If sidewalks, curbings or gutters be not constructed or repaired within fifteen days from the service of the notice provided for in the preceding section, or the completion of the publication thereof, the Director of Public Service may proceed by direct employment of labor, or by contract, to carry out the said construction or repair at the expense of the owner, as in the case of other improvements. Such expense shall be reported by the Director of Public Service to the Council, which shall by ordinance assess said expense upon the owner or owners of the property bounding or abutting thereon. Such assessment shall be collected in the same manner as other assessments, with a penalty of five percent and interest for failure to pay at the time fixed by the assessment resolution.