Every contract for any public work or improvement to be performed at the expense of the City and County, or paid out of moneys deposited in the treasury, whether such work is to be done directly under contract awarded, or indirectly by or under subcontract, subpartnership, day labor, station work, piece work, or any other arrangement whatsoever, must provide:
(a) that in the performance of the contract and all work thereunder, eight hours shall be the maximum hours of labor on any calendar day, except that hours of labor in excess of eight hours per day may be permitted when conditions so warrant upon the approval of the department head responsible for the supervision of the contract, provided that compensation for all hours worked in excess of eight hours per day conforms to the requirements of the Labor Code of the State of California and all applicable federal laws;
(b) that any person performing labor thereunder shall be paid not less than the highest general prevailing rate of wages in private employment for similar work; however, the Board of Supervisors may by resolution exempt from the prevailing wage requirement any contract where the work is to be performed by a non-profit organization that provides job training and work experience for disadvantaged individuals in need of such training and experience, and either (1) has a board of directors which is appointed by the Mayor, or (2) exists primarily to design and build urban gardens, yards and play areas;
(c) that any person performing labor in the execution of the contract shall be a citizen of the United States;
(d) that all laborers employed in the execution of any contract within the limits of the City and County shall have been residents of the City and County for a period of one year immediately preceding the date of their engagements to perform labor thereunder; provided, however, that the officer empowered to award any such contract may, upon application of the contractor, waive such residence qualifications and issue a permit specifying the extent and terms of such waiver whenever the fact be established that the required number of laborers and mechanics possessing qualifications required by the work to be done cannot be engaged to perform labor thereunder.
The term "public work" or "improvement," as used in this section shall, include the fabrication, manufacturing or assembling of materials in any shop, plant, manufacturing establishment or other place of employment, when the said materials are of unique or special design, or are made according to plans and specifications for the particular work or improvement and any arrangement made for the manufacturing, fabrication or assembling of such materials shall be deemed to be a contract or a subcontract subject to the provisions of this section.
The Board of Supervisors shall have full power and authority to enact all necessary ordinances to carry out the terms of this section and may by ordinance provide that any contract for any public work or improvement or for the purchase of materials which are to be manufactured, fabricated or assembled for any public work or improvement, a preference in price not to exceed 10 percent shall be allowed in favor of such materials as are to be manufactured, fabricated or assembled within the City and County of San Francisco as against similar materials which may be manufactured, fabricated or assembled outside thereof. When any such materials are to be fabricated, assembled or manufactured by any subcontractor or materialman for the purpose of supplying the same to any contractor bidding on or performing any contract for any public work or improvement, said sub-contractor or materialman manufacturing, fabricating, assembling or furnishing said materials manufactured, assembled or fabricated within the City and County of San Francisco shall be entitled to the same preferential as would any original contractor or materialman furnishing the same if the Board of Supervisors by ordinance so provide. When any ordinance shall so provide any officer, board or commission letting any contract may in determining the lowest responsible bidder for the doing or performing of any public work or improvement add to said bid or sub-bid an amount sufficient not exceeding 10 percent in order to give preference to materials manufactured, fabricated or assembled within the City and County of San Francisco.