(A) All storm sewer systems shall be designed for the peak rate of runoff from a minimum of a five- year return period storm under non-pressurized gravity flow conditions. The minimum pipe diameter shall be 12 inches. The system shall have a free outlet and shall generally be designed for gravity flow conditions. Low pressure flow conditions may be allowed near the outlet of the storm sewer system if physical conditions preclude a free outlet, as authorized by the Village Engineer.
(B) The maximum distance for overland flow of stormwater runoff shall be 600 feet.
(C) All manholes and catch basins shall be constructed in accordance with the attached standard details.
(D) Sufficient inlets shall be provided so that water will not drain across the crown of any street or flow in the gutter of any street from more than 500 feet during the five-year return period storm event. Flow along the gutter shall extend no more than ten feet out from the face of the gutter during the five- year return period storm event. The subdivider’s engineer shall submit calculations showing compliance with these requirements.
(E) Sewer grades shall be such that a minimum of two feet of cover is maintained over the top of the pipe. Uniform slopes shall be maintained between inlets, manholes, and inlet to manhole. Minimum and maximum allowable slopes shall be those capable of producing velocities between two and ten feet per second, respectively, when the sewer is flowing full.
(F) Storm sewers shall be constructed in a straight line between manholes insofar as possible.
(G) Manholes shall be installed to provide access to continuous underground storm sewers for the purpose of inspection and maintenance. Manholes shall be provided at the following locations:
(1) Where two or more storm sewers converge;
(2) Where pipe size changes;
(3) Where a change in alignment occurs; and
(4) Where a change in pipe slope occurs.
(H) The maximum distance between manholes for sewers 12 to 24 inches in diameter shall be 350 feet and for sewers over 24 inches in diameter shall be 500 feet.
(I) Pipes of equal diameter shall be provided with not less than 0.1 foot of fall across manholes. The 0.8-diameter point of pipes of unequal diameter shall be matched at manholes so as to promote continuous hydraulic grade lines.
(J) Diameter of manholes shall be as follows:
Outlet Pipe Diameter | Manhole Diameter |
18 inch and under | Four ft. |
21 inch to 42 inch | Five ft. |
48 inch to 60 inch | Six ft. |
(K) Pipe for storm sewers shall be as specified in the following divisions, unless directed otherwise by the village’s Maintenance Superintendent. The kind of materials permitted and strength required for respective diameters and fill heights over the top of the pipe shall be as shown in the tables in Article 550.03 of the Standard Specifications for Road and Bridge Construction, IDOT:
(1) Concrete pipe, 12 inches in diameter and larger, shall conform to the design requirements of Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe, AASHTO Designation M170 (ASTM Standard C-76). Joints shall be mastic joints;
(2) Extra Strength Vitrified Clay Pipe (ESVCP) generally conforming to ASTM Standard C-700. The joints for the pipe and fittings shall consist of a PVC ball or collar securely fastened at the factory on the bell end of the pipe in such a manner as to be water- and air-tight, and a polyurethane compression sealing element securely fastened at the factory on the spigot end of the pipe. The joints shall generally conform to ASTM Standard C-425. The material in the PVC bell and collar shall generally conform to the requirements of ASTM Standard D-1784. Pipe with clay bells will not be allowed;
(3) PVC pipe (four through 15 inches in diameter) conforming to Class PS 46 Polyvinyl Chloride (PVC) Pipe, AASHTO Designation M 278; smooth wall, unperforated, with flexible elastomeric joints;
(4) PVC pipe (18 through 27 inches in diameter) conforming to Poly(Vinyl Chloride)(PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings, ASTM Standard F-679; with flexible elastomeric joints;
(5) Corrugated PVC pipe (four through ten inches in diameter) conforming to Poly(Vinyl Chloride)(PVC) Corrugated Sewer Pipe With a Smooth Interior and Fittings, ASTM Standard F-949; unperforated, with flexible elastomeric joints; and
(6) PVC pipe (four through 48 inches in diameter) conforming to Poly(Vinyl Chloride)(PVC) Ribbed Gravity Sewer Pipe and Fittings Based on Controlled Inside Diameter, ASTM Standard F-794; with flexible elastomeric joints.
(L) Storm sewer pipe shall be joined and sealed with tightly drawn, authorized connectors and joints with gaskets or mastic as needed, to provide a tightly sealed joint.
(M) Storm sewer discharges shall be provided with end sections and measures to reduce flow velocity to minimize soil erosion at the discharge point.
(Ord. 97-7, passed 7-1-1997, § 5.19)