The Cost of Surface Inflow

Wet weather inflow and infiltration create sanitary systems capacity problems and result in unnecessary treatment costs that get passed on to the user. Sanitary systems all over are looking to reduce I&I. Surface inflow can be a significant contributor to I&I problems.

A large manhole casting company conducted a study of the inflow through an average 24” manhole with concealed pick holes and found the following:

Calculate Annual System Manhole Inflow Treatment Costs

Of course every system will have different surface inflow rates. But we can use the above information to
begin to put a value on surface inflow costs.

For the ease of calculation, assume treatment costs are $1.00 per 1000 gallons. Then:

Then apply actual treatment costs and multiply by the number of affected manholes and hours of inflow.

Surface Manhole Inflow Treatment Cost Calculator

Controlling Surface (Manhole) Inflow:The Manhole Insert

Manhole inserts are the simplest way to control surface inflow. They are installed in minutes, and inserts offer a quick payback and establish a front line against over-capacity problems during wet weather events

Not all manhole inserts are created equal, however. The Man Pan manhole inserts are made with exceptional strength and rigidity. Their patented designs maximize inflow prevention and minimize chances of collapse. The Man Pan inserts are designed with the field staff in mind, especially The Man Pan Classic, with patented lifting lugs to save backs and fishing around in the dark muck for breakable straps