A novel, in situ remediation technology called Lasagna is being developed for cleaning up contamination in heterogeneous or low-permeability soils. The technology uses electrical current to drive contaminants from the soil into treatment zones installed directly in the contaminated area. The collaboration between a consortium of industry (Monsanto, DuPont, and General Electric) with the Department of Energy (DOE) and the Environmental Protection Agency (EPA) has led to two field tests at a DOE plant, chosen for its combination of low-permeability soil and trichloroethylene (TCE) as the sole contaminant. This paper describes the first field test in which TCE in the contaminated soil was transported into carbon-containing treatment zones where it was trapped. The test was very successful, removing over 98% TCE from the contaminated soil, with most treated samples showing greater than 99% removal. The success of this test paved the way for the second and much larger field test in which TCE was degraded in place.

A full-scale field test of the Lasagna process was conducted at a Department of Energy trichloroethylenecontaminated clay site in Paducah, Kentucky. The test covered an area 21 ft × 30 ft (6.4 m × 9.2 m) and reached 45 ft (13.7 m) deep. A modified sheet piling method was utilized for installing electrodes and treatment zones in thin layers through stiff clay soil without generating solid waste. Iron filings were used in the treatment zones for in situ TCE degradation. Complications encountered during the test included contamination at significantly higher levels than anticipated and complex hydrogeology in the subsurface. Treatment effectiveness seems to vary with location, but in the contaminated areas bracketed by treatment zones, TCE removal ranged from 95% to over 99%. There are strong indications that some of the TCE was transported and degraded in the DNAPL form, which has significant implications. On the basis of the field results, treatment cost for a typical one-acre site with contamination from 15 to 45 ft deep ranges from about $45 to $80/yd 3 . Implemented in its full configuration for the first time at a real site, the Lasagna process has demonstrated its robustness and costeffectiveness in cleaning up TCE-contaminated soil in place.