How to Correctly Interpret Strange Data for Field Permeability (Slug) Tests in Monitoring Wells or between Packers

Falling-head and rising-head permeability tests have been carried out in monitoring wells, driven permeameters, and between packers for approximately one century. Recent tests are usually performed with a pressure transducer and an atmospheric pressure transducer, which should be synchronized, but this is rarely done. This article examines examples of strange test data for aquifers, due to field and human factors, and explains how to make an adequate interpretation. Many quality issues are listed, including poor decisions made by people who interpreted test data. Most often, a slug test has not a single quality issue but an assortment of interactive issues. Eight examples (1–8) are analyzed for (1) a too-small initial water column, (2) a shaky start when using compressed air, (3) inaccurate data for the water column height versus time, (4) variation in atmospheric pressure during the test, and (5–8) a few mixtures of listed issues with a poor estimate of the piezometric level for the test, which is ever-present. Clear plots illustrate each example. Explanations are given and listed on how to proceed to properly take into account quality issues for slug test data in aquifers. Clear rules are given to anyone who has to plan, perform, and interpret a slug test. Recommendations are made to improve a few standards and limit the risks of quality problems.