How to Know if Your Flow Manhole is Surcharging

Sewer Surcharging is overloading the carrying capacity of a sewer system due to inflow and/or infiltration. As part of any inspection of a flow manhole site, the operator should look for signs of surcharging in order to ensure that their collection system is operating correctly.

surcharge flow coming out of a manhole cover

Assuming sewage isn’t spilling out of the top of the manhole when the operator arrives, there are a number of things to look for when inspecting the manhole.

evidence of surcharging in a fiberglass packaged metering manhole

Is the ground around the manhole saturated or moist in comparison to the surround ground?
In cold weather, is the ground around the manhole free of the frost / snow that would otherwise be expected?
Is there a scum line on the inside of the manhole barrel – well above the normal flow elevation?
Does the lower portion of the manhole show considerably more corrosion that the upper portion?
Is there ragging or hanging debris on the manhole walls / ladder?
Is there debris or bioslime on the manhole bench consistent with standing water?
Is there standing water in the bottom of the manhole?

surcharged Parshall flume in a fiberglass packaged metering manhole