I disagree with the majority that the arbitrator did not exceed her authority, and I therefore respectfully dissent. The collective bargaining agreement (CBA) between petitioner and respondent Rochester Teachers Association (Association) established a “Living Contract Committee” *1154(LCC). The LCC consisted of representatives from both petitioner and the Association and provided a means for ongoing discussions between the parties to resolve issues concerning the implementation and interpretation of the CBA. The LCC had the power to “amend [the CBA], provided that any substantive amendments shall be subject to internal ratification and approval procedures of [petitioner] and [the] Association.” Pursuant to the CBA, newly hired teachers who had obtained a Master’s degree prior to their start date would receive a two-step increase on the salary scale. The CBA also established a salary structure providing for salary increases at certain career junctures, e.g., after five years of employment, and also provided that teachers who obtained a Master’s degree during the course of their employment would be entitled to tuition reimbursement. The CBA, however, did not provide a two-step increase on the salary scale for teachers who obtained a Master’s degree during the course of their employment.
It is undisputed that members of the LCC representing the Association sent a memorandum to members of the LCC representing petitioner purporting to “confirm the agreement” between the parties providing that teachers who had not obtained a Master’s degree prior to their start date would receive a two-step increase on the salary scale upon obtaining a Master’s degree during the course of their employment. It is further undisputed that petitioner did not respond to the memorandum and that three such teachers were indeed given a two-step salary increase after obtaining their respective Master’s degrees. The arbitrator found that the “LCC reached the claimed [agreement referred to in the memorandum] properly, pursuant to its charge under the [CBA]” and that petitioner “apparently applied the terms of that Agreement to some teachers.” The arbitrator therefore determined that petitioner breached the CBA by failing to give teachers a two-step increase on the salary scale after they had obtained a Master’s degree.
It is well established that “[a]n arbitration award may not be vacated unless it violates a strong public policy, is irrational, or clearly exceeds a specifically enumerated limitation on the arbitrator’s power” (Matter of Board of Educ. of Arlington Cent. School Dist. v Arlington Teachers Assn., 78 NY2d 33, 37 [1991]; see CPLR 7511 [b] [1] [iii]; Matter of New York State Correctional Officers & Police Benevolent Assn. v State of New York, 94 NY2d 321, 326 [1999]). The CBA provides that “[t]he arbitrator shall have no power or authority to make any decision which . . . adds to, deletes from, or in any way changes, alters, or modifies the terms of this Agreement.” The CBA further provides that it *1155“may not be modified in whole or in part by parties except by an instrument in writing duly executed by both parties and no departure from any provision of this contract by either party or by members of the negotiating units shall be construed to constitute a continuing waiver of the right to enforce such provisions.” In my view, the arbitrator exceeded her authority in disregarding the provision of the CBA requiring that any amendment to it be duly executed by both parties, and in modifying the CBA by providing that teachers obtaining a Master’s degree during the course of their employment would receive a two-step increase on the salary scale (see Matter of Albany County Sheriffs Local 775 of N.Y. State Law Enforcement Officers Union, Dist. Council 82, AFSCME, AFL-CIO [County of Albany], 27 AD3d 979, 981 [2006]). Although it was within the arbitrator’s authority to consider petitioner’s past practice of giving three teachers a two-step increase on the salary scale in connection with the arbitrator’s interpretation of the CBA (see Matter of Aeneas McDonald Police Benevolent Assn. v City of Geneva, 92 NY2d 326, 332 [1998]), in my view, the arbitrator improperly “[rewrote the CBA] by adding a new clause based upon [that] past practice[ ]” (Matter of Hunsinger v Minns, 197 AD2d 871, 871 [1993]; see Matter of West Genesee Cent. School Dist. v West Genesee Teachers Assn., 307 AD2d 718, 719 [2003], lv denied 100 NY2d 516 [2003]). I therefore would reverse the order, grant the petition, vacate the arbitration award and deny respondents’ cross petition seeking to confirm the award. Present—Scudder, EJ., Hurlbutt, Gorski, Centra and Lunn, JJ.