How to Interpret Vibrating Wire Piezometer Data and Understand Pore Pressure Trends

To ensure stability, structural integrity and compliance on site, project managers must have a firm understanding of pore pressure behaviours. For complex sites like tailings dams and deep boreholes, a vibrating wire piezometer (VWP) can prove an important tool.

Known for their high accuracy and reliability in long-term monitoring, VWPs provide the data that allows engineers to make informed, proactive decisions. But what exactly should you be watching for when analysing VWP data?

This article outlines the key pore pressure trends to monitor, what they mean for your project, and how Monitel can support you in interpreting and acting on these changes.

If you would like to learn more about vibrating wire piezometer selection, installation and pricing, please contact our team.

What Is Pore Pressure and Why Does It Matter?

Pore pressure is the pressure exerted by water within the pores of soil or rock. It has a direct influence on ground stability, particularly under load or during changes in moisture, temperature or excavation. If allowed to rise beyond expected levels, pore pressure can slop failures, foundation instability or, in the case of tailings dams, collapse.

Continuous monitoring with a VWP is the surest way to identify warning signs early and implement proactive responses before conditions become unsafe and non-compliant.

What is a Vibrating Wire Piezometer and How Does it Capture Pore Pressure Trends?

Capable of high-performance in harsh environments, VWPs are the preferred sensor for much of WA’s resources and infrastructure industries.

They convert water pressure changes into frequency signals, which are logged either manually or via automated data acquisition systems. This makes them especially useful for establishing baselines and monitoring fluctuations over time. VWPs can be installed in boreholes, embankments and dam walls, amongst other applications.

The 5 Pore Pressure Trends You Should Monitor

1. Seasonal Variation

In surface soils and shallow boreholes, you’ll often see pore pressure fluctuate with seasonal rainfall and evaporation cycles. Sites must ensure that any changes in data match climate variations. For example, higher readings after prolonged wet periods are normal, but sudden increases outside expected rainfall windows may indicate water ingress or drainage failure.

What to watch for:

• Gradual pressure rise during rainy seasons
• Return to baseline during dry conditions
• Anomalous surges outside seasonal norms

2. Construction-Induced Changes

On active sites like road, tunnel or mine developments, pore pressure may change in response to ongoing works. This could be the cause excavation, dewatering or loading. A spike may reflect stress redistribution or soil saturation and more rapid changes should be afforded immediate attention.

What to watch for:

• Sudden jumps in pressure following excavation or fill
• Unexpected recovery of pressure after dewatering
• Persistent pressure elevation without external cause

3. Consolidation Trends

In soft clays, pore pressure will initially rise under new load before dissipating as water escapes and soil consolidates over time. A well-installed vibrating wire piezometer can help track this consolidation curve, indicating settlement rates and potential for future movement.

What to watch for:

• Initial high readings after load placement
• Steady decline in pressure as water drains
• Deviations from expected settlement curves

4. Tailings Dam Pore Pressure Build-Up

Excess pore pressure within a tailings structure could indicate that material is not draining properly or that there’s seepage from upstream sources. When installed at various depths VWPs will pinpoint the layer or zone of concern.

What to watch for:

• Pressure increase after new tailings deposition
• Inconsistent readings between piezometer layers
• Lack of expected dissipation over time

5. Groundwater Recharge and Drawdown

When monitoring wells, VWPs can track groundwater responses to nearby abstraction, rainfall events or aquifer recharge. These trends help model aquifer behaviour and support compliance with the Department of Water and Environmental Regulation (DWER).

What to watch for:

• Slow recharge rates indicating reduced permeability
• Rapid drawdown suggesting over-abstraction
• Long-term baseline shifts across seasons or years

Contact Monitel for Reliable, Accurate & Informed Vibrating Wire Piezometer Data

Pore pressure is a dynamic, high-stakes factor on geotechnical sites. While VWPs provide the raw data, it takes contextual understanding to interpret it. This is where Monitel supports clients: by going beyond installation to create actionable monitoring frameworks.

Our team helps interpret vibrating wire piezometer data by:

• Establishing site-specific baseline pressure levels
• Creating trend thresholds for alerts
• Automating data transmission and flagging anomalies
• Linking pressure changes with onsite activities or environmental events

This ensures that pore pressure trends are not just recorded, but used to improve site safety respond early to prevent instability and delay.

At Monitel, our team have created tailored monitoring systems on sites across Western Australia. To learn more about how we can help you monitor pore pressure safely and effectively, contact us at admin@monitel.com.au or call (08) 6219 8284.