Characterizing Groundwater Flow in Monitoring Wells by Altering Dissolved Oxygen

Vitale, Sarah A.; Robbins, Gary A.

doi:10.1111/gwmr.12157

Cited by 11 publications

(10 citation statements)

References 16 publications

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“…The static well head of SIMA 2 had an elevation of 179.88 m, which resulted in a head difference of 4.46 m from SIMA 1. These wells are known to be hydraulically connected based on observed drawdown in pumping tests (Cagle ) and studies using the dissolved oxygen alteration method (Vitale and Robbins ). The latter showed that the fracture at the depth of 16.5 m in SIMA 1 was connected to the 13.1 m fracture in SIMA 2.…”

Section: Resultsmentioning

confidence: 99%

A Single Packer Method for Characterizing Water Contributing Fractures in Crystalline Bedrock Wells

Flahive

Robbins

2020

Groundwater Monitoring Rem

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Water levels and water quality of open borehole wells in fractured bedrock are flow‐weighted averages that are a function of the hydraulic heads and transmissivities of water contributing fractures, properties that are rarely known. Without such knowledge using water levels and water quality data from fractured bedrock wells to assess groundwater flow and contaminant conditions can be highly misleading. This study demonstrates a cost‐effective single packer method to determine the hydraulic heads and transmissivities of water contributing fracture zones in crystalline bedrock wells. The method entails inflating a pipe plug to isolate sections of an open borehole at different depths and monitoring changes in the water level with time. At each depth, the change in water level with time was used to determine the sum of fracture transmissivities above the packer and then to solve for individual fracture transmissivity. Steady‐state wellbore heads along with the transmissivities were used to determine individual fracture heads using the weighted average head equation. The method was tested in five wells in crystalline bedrock located at the University of Connecticut in Storrs. The single packer head and transmissivity results were found to agree closely with those determined using conventional logging methods and the dissolved oxygen alteration method. The method appears to be a simple and cost‐effective alternative in obtaining important information on flow conditions in fractured crystalline bedrock wells.

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Section: Resultsmentioning

confidence: 99%

A Single Packer Method for Characterizing Water Contributing Fractures in Crystalline Bedrock Wells

Flahive

Robbins

2020

Groundwater Monitoring Rem

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“…The presence of the probe is assumed to have a negligible effect on DO concentrations. Based on testing in Chlebica and Robbins (2013) and Vitale and Robbins (2016), DO profile repeatability in stagnant zones indicates that mixing from density gradients does not have a measureable impact on vertical movement in the well over the course of hours to days, and is therefore assumed to be negligible relative to advective flow in the well in this study. The procedure was tested in Sima 1 using two Instrumentation Northwest (INW) manufactured DO probes.…”

Section: Methodsmentioning

confidence: 99%

“…Vertical movement of the diluted zones showed vertical in‐well flow direction. Chlebica and Robbins () and Vitale and Robbins () determined that flow was the primary factor in changing DO concentration and that the effects of biotic or abiotic reactions were negligible, in the time frame of testing. Gas tracers have two distinct advantages over liquid tracers.…”

Section: Introductionmentioning

confidence: 99%

Measuring Flow Rate in Crystalline Bedrock Wells Using the Dissolved Oxygen Alteration Method

Vitale

Robbins

2017

Groundwater

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Determination of vertical flow rates in a fractured bedrock well can aid in planning and implementing hydraulic tests, water quality sampling, and improving interpretations of water quality data. Although flowmeters are highly accurate in flow rate measurement, the high cost and logistics may be limiting. In this study the dissolved oxygen alteration method (DOAM) is expanded upon as a low-cost alternative to determine vertical flow rates in crystalline bedrock wells. The method entails altering the dissolved oxygen content in the wellbore through bubbler aeration, and monitoring the vertical advective movement of the dissolved oxygen over time. Measurements were taken for upward and downward flows, and under ambient and pumping conditions. Vertical flow rates from 0.06 to 2.30 Lpm were measured. To validate the method, flow rates determined with the DOAM were compared to pump discharge rates and found to be in agreement within 2.5%.

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“…Such occurrences can be important for contaminated site cleanup and research has focused on understanding concentration data collected from monitoring wells (Reilly et al 1989;Church and Granato 1996;Elci et al 2001;Ma et al 2011;McMillan et al 2014;Vitale and Robbins 2016). However, the differences in construction between water supply wells and monitoring wells, primarily casing diameter and length of well screen, create the potential for greater flows through supply wells where there is less resistance to flow as well as greater head difference between shallow and deep strata.…”

Section: Transport Impacts From Intraborehole Flowsmentioning

confidence: 99%

Inactive supply wells as conduits for flow and contaminant migration: conditions of occurrence and suggestions for management

Gailey

2017

Hydrogeol J

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Water supply wells can act as conduits for vertical flow and contaminant migration between water-bearing strata under common hydrogeologic and well construction conditions. While recognized by some for decades, there is little published data on the magnitude of flows and extent of resulting water quality impacts. Consequently, the issue may not be acknowledged widely enough and the need for better management persists. This is especially true for unconsolidated alluvial groundwater basins that are hydrologically stressed by agricultural activities. Theoretical and practical considerations indicate that significant water volumes can migrate vertically through wells. The flow is often downward, with shallow groundwater, usually poorer in quality, migrating through conduit wells to degrade deeper water quality. Field data from locations in California, USA, are presented in combination with modeling results to illustrate both the prevalence of conditions conducive to intraborehole flow and the resulting impacts to water quality. Suggestions for management of planned wells include better enforcement of current regulations and more detailed consideration of hydrogeologic conditions during design and installation. A potentially greater management challenge is presented by the large number of existing wells. Monitoring for evidence of conduit flow and solute transport in areas of high well density is recommended to identify wells that pose greater risks to water quality. Conduit wells that are discovered may be addressed through approaches that include structural modification and changes in operations.

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Characterizing Groundwater Flow in Monitoring Wells by Altering Dissolved Oxygen

Cited by 11 publications

References 16 publications

A Single Packer Method for Characterizing Water Contributing Fractures in Crystalline Bedrock Wells

A Single Packer Method for Characterizing Water Contributing Fractures in Crystalline Bedrock Wells

Measuring Flow Rate in Crystalline Bedrock Wells Using the Dissolved Oxygen Alteration Method

Inactive supply wells as conduits for flow and contaminant migration: conditions of occurrence and suggestions for management

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