Manholes Rehabilitation: Sometimes Misunderstood, Yet Key Infrastructure Solution

First In A Three-Part Series
By Gerhard “Gerry” P. Muenchmeyer, P.E. NASSCO Technical Director | September 2011, Vol. 66 No. 9

• Cover - is used to control access from the ground surface into the manhole. The cover, typically made of cast iron, is replaced if defective;
• Frame - is used to provide support for the manhole cover and connect the cover to the body of the manhole. The frame, also cast iron, is typically replaced if defective;
• Chimney - can be described as a manhole component constructed of brick, concrete or polymer material that connects the frame to the cone of the manhole. In addition to reconstruction, a number of technologies are available to repair and rehabilitate the chimney area of the manhole;
• Cone - is a tapered, transition section frequently installed between the smaller diameter chimney section and the larger diameter wall for a certain depth of manhole. A number of coating, grouting and lining techniques are available to effectively repair and rehabilitate this portion of the manhole;
• Wall – is the vertical section installed from a cone to the bottom of a manhole. A number of coating, grouting and lining techniques are available to effectively repair and rehabilitate this portion of the manhole;
• Joint Seal - is a material or device to prevent intrusion of groundwater water at the joint between precast wall sections, or cone and wall sections. Cementitious, polymer and mechanical repair methods are available for long term rehabilitation;
• Manhole Step - can be metal, plastic or configured as a ladder. These devices can be replaced if defective or removed entirely as specifically required;
• Bench – is the bottom section of the manhole. Typically constructed of brick or mortar, if defective, can be replaced using plastic materials or rehabilitated using a variety of long term proven materials;
• Channel - is a shaped flow-way within the bench which directs sewer flow through the manhole. Usually constructed of cementitious or sewer pipe materials, it can be rehabilitated with grouts and many other available proven products;
• Pipe Connections - Connections are a continuation of the sewer pipe through the manhole wall and into the manhole. Typically the seal through the wall can contribute excessive flow and require rehabilitation;
• Pipe Seal - The pipe seal can be described as the material or device installed at the pipe and wall or whatever manhole component in which the pipe enters. These can be rehabilitated using a number of effective techniques; and

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