It is further found and declared that in certain blighted and substandard areas, or portions of these areas, the physical conditions of the area and the area’s relationship to the general plan for the community may be that the total public acquisition, clearance, and disposition of the entire area or an extensive portion of it may be necessary to accomplish the purposes of chapters 31 — 33 of this title; that other blighted and substandard areas, or portions of them, may be susceptible to rehabilitation and improvement to standard conditions, and the purposes of these chapters may be accomplished by the coordinated application of regulatory controls, together with redevelopment measures, short of total or extensive clearance of the entire area or portions of it.