Sidewalks not less than four feet wide shall be provided on both sides of the new streets within the subdivision and on the abutting side of any existing street contiguous to the subdivision. Installation may be deferred for a period of three years by posting bond, as provided in Section 1181.09, to permit the building of dwellings prior to the installation of sidewalks provided that no such deferment shall be continued in effect or granted as to a particular block in a subdivision after seventy percent or more of the lots in such blocks have dwellings constructed thereon. Sidewalks shall be installed or provisions made to defer installation before occupancy permits are issued. (Ord. 25-70. Passed 5-4-70.)