Water Pressure Monitoring Using Fully-Grouted Vibrating Wire Piezometer Installations

Copyright © 2026 U. S. Society on Dams Printed in the United States of America ISBN 979-8-9870559-4-6 

FOREWORD 

The importance of monitoring programs for dam safety is widely accepted.  There are many historical cases of dam failures where early warning signs of failure might have been detected if a well-designed, well-executed dam safety monitoring program had been in place.  A monitoring program can provide information that is needed for a good understanding of the on-going performance of a dam.  Monitoring programs, including instrumentation and visual inspection, provide dam owners with knowledge of whether a dam is performing as expected and the ability to detect changes in performance.  This knowledge and ability is critical because the dam owner is directly responsible for the consequences of a dam failure.  Therefore, a well-designed, well-executed dam safety monitoring program must be a key part of every dam owner’s risk management program. 

This paper is part of a series of white papers prepared by the United States Society on Dams (USSD) Monitoring of Dams and Their Foundations Committee (the Committee) to address important topics with respect to the development and successful implementation of dam safety monitoring programs.  White papers in this series include: 

• Why Include Instrumentation in Dam Monitoring Programs?
• Routine Instrumented and Visual Monitoring of Dams Based on Potential Failure Modes Analysis
• Development of a Dam Safety Instrumentation Program
• O&M of an Instrumentation Program
• Instrumentation Data Collection, Management and Analysis
• Dam Safety Monitoring Training for Dam Operating Personnel 

While each of the above white papers addresses its topic in a “stand-alone” manner, there are interrelationships between these papers.  Readers of this paper may find it beneficial to refer to one or more of the other white papers for a broader understanding and perspective with respect to dam safety monitoring programs.  Up to this point in time, the series of white papers has primarily addressed programmatic aspects of dam safety monitoring rather than technological advances.  These papers that are programmatic in nature should provide dam owners, large and small, with basic information to evaluate or implement an adequate dam safety monitoring program.  These programs become more and more critical as our nation’s dams (and other infrastructure) reach and extend beyond their design lives. 

This particular white paper moves away from the pattern of discussing more general, programmatic dam safety monitoring topics to address a specific technical matter.  Proposals for the use of fully-grouted piezometer installations, rather than traditional piezometer installations (e.g., VW transducers or Casagrande standpipes installed in boreholes using sandpacks and bentonite chip seals), have resulted in technical discussions where people and organizations have reached a variety of conclusions.  The intent of this white paper is to shed light concerning when the use of fully-grouted 2 piezometer installations may and may not be appropriate and provide current “state-ofthe-practice” guidance for this installation approach.     

This white paper resulted from the work of a Sub-Committee of the USSD Monitoring of Dams and Their Foundations Committee.  Principal contributors to the effort were:

Pierre Choquet, DrEng., PEng., RST Instruments, Lead Author
John Hynes, PE, Stantec
Scott Martens, MEng., PEng., Teck Resources
Rudy Saavedra, PE, Durham Geo Slope Indicator
Jay N. Stateler, PE, retired from U.S. Bureau of Reclamation
Georgette Hlepas, PhD, PE, U.S. Army Corps of Engineers
Gerald Robblee, PE, GE, Schnabel Engineering
Michael Davis, PE, PEng., Stantec/TransAlta
Doug Wahl, PE, Geo-Pentech
Gordon Anderlini, PEng., BC Hydro
John Murphy, PE, U.S. Army Engineer Research and Development Center 

The Sub-Committee members would like to thank Jay N. Stateler for initiating this project and for preparing the first detailed draft that has remained the framework of the final version of the white paper. 

A Publication Review Committee (PRC) was formed by the USSD to review this paper composed of:

Tim Truong, PE, PMP, Yuba Water Agency, USSD Board Member and PRC lead 
Members of the TC220 on Field Monitoring in Geomechanics of the(International Society on Soil Mechanics and Geotechnical Engineering (ISSMGE),with special thanks to Leen De Vos, PhD, Civil Engineer, Flemish Government
Gord McKenna, PhD, Peng, PGeol, McKenna Geotechnical
Brad Long, PE, HDR
Matthew Walker, PE, Barr Engineering
Bradley Forbes, PhD, Peng, BGC Engineering   

The work of all these individuals, as well as the other members of the USSD Monitoring Dams and Their Foundations Committee that provided input regarding this white paper, is acknowledged and appreciated.