Blocks over six hundred sixty feet (660') are not desirable and shall not be approved except where the topography or other special conditions make it imperative, in the reasonable judgment of the planning commission, to provide longer blocks. In every case where blocks of more than nine hundred feet (900') are platted for residential development, they shall be broken near the center by a ten foot (10') walkway. No walkway shall be approved which has a grade exceeding thirty percent (30%). (1962 Code § 10-903; amd. Ord. 75-O-1561, eff. 3-4-1975)