Within 60 days after receiving certifications from the owner or operator and an independent licensed professional engineer or licensed professional geoscientist that plugging and abandonment has been accomplished in accordance with the plugging and abandonment plan, the executive director will notify the owner or operator in writing that he is no longer required by this section to maintain financial assurance for plugging and abandonment of the well, unless the executive director has reason to believe that plugging and abandonment has not been in accordance with the plugging and abandonment plan. Financial assurance may not be released without the written approval of the executive director.