Landfill caps and moisture measurement
25 May 2026
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Why is it important to measure moisture in landfill caps? Monitoring in landfill caps (covers) is critical because water is the primary driver of landfill environmental risk and cap performance degradation. A well designed cap is intended to minimise infiltration—but its effectiveness depends heavily on maintaining suitable moisture conditions.
The primary objective of a landfill cap is to limit rainfall infiltration into waste. Infiltration can be an issue as excess moisture penetrating the cap increases leachate production. This can result in:
- Mobilising contaminants (metals, organics, nutrients)
- Increases load on leachate collection/treatment systems
- Raises risk of groundwater contamination
Understanding moisture levels is also important if an evapotranspiration cover is in use. These covers need to have the correct level of moisture for plants. If too high, then there may be drainage beyond the root zone. If too low, vegetation can die-off leading to an erosion risk.
Use of Aquaflex Soil Moisture Sensor in landfill applications
The Aquaflex soil moisture sensor from OnFarm Data is certainly a suitable instrument for use in landfill cap monitoring. It is a proven soil moisture and temperature sensor, that was developed at Lincoln University in New Zealand some 20 years ago. The sensor measures soil moisture along its 3m length, sampling approximately 6 litres of soil, providing highly reliable data over a large area. Aquaflex is robust, buried in the root zone, easy to install or relocate, and designed for long term continuous monitoring with minimal maintenance. It is pre calibrated for all soil types and also measures soil temperature, which is used internally to compensate moisture readings for improved accuracy.
Aquaflex can be supplied as a standalone sensor for integration with existing loggers, or as a complete monitoring system with data logging and telemetry. It supports manual, Bluetooth, cellular, or mesh radio data collection and is typically solar powered with battery backup. Easy of use and straightforward data presentation make it a great tool for monitoring your landfill cap.
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