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What maximum permeability can be measured with a monitoring well?

Nadège Baptiste and Robert P. Chapuis

Article (2015)

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Cite this document: Baptiste, N. & Chapuis, R. P. (2015). What maximum permeability can be measured with a monitoring well? Engineering Geology, 184(C), p. 111-118. doi:10.1016/j.enggeo.2014.11.006
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Abstract

The PVC screens of recentmonitoringwells (MWs) have thin slots and a lowopen area, usually in the 2–8% range. The MW screen and filter pack may cause important head losses which are not taken into account when interpreting the data of permeability tests performed using the MW. The equivalent hydraulic conductivity K of usual PVC screens was defined by hydraulic tests in a water tank, which have shown that gas microbubbles, a common problem in MWs and filter packs, contribute to increase the parasitic head losses. Closedform equations and numerical models are used to explain by how much a field permeability test in a MW under evaluates an aquifer K value due to parasitic head losses in the screen and filter pack. TheMWcan properly measure the local soil K value only if it is markedly lower than the maximum MWvalue as obtained in a water tank. TheMWmeasuring capacity can reach 5 × 10−3 m/s for large slots and deairedwater, but ismost often between 10−5 and 10−4 m/s for small slots in field conditions, and it can be only 10−6 m/s for poorly designed and installedMWs. The limitedmeasuring capacitymay yield artificial permeability scale effects as often registered in environmental studies.

Uncontrolled Keywords

Monitoring well,Permeability test,Screen,Filter pack,Aquifer

Open Access document in PolyPublie
Subjects: 1000 Génie civil > 1002 Géotechnique (y compris génie géologique)
Department: Département des génies civil, géologique et des mines
Research Center: Non applicable
Funders: Fonds québécois de la recherche sur la nature et les technologies (FQRNT), CRSNG / NSERC
Grant number: RGPIN109540-08
Date Deposited: 09 Jan 2019 13:00
Last Modified: 10 Jan 2019 01:20
PolyPublie URL: https://publications.polymtl.ca/3467/
Document issued by the official publisher
Journal Title: Engineering Geology (vol. 184, no. C)
Publisher: Elsevier
Official URL: https://doi.org/10.1016/j.enggeo.2014.11.006

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