APPLICABLE CONTAMINANT TYPES
Thermal Remediation of Chlorinated Volatile Organic Compounds (CVOC) i.e., halogenated VOCs
With most CVOCs, we recommend a target temperature of 100°C (i.e., boiling point of water at ambient elevation/pressure). As the site is heated, the vapor pressures and Henry’s Law Constants of the various CVOC constituents increase. Therefore, as the temperature is increased, CVOCs will readily enter the gas phase, enabling their removal by vapor extraction and/or multiphase extraction.
Treatment approaches and wellfield configurations for CVOCs vary depending on the nature of the site and which technology or combination of technologies is chosen. The main design objectives are to achieve the selected target temperature throughout the Target Treatment Zone (TTZ), and ensure recovery of the resulting vapors and steam. When properly designed, such a system prevents condensed vapors from being left behind in cold spots.
Achieving 100°C within the treatment zone is sufficient to boil off CVOC DNAPLs and to volatilize and steam-strip dissolved and sorbed CVOCs. Removal (i.e., boiling off) of 10 to 30% of the water within the treatment zone is sufficient to achieve MCLs in groundwater and/or >99.9% reductions in soil concentrations (e.g., <1 mg/kg in source zones).
Thermal Remediation of Semi Volatile Organic Compounds (SVOCs), Polycyclic Aromatic Hydrocarbons (PAHs) and Manufactured Gas Plant (MGP) Coal Tar
Cascade Thermal’s proprietary thermal conduction heating (TCH) technology has been proven capable of complete remediation of Semi-Volatile Organic Compounds (SVOCs) including Polychlorinated Biphenyls (PCBs) (see table below), Creosote, and Coal Tar. Project applications completed to date include PCB sites, Manufactured Gas Plant (MGP) sites, military sites, and former wood treatment facilities.
Thermal Remediation of DNAPL
In Situ Thermal Remediation (ISTR) technologies achieve excellent results in remediation of Dense Non-Aqueous Phase Liquid (DNAPL) source zones in soil and groundwater.
Over the past decade, TCH, steam enhanced extraction (SEE), and electrical resistance heating (ERH), have been employed alone and in combinations to effectively treat DNAPL sites in a wide variety of geological settings.
While SEE has its greatest applicability to higher permeability zones beneath the water table through which injected steam can flow, ERH and TCH are most often applied within low and moderate permeability zones and in heterogeneous geologic settings. The invariance of thermal conductivity across a wide range of soil types means that TCH is an excellent fit in lower-permeability and heterogeneous formations for treatment of DNAPL. ERH and SEE can effectively address DNAPL containing chlorinated solvents, but are limited to achieving the boiling point of water. They are therefore not well-suited to treating higher-boiling types of DNAPL such as coal tar or creosote. TCH alone has applications for contaminants with moderate to high boiling points.