A. Storm sewers, culverts, inlets, and open ditches shall be designed to carry a rate of flow not less than the runoff rate computed by the rational method formula:
Q | = | CIA | ||
Q | = | Runoff rate in cubic feet per second | ||
A | = | Drainage area in acres | ||
I | = | Rainfall intensity for a 10-year storm | ||
C | = | Runoff coefficient using following values: | ||
Commercial and industrial | 0.95 | |||
Residential, single-family | 0.55 | |||
Residential, multi-family | 0.75 | |||
Parks, golf courses, etc. | 0.35 | |||
Undeveloped | 0.15 | |||
B. The storm sewer sizes shall be determined on the basis of the Kutter's formula or the Manning's formula using an "n" roughness coefficient of thirteen-hundredths (0.13) for smooth pipe and twenty one hundredths (0.21) for corrugated pipe. The minimum size storm sewer shall be twelve inch (12") diameter pipe.
C. Storm sewers shall be constructed with reinforced concrete pipe conforming to the latest revision of ASTM specification C76 for class III pipe with all joints sealed with preformed flexible rubber gaskets in accordance with the recommendations of the manufacturer.
D. Culvert sizes shall be designed to carry the 10-year storm with no head available at the culvert inlet. The minimum size culvert shall be fifteen inch (15") diameter pipe. Flared end sections shall be provided for all culvert pipes of twenty four inch (24") diameter and larger sizes. (Ord. 2004-02-03, 2-25-2004)
E. Storm sewer inlets shall be located at street intersections, low points between intersections, and at sufficiently frequent intervals that gutters or ditches will not be overloaded. Low points shall include double inlets. (Ord. 2015-03-02, 3-11-2015)
F. Storm sewer manholes shall be located at all changes in pipe sizes, slope or alignment, at all sewer junctions, and at distances of not greater than five hundred feet (500') for sewer sizes of twelve inch (12") to twenty one inch (21"), and not greater than six hundred feet (600') for sewer sizes of twenty four inches (24") and larger.
G. Catch basins shall not be provided for storm sewer inlets in curbs and gutters. Catch basin type inlets shall be provided for ditch and area drains where excessive silt can be expected to be carried with the stormwater runoff from unpaved areas. (Ord. 2004-02-03, 2-25-2004)
H. Manholes, inlets and catch basins shall be standard types approved by the state of Illinois department of transportation, division of highways. Inlet and catch basin frames and grates shall be consistent with the curb and gutter size. All storm inlets and catch basin frames shall include the "no dumping" stamp.
I. Storm manholes shall have external chimney seals. Chimney seals shall be Cretex or an equivalent external rubber chimney seals as approved in advance in writing by the village's director of public works. (Ord. 2015-03-02, 3-11-2015)