The process of smoke testing is one way to identify problems that
exist in the City's sanitary sewer lines. The process begins by injecting
a non-toxic vapor, referred to as smoke, into a segment of sewer line.
Once the smoke is injected a large blower, or fan, forces the smoke through
the line. Field Technicians then look for smoke exiting the sewer system
in locations that are not normal such as storm drains, down spouts, and
clean outs. These locations allow unwanted rainfall or ground water to
enter the sanitary sewer which leads to sanitary sewer overflows (SSO's)
Smoke Testing, Frequently Asked Questions FAQ's
1. What are smoke tests?
Smoke tests are one way to specifically locate problems in a sewer
system. A white vapor (smoke) is blown into the sewer main and will exit
thru deficiencies in the system. Such deficiencies are missing or broken clean outs, storm
drains connected to sewer lines, down spouts connected, or cracks in
sewer mains, etc. These problems lead to what the profession calls I
and I or Inflow and Infiltration. Inflow is were surface water enters
the system ie clean out or storm drain. Infiltration is were ground water
enters the system either through manholes or broken pipe. Field Technicians
note the locations for repairs.
Smoke exiting storm drain.
2. The Purpose of Smoke Testing?
Smoke testing is the most efficient and economical way to identify sewer system defects.
Roof drain connected to sewer.
3. Is The Smoke Hazardous?
The smoke is utilized throughout the United States by other private sewer consulting firms and municipal governments. Contact should be avoided but is not harmful. Minor irritation to the eyes and nose is possible but will be alleviated when exposure is ceased. A copy of the Material Safety Data Sheet is available on this site.
4. Will Smoke Enter My House?
Smoke will not enter your house unless you have a pipe or pluming defect. The
most frequent way smoke will enter your house is through dry traps. A
trap is located under most drains wether it is a sink or a floor drain.
The purpose of a trap is to "trap" water and create a seal between the
sink and the rest of the pluming system to prevent odors entering your
house . The City will notify you no less than 72 hours prior to conducting
a test. This is to give homeowners plenty of time to make sure all traps
are full of water. Running water for approximately 10 seconds or pouring
a gallon of water in a drain will be enough to assure the trap is full.
See figure below.
5. What other methods are used to locate I & I?
Other methods are flow monitoring and using close circuit television (CCTV).
6. Will anyone contact me with the test results?
The City of Hagerstown Water and Sewer Department will not contact you unless
there is a defect or problem found associated with your property. However we
will answer questions you may have will regards to the testing.
