Section 9. Any municipality acting by and through an industrial development financing authority is hereby authorized and empowered to borrow money in furtherance of the purposes of this chapter and to evidence the same by the issuance of bonds. The bonds may be of one or more series. Any bonds issued under the provisions of this chapter shall be secured by a trust agreement by and between the issuing municipality acting by and through an authority and a corporate trustee, which shall be located within the commonwealth and shall be a trust company or bank having the powers of a trust company, a savings bank as provided in section sixty-six D of chapter one hundred and sixty-eight or a co-operative bank as provided in section thirty-two E of chapter one hundred and seventy. Such trust agreement may pledge or assign the interest of the municipality acting by and through the authority as lessor, seller, mortgagee or lender under the financing document and may convey or mortgage any project or other property held thereunder or any part thereof. Such trust agreement shall contain such provisions for protecting and enforcing the rights and remedies of the bondholders as may be reasonable and proper and not in violation of law, including covenants setting forth the duties of the issuing municipality in relation to the construction, acquisition, equipping or improvement of any project or other property held under the financing document and the duties to be imposed on a user or other party with respect thereto, including the improvement, maintenance, operation, repair and insurance thereof, and the custody, safeguarding and application of all moneys and may contain provisions for the employment of consulting engineers and other experts and specialists in connection with such projects or property. It shall be lawful for any bank or trust company incorporated under the laws of the commonwealth or such savings bank or co-operative bank, which may act as depository of the proceeds of the bonds or of revenues, to furnish such indemnifying bonds or to pledge such securities as may be required by the issuing municipality. Such trust agreement shall set forth the rights and remedies of the bondholders and of the trustee, and may restrict the individual right of action by bondholders. In addition to the foregoing, such trust agreement may contain such other provisions as the authority may deem reasonable and proper for the security of the bondholders. All expenses incurred in carrying out the provisions of such trust agreement may be treated as an item of current expenses.