When any county of this state has adopted or will adopt any sea wall or part of a sea wall constructed prior to October 31, 1931, by a municipality as a part of its general system as provided by Section 65-33-37, and where said county has been unable to take care of or pay the maturing bonds and interest of said municipality from the gasoline tax as provided by said section, the said county may borrow funds necessary to pay outstanding maturing bonds and interest of the municipality issued for said sea wall, or walls. The said county may borrow said funds either upon certificates of indebtedness, notes, or bonds, as in its judgment it may see fit. Said obligation or bonds shall not be for a period longer than ten years and at a rate of interest not exceeding six per cent. Said obligations or bonds shall not be considered as included in any limitation now fixed by law upon the indebtedness of any county, and said obligations or bonds may be issued without notice and without an election on the question of the issuance of same. The said obligation or bonds issued hereunder shall be general obligations of the county and payable out of the gasoline tax when available, as provided in the cited section, and the general sea wall road protection laws. In the event of the failure of sufficient funds from the said gasoline tax, the county shall levy a special tax to pay said bonds. The board of supervisors issuing bonds hereunder may provide that the first obligations or bonds mature as long as three years from the date of their issuance, but all interest shall be paid semiannually. In the event of the failure to collect sufficient gasoline tax to pay said bonds or obligations authorized hereunder, the board of supervisors of the county are authorized to levy ad valorem taxes to pay same as other sea wall or road protection bonds.