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Case Study

Louisville Water Company (LWC)

Following a water main break in 2009 that resulted in the loss of 15 million gallons of treated water, LWC began a Transmission Assessment Program, using various assessment technologies from Pure Technologies.

Project Details

Services
 PureRobotics® electromagnetics (EM) condition assessment

PureRobotics HD-CCTV inspection

Inertial measurement unit for GIS component

Risk prioritization
Timing
 2015
Pipe Material
 PCCP
Inspection Length
 3.4 miles (5.5 kms)
Diameter
 24-30 inches (610-760mm)
Transmission Type
 Water

Project Highlights

EM data identified 17 anomalies warranting further investigation

HD-CCTV identified longitudinal cracks consistent with overloading

One (1) pipe section found to display anomalous EM signals associated with broken wire wraps and wall cylinder loss

Challenge
In the summer of 2015, LWC deployed PureRobotics to assess 3.4 miles of 24 to 30-inch transmission mains in its network. With 4,100 miles of pipeline to maintain, (200 miles of it transmission main) LWC focused its condition assessment on its transmission main system – pipes that would cause the greatest amount of damage in the case of failure. The loss of non-revenue water, either chronically in small amounts or from a catastrophic failure, can result in massive costs to a water utility.

By prioritizing the risk levels associated with their transmission main system, LWC has created an ongoing inspection program to keep a watchful eye on the health of their pipelines. The program utilizes a number of Pure Technologies assessment tools to find active leaks as well as potential future threats.

Solution
In May of 2015, PureRobotics was deployed on the Cross County Header, Ray Lane Easement Pipeline, and Bardstown Road Pipelines. The latest generation robotic crawler is designed to carry sensors and tools up to 1.8 miles (2.9 kilometers) through potable water or wastewater at a speed of 85 feet per minute. For LWC, PureRobotics used CCTV to provide a comprehensive high-definition visual inspection.

The robotic crawler was also outfitted with specialized tools to conduct an electromagnetic assessment on the condition of the pipeline and inertial measurement unit (IMU) for the GIS component. The Inertial Measurement Unit (IMU) deployed with PureRobotics uses a series of Fiber Optic Gyroscopes (FOGs) and accelerometers to track depth, lateral and horizontal movements from a known GPS reference point. The output is a GIS spatial map of the pipeline which depicts elevation changes as well as notable features of interest encountered during the inspection.

Pure’s electromagnetic assessment uses transformer coupling to detect anomalous regions in the pipe cylinder and prestressing wires. This data is correlated with odometer readings from the PureRobotics umbilical tether as well as HD recorded CCTV and IMU to attempt to locate areas of distress in the pipeline.

Results
High definition CCTV inspection results showed a number of longitudinal cracks consistent with overloading. These types of mortar cracks may eventually lead to corrosion of the steel cylinder or prestressing wire and eventually a failure of the pipe.

One pipe section in the Ray Lane Easement pipeline was found to display anomalous electromagnetic signals showing a significant number of broken prestressing wire wrap breaks as well as cylinder wall loss. This was correlated with visual data, showing spalling and exposed steel at the invert of the pipe. LWC intends to investigate this issue at a later date.

Visual assessment also showed a number of pipe sections with spalling. Pure recommended continued monitoring at these locations during future inspections. Electromagnetic assessment also found 11 pipes with anomalous signals not consistent with wire breaks. Investigation performed on one of these anomalous pipes showed a non-standard metal sleeve used in manufacturing. From this information, it was determined that the remaining 10 anomalous pipes could be left in service.

As one of the first utilities to deploy the third generation PureRobotics platform, LWC now has defensible data to move forward with its ongoing rehabilitation program.