(a) The provisions of §§ 9-421.05, 9-421.06, and 9-421.07 shall not preclude the levying of assessments hereunder if the improvement for which such prior assessment was levied, or, if the original paving, curbing, or curbing and guttering, laid at the whole cost of the owner, were completed prior to January 1, 1885.
(b) The provision of § 9-421.08, relating to legal assessments heretofore levied, shall not be applicable where said prior assessments were levied for any improvement completed prior to January 1, 1885.