Sewer Smoke Testing

*Update on October 9, 2018: Sewer smoke testing in Portsmouth has been completed

Work related to City’s ongoing sewer system evaluation study will begin on September 4, 2018 and is expected to continue through mid-October 2018. This work will be used to identify areas of the City where rainwater is entering into the City’s sanitary sewer collection system and prioritize areas for future improvements.

The crews performing the investigations will be “smoke testing” the City’s sanitary sewer collection system as part of this work. The smoke is a non-toxic vegetable based product, has no odor and is stainless. During smoke testing, field crews blow air and smoke into the sanitary sewer system in the street and monitor where smoke escapes the system. The smoke will follow a path of any leak or connection to the ground surface. Crews from the Department of Public Works and subcontractor Flow Assessment Services LLC will access sewer manholes as part of the work. The smoke testing work will begin on Tuesday, September 4, 2018 and will be performed Monday through Friday, 7 a.m. to 4 p.m. through mid-October. A flyer will be distributed in areas scheduled for smoke testing between 24-72 hours before the work is scheduled to begin.

No interruptions in water or sewer service will occur during these activities. Crews performing the work will be wearing marked uniforms. Smoke should not enter your premises unless there is a dry trap in your basement floor drain or any unused plumbing fixtures. If smoke enters your home, please notify workers in the area.

The work will begin in the northern section of the City and proceed southward, displayed in this map (also shown below). For more information, please contact Terry Desmarais, City Engineer, at (603) 766-1421 or tldesmarais@cityofportsmouth.com.

 

What is the purpose of smoke testing?

The purpose of smoke testing is to find potential points of inflow and infiltration in the public and private portions of the sanitary sewer system that could lead to high flows in the separate sewer system during storm events.  Smoke testing can also help locate the following:

• Buildings that have downspouts, cellar, yard or basement drains
• Catch basins and parking lot drains
• Any cross connections between sanitary sewers and storm drains
• Defective sewer connections that could allow sewer gases into a building

 

Where is smoke testing performed in the sewer system?

The City of Portsmouth has two types of sewer collection system – a combined collection system and a separate sewer collection system. In the areas of the combined collection system, the City expects connections between the storm drain system and the sewer system so smoke testing is not performed in those areas. The smoke testing is being performed in the areas of the separated sewer system where storm drain and other types of connections that permit rainfall into the sewer system should not exist.

 

Public Notification

Field crews will distribute a notice door to door approximately 24 to 72 hours in advance. Police, Fire and the Public Works Officials will also be notified daily of work areas.

 

How does smoke testing work?

During smoke testing, field crews blow air and smoke into the sanitary sewer system in the street and monitor where smoke escapes the system.  The smoke, under pressure, will fill the main line as well as any connections and then follow a path of any leak to the ground surface, quickly revealing the source of the problem.  Only enough force to overcome atmospheric pressure is required, and smoke should escape from building roof vents.

 

What are the benefits of smoke testing?

Smoke testing is the most efficient and cost effective way to locate and identify where unauthorized water is entering the public and private portion of the sewer system.  The smoke is harmless and will disappear after only a few minutes.  The testing is also a cost-effective way to find areas of the sewer system that need improvement.  Smoke testing will also help identify plumbing leaks in buildings.  Sewer gases from plumbing leaks can cause health problems for building occupants.

 

Is the smoke harmful?

NO. The "smoke" is not true smoke.  It will not harm your health or leave a stain and will disappear rapidly without leaving an odor.

If the smoke enters your home, it may make you cough, but the smoke is:

• Non-toxic
• Non-staining and odorless
• Harmless to humans, pets, plants, food and material goods
• Creates no fire hazard

 

Will smoke testing of the sewers allow smoke to get into my home?

No, provided that your plumbing is installed and functioning properly, and provided "traps" are filled with water.  Drains that are used frequently should be okay.

If you are not sure, simply run water down the drain for a minute to ensure that the trap is not dry.  It is important to locate dry traps as they could allow sewer gases to enter the home.  Dry traps are most commonly found in basement floor drains that are used only during rare flood events or in unused fixtures.  Please thoroughly check your home.

 

What does it mean if smoke enters my home?

If smoke enters your home during the test, it may indicate there are deficiencies in the plumbing that may allow potentially dangerous sewer gases to enter.

 

How may the smoke enter my house?

Since plumbing fixtures in your home or business are connected to the sanitary sewer system, there is the potential for the smoke to enter if the drains are not connected properly.  This happens particularly under the following circumstances:

• The vents connected to your building's sewer pipes are inadequate, defective or improperly installed
• The traps under sinks, tubs, basins, showers and other drains are dry, defective or improperly installed
• The pipes, connections or seals in the wastewater drain system in and/or under your building are damaged, defective, have plugs missing or improperly installed

 

What should I do if smoke gets into the house?

• Do Not Become Alarmed
• Open windows to allow ventilation and note the location of the smoke emission; smoke will clear within a few minutes
• Exit the building and notify smoke testing personnel in the area

 

How long will the testing take?

While crews might be in your area for a few hours, each actual smoke test setup takes approximately 15 minutes to complete.  Most houses will only be within the testing area for one or two tests.

 

What should I do to prepare for smoke testing?

When you receive notice that smoke testing will take place, you should:

• Check to see that all drain traps under basins, washing facilities and floor drains contain water; simply flush toilets and run or pour water into all drains, including unused fixtures and floor drains.
• If there is an individual in your home or business who has reparatory problems and/or mobility limitations, or if your have any additional questions, contact Flow Assessment Services at 1-888-311-9799 or the City Engineer, Terry Desmarais at 603-766-1421 or tldesmarais@cityofportsmouth.com.

 

Do I have to be home during testing?

No. Inspection crews will not need to enter your home unless smoke is present and you want them to help identify the defect. You are not required to allow entry to our crews.