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

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Scholes, Grant C. and Gerhard, Jason I. and Grant, Gavin P. and Major, David W. and Vidumsky, John E. and Switzer, Christine and Torero, Jose L. (2015) Smoldering remediation of coal-tar-contaminated soil : pilot field tests of STAR. Environmental Science and Technology, 49 (24). pp. 14334-14342. ISSN 0013-936X (https://doi.org/10.1021/acs.est.5b03177)

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Abstract

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.

ORCID iDs

Scholes, Grant C., Gerhard, Jason I., Grant, Gavin P., Major, David W., Vidumsky, John E., Switzer, Christine ORCID logoORCID: https://orcid.org/0000-0003-3679-7683 and Torero, Jose L.;
CORE (COnnecting REpositories)