a progress report that includes any information the commission may require.
up to the amount approved under section 8(2) or 13 of this chapter, whichever is applicable. The public utility may not recover costs in excess of the cost estimate approved by the commission under section 8(2) or 13 of this chapter, whichever is applicable, unless the commission finds that the additional costs were necessary and prudent.
If the commission issues an order approving all or part of the modified environmental compliance plan, the environmental compliance plan constitutes the public utility's approved environmental compliance plan for purposes of this chapter.
IC 8-1-27-19