If the expense of such construction, reconstruction or repair has been more than the aforesaid estimate given by the Department of Public Works, the person shall be indebted to the City and County of San Francisco for such balance; and the same shall constitute a lien upon the property of such person. Said lien shall remain in force until such balance has been paid, or until the lien shall be legally discharged. Said lien may be enforced by suit brought by the said City and County in accordance with the provisions of the Code of Civil Procedure of the State of California.