Non-aqueous phase liquids (NAPLs) are common contaminants that are insoluble in water.
Remediation Management of Complex Sites (RMCS-1)
Section 2.1.4.1
This section discusses contaminant-related conditions that may contribute to a site being considered complex including the presence of NAPLs, recalcitrant contaminants, high concentrations or multiple contaminants, and emerging contaminants