When the owners of a rail yard in Denver, Colorado, needed a quick and inexpensive solution for verifying the as-built documents for their buried stormwater system, GPRS Project Manager Conner Sorensen answered the call.
Sorensen conducted a smoke test on the expansive system to verify which manholes were connected to the buried lines, ensuring our client can effectively plan future renovations and expansions to their property.
“Our client wanted to verify existing plans of their stormwater system,” Sorensen said. “They chose to use the smoke tester so we could quickly find out what manhole structures were tied in together.”
Smoke testing is one of the simplest, non-invasive testing methods to detect sanitary and storm sewer line defects and blockages, pinpoint potential inflow and infiltration (I/I) points, and discover illegal (illicit) sewer tie-ins. While further investigation is often required to deduce the exact source of an issue, smoke testing is perfect for when you just need to know if “something” is wrong or when you need to determine what surface features are connected to a system.
How to Conduct a Sewer Line Smoke Test
The smoke testing process consists of three simple steps:
- Locate Insertion Point: To deploy smoke cartridges (sometimes still called candles, though true smoke candles are now rarely used), access to the sewer lines is required. This access is typically through a manhole, though the type of blower being used can influence the size of the required opening. A clean-out can also serve as an entry point. Two types of blowers are commonly used for sewer smoke testing: the squirrel cage blower and the direct-drive propeller blower. These names reflect the type of fan mechanism each employs. Squirrel cage blowers are generally larger and provide higher static pressure, while propeller-style blowers deliver greater airflow capacity, measured in cubic feet per minute (cfm).
- Deployment/Release: Securely attach a blower equipped with a smoke cartridge to the sewer entry point. Whether using a blower fan over a manhole or blower tubing over a smaller opening, ensure the connection is as airtight as possible. This prevents smoke from escaping prematurely and ensures it travels through the sewer line for effective tracing. The smoke used is non-toxic, typically made from mineral oil, and dissipates quickly.
- Tracking/Reporting: Introduce smoke into the sewer line and trace where it escapes. In a properly connected and maintained system, smoke will emerge from other manhole covers and the plumbing vents of buildings legally connected through private lateral sewer lines. If smoke rises from the ground or seeps through pavement cracks, it indicates a sewer defect and a potential infiltration risk. Smoke emerging from a cleanout often suggests a damaged or missing cleanout cap that needs replacement. If smoke escapes from a residential gutter or downspout, it signals an illicit connection that could adversely affect the wastewater system.
Results of Professional Sewer Smoke Testing
Sorensen completed smoke testing the rail yard’s stormwater system in one day, quickly determining that the client’s existing as-built documentation was accurate and all manholes on property were connected to the system.
“The client was very happy with the results and was able to move forward with their planning knowing what lines were connected and how accurate their original plans were,” Sorensen said.
To obtain a comprehensive map of your subsurface sanitary and storm sewer lines, consider hiring a private sewer inspection company, such as GPRS. We offer NASSCO-certified video pipe inspection reports that identify every blockage and defect in your pipes. These reports can also include a detailed inclination analysis, providing insight into the condition of your mainlines and laterals without the need for costly excavation.
From stormwater lines to skyscrapers, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, and safe.
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Frequently Asked Questions
Does GPRS offer lateral launch services?
Yes, we offer lateral launch capabilities as part of our standard Video Pipe Inspection services.
What deliverables does GPRS offer when conducting a video pipe inspection?
GPRS is proud to offer WinCan reporting to our Video Pipe Inspection clients. Maintaining sewers starts with understanding sewer condition, and WinCan allows GPRS Project Managers to collect detailed, NASSCO-compliant inspection data. GPRS Project Managers not only inspect the interior condition of sewer pipes, laterals, and manholes – they can also provide a map of their location. The GPRS Mapping & Modeling Department can provide detailed GPS overlays and CAD files. Our detailed WinCan/NASSCO reports contain screenshots of the interior condition of the pipe segments that we inspect, as well as a video file for further evaluation, documentation, and/or reference.
What size pipes can GPRS inspect?
Our elite VPI Project Managers have the capabilities to inspect pipes from 2” in diameter and up.
Can you locate pipes in addition to evaluating their integrity?
Yes! Our SIM- and NASSCO-certified Project Managers use VPI technology equipped with sondes, which are instrument probes that allow them to ascertain the location of underground utilities from an inaccessible location. This allows them to use electromagnetic (EM) locating to map sewer systems at the same time they’re evaluating them for defects.
