Power to discontinue payments into sinking fund.

Notwithstanding anything contained in section 70, if at any time the sum standing at credit of the sinking fund established for repayment of any loan is of such amount that if allowed to accumulate at the rate of interest prescribed under sub-section (2) of that section, it will be sufficient to repay the loan at the end of the period agreed upon by the Board, then, the Board may discontinue further annual payment into such fund.