Thermal Design and Best Practices – Real-Time Solutions to Unexpected Challenges Encountered During Thermal Conductive Heating Projects

Steffen Griepke, VP of Technology, TerraTherm, a Cascade Company

Background/Objectives. An in situ thermal design may look good on paper, but how will it perform in the field? Thermal Conductive Heating (TCH) has been utilized commercially for more than 25 years since Shell TerraTherm developed the technology in the early 1990’ies. TCH is now a widely used thermal technology capable of effectively remediating a variety of chemicals in highly variable geological settings, ranging from tight clays, over heterogeneous mixtures and into bedrock, but sometimes operations do not perform as planned. Due to the aggressive nature and high daily operational cost of a thermal remedy, operational issues must be addressed immediately, typically within days rather than weeks. Additionally, remedies implemented in populated settings and sensitive environments often draw a high degree of public focus, and therefore, rapid reactions and responses are needed when problems are encountered.

Approach/Activities. Lessons learned from more than 80 full-scale TCH projects will be discussed, focusing on the common operational issues that arise during full-scale TCH projects, including:

• Handling unexpected deep or shallow groundwater flow cooling the thermal treatment zone;
• Selecting appropriate construction materials for the aggressive environment developed when mixtures of chemicals are heated, temperatures are getting high, and reactions are triggered;
• Selecting appropriate treatment system components to handle high contaminant mass loadings above 2,500 pounds per day and dealing with unanticipated chemicals during heating;
• Addressing health and safety concerns in the vapor treatment system when vapor concentrations are approaching the Lower Explosion Limit;
• Addressing emulsions and biological-related issues in the liquid treatment system;
• Dealing with unanticipated subsidence, that may compromise the basic wellfield design features;
• Adapting to the ever-changing conditions in the thermal treatment system as temperatures and chemical compositions change over time; and
• Mitigating vapor intrusion and odor issues when thermal remedies are conducted near or under buildings or in populated settings.

Results/Lessons Learned. This presentation will focus on solutions implemented at TCH sites in response to real-time challenges, to keep the remedy on track and meet project goals. The presentation will cite and provide examples from numerous full-scale case studies, including thermal remedies implemented at Superfund sites, chemical factories, and waste sites to showcase the ever changing and dynamic world of TCH thermal remediation. The “on the fly” adjustments implemented by the thermal team and the impact on meeting project goals will be presented.

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