Any expense incurred by the commission in making any appraisal or investigation of public utility property under ch. 197 shall be charged directly to the municipality making the application. The commission shall ascertain the expense, and shall render and review any bill under s. 196.85 insofar as applicable. For the purpose of calculating the expense, 90 percent of the costs determined shall be costs of the commission and 10 percent of the costs determined shall be costs of state government operations. If a bill under this section is not paid within the time required by s. 196.85, the bill shall bear interest at the rate of 6 percent per year and the amount of the bill and the interest shall be certified to the department of administration and shall be levied and collected as a special charge in the same manner as a state tax.