Soil and groundwater contamination from volatile organic compounds (VOCs) poses a major threat to the environment, especially in industrial areas. This case study examines a project in Ontario, Canada, where effective remediation techniques were used to handle VOC pollution at a former metal fabrication site. Utilizing In Situ Thermal Desorption (ISTD) alongside soil vapor extraction, the project significantly reduced harmful contaminants and improved overall site safety.
Overview of the Project
This site had alarming levels of VOC pollution. Key contaminants included Trichloroethylene (TCE), Dichloroethylene (DCE), Dichloroacetic Acid (DCA), and Trichloroacetic Acid (TCA), all detected at concentrations well above Canadian water quality standards. The industrial nature of the facility necessitated urgent remediation to protect public health and comply with regulations.
The project aimed to effectively eliminate Dense Non-Aqueous Phase Liquids (DNAPLs) through a structured approach. Over a 84-day period, 50 heating tubes were installed to heat the soil to an impressive 100°C, resulting in a 98% destruction efficiency of these harmful compounds. The combination of technologies not only targeted vapor extraction but also enhanced recovery efforts.
Geology and Remediation Challenges
The geology of the site complicated the remediation plan. Dominated by silty clay and silt, the low permeability of these soils made conventional groundwater remediation methods ineffective. This challenge highlighted the need for a more dynamic solution like ISTD.
To address these geological conditions, the project team installed 50 strategically placed wells. This included 30 Geothermal Treatment Rig (GTR) heaters and 12 Soil Vapor Extraction (SVE) wells, which helped reach a maximum depth of 5 meters. Achieving the target temperature of 100°C was vital to dissolve the VOCs and enhance extraction. This targeted thermal desorption ensured significant breakdown and removal of contaminants, substantially improving the site's environmental safety.
Energy Consumption and Operational Efficiency
Monitoring energy use was critical during the 84-day remediation process. The project consumed a total of 99,719 kWh of electricity and 144,482 m³ of gas. The team placed a strong emphasis on operational efficiency to ensure that while remediation goals were met, energy waste was minimized.
By carefully analyzing energy requirements, the project team made informed adjustments throughout the operation, helping to maintain efficiency while achieving their remediation objectives. This focus on energy consumption not only supported the project’s sustainability goals but also kept operational costs manageable.
Key Remediation Results
After 84 days of dedicated heating, the project successfully eliminated 98% of groundwater contamination. This notable success rate of the ISTD method demonstrated its effectiveness in addressing VOC pollutants in complex industrial settings.
Moreover, the remediation strategy proved to be not only applicable for this specific site but also scalable to other sites with similar geological conditions. With VOC contamination being a prevalent issue in industrial areas, the lessons from this project can inform future efforts and lead to more effective environmental protection strategies.
Closing Thoughts
The case of In Situ Thermal Desorption in Ontario offers a valuable example of tackling VOC contamination in industrial settings. By integrating advanced ISTD methods with soil vapor extraction, the project effectively addressed significant environmental concerns, showcasing remarkable outcomes in a short timeframe.
As the scrutiny over VOCs intensifies due to their health implications, this case underscores the importance of innovative and adaptable remediation techniques. Implementing lessons from this project could help industries facing similar challenges develop sustainable solutions for contaminated soil and groundwater.
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