Except as provided by contract with a participating political subdivision, all moneys received pursuant to the authority of this act, whether as proceeds from the sale of bonds or as revenues or otherwise, shall be deemed to be trust funds to be held and applied solely as provided in this act. All moneys of the Authority shall be deposited as soon as practicable in a separate account or accounts in one or more banks or trust companies organized under the laws of the Commonwealth or national banking associations having their principal offices in the Commonwealth. Such deposits shall be continuously secured in accordance with the Virginia Security for Public Deposits Act (§ 2.2-4400 et seq.). Funds of the Authority not needed for immediate use or disbursement may, subject to the provisions of any contract between the Authority and the holders of its bonds, be invested in securities that are considered lawful investments for fiduciaries.