TCH ModerateTemperature

At moderate temperatures (~100°C), TCH is applied to the recovery of Volatile Organic Compounds (VOCs) such as TCE, PCE, and BTEX. A non-desiccation approach is used for sites impacted with VOCs since it is not necessary to boil off much of the soil water to successfully recover the contaminants. Using the moderate temperature application of TCH, the temperature of the soil within most of the treatment volume is raised to the boiling point of water, generating steam in situ. This results in very effective steam-stripping/distillation of the contaminants. The contaminant vapors and steam are then collected and captured for treatment in an Air Quality Control system.

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Site Location	Major COC	Mean Pretreatment Concentration mg/kg	Mean Post-treatment Concentration mg/kg
Confidential Midwest Site	TCE	99.7 (max conc./history indicate DNAPL likely present)	0.070
Richmond, CA	PCE	34.2 (max conc./history indicate DNAPL likely present)	0.012
Carson, CA	1,2-DCA	903 (max conc./history indicate DNAPL likely present)	0.23
Confidential Southeast Site	TCE	DNAPL	0.017
Syracuse, NY	PCE	2,864 (max conc./history indicate DNAPL likely present)	3.8
NASA Marshall Space Flight Center, Huntsville, AL	TCE	47.65 (max conc./history indicate DNAPL likely present)	0.060

Thermal Solidification of Coal Tar

The moderate temperature application of TCH can also be used to achieve In Situ Thermochemical Solidification (ISTS) of coal tar at sites such as former Manufactured Gas Plants (MGP). During this moderate temperature application of TCH, coal tar is removed and organic compounds such as benzene and naphthalene are volatilized, permanently stabilizing and solidifying any remaining MGP coal tar constituents in place. The remaining constituents are immobilized within an asphaltic matrix, similar to asphalt pavement. They are non-leachable by both Toxicity Characteristic Leaching Procedure and Synthetic Precipitation Leaching Procedure (Hayes, 2002).

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