Section 4010 - Bargaining unit determination(a) An employee organization desiring to be certified as the exclusive representative shall file a petition with the Board, accompanied by the uncoerced signatures of at least 30 percent of the public school employees in the unit claimed to be appropriate, indicating a desire to be represented for the purpose of bargaining collectively with the public employer.(b) If the Board or its duly authorized designee determines that a petition is properly filed and is accompanied by the requisite number of valid signatures, the Board or its designee shall proceed toward defining the appropriate bargaining unit by setting a date for hearing on the matter. If a petition is not properly filed and/or if it is not accompanied by the requisite number of valid signatures, the Board or its designee shall dismiss the petition.(c) After holding such hearings as it deems necessary the Board shall determine the appropriate bargaining unit. The Board may, by rule, delegate its unit definition authority to 1 or more of its members or to its Executive Director, provided that a unit definition order may be subject to review by the Board at the request of any party or upon the Board's own motion in accordance with rules and procedures established by the Board.(d) In making its determination as to the appropriate bargaining unit, the Board or its designee shall consider such factors as the similarity of duties, skills and working conditions of the employees involved; the history and extent of the employee organization; the recommendations of the parties involved; the effect of overfragmentation of bargaining units on the efficient administration of government; and such other factors as the Board may deem appropriate. The Board or its designee shall separate supervisory and nonsupervisory employees into separate appropriate bargaining units for all units created subsequent to July 18, 1990. The Board shall include positions commonly referred to as positions for extra-pay-for-extra-responsibility in the professional bargaining unit for the sole purpose of bargaining the salary for these positions and any other provision mutually agreed to by the parties. (e) Procedures for redefining or modifying a unit shall be set forth in the rules and procedures established by the Board.(f) Any bargaining unit designated as appropriate prior to the effective date of this chapter, for which an exclusive representative has been certified, shall so continue without the requirement of a review and possible redesignation until such time as a question concerning appropriateness is properly raised under this chapter. The appropriateness of the unit may be challenged by the public school employer, 30 percent of the members of the unit, an employee organization, or the Board not more than 180 days nor less than 120 days prior to the expiration of any collective bargaining agreement in effect on the date of the passage of this chapter. The continued appropriateness of any bargaining unit designated as appropriate prior to the effective date of this chapter, for which an exclusive representative is not certified, may be challenged by the public school employer, 30 percent of the members of the unit, an employee organization, or the Board at any time up until 30 days prior to the holding of an election to determine representation. 63 Del. Laws, c. 333, §1; 67 Del. Laws, c. 404, §5; 70 Del. Laws, c. 425, § 352.;