Paid leaves of absence shall be granted for authorized military leave in the military service, under RCW 38.40.060, for periods of required military duty, training or drills for a period not exceeding a total of 21 working days during each year, beginning October 1st and ending September 30th, provided the request for such leave is in writing and accompanied by a validated copy of military orders. Such leave will be in addition to any vacation leave to which an employee might otherwise be entitled.