A. Manholes: Manholes for sewers thirty six inches (36") and smaller shall have an inside diameter of forty eight inches (48"), and a six inch (6") thick precast concrete base, in one piece, bedded in at least two inches (2") of gravel or crushed stone. The sidewalls shall be of precast concrete ring construction which shall have a five inch (5") minimum thickness. Manhole bases for sewers with an internal diameter forty two inches (42") and larger shall have an inside diameter of sixty inches (60") and be constructed of reinforced concrete.
B. Catch Basins And Inlets: Catch basin sidewall and base construction shall conform to manhole requirements for sewers thirty six inches (36") and smaller, except that a sump two feet six inches (2'6") in depth shall be provided below the discharge pipe. Inlets shall have an internal diameter of two feet (2') and a minimum depth of two feet (2'). Sidewalls shall be precast concrete having a thickness of four inches (4"), bedded in a minimum two inches (2") of gravel or crushed stone.
C. Frames And Grates: Frames and grates for manholes, catch basins, inlets and valve vaults shall be similar to Neenah manufacture no. R-1015, with a combined weight of five hundred forty (540) pounds for type B closed lid, and a combined weight of five hundred twenty five (525) pounds for type D open lid. Open curb casting may be used based on approval of the city council. The frames shall be set in a full mortar joint on each structure. (Ord. 0-77-02, 2-7-1977)