It is the intent of this chapter to permit lawful nonconformities to continue until they are removed, but not encourage their survival. Such uses are declared by this section to be incompatible with permitted uses in the districts involved. It is further the intent of this section that nonconformities shall not be enlarged upon, expanded, or extended, or used as grounds for adding other structures or uses prohibited elsewhere in the same district except as may be authorized in this Zoning Code.