In all contracts made with the city, the surplus excavated material shall be deemed to be the property of the city, unless previously removed by the owner of the abutting property, and shall be removed by the contractor at his expense to such point as shall be designated by the city engineer; provided, that such free haul shall in no case for each separate block exceed three-fourths of a mile, beyond which the contractor shall receive one cent per cubic yard for each one hundred foot haul. In all private contracts, the owner of the abutting property or the contractor must remove all surplus excavated materials. (Prior code § 27-43)