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ORDINANCE NO. 2022-18 <br />Page 16 <br />structures shall be formed and channelized to minimize the <br />incidence of quiescent standing water where mosquitoes may breed. <br />e. Headwalls shall be required at all storm sewer inlets or outlets to <br />and from open channels or lakes. <br />6. Water Resource Crossings. The following criteria shall be used to design <br />structures that cross a water resource in the Village: <br />a. Water resource crossings other than bridges shall be designed to <br />convey the stream's flow for the minimum 25 -year, 24-hour storm. <br />However, a 50 -year or 100 year, 24 hour design may be required <br />by the Village Engineer. <br />b. Bridges, open bottom arch or spans are the preferred crossing <br />technique and shall be considered in the planning phase of the <br />development. Bridges and open spans should be considered for all <br />State Scenic Rivers, cold -water habitat, exceptional warmwater <br />habitat, seasonal salmonid habitat streams, and Class III headwater <br />streams. The footers or piers for these bridges and open spans shall <br />not be constructed below the ordinary high-water mark. <br />C. If a culvert or other closed bottom crossing is used, twenty-five <br />(25) percent of the cross-sectional area or a minimum of 1 foot of <br />box culverts and pipe arches must be embedded below the channel <br />bed. The conduit or conveyance must be sized to carry the 25 -year <br />storm under these conditions. <br />d. The minimum inside diameter of pipes to be used for crossings <br />shall be 12 inches. <br />The maximum slope allowable shall be a slope that produces a 10 - <br />fps velocity within the culvert barrel under design flow conditions. <br />Erosion protection and/or energy dissipaters shall be required to <br />properly control entrance and outlet velocities. <br />f. All culvert installations shall be designed with consideration for <br />the tailwater of the receiving facility or water resource. The <br />tailwater elevation used shall be based on the design storm <br />frequency. <br />g. Headwalls shall be required at all culvert inlets or outlets to and <br />from open channels or lakes. <br />h. Streams with a drainage area of 5 square miles or larger shall <br />rw incorporate floodplain culverts at the bankfull elevation to restrict <br />