This project is testing a means to commercially demonstrate new, environmentally superior technology under section 112 of the Clean Air Act. Georgia-Pacific owns and operates a semi-chemical (non-sulfur, non-bleaching) pulp and paper mill in Big Island, Virginia. The mill produces the components of cardboard and emits pollutants during manufacture. In January of 2001, EPA published a performance standard (MACT II) which, regulates hazardous air pollutant emissions from combustion sources specifically associated with the recovery of pulping chemicals from spent pulping liquor (aka "black liquor"). Presently, Georgia-Pacific employs evaporators to concentrate black liquor and subsequently combust it in two high temperature recovery furnaces. Georgia-Pacific has decided that the furnaces need to be replaced and plans to install a new gasifier, which has yet to be commercially demonstrated. Compared to conventional technology, the gasification process is projected from pilot studies to emit significantly lower pollutant levels and require much less energy use, and by its design would eliminate the potential explosion hazard that exists with the conventional technology. Because this is a new technology and the first commercial scale demonstration of this type of gasifier, there is some risk that the technology will not work at all or will not work as well as anticipated. Under these scenarios, Georgia-Pacific will need time to install conventional recovery system and may have hazardous air pollutant emissions in excess of the EPA MACT II performance standard. Under Project XL they sought allowance for such emissions for a set period of time (until a conventional recovery system can be built).