It is hereby found and declared that (a) certain of the blighted areas may, through the means provided herein, be susceptible of conservation or rehabilitation in such manner that the conditions of blight may be eliminated, remedied or prevented and, to the extent feasible, the salvable blighted areas should be conserved and rehabilitated through voluntary action and the regulatory process, and (b) all powers conferred in this chapter are for public uses justifying the use of the powers of eminent domain when exercised consistent with N.H. Rev. Stat. § 205:3-b and public purposes for which public money may be expended and such other powers exercised, and the necessity in the public interest for these provisions is hereby declared as a matter of legislative determination.