GENERAL REQUIREMENTS.  The Contractor at its sole expense shall procure and maintain, during the entire period of performance under this contract, the types of insurance specified below.  The Contractor shall have its insurance broker or insurance company submit a Certificate of Insurance to the CO giving evidence of the required coverage prior to commencing performance under this contract.  In no event shall any work be performed until the required Certificates of Insurance signed by an authorized representative of the insurer(s) have been provided to, and accepted