Should any member of this plan retired for disability engage in a gainful occupation prior to attaining the age at which he or she would have been entitled to voluntarily retire for service, the retirement system manager shall reduce the pension portion of such member's monthly retirement allowance so that the resultant retirement allowance when added to the average gross amount earned monthly by him or her in such occupation, will not exceed the greater of the following:
A. The amount of his or her final compensation; or
B. The amount of the compensation earnable by a person holding the position in the same salary step which such member held at the time of his or her retirement, or if the position has been abolished, the maximum compensation earnable by the person holding such position immediately prior to its abolition.
The reduction provided for in this section shall not exceed the amount of the pension portion of the retirement allowance and shall terminate when such member attains the age of eligibility for voluntary service retirement. (Prior code § 34.06.621)