How and why piezometers in an earth dam?

ABSTRACT: The focus of this paper is to explain how and why piezometers should be installed in an earth dam. The paper describes the importance of piezometer installation in the core, the filter and the foundation of an earth dam. During the first filling of the reservoir, piezometers help to understand the effect of core saturation on dam stability and the effect of rising pore water pressure in its foundation and the dam itself. During the first year after the first filling, the piezometer readings can detect a defect or an unpredicted behaviour. Finally, for the purpose of performance evaluation, piezometric level facilitate the understanding of dam behaviour or can reveal unexpected high pore water pressures. The article also briefly discusses other instruments that can be paired with piezometers. Additionally, the paper presents the important elements to consider for the piezometer and its components. Some installation procedures are presented to ensure a good working order for the longest life expectancy of the instrument. These procedures include the activities for the verification of instruments on the site, the general installation steps and the on-site method for putting in place the instrument from the measuring point to instrument shelter. The associated elements required to protect the piezometer are also described. Furthermore, some constraints for construction equipment after installation, the selection of piezometer locations and redundancy requirements are presented.