A. Manholes shall be installed:
1. At the end of each line;
2. At all changes in grade, size, or alignment;
3. At all intersections; and
4. At distances not greater than four hundred (400) feet for sewers fifteen (15) inches and smaller and five hundred (500) feet for eighteen (18) inches in diameter and larger.
B. The difference in elevation between an incoming sewer and the manhole invert shall not exceed twelve (12) inches, except where required to match crowns. The use of drop manholes will require approval by the local government engineer. The minimum inside diameter of the manholes shall conform to those specified by the local government engineer. Inside drop manholes will require special considerations; however, in no case shall the minimum clear distance be less than that indicated above. When a smaller sewer joins a larger one, the crown of the smaller sewer shall not be lower than that of the larger one. The minimum drop through manholes shall be two tenths (0.2) feet.
(Code 1991, §§ 12-490, 12-491)