Opinion by
Judge Blatt,The Rose Tree Media School District (school district) appeals here from an order of the Court of Common Pleas of Delaware County which affirmed an arbitrator’s award made under a collective bargaining agreement between the School District and the Rose Tree Media Education Association (Association). The School District argues that the award should be set aside because (1) it is not rationally derived from the agreement and (2) it is unconscionable.
At issue is the construction of a provision in the agreement which grants teachers a special retire*370ment salary increment based on accumulated unused sick-leave days r1
Teachers contemplating retirement under the Pennsylvania Public School Employee’s Retirement System may notify the Board of this intention within three years prior to their effective retirement date. The Board shall grant the pending retiree a special salary increase of 1/N (N = number of years prior to retirement teacher entered the plan) of all unused accumulated sick leave days over thirty (30) days. The employee’s base per diem rate shall be used to determine this increase. This special increment shall be calculated once at the initiation of the plan only.
Although the provision does not by its terms mention any limit on the number of days that can be accumulated or on the amount of the increase, the School District argues that a teacher’s increment for any single year cannot exceed the teacher’s maximum salary for that year as provided in the salary schedule of the agreement. The Association’s position is that no maximum is applicable. The arbitrator, to whom the question of interpretation was submitted, agreed with the Association, and we, of course, must uphold the arbitrator “[i]f his interpretation can in any rational way be derived from the Agreement viewed in light of its language, its context and any other indicia of the parties’ intention.” County of Lachawanna v. Service Employee’s International Union, 35 Pa. Commonwealth Ct. 531, 536, 387 A.2d 161, 164 (1978).
*371'The arbitrator’s conclusion was buttressed by evidence consisting of letters (written several months after the agreement was reached) from correspondence between a teacher and the assistant superintendent in which the teacher inquired whether or not the salary máximums applied to the special increment and the school official replied unequivocally that they did not.2 Clearly, therefore, the arbitrator’s interpretation was rationally derived from the unambiguous language of the agreement and the written indicia of the parties ’ intent.3
The School District’s argument, that we ought to vacate the award as unconscionable because the cost of paying the special increments under the award would be prohibitive, is based upon the School District’s calculations as to the increments it would have to pay under the award. It asserts that, of the two *372teachers'who so far have requested their increments, one would receive $18,183.90 and the other $21,362.88 above their respective normal salaries for the last year of their employment. We see no basis, however, for its application of this argument here. In the first place, we are aware of no authority, and the School District cites none, for the application of a doctrine of unconscionability to collective bargaining agreements. In the second place, while the award may, as the School District argues, result in a financial burden, the record before us contains no evidence as to any mistake which would justify our relieving the School District of its obligation under the doctrine of rescission: Although it may not have fully understood the consequences of its-agreement,4 it is clear from the letter of its assistant superintendent that it intended the construction which the arbitrator has given to the disputed provision. Finally, the mere improvidence of an agreement does not justify the intervention of a court, Harnish v. Shannon, 392 Pa. 419, 141 A.2d 347 (1958), especially where, as here, the parties were dealing at arms’ length, were of equal bargaining power, and were each represented by counsel.
The order of the court of common pleas affirming the arbitrator’s award is therefore affirmed.
Order
And Now, this 9th day of January, 1980, the Court of Common Pleas of Delaware County is hereby affirmed.
*373This decision was reached prior to the expiration of the term of office of Judge DiSalle.
We upheld the validity of bargaining for such a provision in Pennsylvania State Education Association v. Baldwin Whitehall School District, 30 Pa. Commonwealth Ct. 149, 372 A.2d 960 (1977).
The teacher wrote:
Dear Dr. Baillie:
Am I correct in assuming that the special increment to my salary from unused sick leave would be applicable in full in 1975-76 and 1976-77 regardless of the stated maximum?
Sincerely,
/S/ H. E. Marie Boyle
The assistant superintendent replied:
Dear Ms. Boyle:
You are correct in assuming that the special retirement increment will be applicable to your salary regardless of stated maximum. It is, in effect, a super-maximum.
Very truly yours,
/S/ John K. Baillie
Assistant Superintendent for Administration
We note, in addition, that a similar provision in the parties’ agreement as to previous years contained a maximum number of days which could be accumulated. It would appear, therefore, that the School District could have again bargained for a maximum had it so desired.
The arbitrator believed that the School had “stumbled” into an unfortunate agreement “because it had not fully analyzed the language for which it settled.” He concluded:
It may not be wise for the Union to collect its pound of flesh, but this consideration can emerge only as a voluntary agreement between the parties.