Smoldering remediation of coal-tar-contaminated soil: pilot field tests of STAR

Grant C. Scholes, Jason I. Gerhard, Gavin P. Grant, David W. Major, John E. Vidumsky, Christine Switzer, Jose L. Torero

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55 Citations (Scopus)
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Self-sustaining treatment for active remediation (STAR) is an emerging, smoldering-based technology for nonaqueous-phase liquid (NAPL) remediation. This work presents the first in situ field evaluation of STAR. Pilot field tests were performed at 3.0 m (shallow test) and 7.9 m (deep test) below ground surface within distinct lithological units contaminated with coal tar at a former industrial facility. Self-sustained smoldering (i.e., after the in-well ignition heater was terminated) was demonstrated below the water table for the first time. The outward propagation of a NAPL smoldering front was mapped, and the NAPL destruction rate was quantified in real time. A total of 3700 kg of coal tar over 12 days in the shallow test and 860 kg over 11 days in the deep test was destroyed; less than 2% of total mass removed was volatilized. Self-sustaining propagation was relatively uniform radially outward in the deep test, achieving a radius of influence of 3.7 m; strong permeability contrasts and installed barriers influenced the front propagation geometry in the shallow test. Reductions in soil hydrocarbon concentrations of 99.3% and 97.3% were achieved in the shallow and deep tests, respectively. Overall, this provides the first field evaluation of STAR and demonstrates that it is effective in situ and under a variety of conditions and provides the information necessary for designing the full-scale site treatment.

Original languageEnglish
Pages (from-to)14334-14342
Number of pages9
JournalEnvironmental Science and Technology
Issue number24
Publication statusPublished - 2 Nov 2015


  • self-sustaining treatment for active remediation (STAR)
  • nonaqueous-phase liquid (NAPL)
  • coal tar
  • creosote
  • soil contamination
  • smoldering remediation


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