Untied states Environmental Protection

Radio frequency heating (RFH) technologies use electromagnetic energy in the radio frequency (RF) band to heat soil in situ, thereby potentially enhancing the performance of standard soil vapor extraction (SVE) technologies. Contaminants are remove d from in situ soils and transferred to collection or treatment facilities. (IITRI) RFH process was evaluated under the U. S. Environmental Protection Agency (EPA) Superfund InnovatIveTech-nology Evaluation (SITE) Program at a site containing various organic contaminants in a heterogeneous soil matrix. Due to changes in the original design and operational problems experienced during the demonstration, the treatment area was evaluated as two separate zones: the " revised' design treatment zone and the " heated' zone. The revised design treatment zone reflects both changes made to the design of the RFH system and operational problems associatsd with shallow groundwater at the test site. The heated zone consists of the area that achieved the target temperature of 15O o C. Concentration changes were calculated from paired pre-and post-demonstration soil samples; these concentration changes were evaluated for statistical significance. Conclusions have been drawn based only on data thal were statistically significant at greater than or equaI to the 90 percent confidence Ievel. Within the revised design treatment zone the estimated mean concentration decrease for Total Recoverable Petroleum Hydrocarbons (TRPH) was 60 percent. Estimated mean concentration decreases for two semivolatile organic c o m-pounds (SVOCs), pyrene and bis(2-ethylhexyl)phthalate were 87 and 48 percent respectively. There were statistically sig-nifiiant increases in the concentrations of four volatile organic compounds (VOCs); the estimated mean concentration increases were 457 percent for 2-hexanone; 263 percent for 4-methyl-2-pentanone; 1,073 percent for acetone; and 683 percent for methyl ethyl ketone. Outslde of the revised design treatment zone, only TRPH showed a statistically significant change with an estimated 88 percent increase in the mean concentration. Within the heated zone the estimated mean concentration decrease was 95 percent for TRPH. Outside the heated zone, the estimated mean concentration decrease was 37 percent for bls(2-ethylhexyl) phthalate; estlmated mean concentration increases were 423 percent for 2-hexanone: 249 perce nt for 4-methyl-2-pentanone; 1,347 percen t for acetone: and 1,049 percent for methyl ethyl ketone. Several possible reasons exist for changes In concentration observed. They include inward contaminant migration, low extraction rates, widely varying soil temperatures, low pretreatment contaminant concentrations in the soil, and the potential degradation of TRPH and SVOCs. The estimated cost to treat 10,152 tons of contaminated soil based …