If the board of supervisors finds that compliance with the requirements of this chapter, or any of its provisions, will result in an arbitrary or unreasonable taking of property or in the practical elimination of any lawful business, occupation or activity, in either case without a sufficient corresponding benefit or advantage to the people in the improvement or protection of the public health, safety or general welfare, it shall prescribe other different requirements of not more onerous application with respect to the preparation, storage, collection, transportation or disposal of waste, refuse, garbage, rubbish, industrial waste, commercial garbage, or refuse garbage or any thereof; provided, however, that no variance may permit or authorize the maintenance of a nuisance or any unnecessary and injurious method or operation. (Prior gen. code 3-72.0)