Smoke Testing

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During the 2016 – 2017 rain season, the City of Vacaville experienced several episodes of heavy rain. These heavy rain events caused certain sewer shed areas to either overflow or reduce the pipe capacity significantly.

City staff responded to a Sanitary Sewer Overflow (SSO) in the sewer shed in Area 1 of 1,066 gallons on February 7, 2017. SSO’s are prohibited by State regulations and carry a potential monetary liability of $10,000 per day and $10 per gallon of sewer overflow. In addition, a sewer flow meter located on W. Monte Vista Ave. near Chandler Street and a sewer level meter near 134 West Street provided flow and level information that showed the sewer shed for Area 2 was causing the sewer line capacity to quickly diminish and potentially causing an SSO.

Subsequent sewer system map research and field investigations concluded that the cause of the SSO and capacity issue was due to the high volume of inflow and infiltration flow. The goal of the smoke testing project is to identify missing cleanout caps, broken cleanouts or lateral connections, broken sewer mains, and illegal sewer connections from rain gutters, area drains, or basement drains.

After identification and recording of the sewer system deficiencies, a repair/replacement or a sewer system modification plan will be prepared along with a prioritized schedule to correct the sewer system deficiencies.

Smoke Test Implementation

Smoke Testing will occur from September 18 through September 29, between the hours of 8 a.m. and  3 p.m., Monday through Friday.

Smoke Testing Frequently Asked Questions

The City of Vacaville Utilities Department will conduct smoke testing of the sewer mains in the downtown Vacaville area.

Q. Why is smoke testing the sewer mains in my neighborhood necessary?
A. The purpose of this test is to identify defects where storm water may enter the public sewer system from the street or the sewer line easement. Detecting storm water intrusion into the sewer system reduces costly sewer treatment and the need for larger sewer mains.

Q. When will the work start?
A. Work is scheduled to begin September 18, 2017. Normal smoke testing hours will be from 8 a.m. to 3 p.m., Monday through Friday. An additional reminder will be placed at your residence or business one week before and again within three (3) days of the actual work.

Q. When will the work end?
A. Work is to be completed September 29, 2017.

Q. How will the City inspect the sewer mains?
A. The City of Vacaville has hired a contractor to introduce smoke into the sewer manholes and blow it through the sewer mains with forced air. A special non-toxic smoke made for this application will be used for this test. The smoke used is non-staining, leaves no residue, does not create a fire hazard, does not harm animals or plant life and will dissipate in a few minutes.

Q. What can I expect to see during the smoke test in my neighborhood?
A. Homes and buildings are connected to the public sewer main through pipes called laterals. The laterals connect to the plumbing from the bathroom and kitchen of your home or building. A vent pipe located on the roof is also part of your home’s plumbing system. Normally, smoke should exit the sewer system through existing vents on the roof of your residence or building and through the manholes in the street.

Q. Will smoke enter my home or building?
A. On very rare occasions, you may notice smoke inside your residence or building, DO NOT BE ALARMED, ventilate by opening doors and windows and avoid unnecessary exposure by leaving the premises. This may be a result of inadequate, defective, or an improperly installed plumbing system. It is advisable that you call a licensed plumber to repair possible defective plumbing and assess the potential for leakage of sewer gases into your home or building. Please contact the crews working in the vicinity or call the phone number below. Our crews will take your information.

Q. Is it normal to see smoke coming up from the ground, lawns, or streets?
A. If there are defects in the sewer mains and laterals, you may notice smoke venting out of holes or fissures on the ground, the lawn, or the street. Our crews will investigate and log the source for future repair work. AT NO TIME WILL FIELD CREWS HAVE TO ENTER YOUR HOME. However, if our crews notice smoke on your property, a City of Vacaville employee may request access to your property (i.e. backyard, side yard) to investigate.

Q. Do I have to be home for the City of Vacaville to perform the smoke test?

A. No, you do not have to be home during the test.

Q. What can I do if there is smoke inside my home or my business?
A. Although the smoke is not dangerous, it is advisable to prevent unnecessary exposure. Please ventilate the smoke by opening doors and windows and leave the immediate area. The smoke dissipates quickly. A City employee will be called to your home or business. Please provide name, address, phone number, and details of location of the smoke. Smoke coming out of the plumbing vent stack on your roof is normal. Neither the City employee nor the field crew will enter your home.

Q. Do I call the Police or Fire Depts.?
A. We have notified both Departments about the smoke testing schedule. But if you are in doubt of where the smoke is coming from, do not hesitate to call 9-1-1.

Q. What if a resident in the area to be tested is an elderly person or has respiratory difficulties and cannot make other arrangements to leave their home?
A. We will take your name, address, and phone number to notify you of the actual date the smoke test is going to take place in your neighborhood. We will notify field crews to pay special attention to your address. If smoke does enter your home, remove people from the immediate area to fresh air.

Q. Can I prevent smoke from coming into my house or business?
A. You can pour about 1 gallon of water into any unused sinks, drains, shower stalls/tubs, and toilets. This will help to prevent smoke from entering your house via seldom used drains.

Q. When the testing starts, can I flush my toilet? Pour water down my drain?
A. Yes, sewer service will not be interrupted.

Q. Is my drinking water affected?
A. No, sewer system and water system are two different and separate systems.

Q. Will I smell smoke?
A. There is a distinct odor, but not unpleasant. The smoke is light gray to white in color. It may make children and the elderly cough if exposed to an extended period of time, but it is not harmful to your health and will not harm clothing, drapes or furniture.

Q. If smoke is detected in my backyard, will you have to work in my yard?
A. No, we will not need to work in your backyard immediately after the smoke testing. We will first analyze the information and then recommend possible solutions. The purpose of the smoke test is to document possible sources of clean water entering the sewer system

Q. What if a resident in the area to be tested is an elderly person, a toddler, or has
respiratory difficulties?

A. While it is highly unlikely that smoke will enter your home, for your peace of mind, you may consider making other arrangements prior to the test to help avoid any confusion or alarm to elderly people in your home and avoid unnecessary exposure to toddlers or people with respiratory conditions such as asthma, bronchitis, or emphysema. The smoke is non-toxic and is most often used in testing household plumbing. The Manufacturer’s safety data sheets for the smoke are available to all upon request. Use the number listed at the end of this notice to request notification immediately prior to the test.

If you have any questions regarding the testing program, please call City of Vacaville staff at

(707)469-6400