The obligation to bargain in good faith imposed upon an employer and the exclusive representative of its employees, respectively, by RCW 41.59.020(2) and 41.59.140 (1)(e) or (2)(c) includes:

(1) The obligation to submit, as to each subject for bargaining advanced by the party, a written statement of the language proposed for incorporation in or deletion from the collective bargaining agreement between the parties, together with a written or oral explanation or justification of the proposals.

(2) The obligation to submit, as to each subject for bargaining advanced by the other party, at least one written response, together with a written or oral explanation of the response. However, a party which asserts in a written response that a subject for bargaining advanced by the other party is not a mandatory subject for collective bargaining may thereafter refuse to make further proposals as to the subject or subjects for bargaining.

(3) The obligation to receive proposals from the other party as to all subjects for bargaining in dispute between the parties and, until a legal impasse has been reached, to refrain from demanding the removal of the subject from the bargaining table on the basis that it is not a mandatory subject for collective bargaining.

(4) The obligation to exhaust the mediation and fact finding procedure established pursuant to RCW 41.59.120 before implementing all or any part of a final offer in negotiations, except as provided in RCW 41.59.930.