WHAT: During the month of November 2019 the City of Folsom will be smoke testing the sanitary sewer lines around the Natomas Heights and Alice Wild subdivisions. Work will occur Monday through Friday between the hours of 7:00 a.m. and 4:00 p.m. Notification in these areas via mailers or doorhangers will occur 10 days and 2 days before smoke testing.
WHY: Over the past ten years, the City has been testing and upgrading
its sanitary sewer system. Damaged pipes, improper private sewer
construction or illegal connections to the sewer offer an easy route for storm
water or other non-wastewater discharges to enter the sanitary sewer collection
system. Non-wastewater flows entering the sanitary sewer collection
system not only takes up valuable capacity (which could potentially cause raw
sewage spills), but costs extra money to treat and convey.
Figure 1- Crew performing smoke testing in a residential area.
The City has implemented a comprehensive program to evaluate and maintain the sewage system, and make repairs as they are discovered. Several different operations are used to evaluate the system, which include; internal inspection of pipe using video equipment; visual manhole inspections; flushing and cleaning of the pipes; and smoke testing for illicit connections.
Smoke testing is a simple, cost effective way of locating sewer problems with little disruption to the system or the residents. Another advantage of this method is that it will not only test the City maintained mainline but will also test the integrity of the laterals. This method has been used extensively all over the country for many years to locate defects in sewer systems.
WHEN and WHERE: The areas to be tested are in sewage collection system sub-basin 6A as shown in the Figure 2 below.
Figure 2 – City of Folsom Sewer Collection System Sub-Basin Map
HOW: During this phase of the project, city crews will be conducting the smoke testing project to locate breaks, defects and illegal connections in the sanitary sewer system. This project will require the opening of manholes, which are located in the streets, utility easements and/or alleys. Once opened, a blower is placed on top of the open manhole which forces a non-toxic smoke into the system. As the smoke is forced through the sewer lines it will be forced from any openings or defects in the system, as shown in Figure 3. The white or gray smoke exiting the system is easily observable by the field crews performing the test, who will log each occurrence. Each of these occurrences will be mapped and analyzed.
Figure 3- Diagram of a smoke testing operation.