Upon receipt of such petition and map and before the petition is granted, the city council shall determine what portion, if any, of the extension of the municipal water mains to the municipal limits the city shall construct, and shall obtain from the water superintendent a verified statement showing the whole cost and expense of making such extension. Such costs and expenses shall include administrative and supervisory expenditures of the municipal water department, which shall in no event be deemed to be less than ten percent (10%) of the cost of materials and labor. (Prior Code § 14-154)