A Hydrostratigraphic Framework Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 98: Frenchman Flat, Clark, Lincoln and Nye Counties, Nevada

Nevada, Bechtel

doi:10.2172/859292

Cited by 9 publications

(11 citation statements)

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“…Geologic, hydrologic, and water-chemistry data were integrated to evaluate water-level changes in the well ER-5-3-2 hydrograph. Geologic data included the lithologic well log for borehole ER-5-3-2 and hydrostratigraphic cross sections (Bechtel Nevada, 2005a;Fenelon and others, 2010). Hydrologic data included water levels for well ER-5-3-2 and nearby wells open to carbonate rocks and the single-well aquifer-test transmissivity estimate for well ER-5-3-2.…”

Section: Purpose and Scopementioning

confidence: 99%

Evaluation of potential stresses and hydrologic conditions driving water-level fluctuations in well ER-5-3-2, Frenchman Flat, southern Nevada

Jackson¹,

Frus²

2023

Scientific Investigations Report

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Well ER-5-3-2 is part of a well network designed to monitor long-term water levels and radionuclide concentrations downgradient from underground nuclear tests that occurred in Frenchman Flat, an area of the U.S. Department of Energy Nevada National Security Site in southern Nevada. Interpretation of monitoring records for well ER-5-3-2 was confounded by previously unexplained water-level fluctuations in the well hydrograph. This study integrated geologic, hydrologic, and water-chemistry data to evaluate potential stresses and hydrologic conditions that likely affected the well ER-5-3-2 hydrograph. Numerical groundwater models were applied to evaluate four model scenarios: (1) wellbore leakage without recharge, (2) wellbore leakage with recharge, (3) equilibration to vertical heterogeneities between shallow (low transmissivity) and deep (higher transmissivity) carbonate zones, and (4) equilibration to lateral heterogeneities in carbonate rocks.Meteoric recharge was not the cause of the 21-foot (ft) water-level rise in well ER-5-3-2 from 2001 to 2011 or the 4-ft decline from 2012 to 2016. Based on observed water-level fluctuations in nearby wells, the water-level rise and decline from recharge for these periods was less than 3 and 1 ft, respectively. The lateral-heterogeneity scenario is based on the assumption that the 21-ft water-level rise from 2001 to 2011 was a natural water-level reequilibration following the pumping-induced depressurization of a large volume of high transmissivity and low-storage carbonate rock that is surrounded by low transmissivity and high-storage carbonate rock. The lateral-heterogeneity scenario was discounted because simulated water levels cannot match the well ER-5-3-2 hydrograph. Underground nuclear testing and temperature effects were discounted based on hydraulic connections and water-temperature data.Wellbore-leakage scenarios are based on the assumption that the water-level rise was sustained from leakage rates required to cause a localized mounding in the carbonate system near well ER-5-3-2, where the carbonate transmissivity is 530 square feet per day. Even though simulated and measured water levels compare favorably for scenarios of wellbore leakage with and without recharge, large volumes (178-184 million gallons) of

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Section: Purpose and Scopementioning

confidence: 99%

Evaluation of potential stresses and hydrologic conditions driving water-level fluctuations in well ER-5-3-2, Frenchman Flat, southern Nevada

Jackson¹,

Frus²

2023

Scientific Investigations Report

View full text Add to dashboard Cite

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“…Additional information regarding other HSUs is summarized in tables introduced in Section A.2.5 below where the hydrogeology of Yucca and Frenchman Flats, and Pahute and Rainier Mesas UGTAs at the NTS is addressed. Additional information can be found in the documenttation packages for the UGTA Corrective Action Unit (CAU)-scale hydrogeologic models (BN, 2002b;2005;2006;NSTec, 2007).…”

Section: A232 Hydrostratigraphic Unitsmentioning

confidence: 99%

“…As pointed out in Section A.2.3.1, the volcanic rocks are divided into aquifer or confining units according to lithology and secondary alteration. More detailed information can be found in the documentation packages for the UGTA CAU-scale hydrogeologic models (BN, 2002b;2005;2006;NSTec, 2007).…”

Section: A232 Hydrostratigraphic Unitsmentioning

confidence: 99%

Nevada Test Site Environmental Report 2007 Attachment A: Site Description

Wills¹

2008

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“…Since that time additional studies at various scales have been conducted to aid in the understanding of groundwater flow at the NTS. The current understanding of the regional groundwater flow at the NTS is derived from work by Winograd and Thordarson (1975), which was summarized and updated by Laczniak et al (1996), and has further been developed by the UGTA Project hydrogeologic modeling team (IT, 1996a;BN, 2002a;2005). See Chapter 14 for a description of the UGTA Project.…”

Section: A23 Hydrogeologic Framework For the Nts And Vicinitymentioning

confidence: 99%

“…Additional information regarding other HSUs is summarized in tables introduced in Section A.2.5 below where the hydrogeology of Yucca and Frenchman Flats, and Pahute and Rainier Mesas UGTAs at the NTS is addressed. Additional information can be found in the documentation packages for the UGTA CAU-scale hydrogeologic models (IT, 1996a;Gonzales and Drellack, 1999;BN, 2002a;2005).…”

Section: A232 Hydrostratigraphic Unitsmentioning

confidence: 99%

Nevada Test Site Environmental Report 2005, Attachment A - Site Description

Wills¹

2006

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A Hydrostratigraphic Framework Model and Alternatives for the Groundwater Flow and Contaminant Transport Model of Corrective Action Unit 98: Frenchman Flat, Clark, Lincoln and Nye Counties, Nevada

Cited by 9 publications

References 0 publications

Evaluation of potential stresses and hydrologic conditions driving water-level fluctuations in well ER-5-3-2, Frenchman Flat, southern Nevada

Evaluation of potential stresses and hydrologic conditions driving water-level fluctuations in well ER-5-3-2, Frenchman Flat, southern Nevada

Nevada Test Site Environmental Report 2007 Attachment A: Site Description

Nevada Test Site Environmental Report 2005, Attachment A - Site Description

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