Biological and Physical Clogging in Infiltration Wells: Effects of Well Diameter and Gravel Pack

Kalwa, Fritz; Binder, Martin; Händel, Falk; Grüneberg, Luzie; Liedl, Rudolf

doi:10.1111/gwat.13104

Cited by 6 publications

(2 citation statements)

References 38 publications

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“…Drilled water wells are important, widely-used, sources of water; however, as they age, their speci c water yield may decline. This decrease in water yield, and consequently water level, in the well is usually the result of colmatation (clogging of originally porous media) of the gravel pack surrounding the ltering tube, causing it to become clogged with sand, bacterial bio lms or iron (Fe) oxides from the well's steel casing (Deed and Preene 2015;Abramova et al 2017; Kalwa et al 2021). Biological fouling is caused by microbial activity and their living processes.…”

Section: Introductionmentioning

confidence: 99%

Effective water well rehabilitation using a combined ultrasonic-mechanical method

Pavelková,

Pluhař,

Procházka

et al. 2024

Preprint

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Background The restoration of original boreholes is preferable to building new ones as the process is more cost-effective. However, traditional chemical or mechanical regeneration methods may cause soil contamination or destruction of the borehole equipment. Materials and methods Here, we report on a newly developed ultrasound device that has been designed to reduce the need for the heavy lifting equipment, such as cranes, that typically accompany commercially available equipment. The device is minimized in size and equipped with a PLC, allowing the unit to be controlled remotely using a laptop computer. We tested the prototype ultrasound device on a fifty-year-old borehole and used standard geophysical well-logging techniques to evaluate its regeneration efficiency. Results After regeneration the fundamental change was an increase in the intensity of the downward flow, the water no more flows across the borehole, but exclusively downward (Q=115,000 l/day) what was thirty-fold acceleration of the flow of water through the well. New tributaries to the well were activated, which also signalled cleaning of the formerly clogged gravel sheath. The specific yield derived after regeneration was 1.13-1.49 fold higher than the specific yield before regeneration. Conclusion Borehole regeneration using ultrasound, while a less widely used method, offers adequate regeneration efficiency and is more environmentally friendly. Moreover, the presented prototype also offers reduced financial costs for regeneration compared to similar techniques that currently use heavy equipment and enables better mobility for harder-to-reach wells.

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Section: Introductionmentioning

confidence: 99%

Effective water well rehabilitation using a combined ultrasonic-mechanical method

Pavelková,

Pluhař,

Procházka

et al. 2024

Preprint

View full text Add to dashboard Cite

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“…Furthermore, the hydrological conditions found in larger scale setups are more complex with unsaturated or variably saturated soils. The corresponding changes in porosity, hydraulic conductivity, and permeability due to clogging must be considered (Kalwa et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Determining the impact of flow velocities on reactive processes associated with Enterococcus faecalis JH2-2

Chandrasekar

Binder

Liedl

et al. 2021

Water Science and Technology

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This study focuses on the impact of infiltration rates on colloidal transport and reactive processes associated with E. faecalis JH2-2 using water-saturated sediment columns. The infiltration rates influence the physical transport of bacteria by controlling the mean flow velocity. This, in turn, impacts biological processes in pore water owing to the higher or lower residence time of the bacteria in the column. In the present study, continuous injection of E. faecalis (suspended in saline water with varying conditions of dissolved oxygen and nutrient concentrations) into a lab-scale sediment column was performed at flow velocities of 0.02 cm min−1 and 0.078 cm min−1, i.e., at residence times of 1–5 hours. The impact of residence times on reactive processes is significant for field scale setups. A process-based model with a first-order rate coefficient for each biological process was fitted for each obtained condition-specific dataset from the experimental observations (breakthrough curves). The coefficients were converted to a dimensionless form to facilitate the comparison of biological processes. These results indicate that the processes of attachment and growth were flow-dependent. The growth process in the absence of dissolved oxygen was the most dominant process, with a Damkoehler number of approximately 48.

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Os poços na zona vadosa podem ser retrolavados para recuperar a capacidade de infiltração? Conceito e teste de laboratório

Kalwa

2023

Hydrogeol J

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Vadose zone wells (VZW), or drywells, allow for high infiltration rates combined with small area demand. Nevertheless, they are rarely used for managed aquifer recharge, since turbid water leads to gradual clogging and a reduction in infiltration capacity. Established redevelopment measures require backflushing, which is commonly considered impossible for VZWs, making them “non regenerable”. In this study, the possibility of backflushing a VZW is discussed. Key to the underlying approach is isolating the lower (clogged) section of a well and saturating its surrounding with water by infiltration via the upper (unclogged) screen. Subsequently, underpressure sucks water from the surrounding soil into the isolated section. The approach was tested with and without a gravel pack, on laboratory scale, showing a successful reversal of flow direction in both cases. The degree of redevelopment was quantified by measuring the drainage time of the well, which increased from initially 45 s without gravel pack and 40 s with gravel pack to 9,500 and 11,000 s, respectively, after clogging. After backflushing, the well with gravel pack showed a median drainage time of 95 s, which remained stable over ten cycles of clogging and backflushing. In contrast, drainage time of the well without gravel pack increased continuously to >170 s, even after vibrator application. In conclusion, it can be stated that the backflush of a VZW with the presented approach is possible and has an effect on the well’s infiltration capacity, though it seems more effective for wells with gravel pack.

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Biological and Physical Clogging in Infiltration Wells: Effects of Well Diameter and Gravel Pack

Cited by 6 publications

References 38 publications

Effective water well rehabilitation using a combined ultrasonic-mechanical method

Effective water well rehabilitation using a combined ultrasonic-mechanical method

Determining the impact of flow velocities on reactive processes associated with Enterococcus faecalis JH2-2

Os poços na zona vadosa podem ser retrolavados para recuperar a capacidade de infiltração? Conceito e teste de laboratório

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