(a) A public agency shall establish, maintain, and adjust the rates charged by the public agency for solid waste disposal services if:
(1) the public agency executes a contract with a county under this chapter; and
(2) the payments under the contract are to be made either wholly or partly from the revenues of the public agency’s solid waste disposal fund.
(b) The revenues of the public agency’s solid waste disposal fund, and any taxes levied in support, must be sufficient to pay:
(1) the expense of operating and maintaining the solid waste disposal service or system; and
(2) the public agency’s obligations to the county under the contract and in connection with bonds issued or that may be issued that are secured by revenues of the solid waste disposal service or system.

(c) A contract between a public agency and a county may require the use of consulting engineers and financial experts to advise the public agency whether and at what time rates are to be adjusted under this section.