The proposed rule amendments will fulfill a statutory requirement that the Department of Environmental Protection (DEP) adopt criteria to determine whether any proposed change at certain hazardous waste facilities constitutes a “substantial modification.” Section 403.7211, F.S., establishes specific siting requirements for permitted hazardous waste facilities that manage hazardous waste generated offsite, including federal facilities with hazardous waste permits. DEP is prohibited from issuing a permit for the construction, initial operation or substantial modification of such facility unless the siting requirements are met. The statute also applies to hazardous waste transfer facilities. The statute defines substantial modification as “any physical change in, change in the operations of, or addition to a facility which could increase the potential offset impact, or risk of impact, from a release at that facility; and any change in permit conditions which is reasonably expected to lead to greater potential impacts or risks of impacts, from a release at that facility,” and directs DEP to adopt criteria, by rule, to determine whether a facility has been substantially modified.