Electrical resistance heating (ERH) is an in situ thermal treatment for soil and groundwater remediation that can reduce the time to clean up volatile organic compounds (VOCs) from years to months. The technology is now mature enough to provide site owners with both performance and financial certainty in their site-closure process. The ability of the technology to remediate soil and groundwater impacted by chlorinated solvents and petroleum hydrocarbons regardless of lithology proves to be beneficial over conventional in situ technologies that are dependent on advective flow. These conventional technologies include: soil vapor recovery, air sparging, and pumpand-treat, or the delivery of fluids to the subsurface such as chemical oxidization and bioremediation. The technology is very tolerant of subsurface heterogeneities and actually performs as well in low-permeability silts and clay as in higher-permeability sands and gravels. ERH is often implemented around and under buildings and public access areas without upsetting normal business operations. ERH may also be combined with other treatment technologies to optimize and enhance their performance. This article describes how the technology was developed, how it works, and provides two case studies where ERH was used to remediate complex lithologies. © 2005 Wiley Periodicals, Inc. INTRODUCTIONElectrical resistance heating (ERH) was developed at the Pacific Northwest National Laboratory (PNNL) in the early 1990s with funding provided by the U.S. Department of Energy's (DOE's) Office of Science and Technology.The technology was originally conceived as a dewatering tool for the PNNL's in situ vitrification process. It was later discovered that ERH was remarkably well suited for the in situ thermal remediation of volatile contaminants and petroleum hydrocarbons. In such applications, the subsurface is heated to the boiling temperature of water and steam is generated in situ; however, only a small portion of the groundwater or soil moisture is boiled off during the remediation.ERH became commercially available for use as a stand-alone technology in 1997. ERH can be applied using three or six phases of electricity; three-phase heating is generally more applicable for full-scale treatment and six-phase heating is generally more applicable to the pilot scale. Because pilot applications were more common in the early years, the term six-phase heating became almost synonymous with ERH. Full-scale heating applications are more common today, and the more general term electrical resistance heating is now used to describe the remediation technique, regardless of whether three or six electrical phases are used. In Situ Thermal Remediation of DNAPL and LNAPL Using Electrical Resistance HeatingThe technology was first field-tested at the DOE Hanford,Washington, facility in an arid soil setting. In 1993, ERH was used at the Department of Defense (DOD) Savannah River, South Carolina, facility to clean tetrachloroethene (PCE) from a 10-foot-thick clay lens located 30 feet below the su...

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Using the transpiration method, the volatility of uranium oxide in the presence of oxygen and water vapor has been measured at temperatures ranging fiom 1173 to 1573 K and the volatility of uranium oxide in the presence of oxygen and chlorine has been measured at 1175 K. The major vapor species in the presence of oxygen and water vapor are found to be U03(g) and U02(0H)2(g). Third law treatment of the vaporization data yields AHf(298) values of-790.52 f 7.32 and-1199.94 f 10.25 kJ/mol, respectively. The major vapor species in the presence of oxygen and chlorine is found to be U02Clz(g). Third law treatment of the vaporization data yields a AHt"(298) value of-1002.04 f 3.26 W/mol. From an assessment of all the thermodynamic data available for uo3(g), U02(0H)2(g), UOzCh(g), and UO2F2(g), the best AHp(298) values for each of these species are calculated to be-796.74 f 3.52,-1199.94 f 10.25,-999.64 f 2.40, and-1369.22 f

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