In addition to the exemptions set forth in RCW
41.06.070, the provisions of this chapter shall not apply in the department of social and health services to the secretary; the secretary's executive assistant, if any; not to exceed six assistant secretaries, thirteen division directors, six regional directors; one confidential secretary for each of the above-named officers; not to exceed six bureau chiefs; and all superintendents of institutions of which the average daily population equals or exceeds one hundred residents.