Pinellas County Challenging Leak Ductile Iron Sewer Pipeline
In Pinellas County – Florida’s most densely populated county – residents and government work together to conserve water. A major component of this water reclamation process is the South Cross Bayou Water Reclamation Facility, which is designed for an average flow of 33 MGD. After a failure in June 2013 on a 42-inch ductile iron pipe in the reclamation facility, the Pinellas County Department of Environmental and Infrastructure rehabilitated and replaced portions of the facility’s pipeline. In September 2013, the Division of Engineering and Technical Support suspected that a small leak (estimated at 19 gallons/hour) had developed on a section of pipeline, originally thought to be in good condition, which was not rehabilitated after the failure. In metallic pipe materials, pipe failure is often preceded by a period of leakage. After already having a significant failure and investing in rehabilitation on a significant amount of pipeline, the County was adamant about identifying the location of any further leaks, which were impacting normal facility operation. After unsuccessfully trying a number of different leak detection techniques, the County turned to inline leak detection to identify the leak on the 627-foot (191-meter) stretch of pipeline. However, one of the challenges was that the pipeline had no flow due to implemented bypass procedures. To locate the leak, the County and Pure Technologies (Pure) took an innovative approach by using a tethered SmartBall® tool.
The SmartBall tool is a free-flowing leak detection technology that identifies the acoustic anomalies associated with leaks and gas pockets. Typically, it travels with the product flow in live pipelines, however, in no-flow conditions it will not move.
To overcome this challenge, the County and Pure temporarily pressurized the pipeline, tethered the tool using a mule tape and winched it through the planned inspection distance 627-feet (191-meters). The County took this approach because the insertion point was in the middle of one of the facility treatment trains– meaning a compact tool was needed to meet the logistical difficulties.
During inspection, the tethered SmartBall tool collects data twice since it is winched back to its insertion point. For this inspection, two runs were completed to confirm the leak size and location accuracy for the County. Upon review of the data and during the actual inspection, a leak was determined to be on a sleeve at the invert near the inline magmeter, which was the downstream limit of our inspection. The area outside of the magmeter vault was difficult and expensive to expose. Therefore, the County filled the area with grout and placed the pipeline back into service.
Highly accurate inline leak detection systems that can detect leaks and gas pockets in operational pipelines. These systems are used primarily on larger diameter water and wastewater transmission mains of all materials as well as oil & gas pipelines.