Fog Testing of Sanitary Sewers in the Glen Cairn Area

The City of Ottawa is continuing its investigation of possible solutions to help reduce the risk of future flooding in your area. As part of the investigation, the City will begin conducting sanitary sewer fog testing in the area of Glen Cairn (see map below) the week of November 9, 2009 and this will extend to mid-December, 2009 (weather-permitting). This commonly used and effective practice is being conducted to assist staff in identifying areas that may need improvements within the sanitary sewer system.

We appreciate your patience on this matter, and we assure you this is a priority at the City. The following information is being provided to assist in responding to your questions.

Fog Testing: Questions and Answers

What is fog testing?

Fog testing is a safe, quick way to find areas of the sewer system that need updating. The fog used in the test has no odour, isn’t harmful to your health, and will disappear in a few minutes.

The test consists of blowing a harmless coloured vapour into the sanitary manholes and observing the points where the fog exits. The fog is expected to exit from manholes and the sewer stack at the top of your house. The fog should not enter your home if it is properly plumbed and if your sink and drain traps contain water. This test will not cause sewer backups.

What is the purpose of fog testing?

The purpose of the testing is to find potential points of inflow and infiltration in the sanitary sewer system. Fog testing can help locate improper connections where unwanted water could be entering the sanitary sewers. If a problem is found, the City will take appropriate action.

Is the fog harmful? Do I need to be at home during the test?

The fog is not harmful to your health, however you should avoid unnecessary exposure. It is relatively safe but may cause temporary minimal irritation to nasal passages. Any irritation should quickly disappear after exposure has ceased. As an added precaution, persons with heart and respiratory ailments should notify the City at 3-1-1 so they can be advised of the specific day of the test. The fog will not harm or stain clothing, drapes or furniture and is not harmful to pets.

There is no need to be at home during the fog test and inspection crews do not require entry into the house to conduct the test.

How can I prepare for the fog testing?

If the plumbing in your house functions properly, there should not be any fog entering your home. As a precaution, you should check to see that all traps under sinks, washing facilities and floor drains have water in them.

Run the faucet of your laundry tub for 30 seconds to fill the tub trap and use a bucket to pour a litre of water into each of your floor drains and sinks to help prevent fog from entering your home. You can also leave upstairs windows open slightly for better ventilation.

What should I do if fog gets into the house?

If all the traps are filled with water and if fog enters your home during the test, it probably means there are deficiencies in the plumbing that may allow sewer gas to enter. This would indicate that there is a problem with your internal house plumbing.

You should contact 3-1-1 and indicate your address as well as the location where the fog has entered your home. The call centre staff will put you in contact with one of the crew persons conducting the test. City staff will discuss with you what should be done to correct the problem.

The City will continue to explore ways to reduce the risk of future flooding and make our sewer system more efficient.