California Updates Outdated Sewer-Inspection Technology

June 17, 2016 | Comments

The Environmental Protection Agency (EPA) in the US estimates that one-sixth of the country’s potable water is lost due to leakage. Unsurprisingly, wastewater leakage is also a nation-wide problem that is similar in scope.

In light of this, Northern California is rapidly adopting technology from Electro Scan and using it to monitor the condition of sewer mains. Electro Scan offers leak detection devices and cloud computing applications for water, sewer and gas pipelines.

Closeup of worker's hand pointing to area of sewer line that has been invaded by tree roots. He is in the process of digging out tree roots and replacing the sold clay ceramic sewer line with a cleanout.

Sewer pipes are subject to all sorts of natural elements. The one in the above image was invaded by tree roots.

The incorporation of Electro Scan’s technology gives perspective to just how outdated current leak detection tools for sanitary sewers are, as a number of pipeline surveys have compared Electro Scan to other pipe detection services and found surprising results.

 

Current Pipe Inspection Tools Are Not Working

Analyzing the conditions of sanitary sewers is commonly performed with closed circuit television (CCTV). For this method, civil engineers pass high-resolution cameras through the pipelines and visually inspect the video feed for evidence of breaks and leaks in the sewer structures.

A number of recent surveys compared CCTV inspection to Electro Scan techniques, and one found that the latter method detected ten times as many leaks as the former. Another survey found that the majority of CCTV inspections rated pipes as ”leak free,” or having no evidence of infiltration, while Electro Scan technology found major leaks in more than 80 percent of the pipes surveyed.

 

How Electro Scan Works

After the appropriate equipment set up, the civil engineering crew fills up the sewer main with water until it reaches a few inches above the top of the pipe. A probe is then passed through the length of the pipe at approximately one ft every two seconds. The Electro Scan recorder in the probe detects whether or not water is penetrating the sewer line through infiltration or exfiltration.

Electro Scan technology takes advantage of the fact that most sewer pipe materials are poor conductors of electricity, while water is a good conductor by comparison. Electro Scan claims that by recording electric signals, it can interpret what type of defects exist in the pipelines, whether they are joints, taps or cracks.

probe collage

Images demonstrate how the probe appears and how it is used in practice. In the diagram on the right, the symbols (plus marks, triangles, diamonds) indicate the nature of the pipe defects. (Image courtesy of Electro Scan.)

Using its Critical Sewers cloud application, reports on the location and severity of these leaks are available to the crew within minutes.

While Electro Scan may be promising compared to CCTV, there are still setbacks in that Electro Scan depends on the sewer pipe materials to be low in electrical conductivity. This means that any metals present in the sewer pipes may skew the results. Fortunately, poor conductors like clay, plastic, concrete, reinforced concrete and brick are all common sewer pipe materials.

 

Electro Scan in Practice

Electro Scan is involved in numerous projects to assess the condition of sanitary sewers in Northern California, advertising its work completion capabilities to be within a short time frame. One recent project was conducted in a community in the Sacramento River Delta, where 13,000 ft of pipe (consisting of 77 sewer mains) was assessed within four days.

The implementation of this technology has arrived while California is in the midst of acting on Senate Bill 555, a regulation passed in October 2015. This bill will require retail water suppliers to submit annual water loss audit reports as adopted by the Department of Water Resources, beginning October 1, 2017, and all reporting for the preceding year.

The use of technologies like Electro Scan may be a stepping stone to responsible water management in the United States. To learn more about this technology and its applications, visit the Electro Scan website.

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