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WaterOperator.org Blog

Articles in support of small community water and wastewater operators.

Featured Video: Sewer Dye Testing

Featured Video: Sewer Dye Testing

A municipal sanitary sewer system is designed to collect and transport wastewater from homes, offices, businesses, restaurants and other sources to a municipal wastewater treatment plant for treatment and safe discharge into the environment. If other sources of water are allowed to enter the sewer system, the collection system and wastewater treatment plant can become over loaded allowing untreated water to be discharged. This is defined as sanitary sewer overflows, or SSO’s. One of the biggest sources of excess water is infiltration of storm water and groundwater into the sanitary sewers. A method to detect this infiltration is through dye testing.

Dye testing is a simple procedure where storm drains, yard drains, and the outside of the foundation walls of the house, or other areas are flooded with water to simulate a period of heavy rainfall. The colored water is pumped through the ground and storm water system and appears in the sanitary sewer collection system where leaks occur. This test is simple and complements smoke testing that may have been done previously.

The dye testing procedure can be accomplished in the following steps.

  1. Isolating a section of the storm water network to test by plugging pipes at specific locations. 
  2. Then, bright-dyed water is pumped into the storm water network until it reaches capacity. 
  3. Remote CCTV cameras are deployed into the sanitary sewer system, where any points of storm water ingress are highlighted clearly by the dyed water.

Once the testing is completed, the locations of these sources of infiltration makes the process of repairing these leaks far more straightforward facilitating effective piping and system repairs which keep infiltration to a minimum.

A video showing how dye testing can be carried out is shown below:

Featured Video: Sewer Cleaning in Los Angeles California with Kent Carlson

Featured Video: Sewer Cleaning in Los Angeles California with Kent Carlson

For roughly 30 years Kent Carlson worked for the City of Los Angeles to bring innovation and new technology to the Department of Public Works’ Bureau of Sanitation. When the Bureau observed that new technology was falling behind on their collections side, Kent was brought over to assist with tool development and the standardization of sewer cleaning procedures. Under the mission to reduce sewer overflows and recognize increasing drought in southern California, one of his favorite inventions featured a sewer nozzle designed to reduce water use and save time during cleaning.

In his article with CWEA Water News he offers his predictions on the future of the sewer profession asserting, “I think it’s an exciting future – technology is exploding in this sector – CCTV, GIS, computers on the trucks. Sewer workers of the future will be much better with technology. Rather than using rudimentary brute force for cleaning we’ll get smarter, more strategic and more efficient at what we do.”

Kent’s enthusiasm for tool development is demonstrated in this week’s featured video. The 5-minute video highlights the history of sewer cleaning in Los Angeles as well as a demonstration of how his team tests and develops their sewer cleaning tools. Back in the day, sewer cleaning featured manual removal of clogged pipes and sewer mains. Today, his team takes advantage of high-pressure tools and robotics. Kent says the best tools for sewer cleaning are designed or personally modified by the facility staff. These tools ultimately help the Bureau of Sanitation affordably maintain approximately 6,500 miles of pipe, some of which was originally installed as far back as 1883. We hope this week's featured video inspires your system to find new and innovative ways to help your utility operate more efficiently.

Featured Video: The Science Behind Exploding Manhole Covers

Featured Video: The Science Behind Exploding Manhole Covers

Every season has its challenges for public works departments, and now that spring is just around the corner, it is pretty obvious that this past winter came with more than its fair share. Yet we are not in the clear quite yet, as this news story about two manhole explosions just a few weeks ago demonstrates. In fact, as winter winds down, accumulated road salt compounds corrode through underground electrical cables, causing sparks to ignite gases that can build up in confined spaces. With over 2,000 annual incidents in New York City alone, exploding manholes are not a joke: they can be dangerous, destructive and downright difficult to predict.

And while large cities like New York City are especially prone to these incidents due to aging infrastructure and the sheer amount of underground electrical cables present, small towns are definitely not immune. For example, in 2014 the tiny town of Sauget, Illinois (pop. 150) experienced an explosion so powerful manhold covers damaged overhead power lines.  

 Find out more about how road salt compounds contribute to this problem in this week's featured video.  

While explosions are the most dramatic hazard associated with manholes, research suggests that manholes are in general one of the most dangerous work locations for water system staff. In fact, according to AFSCME, fully one-third of all injuries/deaths of workers occur in or around manholes. Check out this safety presentation hosted by Michigan WEA for more information on the types of hazards presented by manholes and how to protect yourself from them. 

And if you have any lingering doubts about the force, and destructive power, of an expoding manhole, take a look at this video