Asbestos Cement Pipe Condition Assessment

By: Echologics  09-12-2011
Keywords: Condition Assessment, Water Distribution Pipes


Accurate, non-invasive measurement of the effective wall thickness of the Asbestos Cement pipe

Asbestos Cement (AC) water mains were installed throughout North America, Europe and Australia from the late 1920s to the early 1980s and still form a significant component of the water distribution systems of many cities. If fact, it is estimated that 18% of water distribution pipes in North America are constructed of AC, according to the American Water Works Association.

Fortunately, Echologics’ non-invasive Asbestos Cement Pipe Condition Assessment service provides municipalities with an accurate measurement of the remaining wall thickness of selected AC pipes of all sizes in their water systems, helping them to efficiently and cost-effectively mitigate risks associated with deteriorating AC pipe walls, prioritize repairs and replacement, and simultaneously detect and locate leaks—all without breaking ground or disrupting service.

Echologics Asbestos Cement Pipe Condition Assessment service is completely non-invasive, and, unlike other AC pipe condition assessment services and technologies, it is accurate and cost-effective, and it does not present any health or environmental risks.

Key Advantages of Echologics Asbestos Cement Pipe Condition Assessment Service

  • Accurately measures the remaining wall thickness of selected AC pipes of all sizes
  • Helps municipalities to:
    -mitigate risks associated with deteriorating AC pipe walls
    -prioritize repairs and replacement
    -improve conservation
  • Completely non-invasive and non-destructive
  • 0% probability of:
    -foreign organisms being introduced into the pipe
    -loss of components in the pipe
    -disturbance of sediment or exposed asbestos fibers in the pipe
  • Low cost of implementation
  • Does not disrupt flow or service
  • No requirement to close service take-offs
  • No need for specialized ports
  • Can accurately identify large leaks many miles away

How Echologics Asbestos Cement Pipe Condition Assessment Works

  • Echologics Asbestos Cement Pipe Condition Assessment service is completely non-invasive and involves two hydrophone sensors that are separately mounted outside of a selected section AC pipe on air valves, fire hydrants or other existing appurtences.
  • Distances between the two sensors can range anywhere from 150ft (50m) to more than 5000ft (1300m).
  • Acoustic signals are transmitted along the span of pipe, while a correlator listens for changes in the signals’ transmission or propagation velocity; signal changes are indicative of changes in the pipe’s wall thickness.
  • The correlator also listens for leaks that may exist in the span of pipe between the two sensors.
  • The specific location of a leak is determined by the length of time it takes the noise it creates to reach each sensor.

With limited water resources, the Las Vegas Valley Water District takes water-loss management and asset-planning very seriously. When an Echologics’ assessment of two sections of 6” AC pipe and a length of 24” AC pipe suggested the pipe was intact and not in need of replacement, the client excavated one portion to verify those results. With the accuracy of our non-invasive technology confirmed, Echologics has become a critical partner in helping the Las Vegas Valley Water Department achieve one of the lowest (5%) water loss measures in the U.S.

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  • How does this new technology work?

    It’s quite innovative. The new technology works by measuring how quickly acoustic signals are transmitted along a section of pipe.

    Acoustic signals are induced in pipes by releasing water at fire hydrants in a controlled manner. Then, they are measured using acoustic sensors positioned at two longitudinally separated points on a pipe. The sensors are attached at easy-to-access points, such as fire hydrants and control valves, or directly on pipes in existing access manholes. A schematic of the measurement setup is shown below .

    The acoustic propagation velocity is calculated based on the sensor spacing and time delay between the measured acoustic signals. Average wall thickness of the pipe section between the acoustic sensors is then back calculated from this.

  • Echologics has conducted successful pilot studies in diverse environments across North America and the UK.  Using our technology, we have provided unrivaled accuracy, even in the most challenging situations. These include:

    • City of Hamilton (ON)
    • City of Winnipeg (MB)
    • Maple Ridge (BC)
    • Bristol Water (UK)
    • US DOD, Naval Base San Diego
    • Las Vegas (NV) Valley Water Department
    • Columbus (OH)
    • Boston (MA)

    “We knew we had issues with some of our AC and CI pipes and we wanted a method to determine which pipes to prioritize for replacement. We already knew where some pipes were degraded, and wanted to see if we could accurately identify them. With Echologics we were able to determine the wall thickness had deteriorated 54.2%. The excavated pipe looked like ‘porridge’! “

    “Echologics is pretty much the only game in town in non-intrusive condition assessment.”
    Ed Mitchell, Waterworks Superintendent, Maple Ridge (BC)

    “We tested two sections of 6” AC pipe and then excavated to confirm the accuracy of our results. Further testing of a 24” AC pipe showed it was in good condition and we were satisfied that Echologics could meet our requirements.  Due to our limited water resources, we are very aggressive in water loss management and asset planning. Echologics is a critical partner in helping us to achieve one of the lowest (5%) water loss measures in the country.”
    Ryan Benner, Asset Manager, Las Vegas Valley Water Department

    “Here in North Bay we have severe soil conditions with hard water and it’s pretty tough on our pipes. We were looking for a way to prioritize the rehabilitation and replacement budget so we conducted a pilot study of ~20 km (12.4 mi) with Echologics Condition Assessment. We had very good success on ductile iron in this study.”
    Dominic Schiavone, Water Manager, North Bay (ON)

Keywords: Condition Assessment, Water Distribution Pipes

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