and in ideal conditions, the treatment yields are usually very high (sometimes above
99%), and treatment duration is relatively short (from a few weeks to a few months).
Additionally, free product thermal enhancement recovery improves the remediation rates and yields of the DNAPL. Large diameter auger soil mixing with steam
injection and electrical resistance heating are more appropriate for less permeable
soils. Depending on the heating temperatures, ISTT may be used in combination
with physical recovery, chemical reactions, and biological treatment processes.
The ISTT process, though tested and approved, does require very advanced
studies and tests to be conducted beforehand. The process is often costly so it should
primarily be used for contaminated hot spots. The high remediation rate and short
treatment durations are definitely the added value of this technique which can make
it a cost-saving option in some cases (if one considers the overall investment and
operation costs). Research efforts must be undertaken to improve calculations of the
Scale:
Fig. 3.26 Temperature fields in the ground, vertical sections (at the end of the 72-day heating
period) (Broquaire et al. 2014)
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