Each person maintaining such a sign shall file with the city clerk a bond or indemnity policy in the sum of fifty thousand dollars ($50,000.00) conditioned to indemnify the city for any loss or damage or liability that may result from the construction or maintenance of such sign or canopy. Provided, that if the city council has secured a blanket policy to protect against risks, then no such bond shall be required. (1967 Code § 12.302)