(1) All rulings upon objections to the admissibility of evidence shall be made in accordance with the provisions of RCW 34.05.452.

(2) Where practicable, the presiding officer may order:

(a) That all documentary evidence which is to be offered during the hearing or portions of the hearing be submitted to the presiding officer and to the other parties sufficiently in advance to permit study and preparation of cross-examination and rebuttal evidence;

(b) That documentary evidence not submitted in advance as required in (a) of this subsection be not received in evidence in the absence of a clear showing that the offering party had good cause for his or her failure to produce the evidence sooner, unless it is submitted for impeachment purposes;

(c) That the authenticity of all documents submitted in advance in a proceeding in which such submission is required be deemed admitted unless written objection thereto is filed prior to the hearing, except that a party will be permitted to challenge such authenticity at a later time upon a clear showing of good cause for failure to have filed such written objection.

(3) When portions only of a document are to be relied upon, the offering party shall identify the pertinent excerpts and state the purpose for which such materials will be offered. Only the excerpts, in the form of copies, shall be received in the record. However, the whole of the original documents, except any portions containing confidential material protected by law, shall be made available for examination and for use by all parties.

(4) No former employee of the council shall appear, except with the permission of the council, as an expert witness on behalf of other parties in a proceeding in which the former employee participated.

(5) The refusal of a witness to answer any question which has been ruled to be proper shall, in the discretion of the presiding officer, be grounds for striking all testimony of the witness.

(6) Any party bound by stipulation or admission of record may, at any time prior to closure of the record, be permitted to withdraw its agreement in whole or in part by showing to the satisfaction of the presiding officer that such stipulation or admission was made inadvertently or under a bona fide mistake of fact contrary to the true fact and that its withdrawal at the time proposed will not unjustly prejudice the rights of other parties to the proceeding.