(1) Whenever it appears to the trust that -
(a) any buildings which are used or are intended or likely to be used as dwelling places within its local area are unfit for human habitation, or
(b) danger is caused or likely to be caused to the health of the inhabitants of such local area or part thereof by reason of -
(i) the congested condition of streets or buildings or groups of buildings in such local area or part, or
(ii) the want of light, air, ventilation or proper conveniences in such local area, or part, or
(iii) any other sanitary defects in such local area or part, the trust may pass a resolution to the effect that such local area or part is in an insanitary locality and that "a general improvement scheme" ought to be framed in respect of such locality and may then proceed to frame such a scheme.
(2) Whenever the trust declares any local area or part thereof to be an insanitary locality within the meaning of this section, and is of opinion that having regard to the comparative value of the buildings in such local area or part and the sites on which they are erected it is undesirable to frame a general improvement scheme and the most satisfactory method of dealing with the local area or any part thereof is "a rebuilding scheme," it may proceed to frame such a scheme, which may provide for the reservation of streets and the enlargement of existing streets; the relaying out of the sites of the local area or part thereof upon the streets so reserved or enlarged; the demolition of existing buildings and their appurtenances upon such sites; and the erection of buildings in accordance with the scheme.
Section 23