U.S. Geological Survey combined well-bore flow and depth-dependent water sampler

Izbicki, John A.; Christensen, Allen H.; Hanson, Randall T.; Martin, Peter M.; Crawford, Steven M.; Smith, Gregory A.

doi:10.3133/fs19699

Cited by 22 publications

(27 citation statements)

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“…To optimize sampling of long‐screened or open wells, it is important to measure the flow profile in un‐pumped conditions and at the pumping rate used for sampling. Methods to measure flow profiles include borehole flowmeter (Molz et al ; Boman et al ; Newhouse et al ), tracer‐dilution tests in un‐pumped conditions (Maurice et al ), tracer‐pulse tests while pumping (Izbicki et al ) and tracer‐dilution tests while pumping. The latter can be performed with a constant injection of tracer (Brainerd and Robbins ) or with single replacement of the borehole fluid column (e.g., Doughty and Tsang ; Paillet ).…”

Section: Discussionmentioning

confidence: 99%

Effects of Intraborehole Flow on Purging and Sampling Long‐Screened or Open Wells

et al. 2018

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Hydraulic head differences across the screened or open interval of a well significantly influence the sampled water mixture. Sample bias can occur due to an insufficient pumping rate and/or due to native groundwater displacement by intraborehole flow (IBF). Proper understanding of the sampled water mixture is crucial for accurate interpretation of environmental tracers and groundwater chemistry data, and hence groundwater characterization. This paper uses numerical modeling to quantify sample bias caused by IBF in an un-pumped high-yield well, and the influence of pumping rate and heterogeneity on the volume of pumpage required to purge an IBF plume. The results show that (1) the pumping rate must be at least an order of magnitude greater than the IBF rate to achieve permeability-weighted yield, (2) purge volume was 2.2 to 20.6 times larger than the IBF plume volume, with the ratio depending on plume location relative to hydraulic conductivity and head distributions, and (3) after an example 1000-day un-pumped period, purging required removal of at least three orders of magnitude more water than the common practice of three to five well volumes. These results highlight the importance of knowing the borehole flow regime to identify IBF inflow and outflow zones, estimate IBF rates, and to develop a strategic sampling approach.

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Section: Discussionmentioning

confidence: 99%

Effects of Intraborehole Flow on Purging and Sampling Long‐Screened or Open Wells

et al. 2018

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“…Wells 2N/21W‐34G1 and 1N/21W‐8R1 have depth‐dependent water quality data collected during 1993 using the methods described by Izbicki et al (1999). In addition, depth‐dependent water‐quality data from well 34G1 also were collected using a commercial wire line sampler in 1992 and 1993.…”

Section: Approachmentioning

confidence: 99%

“…Samples collected from the deepest part of the well were considered to be representative of water in the aquifer at that depth, and samples collected at the next higher depth were a mixture of water already in the well and water that entered the well from the aquifer between the sample‐collection depths. The concentration of a constituent in water that entered the well from the aquifer between sample‐collection depths can be calculated, assuming simple mixing within the well, according to the following (Izbicki et al 1999): where C a and Q a are the constituent concentration ( C ) and the volume of water that entered the well from the aquifer between sample‐collection depths ( Q ), C 1 and Q 1 are the constituent concentration and the volume of water in the well at the deeper sample depth, and C 2 and Q 2 are the constituent concentration and the volume of water in the well at the shallower sample depth.…”

Section: Approachmentioning

confidence: 99%

Temporal Changes in the Vertical Distribution of Flow and Chloride in Deep Wells

Izbicki¹,

Christensen

Newhouse

et al. 2005

Groundwater

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The combination of flowmeter and depth-dependent water-quality data was used to evaluate the quantity and source of high-chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher-quality water with poorer-quality water from deeper depths, and in some cases with poorer-quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth-dependent water quality data yielded information about sources of high-chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor-quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

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“…Flow logs collected from wells under pumped conditions were coupled with depth-dependent water-chemistry data (collected from discrete depths within these wells) to evaluate aquifer water quality using techniques described by Izbicki et al (1999) and Izbicki (2004). In general, when using these techniques, the deepest sample is representative of the aquifer chemistry at that depth.…”

Section: Sample Collection and Laboratory Methodsmentioning

confidence: 99%

“…These data were collected using several different techniques including: (1) commercially available impeller or vertical-axis velocity meter (also known as spinner tools; Hill 1990) (2) electromagnetic (EM) velocity meter (Paillet 2000), and (3) the tracer-pulse method (Izbicki et al 1999). The vertical-axis and the EM velocity meters were used in wells where access tubes allowed meter deployment below the production pump or in wells where the production pump had been removed and a smalldiameter temporary pump had been installed for data collection.…”

Section: Sample Collection and Laboratory Methodsmentioning

confidence: 99%

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

2015

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As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency's secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100-2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of highchloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ 18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

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U.S. Geological Survey combined well-bore flow and depth-dependent water sampler

Cited by 22 publications

References 0 publications

Effects of Intraborehole Flow on Purging and Sampling Long‐Screened or Open Wells

Effects of Intraborehole Flow on Purging and Sampling Long‐Screened or Open Wells

Temporal Changes in the Vertical Distribution of Flow and Chloride in Deep Wells

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

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