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Program (NURP). 5. Provide for overflow routes to drain low points along streets or lot lines to ensure a freeboard of 2' from the lowest exposed structure elevation and the calculated 100 - year storm HWL elevation. Design criteria verifying the adequacy of the overland drainage route capacity is required. At low points in the street, the catch basin grates shall be assumed to be 50% plugged for design purposes. 6. The storm sewer alignment shall follow the sanitary sewer and watermain alignment where practical with a minimum of 10' of separation. Storm sewer placed along the curb alignment shall be along the curb opposite the watermain to maintain the 10' separation. Catch basins shall be located on the tangent section of the curb at a point 3' from the radius. Mid -radius catch basins will not be allowed. Also, catch basins shall be designed to collect drainage from the upstream side of the intersection. 8. The maximum spacing between manholes is 400'. 9. Manholes steps will be aligned and over the downstream side of the manhole. Steps within manholes will be: V+ horizontal alignment 1 "+ vertical alignment with 16" spacing as the standard 10. Any connections to existing manholes or catch basins shall be core drilled or the opening cutout with a concrete saw. No jack hammering or breaking the structures with a maul is permitted. Also, all connections to an existing system will require a manhole for access. 11. To the greatest extent possible, manholes shall be placed in paved surfaces outside of wheel paths (3' and 9' off centerline) or other readily accessible areas. 12. Minimum pipe size shall be 12" in diameter. 13. Type of pipe shall be Reinforced Concrete Pipe (RCP). All storm sewer pipe beneath roadways or pavement shall be Class 5. The table below shows the allowable class of pipe for storm sewer outside of the roadway: PIPE DIAM. CLASS 2 CLASS 3 CLASS 4 CLASS 5 12" — 18" X 21" X X 2411-3311 X X X > 36" X X X X Show the class of pipe in the profile view only. For areas outside of the roadway, the City may allow the use of HDPE (High Density Polyethylene) pipe.