Plans, profiles, and details for storm drains may be prepared on separate drawings or on the same drawings used for sanitary sewers. All calculations leading to the locations of inlets and the sizes and slopes of storm drains shall be submitted with the plans or previous to the plans. This is to include: The intensity of rainfall to be considered; Its frequency of occurrence; The coefficients of runoff; The inlet time; The summation of calculated flows at various progressive distances along the drains; The spacing and types of inlets; The hydraulic calculations leading to the selection of pipe sizes and slopes; and Details of manholes, inlets, headwalls, and appurtenances.