wells have increased heads and have detected increases in tritium associated with the SALDS wastewater disposal.…”

Section: 17mentioning

confidence: 99%

“…The vertical addition of contaminant/ effluent releases from other sources would also tend to chemically alter, i.e., diluting the existing contaminants moving beneath the release site. Barnett (2000) provides a present-day example of this deep displacement mechanism, which is occurring at the SALDS. The SALDS, an effluent disposal facility, is located at the north end of the 200-West Area (Plate 1) over that portion of the unconfined aquifer where the Ringold Unit 8 confining interval is absent.…”

Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 99%

“…In addition, one deep groundwater-monitoring well was installed downgradient with a sample point approximately 24 m (79 ft) below the water table. As discussed in Barnett (2000), initially, the liquid effluent disposed to SALDS moved through the vadose zone along south dipping bedding planes (e.g., the Plio-Pleistocene silt and caliche [hydrogeologic Units 2 and 3]) (Figure 4.13). Because of this vadose flow path, the waste stream break through to groundwater (first significant tritium activity increase) was first observed in June 1996 in the upgradient well 699-48-77A located south of the SALDS disposal ponds.…”

Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 99%

See 3 more Smart Citations

Revised Hydrogeology for the Suprabasalt Aquifer System, 200-West Area and Vicinity, Hanford Site, Washington

Williams¹,

Bjornstad²,

Schalla³

et al. 2002

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The primary objective of this study was to refine the conceptual groundwater flow model for the 200-West Area and vicinity. This is the second of two reports that combine to cover the Central Plateau, an area that holds the largest inventory of radionuclide and chemical wastes on the Hanford Site. This inventory is located in underground storage tanks, the vadose zone, and the saturated zone. Within the saturated zone, groundwater contaminant plumes, originating from past-practice activities at facilities within this area, are migrating toward the Columbia River where they may be accessible to the public. This study supports the Hanford Groundwater/Vadose Integration Project objectives to better understand the impacts of groundwater contamination and potential risk to the public via the groundwater flow pathway. The primary components of the conceptual groundwater flow model are 1) the static elements of the subsurface that form the hydrogeologic framework and 2) the groundwater that moves through this framework in response to stresses within the aquifer. The previous conceptual model was used as the baseline and was updated using new data and by re-evaluating existing data and reports from previous investigations to include essentially all the suprabasalt hydrogeology and associated groundwater flow information beneath the 200-West Area and vicinity. Current groundwater monitoring and cleanup efforts are focused on the upper portion of the unconfined aquifer within the suprabasalt aquifer system. This report evaluates more completely the entire vertical sequence of the suprabasalt sediments including description of the aquifer systems separated by the Ringold Unit 8. Contaminants have been detected in groundwater at various depths within these two systems, but our current understanding of groundwater flow and contaminant transport in the lower portion of these aquifers is limited. Based on this study, hydrogeologic mapping indicates that the confining (Aquitard) Ringold Unit 8 rises to the east and is located at or near the water table of the upper unconfined aquifer in the northeast portion of the study area, downgradient from 200-West Area contaminant source areas. Groundwater and contaminants from the northern portion of the 200-West Area will likely flow northeast into more permeable Hanford formation sediments within an erosional paleochannel. Continued water-level decline will expose more of Ringold Unit 8 and the Columbia River basalt above the water table northeast of 200-West Area near Gable Gap, restricting groundwater and contaminant flow in that direction and possibly diverting contaminant plumes to the southeast across 200-East Area. The uppermost-unconfined aquifer averages about 40 m (131 ft) thick beneath most of the 200-West Area. Characterization of contaminants located in the lower three-fourths of the unconfined aquifer and the confined Ringold aquifer beneath the 200-West Area and vicinity is very limited. The assessment of these contaminants may be important in developing successful cleanup...

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Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 65%

Section: 17mentioning

confidence: 99%

Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 99%

Section: Vertical Contaminant Distribution Within the Suprabasalt Aqumentioning

confidence: 99%

See 2 more Smart Citations

Revised Hydrogeology for the Suprabasalt Aquifer System, 200-West Area and Vicinity, Hanford Site, Washington

Williams¹,

Bjornstad²,

Schalla³

et al. 2002

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show abstract

“…During FY 2000, it was speculated that results from wells 299-W7-3 and 299-W7-7 may have indicated the first arrival of tritium from the SALDS in this area (note departures in Figure 9; Barnett 2000b). Results of reanalysis of the samples and subsequent sampling now suggest that such speculation may be in error, and that results thus far provide no conclusive evidence of incursion of SALDS effluent in these wells.…”

Section: Results Of Groundwater Analyses For Tritiummentioning

confidence: 99%

Results of Tritium Tracking and Groundwater Monitoring at the Hanford Site 200 Area State-Approved Land Disposal Site--Fiscal Year 2001

Barnett¹,

Rieger²

2001

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The Hanford Site 200 Area Effluent Treatment Facility (ETF) processes contaminated aqueous wastes derived from Hanford Site facilities. The treated wastewater occasionally contains tritium, which is not removed by the ETF, and is discharged to the 200 Area State-Approved Land Disposal Site (SALDS). Groundwater monitoring for tritium and other constituents is required by the state-issued permit at 3 monitoring and 19 tritium-tracking wells.Water level measurements in nearby wells indicates the persistence of a small hydraulic mound beneath the SALDS facility as a result of discharges. This feature is directing groundwater flow radially outward a short distance before the regional northeasterly flow predominates. This condition also places several wells south of the SALDS hydraulically downgradient of the facility. With the continued monitoring of these wells, the network is currently adequate for tracking potential effects of the SALDS on the groundwater.During FY 2001, tritium activities in the SALDS proximal well 699-48-77A increased (maximum 670,000 pCi/L) as a result of the resumption of tritium disposal in September 2000, following a 16-month hiatus in significant tritium discharges. Well 699-48-77C, where tritium results reached a maximum value of 980,000 pCi/L, is reflecting the result of the delayed penetration of effluent deeper into the aquifer from 1999 SALDS tritium discharges. Speculation in FY 2000 that tritium may have reached two wells due south of the facility is probably premature. FY 2001 results indicate no departures from historical levels of tritium in these wells.Of the 11 constituents with permit enforcement limits, which are monitored in SALDS proximal wells, all were within permit groundwater limitations during FY 2001. Analyses for conductivity, total dissolved solids, chloride, sulfate, dissolved calcium, and dissolved sodium indicate that SALDS proximal wells show the effects of dilute effluent entering groundwater, resulting in a depression of concentrations of these constituents below natural background levels. Earlier elevated levels of these constituents were the result of the dissolution of natural soil salts by SALDS effluent.Recommendations for future monitoring include retaining in the well network all current tritium tracking wells to the south of the SALDS. This measure will provide accurate determination of the southern bounds of the SALDS-generated tritium plume, provide estimates of travel time for model comparisons, and help preserve the distinction between this plume and the older 200 West tritium plume farther east. v

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Identification of Pumping Influences in Long-Term Water Level Fluctuations

Harp¹,

Vesselinov

2011

Ground Water

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Identification of the pumping influences at monitoring wells caused by spatially and temporally variable water supply pumping can be a challenging, yet an important hydrogeological task. The information that can be obtained can be critical for conceptualization of the hydrogeological conditions and indications of the zone of influence of the individual pumping wells. However, the pumping influences are often intermittent and small in magnitude with variable production rates from multiple pumping wells. While these difficulties may support an inclination to abandon the existing dataset and conduct a dedicated cross-hole pumping test, that option can be challenging and expensive to coordinate and execute. This paper presents a method that utilizes a simple analytical modeling approach for analysis of a long-term water level record utilizing an inverse modeling approach. The methodology allows the identification of pumping wells influencing the water level fluctuations. Thus, the analysis provides an efficient and cost-effective alternative to designed and coordinated cross-hole pumping tests. We apply this method on a dataset from the Los Alamos National Laboratory site. Our analysis also provides (1) an evaluation of the information content of the transient water level data; (2) indications of potential structures of the aquifer heterogeneity inhibiting or promoting pressure propagation; and (3) guidance for the development of more complicated models requiring detailed specification of the aquifer heterogeneity.

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Results of Tritium Tracking and Groundwater Monitoring at the Hanford Site 200 ARea State-Approved Land Disposal Site--Fiscal Year 2002

Cited by 3 publications

References 7 publications

Revised Hydrogeology for the Suprabasalt Aquifer System, 200-West Area and Vicinity, Hanford Site, Washington

Revised Hydrogeology for the Suprabasalt Aquifer System, 200-West Area and Vicinity, Hanford Site, Washington

Results of Tritium Tracking and Groundwater Monitoring at the Hanford Site 200 Area State-Approved Land Disposal Site--Fiscal Year 2001

Identification of Pumping Influences in Long-Term Water Level Fluctuations

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