The I-4 zone district consists of seven distinct subzones or overlays. Approval of each overlay shall require a map amendment. Two or more overlays may be approved on the same parcel of land at the same or separate times. The overlays of the I-4 zone district shall not be applied to any other zone district. The seven overlays shall be as follows:

A. Hazardous waste treatment facility with on-site disposal.

B. Hazardous waste treatment facility without on-site disposal.

C. Hazardous waste storage facility.

D. Hazardous waste resource recovery facility.

E. Hazardous waste research and development facility.

F. Hazardous waste transfer facility.

G. Hazardous waste testing laboratory.