SSOs happen when there's so much water in the sanitary sewer system that it gets overloaded, Sumner explained. The hydraulic pressure build-up pops the lids off manhole covers in some situations ...

Carson said most of the manhole covers in the area remain the former, generic checkered-plated cast-iron lids, which reads “sanitary sewer,” because, in 1990, MSD inherited the bulk of the ...

Manholes are most commonly used to provide access to storm and sanitary sewer systems, which rely on gravity to move material through a gently sloping network of underground pipes that typically ...

Sanitary sewer manhole covers have gaps in them, so at high tide and during rain, excess water gets in and can overwhelm the sanitary sewer system, Grant said.

Renaud did note that deficiency with the manhole covers include low lying manholes, frame and wall deterioration, root intrusion, and active inflow at joints or pipe penetrations. Additionally, Renaud ...