Every drop of liquid treated in a sewer plant costs money to treat. Utilities, therefore, have a strong incentive to reduce unnecessary inflow.

Enter smoke testing. Smoke testing does a great job of finding inflow cheaply and quickly.

The “smoke” is not really smoke, but a harmless vapor that is highly visible. Why It Is Used and How It Works


Utilities love smoke testing because it is a fast and affordable way to check for storm water inflows. When compared to alternative methods, smoke testing has an average daily production of 15,000 ft. Furthermore, the low price of smoke testing makes it an attractive option. Smoke testing can expose information that would have otherwise remained undiscovered, such as damaged sewers near drainage paths and cross connections between the storm and sanitary systems.

The “smoke” is not really smoke, but a harmless vapor that is highly visible. By placing a smoke blower over a manhole, the blower forces the smoke into the wastewater system. Depending on where the smoke comes out, determines whether  there is a problem. Emitted smoke is evidence of plumbing issues (e.g. improper, illegal, or defective plumbing), cross connections and wastewater system damage.

Smoke emissions can be found coming out of:
• Public storm system components (e.g. manholes, catch basins, area drains, etc.)
• Public sanitary system components (e.g. manholes, lift stations, broken sewer mains, buried assets, etc.)
• Private storm system components (e.g. sump pits, drain tiles, downspouts, radon exhausts, etc.)
• Private sanitary system components (e.g. broken/defective cleanouts, cisterns, dry taps, broken service lines, plumbing vents, improper/illegal plumbing, etc.)

Smoke Testing Goes DigitalSmoke Testing Goes Digital


A typical field crew uses handwritten notes to document their field observations. The final deliverable, then, tends to be a compilation of these hand-written notes, which requires much diligence on the part of the utility to sift through all of the paper documents. At best, these hand-written notes are transcribed onto a spreadsheet.

Realizing how cumbersome it can be to review paper documents, Wachs Water Services takes a digital approach, using tablet devices running ArcGIS online. During field observations, the field crew is able to add each observational record into the GIS database, collect pictures/videos using the tablets and automatically all data is linked correctly. For each smoke observation, the utility is provided with a wealth of data pinpointing the exact nature and location of the problem.

“Utilities don’t just end up with a big stack of papers,or a spreadsheet made from someone else’s big stack of papers,” says Wachs Water Services project manager Justin Vangelista. “The data the inspector collects is immediately usable. It’s there.”

By submitting findings in digital format, a world of possibilities becomes available for users of the data: •
• Viewing results in real-time
• Looking at results on a map
• Drawing visual patterns from the data
• Querying results that are private responsibility versus public responsibility
• Generating work orders
• Easily accessing all pictures containing smoke emissions
• Visually seeing the location of all smoke emissions
• Viewing this data in tabular format if desired
• Printing findings in report format, if desired

One Illinois Utility’s Story


An Illinois utility recently engaged Wachs Water Services to perform smoke testing on a portion of its wastewater system. The project lasted eight days and consisted of approximately 130,000 ft of smoke testing. The reason for the project was twofold: (i) to complete the final phase of a multi-year inaugural sweep of its entire system, and (ii) to use smoke testing as an indicator in determining where storm water may be entering into the wastewater system. Years ago, the utility separated its combined storm/sewer system. However, city ordinances prevented utility personnel from being allowed to physically go into the homes and businesses to check that their storm system is separate from their sewer system.

Fortunately for the utility, the majority of its system is in good operating condition. However, the smoke testing did identify significant defects such as locations where smoke was emitted from storm culverts and basements of property owners through sump pits. The crews also observed smoke coming out of radon pipes, indicating their pumps/drain tiles may be tied into the wastewater system. Another instance occurred when one homeowner’s entire foundation was smoking, providing strong evidence that the house’s storm water system is still tied into the wastewater system. Yet, the most interesting find was one in which the Wachs Water Services team found a building with a roof equal to 0.5 acres, in which all downspouts went into the wastewater system. Given the size of the footprint, it is estimated that 13,500 gals of storm water is entering the wastewater system for every inch of rain. This means that in 2013, this single building improperly sent more than 562,000 gals of water into the city’s wastewater system.

One Texas Utility’s Story


A recent hurricane left 2 ft of standing water in a few neighborhoods in a Texas city. Some of this storm water made its way into the wastewater system, requiring the City’s sewer department to treat the storm water. To minimize such a scenario in the future, the City decided to identify and repair all cross connections. Wachs Water Services performed smoke testing on 108,000 ft of pipe to identify all cross connections for the City.

The Challenge: Most cities install sewer manholes in front of houses, allowing a service crew to easily access manholes. However, this City’s manhole configurations presented a challenge to our crew, given that they were in the back yards of homeowners. Due to their configuration, the crew was frequently faced with challenges such as locked back yards, barking dogs, hidden manholes, etc. Nevertheless, the crew quickly and accurately completed the smoke testing.

Pierre Mikhail is director of technical services at Wachs Water Service.

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