Abstract

The pump-and-treat methodology represents a common remediation approach to mitigate hydrocarbon contaminations. In a well-studied site contaminated by large volume of jet fuel, continuous monitoring of the water table and floating phase thickness at a widely studied site contaminated by a large volume of jet fuel revealed the phenomenological process governing the effectiveness of the site's active remediation system. The floating phase thickness recorded in the monitored wells broadly varied and was negatively correlated with the water table level. Although the dependency of LNAPL thickness on water table fluctuations is widely recognized, the LNAPL recovery, which is governed by alternating cycles of release and entrapment of LNAPL in pore spaces, has been poorly described. Thus, we present a peculiar case in which the LNAPL recovery is expected only episodically, when water table falls sufficiently. In the period spanning from 2006 to 2008, LNAPL remediation recovered nearly 180 m3 of oil. In later years, the volume of recovered LNAPL declined and ceased between 2010 and 2014, when the water table rose. The conditions observed at the study site are likely common and may have important implications in the management of contaminated sites.