All of the powers of a slum clearance and redevelopment authority which now or hereafter shall be authorized under Chapter 45 of Title 31 and all of the powers of a housing authority which are now or hereafter shall be authorized under Chapter 43 of Title 31 may be vested by ordinance of New Castle County in such department or departments of the County Council as County Council may determine and County Council may delegate to a department director or directors the authority to execute contracts, deeds, leases, mortgages and other instruments necessary to carry out the aforesaid powers.