The governing body of any political subdivision, including any school district, educational service unit, or community college, may purchase a policy of liability insurance insuring against all or any part of the liability which might be incurred under the Political Subdivisions Tort Claims Act and also may purchase insurance covering those claims specifically excepted from the coverage of the act by section 13-910. Any independent or autonomous board or commission in the political subdivision having authority to disburse funds for a particular purpose of the subdivision without approval of the governing body also may procure liability insurance within the field of its operation. The procurement of insurance shall constitute a waiver of the defense of governmental immunity as to those exceptions listed in section 13-910 to the extent and only to the extent stated in such policy. The existence or lack of insurance shall not be material in the trial of any suit except to the extent necessary to establish any such waiver. Whenever a claim or suit against a political subdivision is covered by liability insurance or by group self-insurance provided by a risk management pool, the provisions of the insurance policy on defense and settlement or the provisions of the agreement forming the risk management pool and related documents providing for defense and settlement of claims covered under such group self-insurance shall be applicable notwithstanding any inconsistent provisions of the act.