(a) As soon as practicable following the certification of the record and the filing by the parties of briefs and proposed findings of fact and conclusions under § 104.11, the Administrator, with such staff assistance as he deems necessary and appropriate, shall review the entire record and prepare and file a tentative decision based thereon. The tentative decision shall include findings of fact and conclusions, and shall be filed with the hearing clerk who shall at once transmit a copy thereof to each party who participated at the hearing, or his attorney or other representative.

(b) Upon filing of the tentative decision, the Administrator may allow a reasonable time for the parties to file with him any exceptions to the tenative decision, a brief in support of such exceptions containing appropriate references to the record, and any proposed changes in the tentative decision. Such materials shall, upon submission, become part of the record. As soon as practicable after the filing thereof the Administrator shall prepare and file a final decision, copies of which shall be transmitted to the parties or their representatives in the manner prescribed in paragraph (a) of this section.

(c) In the event that the Administrator determines that due and timely execution of his functions, including compliance with time limitations established by law, imperatively and unavoidably so requires, he may omit the preparation and filing of the tentative decision and related procedures set forth in paragraph (b) of this section, and shall instead prepare and file a final decision, copies of which shall be transmitted to the parties or their representatives in the manner prescribed in paragraph (a) of this section.

(d) Any decision rendered by the Administrator pursuant to this section shall include a statement of his findings and conclusions, and the reasons and basis therefor, and shall indicate the toxic pollutant effluent standard or standards which the Administrator is promulgating or intends to promulgate based thereon.