Exemption for works in progress, etc

Nothing contained in section 9 shall apply to -

(a) the erection of any building or the making or extension of any excavation or the carrying out of any mining or other operation or the making of any material change or the construction, formation or laying out of any means of access or of works already commenced, or

(b) any excavation or works necessary for the repairs, renewal, enlargement or maintenance of any sewer, drain, electric line, pipe, duct or other apparatus made or extended or constructed, formed or laid out in, or over, or under, any land,

before the date of the publication of the notification under sub-section (1) of section 8.