Scope of Work This study was conducted over a 3-year period. In September of 1992, 50 liters of a synthetic gasoline were released to the test cell. The gasoline was comprised of pentane, methyl-tert-butyl-ether (MTBE), 2-methylpentane, hexane, benzene, trichloroethlene (TCE), heptane, isooctane, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene, 1,2,4-trimethylbenzene, and naphthalene. Samples were collected and analyzed (for gasoline range organics) to establish the three-dimensional distribution of the release. One year after the release, SVE from trenches was conducted for 3 months, followed by a short period of air sparging and a second collection of soils samples. Two years after the release, SVE from vertical wells alone was performed, followed by SVE from both the vertical wells and trenches in various combinations. During this phase of the study, a horizontal fracture was created below the zone of contamination and was used for dewatering. During all air flushing activities, soil vapor composition and concentration were continuously analyzed. Approximately 3 years after the release, a final set of soil samples was analyzed and volatilization flux experiments were conducted as portions of the test cell were excavated. Microbial studies were also performed at this time.