Case study - North Texas Municipal Water District

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Courtesy of Pure Technologies

Service: Leak Detection
Client: North Texas Municipal Water District
Type of Pipeline: Transmission Main
Diameter: 42-inch
Pipe Material: PCCP
Length: 0.186 miles

The North Texas Municipal Water District (NTMWD) provides water, wastewater, and solid waste disposal services on a regional basis to its 13 Member and 61 Customer Cities. NTMWD operates over 375 miles of water transmission pipelines within its 1,600 square mile service area and serves 1.3 million people. During NTMWD's last Water Year (August 2003-July 2004), the District treated and delivered 82.1 billion gallons of water.

One of NTMWD's pipelines is a 42' reinforced concrete main that supplies water to NTMWD's southern service area. District staff knew that this line had a leak as water was surfacing in the intersection of Jupiter and Beltline, a very busy intersection in Dallas County. To make matters difficult, this intersection is populated by a number of utility services, including parallel water lines owned and operated by Richardson and Garland. 'Water was surfacing on the eastern side of the intersection,' stated NTMWD's Operations Coordinator and Safety Officer. 'However, to minimize disruption of commuters during the excavation and repair process, we needed to know exactly where the leak was.'

Consequently, on November 17th, 2005, Pure Technologies inspected 984 feet of this 42' main using its Sahara Leak Detection Technology. The Sahara inspection was conducted during the evening hours between 17:30 and 24:00 to minimize traffic disruption. NTMWD staff increased the flow rate in the line to 3.0 ft/s using pumps at the pumping station upstream from the insertion location.

A single, medium-magnitude leak was detected 410 feet south of the insertion point on the western side of the intersection. The leak's location was derived by using a measuring wheel and Sahara encoder equipment. The PipeSpy system / GPS receiver was not utilized to mark the leak's location due to high vehicle traffic. The leak's position was marked on the street with blue paint. While on site, NTMWD and PPIC correlated the location of the leak with the drawings and determined that the leak was located at an air release valve near the edge of the steel encasement.

'NTMWD staff excavated the main at the indicated leak position and verified the presence of the leak,' confirmed NTMWD staff. 'Because the Sahara system was able to pinpoint the location of the leak within inches, we were able to complete the excavation and repair operation between the hours of 0600 and 1100. I estimate that we saved a considerable amount of time and money using the Sahara system.'

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