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.