Laserfiche WebLink
3.03 Manhole Construction <br /> A. Standard manholes shall be installed in accordance with Standard Drawings. <br /> B. Flat-top manholes shall be installed in accordance with Standard Drawings. <br /> 1. Flat-top manholes are required whenever the distance between the finished <br /> ground surface and the manhole barrel section does not allow room for a cone <br /> section. <br /> 2. Access holes for flat-top manholes shall be offset from center. <br /> a. If the distance from the manhole cover to the invert of the sanitary <br /> sewer line main is less that 3 feet,the access hole shall be centered. <br /> C. Cast-In-Place Concrete Base <br /> 1. Invert channels shall be smooth and semi-circular in shape conforming to the <br /> inside of the adjacent sanitary sewer pipe section. <br /> 2. Form inverts directly in the concrete of the base, or for a straight through <br /> manhole with no other inlets the channel may be constructed by laying a full <br /> section pipe through the manhole and by cutting out the top half of the pipe <br /> after the surrounding concrete has hardened. <br /> 3. Changes in direction of flow shall be made with a smooth curve having as <br /> large a radius as the manhole will permit. <br /> 4. The floor of the manhole outside of the channels shall have a smooth trowel <br /> finish and shall slope toward the channels at one-inch(1")per foot. <br /> 5. Pipe size changes shall be accomplished by matching the pipe crowns and <br /> forming the channel to accommodate the pipe size differential. <br /> 6. Where shown on the approved Construction Drawings, a piece of pipe of the <br /> proper size shall be built into the manhole where future laterals may be <br /> connected. <br /> a. The stub-out shall be sealed with a plug at its outer end and an invert <br /> shall be built into each manhole for such lateral connections. <br /> 7. Manhole bases shall be thoroughly bonded to the barrel of the pipe. <br /> a. Provide a rubber gasket on the pipe barrel for PVC pipe. <br /> b. All connections with the pipe shall be made without projections or <br /> voids. <br /> Boyd Freeman Ditch Improvements 02605-5 Manholes <br /> August 2005 <br />