(a) A complete storm sewer system and other drainage improvements shall be constructed in accordance with these standards. Where downstream storm drainage facilities are inadequate, consideration shall be given to detention basins, oversized storm sewers or other techniques to minimize the amount of runoff developed and to provide a means of controlling the discharge to off-site outlets.
(b) A ten-year storm frequency shall be used in the design of all storm sewers and ditches, and a twenty-five-year storm frequency shall be used in the design of major facilities such as culverts and detention facilities.
(c) Pipes shall conform to the following standards:
(1) Minimum size shall be 12 inches.
(2) Minimum cover shall be two feet.
(3) Minimum grade for smooth pipe shall be as per Table 1 in Appendix C of this chapter.
(4) Materials shall consist of reinforced concrete, smooth interior high density polyethylene, corrugated aluminum, aluminized steel or galvanized steel or PVC.
No open ditches will be permitted where flow requiring a pipe of 36" in diameter or less would be required. A swale shall be placed above the pipe to handle any overflow from storm of ten year or greater frequency.
(d) Storm sewers installed under or within five feet of pavements and sidewalks shall be reinforced concrete or high density polyethylene installed per ODOT 603. One year of natural settlement may be accepted in lieu of granular material compacted in place if soil conditions appear to be suitable (subject to Village approval).
(e) Storm sewer manholes, or inlets serving as manholes, shall be spaced at intervals of 400 feet or less for pipe less than twenty-four inches, and at all grade, alignment and pipe size changes. Manholes shall conform to ODOT 604 and be designed per ODOT Standards Construction Drawing MH-3. Layed up manholes may be permitted providing they are specified at the time of improvement plan submission, constructed in accordance with ODOT Standard Construction Drawing MH-1 and are plastered with cement mortar both inside and out to ensure water tightness. Manhole castings located in asphalt pavement shall be set in a minimum twelve inch wide concrete collar with a thickness equal to the pavement section and finished one quarter inch below the pavement surface. Seal the concrete/asphalt interface with liquid asphalt cement.
(f) Storm sewer inlets shall be designed and constructed in conformance with ODOT Item 604 and ODOT Standard Construction Drawings for CB 2-2-A and B; CB 2-3 and 2-4; CB 2-5 and 2-6; and CB-3 and 3A. Inlet CB-3 or CB-3A shall be used with curbing wherever possible and shall be fitted with vee type grates. Inlets shall be designed to accept not less than one and one-half cubic feet of stormwater per second. Inlet time shall be computed based upon Table 2 in Appendix C. Layed up catch basins may be permitted providing they are specified at the time of improvement plan submission, constructed in accordance with the time appropriate ODOT Standard Construction Drawing and are plastered with cement mortar both inside and out to ensure water tightness. When inlets are located in asphalt pavement, seal the concrete/asphalt interface with liquid asphalt cement.
(g) The allowable velocity in open drainage channels shall not exceed the values shown below for the various soil types and flexible linings. If the calculated velocity exceeds that shown, a gabion lining or other satisfactory treatment shall be required.
ALLOWABLE DITCH VELOCITY (feet per second)
Soil Type | Seed Lining ODOT 659 | Sod Lining ODOT 660 | Jute or Excelsior Matting ODOT 667 or 669 |
Sand | 1.5 | 3.5 | 3.0 |
Firm loam | 2.0 | 4.0 | 4.0 |
Clay | 2.5 | 5.0 | 4.0 |
Gravel | 3.5 | 6.0 | 5.0 |
Weathering shale | 4.5 | 6.0 | 5.0 |
(Ord. 81-56. Passed 12-28-81; Ord. 88-5. Passed 3-7-88; Ord. 91-35. Passed 5-20-91; Ord. 93-31. Passed 11-5-93.)
(h) The developer shall also comply with all provisions of the Richland County Stormwater Management and Sediment Control Regulations as adopted by the Richland County Commissioners on July 25, 2000.
(Ord. 00-61. Passed 12-4-00.)