Elevated temperatures have been measured in some municipal solid waste landfills. These temperatures, at times greater than 300°F, are not caused by fire but can cause significant difficulties with gas and leachate management systems.
And because ETLFs are of environmental concern to landfill owners, designers, and regulators, Geosyntec was asked to design and install instrumentation to measure temperatures in a dozen elevated temperature landfills (ETLFs) across the U.S. The objectives of the assignment are to better understand the magnitude of the temperatures and the spatial distribution of the thermal conditions inside these landfills, and to provide data that can be used for thermal modeling to diagnose what is causing the rise in temperatures and monitor the effectiveness of remedial actions to contain and possibly cool the exothermic reaction.
Geosyntec's Scope of Services
After researching various types of instrumentation, Geosyntec's engineers realized that the harsh leachate, gas, and waste conditions in ETLFs would render the service life of traditional types of thermal instrumentation such as thermocouples and thermistors to unacceptably short durations. Therefore, we chose to adapt fiber optic distributed temperature sensing (FODTS) technology which has been used to measure downhole temperatures in oil and gas wells for many years. The FODTS system Geosyntec developed is much more flexible and durable than other instrumentation and allows for data verification by numerically comparing feedback from various wavelengths (a method known as Stokes/anti-Stokes analysis) without needing to remove the optical fibers from the landfills.
Geosyntec installed FODTS cables in a number of landfills and trained site personnel in how to obtain the fiber optic measurements. We are also performing maintenance of the FODTS systems on an as-needed basis and are providing interpretation of the data to guide the client in regulatory interactions and planning remedial activities.
Geosyntec worked closely with a notable fiber optics supplier to provide cable with robust yet flexible steel armoring to withstand the harsh ETLF conditions yet remain flexible enough for easy installation and to tolerate movements caused by waste consolidation. We coordinated the manufacturing of over four kilometers of the fiber optic cable on a very tight schedule such that installation at all the landfills could be completed within a 6-month timeframe. While installing the FODTS systems at the landfills, Geosyntec also developed vertical profile graphing and 3-dimensional imaging routines to assist the client in visualizing the temperature distribution within the various sites.
The wide geographic spread of Geosyntec's offices and versatility of our staff allowed us to use local field personnel at the numerous sites. As such, the work at all twelve landfills was accomplished on time and under-budget. The client has recently approached Geosyntec for temperature monitoring at additional sites and follow-on 3D modeling of the ETLFs going forward.
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- Location: North America
- Client: Confidential
- Project Practice Areas: Waste Management, Geotechnical
- Type of Facility: Solid waste landfill
- Services Provided: Thermal Instrumentation Design, Data Collection & Monitoring, Data Analysis & Interpretation / Consulting
- Type of Work: Geotechnical monitoring
- Governing Regulation: Federal and state regulations