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Some errors could be introduced when partitioning interwell tracer tests (PITTs) are employed to measure subsurface contamination by nonaqueous phase liquids (NAPLs). The PITTs should use a corrected partitioning coefficient when measuring NAPLs using a solubilization mechanism. Ideally, PITTs technology can be used to measure contamination effectiveness for a variety of remediation processes.

The article presents a discussion on two leaded-gasoline additives, ethylene dibromide and 1,2-dichloroethane. Much recent attention has focused on the gasoline additive methyl tert-butyl ether (MTBE), which is mobile and persistent in the environment. The additive contaminates public water supplies. Hundreds of millions of dollars have been spent to address the MTBE problem, but two other gasoline additives that are far more toxic have been mostly overlooked. The volatile organic chemicals 1,2-dibromoethane (ethylene dibromide; EDB) and 1,2-dichloroethane (DCA) were ubiquitous components of lead-based antiknock additive mixtures, which were used from the 1920s through the late 1980s to increase gasoline octane ratings. Today, EDB and DCA are among the most commonly detected contaminants in U.S. public drinking-water systems that rely on groundwater. Typically, groundwater contamination by these chemicals is attributed to agricultural (EDB) or industrial (DCA) releases. Both EDB and DCA tend to be mobile in ground-water because of their low octanol-water partition coefficients.

This study was conducted to experimentally demonstrate removal of a chlorinated volatile organic compound from fractured rock by boiling. A Berea sandstone core was contaminated by injecting water containing dissolved 1,2-DCA (253 mg/L) and sodium bromide (144 mg/L). During heating, the core was sealed except for one end, which was open to the atmosphere to simulate an open fracture. A temperature gradient toward the outlet was observed when boiling occurred in the core. This indicates that steam was generated and a pressure gradient developed toward the outlet, pushing steam vapor and liquid water toward the outlet. As boiling occurred, the concentration of 1,2-DCA in the condensed effluent peaked up to 6.1 times higher than the injected concentration. When 38% of the pore volume of condensate was produced, essentially 100% of the 1,2-DCA was recovered. Nonvolatile bromide concentration in the condensate was used as an indicator of the produced steam quality (vapor mass fraction) because it can only be removed as a solute, and not as a vapor. A higher produced steam quality corresponds to more concentrated 1,2-DCA removal from the core, demonstrating that the chlorinated volatile compound is primarily removed by partitioning into vapor phase flow. This study has experimentally demonstrated that boiling is an effective mechanism for CVOC removal from the rock matrix.