Troubleshooting Your Vibrating Wire Piezometer: Common Errors and How to Fix Them

The vibrating wire piezometer (VWP) is known for its durability, accuracy and reliability in long-term geotechnical monitoring. But even the most robust of these sensors can run into problems if not installed, configured and maintained correctly.

Understanding the most common VWP errors (and how to fix them) is essential in keeping your monitoring system accurate and compliant with Western Australian regulations.

In this post, we cover typical issues encountered with VWPs across boreholes, tailings dams and settlement monitoring programs. You’ll also learn how Monitel helps clients prevent and resolve these errors in the field.

What Is a Vibrating Wire Piezometer?

A vibrating wire piezometer measures pore water pressure by detecting changes in the tension of its main wire. As pressure on the diaphragm changes, the frequency of the vibrating wire shifts. The frequency is then converted into readable data either manually or via automated loggers.

VWPs are known for their resistance to electrical interference and moisture, making them ideal for the challenging conditions so common across WA. However, their performance still depends on proper installation, configuration and calibration.

Common VWP Issues and How to Fix Them

1. No Signal or Flatline Readings

What’s the issue?: The sensor is not outputting any data or the signal is stuck at a constant value.

Possible Causes:

• Broken or damaged cabling
• Incorrect wiring to the data logger
• Moisture ingress into the cable or junction box
• A failed sensor (although this is unlikely)

How to Fix It:

• Inspect all cabling and connectors for damage or water ingress.
• Test the continuity of the cable using a multimeter.
• Ensure that polarity and signal wiring are correctly configured at the logger.
• If everything checks out but the sensor remains unresponsive, replacement may be necessary.

2. Unstable or Noisy Readings

What’s the issue?: The data shows irregular spikes, oscillations or inconsistent values.

Possible Causes:

• Electrical noise interference (possibly from nearby equipment)
• Poor grounding of the logging system
• Loose connections or compromised shielding
• Temperature fluctuations affecting unshielded installations

How to Fix It:

• Relocate the sensor cable, creating distance from power sources or high-voltage equipment.
• Check that the logger and all sensor cabling are properly grounded.
• Use shielded cables and ensure connections are tight.
• Consider using temperature compensation in the logger settings.

3. Drift Over Time

What’s the issue?: The sensor data gradually changes in one direction without any real change in pore pressure.

Possible Causes:

• Sensor diaphragm degradation
• Excessive temperature exposure (especially above rated range)
• Air entrapment around the diaphragm
• Long-term material fatigue

How to Fix It:

• Use high-temperature VWPs such as the VWPHT-3600 for thermally active sites.
• During installation, ensure full saturation of the filter tip to avoid air pockets.
• If drift persists, recalibration or sensor replacement may be necessary.

4. Zero Readings in a Wet Environment

What’s the issue?: The piezometer is reading no pressure despite being submerged.

Possible Causes:

• Incorrect elevation reference used during installation
• The filter tip may not be fully saturated
• Sensor was installed above the water table or pressure zone
• Faulty logger calibration

How to Fix It:

• Double-check piezometer depth against borehole logs or groundwater level data.
• Ensure proper installation of sand and bentonite seals around the filter tip.
• Validate and adjust logger calibration or reference values.

Preventing Errors During Vibrating Wire Piezometer Installation

With proper planning and execution, projects can avoid many of the problems listed above. At Monitel, we follow a strict vibrating wire piezometer installation process that ensures:

• Sensors are selected based on site conditions (e.g. high-temp VWPs for heated environments)
• Cabling and junction boxes are sealed and weatherproof
• Boreholes are prepared with the correct sand filter and bentonite seal configuration
• All sensors are tested and zeroed prior to installation
• Data loggers are configured with project-specific tolerances and alert thresholds

We have designed this approach to keep all monitoring systems compliant with the the Work Health and Safety (Mines) Regulations 2022 and Mines Safety and Inspection Regulations 1995.

Effective monitoring and proven compliance are our priority. That is why we champion a product and technology agnostic approach, always choosing the best sensor for your site, not our bottom line.

Design and Implement a Monitoring System with the Monitel Team

Whether you’re installing VWPs for the first time or troubleshooting an existing system, the Monitel offers practical support. That includes:

• Diagnostic testing for sensor and logger faults
• Field recalibration and replacement services
• Automated alert configuration and data reporting
• System audits to ensure compliance with local requirements

If you would like to speak with our team about unusual data, absent data or another issue, please contact Monitel at admin@monitel.com.au or call (08) 6219 8284. Our team can help identify the cause and get your monitoring system back on track.