Introduction to Electrokinetics - Electrokinetics for Petroleum and Environmental Engineers - page 15

and give their characteristics. A good classification of the bioremediation
methods with general recommendations of their applications was pre-
sented by Pollard et al. (1994).
For any particular contaminated site, one should select the most appro-
priate cleanup technology (or the most appropriate combination of differ-
ent technologies). The choice of a technology (or technologies) depends
on many factors, e.g., the site size, type of predominant contamination,
the site's future use, and available resources (time and money). Examples
of such an approach to the selection of cleanup strategy were presented by
Blacker and Goodman (1994) and Fairless (1990). They developed some
reasonable selection methodology of cleaning technologies, based on the
principles of system analysis from the final goal, through the quantitative
characterization of the problem, to the choice of preferable alternatives.
W. Loo and his associates presented many good examples of the suc-
cessful application of combined technologies. Loo (1994) used a combined
system, including primarily passive cometabolic biotreatment and electro-
kinetic transport of amendments and contaminants in solution for deg-
radation of gasoline and diesel in the soil and groundwater. In one case,
spills of gasoline and diesel from an underground storage tank caused soil
and groundwater contamination in the clayey Bay Mud, City of Hayward,
California. The soil contamination extended to a depth of about 10 ft with
a total petroleum hydrocarbons (TPH) concentration of 100 to 3,900 ppm.
The gasoline and diesel in the soil were degraded to less than 100 ppm of
TPH, and to less than 10 ppm in groundwater. The remediation process
was completed in four weeks.
A combination of biodegradation and electrokinetic transport with a
hot air venting system and ultraviolet light biocontrol system was used by
Loo et al. (1994) for the degradation of gasoline in the clayey soil. The gaso-
line soil plume covered an area of about 2,400 sq ft, to a depth of about 30
ft. The upper 15 ft. of sediment was composed of highly-conductive marine
clay, whereas the lower 15 ft. consisted of well-cemented conglomeratic
sandstone. The gasoline concentration ranged from 100 to 2,200 ppm. The
process of remediation was completed after about 90 days of treatment.
The concentration of gasoline in the soil after treatment was far below the
proposed cleanup level of 100 ppm. The cost of treatment was about $50
(US 1997) per ton of soil for this advanced soil treatment process, which
provided a cost effective remediation with minimum disruption to busi-
ness operations at the site (Chilingar et al., 1997).
A closed recovery system for soil and groundwater for a site contami-
nated with gasoline in Greenville, North Carolina, was developed by
Burnett and Loo (1994). The dissolved contaminant plume covered an area