WSSC Robotic Electomagnetics EM AFO Monitoring

After spending eight years assessing the condition of and monitoring 77 miles of 48-inch and larger PCCP with a variety of methods, WSSC has shifted its focus to 68 miles of 36- and 42-inch mains. Many of these assets have been in the ground for decades and have never been inspected for structural deterioration.

To assess the mains, WSSC is using PureRobotics™ equipped with electromagnetic (EM) sensors. The tool is also equipped with high-definition closed-circuit television (HD-CCTV), which allows WSSC to identify cracks of the inner concrete core and determine joint condition.

WSSC recently produced a video to demonstrate how the tool works and its role within the overall PCCP assessment program.

How the Technologies Work

The EM sensors on the robotic tool identify the quantity and location of broken wire wraps in PCCP pipelines. The wire wraps in PCCP are the main structural component – as wraps begin to deteriorate and break, the pipe section becomes weaker and more likely to fail catastrophically.

By identifying broken wire wraps, WSSC is able to repair or replace specific pipe sections when they reach a wire break limit. The robotics tool used by WSSC also has an inertial mapping unit, which allows damaged pipes to be located with very close location accuracy, usually within 3 feet.

After acquiring a baseline condition of its transmission mains, WSSC plans to install an Acoustic Fiber Optic (AFO) monitoring system to track ongoing deterioration. The AFO system records the sounds of wire wraps snapping, which allows WSSC to intervene and replace a pipe section when too many wire wraps snap in a short span – which indicates accelerating distress – or the amount wire breaks reaches a certain level.

WSSC’s PCCP program is one of the largest and most advanced infrastructure management programs in the industry; however the cost of assessing, monitoring and managing its most critical assets is roughly 6 percent of the $2-billion capital replacement estimates.

To date, WSSC’s inspections have shown that about 95 percent of pipes are in “like new” condition and less than 2 percent require any immediate rehabilitation or replacement. By identifying select distressed areas, WSSC was able to avoid a full replacement program and avoided massive capital replacement costs by rehabilitating the identified sections.


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