Level-determined groundwater sampling from open boreholes

Bishop, P. K.; Gosk, Edmund; Burston, M. W.; Lerner, David N.

doi:10.1144/gsl.qjeg.1992.025.02.08

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…The average concentration of fluorescein in the water entering the abstraction borehole from layer n , C n [M/L 3 ], can be calculated by considering the mass balance in the section of the borehole intersecting that layer (e.g., Bishop et al ). Assuming that there is complete and effectively instantaneous mixing of water in this zone, the mass balance equation can be written:

Q_{n} C_{n} = (true \sum_{i = 1}^{n} Q_{i}) {C^{'}}_{n} - (true \sum_{i = 1}^{n - 1} Q_{i}) {C^{'}}_{n - 1}

where Q i [L 3 /T] is the discharge from layer i to the abstraction borehole, and C ′ n [M/L 3 ] is the concentration sampled from the top of layer n .…”

Section: Data Processingmentioning

confidence: 99%

“…The average concentration of fluorescein in the water entering the abstraction borehole from layer n, C n [M/L 3 ], can be calculated by considering the mass balance in the section of the borehole intersecting that layer (e.g., Bishop et al 1992). Assuming that there is complete and effectively instantaneous mixing of water in this zone, the mass balance equation can be written:…”

Section: Data Processing High Frequency Sampling-fluoresceinmentioning

confidence: 99%

“…Simultaneous testing requires the use of sampling techniques that allow identification of level‐specific tracer breakthrough curves. Bishop et al () tested three methods: pumping from above an inflatable packer that has to be moved between samples at different depths; separation pumping, which employs two pumps in the sampling borehole to create a movable flow divide; and flow logging combined with a movable pump. The third of these methods, which has been used subsequently by a number of workers including Gossell et al (), Izbicki (), and Landon et al (), is appealingly simple.…”

Section: Introductionmentioning

confidence: 99%

“…Simultaneous testing requires the use of sampling techniques that allow identification of level-specific tracer breakthrough curves. Bishop et al (1992) tested three methods: pumping from above an inflatable packer that has to be moved between samples at different depths; separation pumping, which employs two pumps in the NGWA.org Vol. 52, No.…”

Section: Introductionmentioning

confidence: 99%

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A Method for Conducting Simultaneous Convergent Tracer Tests in Multilayered Aquifers

et al. 2013

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Forced gradient tracer tests between two boreholes can be used to study contaminant transport processes at the small field scale or investigate the transport properties of an aquifer. Full depth tests, in which tracer samples are collected just from the discharge of the abstraction borehole, often give rise to breakthrough curves with multiple peaks that are usually attributed to different flow paths through the aquifer that can rarely be identified from the test results alone. Tests in selected levels of the aquifer, such as those between packer-isolated sections of the boreholes, are time consuming, expensive; and the identification of major transport pathways is not guaranteed. We present a method for simultaneously conducting multiple tracer tests covering the full depth of the boreholes, in which tracer sampling and monitoring is carried out by a novel multilevel sampling system allowing high frequency and cumulative sampling options. The method is applied to a tracer test using fluorescein conducted in the multilayered sandstone aquifer beneath the city of Birmingham, UK, producing six well-defined tracer breakthrough curves.

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Q_{n} C_{n} = (true \sum_{i = 1}^{n} Q_{i}) {C^{'}}_{n} - (true \sum_{i = 1}^{n - 1} Q_{i}) {C^{'}}_{n - 1}

where Q i [L 3 /T] is the discharge from layer i to the abstraction borehole, and C ′ n [M/L 3 ] is the concentration sampled from the top of layer n .…”

Section: Data Processingmentioning

confidence: 99%

“…The average concentration of fluorescein in the water entering the abstraction borehole from layer n, C n [M/L 3 ], can be calculated by considering the mass balance in the section of the borehole intersecting that layer (e.g., Bishop et al 1992). Assuming that there is complete and effectively instantaneous mixing of water in this zone, the mass balance equation can be written:…”

Section: Data Processing High Frequency Sampling-fluoresceinmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Method for Conducting Simultaneous Convergent Tracer Tests in Multilayered Aquifers

et al. 2013

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show abstract

“…To control for the bias induced by ambient flow, depth-dependent sampling [ 35 , 47 , 48 , 49 ] or vertical monitoring well nests [ 28 , 34 , 50 , 51 ] have been employed in many studies. However, these methods are technically challenging and expensive.…”

Section: Introductionmentioning

confidence: 99%

Water Quality Assessment Bias Associated with Long-Screened Wells Screened across Aquifers with High Nitrate and Arsenic Concentrations

Huang

Knappett

et al. 2022

IJERPH

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Semi-arid regions with little surface water commonly experience rapid water table decline rates. To hedge against the falling water table, production wells in central Mexico are commonly installed to depths of several hundred meters below the present water table and constructed as open boreholes or perforated casings across their entire length. Such wells represent highly conductive pathways leading to non-negligible flow across chemically distinct layers of an aquifer—a phenomenon known as ambient flow. The objectives of this study were to estimate the rate of ambient flow in seven production wells utilizing an end-member mixing model that is constrained by the observed transient chemical composition of produced water. The end-member chemical composition of the upper and lower layers of an urban aquifer that overlies geothermal heat is estimated to anticipate the future quality of this sole source of water for a rapidly growing urban area. The comprehensive water chemistry produced by seven continuously perforated municipal production wells, spanning three geologically unique zones across the city of San Miguel de Allende in Guanajuato State, was monitored during one day of pumping. The concentration of conservative constituents gradually converged on steady-state values. The model indicates that, relative to the lower aquifer, the upper aquifer generally has higher specific conductance (SC), chloride (Cl), nitrate (NO3), calcium (Ca), barium (Ba) and magnesium (Mg). The lower aquifer generally has a higher temperature, sodium (Na), boron (B), arsenic (As) and radon (Rn). Ambient flow ranged from 33.1 L/min to 225.7 L/min across the seven wells, but this rate for a given well varied depending on which tracer was used. This new 3D understanding of the chemical stratification of the aquifer suggests that as water tables continue to fall, concentrations of geothermally associated contaminants of concern will increase in the near future, potentially jeopardizing the safety of municipal drinking water.

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2017

Water Wells and Boreholes

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Level-determined groundwater sampling from open boreholes

Cited by 12 publications

References 17 publications

A Method for Conducting Simultaneous Convergent Tracer Tests in Multilayered Aquifers

A Method for Conducting Simultaneous Convergent Tracer Tests in Multilayered Aquifers

Water Quality Assessment Bias Associated with Long-Screened Wells Screened across Aquifers with High Nitrate and Arsenic Concentrations

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