The mains and pipes of the Company must be so placed as not to interfere unnecessarily with water pipes, drains, sewers and fire plugs which have been or may hereafter be placed in any street, alley and public places in said City nor unnecessarily interfere with the proper use of the same, including ordinary drainage, or with the sewers, underground pipe and other property of the City. The Company, its successors and assigns shall hold the City free and harmless from all damages arising from the negligent acts or omissions of the Company in the laying down, operation and maintenance of said natural gas distribution system.