(3) That the acquisition of a particularly described area of the undeveloped vacant land (hereinafter called an "auxiliary redevelopment area"), suitable for development for predominantly residential uses and so characterized in the master plan, is essential to the proper clearance or redevelopment of blighted or disaster areas or a necessary part of the general program for clearance or redevelopment of blighted or disaster areas in the county; then, subject to the conditions hereinafter stated, the acquisition, planning, preparation for development, or disposal of such auxiliary redevelopment area shall constitute a redevelopment project which may be undertaken by the agency in the manner provided by this part. The procedure for the preparation, submission, and the final approval, amendment and approval, or disapproval, of the redevelopment project, and subsequent proceedings with respect thereto, shall be the same, as nearly as may be, as in the case of other redevelopment projects, except that:
(1) The council shall not approve such plan or project unless it shall by resolution, concur in every finding of the agency required by this section and also find that the auxiliary redevelopment area will be developed for predominantly residential uses; and(2) The requirement of a finding that the redevelopment project is in a blighted area prescribed by section 53-6 shall not be applicable.