Resolutions-1997-021

B. Drop Connections: An external or internal drop pipe shall be provided for a sewer entering a manhole at an elevation of 24 inches or more above the manhole invert. Where the difference in elevation between the incoming sewer and the manhole invert is less than 24 inches, the invert shall be filleted to prevent solids deposition. C. Minimum Drop Across Manholes 1. For the same size pipe with a change in alignment of 45 degrees or less, no drop is required. 2. For the same size pipe with a change in alignment of greater than 45 degree, or junction of two inflow pipes, a 0.2 foot drop is required. 3. For the same size pipe with a junction of three or more inflow pipes, a 0.3 foot drop is required. 4. When a smaller sewer joins a larger one, the invert of the larger sewer shall be lowered sufficiently to match the 0.8 depth point of both sewers at the same elevation. D. Bedding: All manholes shall be placed on a minimum of 6 inches of crushed stone bedding. E. Materials: 1. Joints: All joints will be confined O-ring gasket meeting ASTM C443. 2. No lift holes through the entire wall. 3. Mark date of manufacture. 4. Inverts: Precast and cast-in-place inverts must provide a channel at least one-half the depth of the pipe and match the full cross-sectional area of the pipe. All junctions and changes in directions of inverts shall be smooth and rounded to the maximum extent possible to supplement flow through the manholes. 5. Diameter: The minimum diameter for manholes is 48 inches for pipe 21 inches in diameter and smaller, and 60 inches for pipe greater than 21 inches in diameter. 6. Castings shall be Neenah R-1670 non-rocking self-sealing or approved equal. F. Standard manholes, step details, drop connections and risers are shown in Figures 8.1, 8.2, and 8.3. G. All manholes shall be marked with two metal fence posts to remain in place until landscaping is complete. In subdivisions, the posts shall remain in place until landscaping has been completed by the lot owner. H. If a manhole is in an area subject to surface water inundation, the casting shall be bolted to the cone section with stainless steel anchors. In addition,