Journal Published Online: 10 February 2022
Volume 45, Issue 3

Barometric Fluctuations and Duration of Variable-Head (Slug) Field Permeability Tests

CODEN: GTJODJ

Abstract

Variable-head (VH) permeability tests are carried out in monitoring wells, driven permeameters, and between packers to assess local values of hydraulic conductivity. Most often, the water level position data are given versus time by a pressure transducer (PT) and an atmospheric pressure transducer (APT). Because the data vary with time, the PT and APT need to be synchronized. This article first shows what happens when a single correction for atmospheric pressure, patm, is used for all PT data for two slug tests, one in an aquifer, the other in an aquitard. Then, the article documents the patm fluctuation, including its maximum and minimum values during a given time, pmax and pmin, at a site and their statistical analysis for periods from 1 h up to 1 year, based on a 59-year data set. During a given time, the (pmax − pmin) value follows a lognormal distribution. For short testing times, typically less than 2 h, the patm value varies by less than 2 or 3 cm in 99 % of cases. The mean of the lognormal distribution increases with the observation time or test duration. The standard deviation is nearly constant for periods up to 30 days, and then decreases for periods from 1 month to 1 year. Synchronized data are needed to make a time-variable correction for all tests lasting more than 2 h, and the time-variable correction is the correct method for all slug tests, including short duration ones in aquifers.

Author Information

Chapuis, Robert P.
Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montreal, Quebec, Canada
Marefat, Vahid
Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montreal, Quebec, Canada Department of Earth and Infrastructure, BBA, Montreal, Quebec, Canada
Zhang, Lu
Department of Civil, Geological and Mining Engineering, Polytechnique Montréal, Montreal, Quebec, Canada College of Construction Engineering, Jilin University, Changchun, China
Pages: 18
Price: $25.00
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Stock #: GTJ20200287
ISSN: 0149-6115
DOI: 10.1520/GTJ20200287