The Probation Department shall allow PDA use of available bulletin board space for communications involving official organization business, such as times and places of meetings, provided such use does not interfere with department needs. PDA may distribute materials to unit employees through County mail distribution channels if approved by the Human Resources Director. If the Association violates the terms of this provision, the County may take such action it deems appropriate, to the extent authorized by law. PDA representatives shall give notice to the employees’ department head or designee at least twenty-four (24) hours in advance of contacting departmental employees during an employee’s duty period, provided that solicitation for membership and other internal employee organization business shall be conducted only during the non-duty hours of all employees concerned. Pre-arrangement for routine contact may be made by agreement between the Union and the department head and when made shall continue until revoked.