(A) Storm water drainage shall be accomplished through use of storm sewers unless the Village Engineer shall certify that there exist unusual topographic, erosive or other site-specific conditions which shall render the same impractical or unsound based upon a reasonable degree of scientific and engineering certainty. All drainage systems planned, built or installed within the village which connect to existing ditches shall be designed and engineered to transition smoothly with the storm sewers in the new installation as may be directed by the Village Engineer.
(B) The design and construction of storm sewers shall be in conformance with the standard specifications, the Highway Standards Manual, and the Highway Design Manual. The storm sewer system shall be designed by the "rational method" with self-cleaning velocities in conformance with the following requirements:
(1) That part of the system which serves as main or terminal collector shall be of sufficient capacity to carry the maximum discharge for a storm of ten-year frequency. Overland relief routes must be provided to carry a 100 year storm event.
(2) Those parts of the system which serve as lateral collectors, and which can readily be augmented by future additions, shall be of sufficient capacity to carry the maximum discharge for a storm of 10 year frequency.
(3) The Village Engineer shall select coefficients of runoff based on the types of development anticipated in all parts of the watershed affecting the drainage structure.
(4) The system shall include all necessary appurtenances such as inlets, catch basins, and manholes as may be required for proper operation and maintenance.
(5) In those cases where a subdivision is subject to storm water flow from adjoining properties, provisions shall be made to provide for unrestricted flow of that volume of water generated by the adjoining land for a storm of 100-year frequency. The subdivider may be permitted to substitute for the storm sewer an open ditch. Such ditch shall comply with grading, seeding, sodding, and easement specifications of this chapter or the county requirements, whichever best protects all the property involved.
(6) All storm sewers shall be at least 12 inches in diameter except that a ten-inch diameter may be used for connecting a single structure to a manhole, or as directed by the Village Engineer.
(7) Special considerations shall be given to the avoidance of problems which may arise from the concentration of storm water runoff unto adjacent property which may crate a nuisance or maintenance difficulty. All storm drainage shall be conducted or connected to an approved outfall and shall be included in the subdivider's plans for storm water management in accordance with the requirements of the county.
(C) Related structures.
(1) Catch basins, manholes, inlets, frames, and grates shall conform to the Highway Standards Manual and the Standard Specifications.
(2) The spacing of pavement drainage structures shall be at maximum intervals of 300 feet or as directed by the Village Engineer.
(3) No field tile shall be permitted to remain under the roadway. It shall be replaced with load bearing tile and where feasible shall be incorporated into the proposed storm sewer system.
(4) No field tile shall be permitted to remain under the roadway. It shall be replaced with load bearing pipe and shall be incorporated into the proposed storm sewer system.
(Ord. 1995-0-25, passed 12-26-95; Am. Ord. 1999-O-21, passed 9-21-99)