and

A new form of in situ vitrification (ISV) has been developed for remediating both underground storage tanks (USTs), and waste sites containing large quantities of vaporizable material coupled with relatively impermeable barriers (such as basalt or clay). The new process, called planar-ISV, was developed by Geosafe. Planar-ISVuses two vertical planes of starter material to initiate ISV processing. The molten planes then process the tank or site in a “downward and inward ” fashion. During planar-ISV processing, the volatile and semivolatile contaminants in the waste are destroyed or processed by the planar-ISV melts that surround the site. Once the gas-generating materials have been processed and the region between the melt planes has dried out, the melt planes converge, to rapidly process the waste site area and its associated nonvolatile materials. The new process eliminates concerns over melt expulsion events during ISV processing. Planar-ISV was recently evaluated in a treatability study for the Idaho National Engineering and Environmental Laboratory (INEEL). The treatability study evaluated the application of planar-ISV to large USTs containing various mixed, hazardous and radioactive wastes, includin