In urban areas, old industrial sites often hide contamination that threatens public health and the environment. This case study focuses on a former dry cleaner site in Quebec, Canada, where harmful substances like Perchloroethylene (PCE) and Total Petroleum Hydrocarbons-diesel (TPH-d) posed significant challenges. This post outlines how an in situ thermal treatment (ISTD) project effectively remediated this site, showcasing the technology used, the impressive outcomes, and the lessons learned for sustainable redevelopment.
Project Setting
The site in question featured a mix of silty clay, silt, and gravel, complicating the remediation process. The historical use of PCE for dry cleaning led to severe contamination that called for immediate action. To remedy this, the project aimed to reach a temperature between 80°C and 100°C during a 135-day heating period. This was crucial to effectively vaporize and remove the volatile organic compounds (VOCs) and TPH-d trapped within the soil and groundwater.
The project involved the installation of 33 Thermal Conductive Heating (TCH) wells at a depth of 25 feet and 18 Multi-Phase Extraction (MPE) wells to extract contaminated air and liquids concurrently. This detailed setup allowed for effective management of the complex contamination issues present at the site.
Remediation Goals
The main goal was to reduce PCE levels in the soil to below 5 mg/kg, completely eliminate light non-aqueous phase liquids (LNAPL), and achieve a contaminant removal efficiency exceeding 99%. In situ thermal treatment was selected for its target-specific approach to degrading contaminants in both soil and groundwater.
Throughout the project, constant monitoring of temperature was essential. This rigorous oversight ensured optimal heating behavior and an efficient breakdown of harmful compounds.
Implementation and Results
Once initial site preparations were completed, the ISTD technology was put into operation. Over the course of 135 days, the project team achieved impressive results. A greater than 99% reduction in contaminants within both the soil and groundwater was realized.
A noteworthy achievement was the complete removal of LNAPL (TPH-d) along with significant reductions in PCE and other VOCs. Follow-up sampling confirmed compliance with established remediation goals, marking this project as a resounding success.
These results illustrated how effective ISTD can be, even in complex geological conditions. The success of this project not only addressed contamination issues but also supported the case for safe redevelopment of industrial sites.
Implications for Redevelopment
The successful remediation of the dry cleaner site paves the way for sustainable redevelopment. By tackling environmental contamination head-on, the project lays a foundation for future urban development efforts.
Moreover, achieving substantial reductions in contaminants has a positive impact on indoor air quality for surrounding businesses, enhancing community health and safety. This dual benefit shows that effective remediation not only reduces environmental hazards but also revitalizes urban areas, promoting economic growth.
Summary of Findings
In situ thermal treatment has emerged as a capable solution for remediating industrial sites plagued by persistent contaminants like PCE and TPH-d. This project exemplifies how careful planning, proper implementation, and continuous monitoring can lead to successful outcomes, even in challenging geological contexts.
The documented outcomes from this case study make a compelling case for ISTD as a solution in future urban remediation projects. With the right strategy and technology, it is possible to proceed with sustainable redevelopment. This project stands as an important reference for environmental professionals and stakeholders interested in fostering safer urban environments.
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