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Out in the Field - Finding and Fixing I/I
How do you reduce or eliminate I/I?
 Once an
I/I problem has been identified, there are a number of ways I/I can be
reduced. It is a goal of this program that pilot
projects will demonstrate various infiltration and inflow removal
technologies and techniques. There are many methods and technologies that
are available to remove and reduce I/I. One primary method focuses on
fixing the broken pipelines, manholes, and joints where they are below
ground water. Another focuses on limiting the amount of I/I that enters
the sanitary sewer system from storm events, such as rainstorms or snowmelt
through manhole lids, stormwater catch basins, house drains, and other
direct connections.
To reduce or eliminate I/I, sewer components can be replaced or rehabilitated.
Rehabilitation methods are less invasive, because repairs can be made
from inside the pipe or manhole, or only a small excavation is needed
to expose the pipe. Examples of I/I control techniques are listed in the
following table.
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Sewer Component
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How to Fix I/I
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I/I Control Methods
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Pipelines (side sewers, laterals, mains)
Side sewers and some laterals are on private property. Most mains
are on public property.
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Replace or repair sewer pipes.
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Replacement
Rehabilitation
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Pipe grouting – cement based grout is
injected from the inside of a pipe to fill a hole or crack
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Pipe relining - flexible liner is inserted
into a pipe either by pulling it through an existing pipe or
inverting it using water pressure – like a sock turned
inside out
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Pipe bursting – existing pipe is expanded
with a bursting tool and a new pipe is pulled through
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Spot repairs – problem pipe is exposed
and replaced or a repair sleeve is attached
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Manholes
Location: Most are on public property.
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Replace or repair existing manholes.
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Replacement
Rehabilitation
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Stormwater Component
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How to Fix I/I
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I/I Control Methods
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Building Connections
Most are on private property.
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Disconnect and reroute to separate stormwater system or remove
and allow water to soak into the ground.
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Stormwater system disconnection
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Roof drains
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Downspouts
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Yard drains
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Catch basins
Groundwater control system disconnection
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Foundation drains
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Sump pumps
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The above table is also available as an Acrobat
PDF file -- page 3 of program
flyer (416 K).
» Finding Infiltration and Inflow (I/I)
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