A trio of CEC Monroeville Waste Management practice staffers co-authored an article appearing in the February 2025 issue of Waste Advantage magazine.
Tim Mitchell, P.E., Principal; Zach Metzler, E.I.T., Project Manager; and Brad Nagy, Project Consultant, explained the benefits of using remote monitoring of landfills for our waste clients and improving the overall safety at various sites in the article — Management of Slope Stability Risks Using Geotechnical Instrumentation in Landfills.
Geotechnical instruments are ideal for monitoring the long-term stability of landfill slopes. They offer real-time data that aids in making informed decisions about necessary interventions and helps manage or reduce potential risks. The data from these remote devices allows our engineers to detect and address issues before they become critical and costly to our clients.
The implementation of various sensors and devices allows the client, as well as CEC, to monitor the physical properties and behavior of the waste mass. The instruments used include piezometers/vibrating wire piezometers; stability monitoring points (SMPs), global positioning (GPS) units and settlement plates; inclinometers and tiltmeters; and thermistors. All of these instruments can be set up for cloud-based data collection, storage, and interpretation.
Beneficial In Both Data Collection and Cost Savings
Traditional monitoring is labor-intensive which leads to infrequent data events. The observation at the sites is also subjective. What one inspector deems normal, the next might see it as a possible problem.
“Ten years ago, we had to collect the data manually, then that data was reduced and interpreted by an engineer, and finally, shared with the stakeholders,” Tim says. “Now all of the data is interpreted immediately, with CEC and the clients seeing it all in real time.”
Brad adds, movement thresholds are in place for each type of instrumentation, allowing automated alerts to convey concerning observations immediately, without the need for engineering review. “The traditional method of data collection is super labor intensive. Now we have a constant data stream every hour, on the hour,” he adds.
While the initial cost of installing these instruments is higher than traditional methods, over the life cycle of the project, the cost savings can be significant associated with reduced trips to the site to collect data.
The safety benefits are immeasurable. “The old way of collecting data put people in danger, especially in unstable slope areas, where these automated systems keep people safe,” Zach says.
Traditional Monitoring vs. Remote Monitoring
Traditional slope monitoring:
- Labor-intensive which leads to infrequent data events
- Personnel put in danger
- Time delays to interpret data
- Time delays to relay observations
Remote monitoring:
- Higher initial cost, but much more affordable long term
- Keeps personnel safe
- Provides real-time, constant stream of data
- Automated alerts convey concerning observations immediately
What Do the Instruments Measure?
Piezometers are used to measure pore pressures within the waste mass. Those typically used at landfill facilities are open standpipes piezometers and vibrating wire piezometers. The SMPs, GPS sensors, and settlement plates monitor horizontal and vertical movement of the landfill slopes over time. The inclinometers measure the angle of the slope (the tilt) and are crucial for monitoring the stability of the landfill slope and detecting ground movement. Tiltmeters are attached to a post and installed three feet below ground level to monitor ground movement near an excavation or an area of known movement. Thermistors can be used at sites with elevated temperature concerns, providing data at the subsurface level, as well as giving a profile view. Remote sensing data can be integrated with ground-based geotechnical instruments to check areas susceptible to slope stability issues. These remote sensing units are also used to detect long-term trends and patterns.
Presenting on the Topic at Step Up Your Game
In addition to contributing to the Waste Advantage article, Zach and Brad will be presenting the topic at CEC’s next Step Up Your Game conference. Step Up Your Game (SUYG) is a technical conference held at our headquarters. It allows our employees the opportunity to create fresh content and work with a senior mentor from the SUYG Steering Committee to develop and polish a presentation.
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