ABSTRACT
Bioslurping (also termed multiphase or two-phase extraction) is an innovative in situ technology that simultaneously removes light nonaqueous-phase liquid (LNAPL) from fuclsaturated soil and biovents the contaminated vadose zone through vacuum-assisted skimming at or near the water table (Hoeppel et aI., 1996; Wickramanayake ct aI., 1996). Monitored natural attenuation (MNA) involves determining the natural subsurface processes (e.g., dilution, sorption, dispersion, volatilization, and biodegradation) and rates that provide for reduction of human and ecological risk from harmful contaminants to acceptable levels prior to reaching potential biological receptors. Microbiological processes are most important for reducing in situ contaminant concentrations (Wiedemeier et aI., I 996a, I996b). Since LNAPL acts as a source area for soluble contaminants in groundwater, its removal is important in controlling the ultimate spread and decline of groundwater contaminant plumes. This is especially true when the LNAPL also is contaminated with chlorinated solvents such as perchloroethene (PCE) and trichloroethene (TCE), since the bulk of the chlorinated solvents and perhaps some transformation products may be strongly bound to and released slowly from the fuel.
