Detection and Remediation of Hydrocarbon Contamination in a Latin American Petroleum Facility

David A. Link, Patrick N. Agostino, Victor T. Jones III

During the paving of a residential street in an area adjacent to a petroleum complex in Latin America, water contaminated by hydrocarbons was detected within one meter of the surface. The contaminated liquids were immediately recovered, 22 monitor/recovery wells were installed in the contaminated area and near suspected sources of the contamination, and an interceptor trench was installed between the contaminated area and the suspected contaminant source. Except for near the discovery site, most of the monitor wells and the trench recovered little or no contamination. A multi-phase environmental study of the petroleum facility and environs was then initiated.

A geochemical soil gas survey of 5100 samples covering 1.5 km₂ established the horizontal extent of the contamination. To locate monitor wells and recovery systems, concentrations of C_1^-C_5⁺ gases were mapped on the basis of the local geology to identify areas with high concentrations of light gases and contaminants. Approximately 13 different products (gasolines, diesel, oils, crudes) have leaked into the subsurface over 60 years with the product reservoirs and paths of migration controlled by Recent environments of deposition. Contaminant reservoirs are vadose zone silts and fine sands 4-10 ft deep, and migration is along either old floodplain channels or old alluvial fan channels entering the floodplain. Man-made utilities trenc es modify the migration routes.

Based on the soil gas results, 104 monitor wells were installed; 82 had significant concentrations of contaminants, with 63 having up to 2 ft of liquid hydrocarbons on the ground water. Interceptor/recovery trenches, totaling 1600 ft in length and located on the basis of the soil gas survey, recovered over 1300 barrels of hydrocarbon products in less than one year.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995