(a) The sponsor of any proposed construction or alteration covered by
this part may revise his proposal at any time before or during the
hearing. If he revises it, the presiding officer decides whether the
revision affects the proposal to the extent that he should send it to the
Administrator for a redetermination of the need for a hearing.
(b) If the presiding officer decides that it does not need to be
resubmitted to the Administrator, he advises the parties of the revised
proposal and takes the action necessary to allow all parties to
effectively participate in the hearing on the revised proposal. Without
limiting his discretion, the presiding officer may recess and reconvene
the hearing, or hold another prehearing conference.