Testing Program To Study Leak Detection Systems
Dallas Water Utilities (DWU) provides water and wastewater services to about 1.9 million people in Dallas and 26 nearby communities...
Dallas Water Utilities (DWU) provides water and wastewater services to about 1.9 million people in Dallas and 26 nearby communities and operates over 4,700 miles of water transmission pipelines. Recently, the State of Texas and the Texas Administrative Code mandated a program of leak detection, repair, and water loss accounting for all water transmission, delivery, and distribution systems serving a population greater than 5,000. Accordingly, DWU designed a study comparing the various technologies used to detect and locate leaks within its water transmission system.
“The goal of this study is to determine which technologies are effective at identifying and locating leaks in pipe of varying material composition and diameter. DWU will use the results of this study to minimize the cost of complying with the program while maximizing leak detection and location,” said Randall Payton, Senior Program Manager for DWU.
In order to identify the location of the leaks that would form the basis for this comparison, DWU contracted with the Pressure Pipe Inspection Company (PPIC) to perform leak detection surveys using the patented Sahara Leak Detection Technology.
Accordingly, in July 2005 PPIC inspected several small diameter pipelines in Fair Park using the Sahara system. The inspection was conducted in 17 different areas on pipelines constructed of 12 and 16 inch diameter cast iron and PVC. The overall inspected distance was 14,703 feet. Analysis of the data obtained during this inspection revealed a single small leak within the areas tested.
In August 2005, PPIC continued its assessment and inspected several small diameter water lines in Deep Ellum. This inspection was conducted throughout 31 different areas on pipelines constructed of 12, 16, 20, 30 and 36 inch diameter cast iron and/or PVC. The overall inspected distance was 35,229 feet. Analysis of the data obtained during this inspection revealed 17 leaks within the areas tested. These leaks ranged from small to large in magnitude.
Dallas Water Utilities verified the results of this inspection through excavation at GPS co-ordinates provided by PPIC. The utility reported a 100% accuracy record and has repaired the distressed pipe.
PPIC’s Sahara features a probe that can be inserted into a live transmission main through any tap 2" or greater in diameter. It is safe for use in potable water systems.
In operation, the probe is carried along the pipe by the flow of water. The system locates leaks as small as 0.25 gallons/hr, in real time, through identification of the distinctive acoustic signals generated by leaks in the pipe wall, the joints or steel welds.
Once a leak has been detected, the sensor head can be stopped at the precise position of the leak. Its location within the main can be identified from the surface and marked for subsequent excavation and repair.
As a side benefit, operators can also use Sahara to map the course of a pipeline. Depending on the pipe configuration, lengths up to 6,000 fee can be surveyed with a single insertion. Inspections can be carried out in mains with a diameter of greater than 12"; there is no limit on the maximum diameter.
For more information about the system, visit the company’s website at www.ppic.com.