The city manager may exempt a shopping cart owner from some or all of the provisions of this chapter if the shopping cart owner has implemented a plan whereby employees provide shopping cart retrieval, or where the shopping cart owner has entered into a contract with a shopping cart retrieval service and has provided the city with proof of such retrieval plan or contract; provided, that such plan or contract shall provide that carts will be retrieved within sev-enty-two hours after abandonment and shall contain appropriate enforcement mechanisms. If an approved plan or contract fails to retrieve carts within seventy-two hours, the city manager may revoke such approval. Such revocation shall subject the shopping cart owner to the provisions of this chapter. (Ord. 907-02 § 1 (part))