Dallas Water Utilities (DWU)
Pipe Diameter: 72"
Pipe Type: PCCP
Distance Inspected: 2.95 miles
Service: Remote Field Transformer Coupling (RFTC)
Challenge: Pipe located under a river
The 72” Simpson Stuart Supply Main, owned and operated by City of Dallas, Dallas Water Utilities (DWU) is a critical pipeline that provides treated water to the southern part of Dallas and Dallas Water Utilities southern customer’s. The supply for the Simpson Stuart Pipeline starts at the Lake June Pump Station. Potable water is pumped from the East Side Treatment Plant. Treated water is then conveyed through the pipeline under the Trinity River to the South Cliff Pump Station.
Since 2005, DWU has been interested in a condition assessment of the nearly 50 year old large-diameter main, but has faced a lot of challenges. First, it’s size. Additionally, because of its criticality, the line can only be taken out of service for a very limited period of time. Furthermore, it was understood that the segment under Trinity River would have to be dewatered.
In recent years, the capabilities of PPIC’s PipeCrawler™, a Remote Field Transformer Coupling (RFTC) tool, have increased to inspect large-diameter PCCP. Additionally, PipeCrawler™ does not require full dewatering of a main, making it the perfect solution for DWU.
After determining how much time would be required for equipment set-up and the inspection, it was decided that PPIC would inspect the line from both ends using two crews. This way, water service would be halted for as little time as possible, and PPIC would be able to meet the tight time constraints.
In May 2009, PPIC performed a condition assessment for DWU utilizing PipeWalker™ and PipeCrawler™ for an overall distance of 2.95 miles. The PipeCrawler™ unit was mobilized to inspect the portion of main located under the Trinity River. The PipeWalker™ crew commenced their inspection at the far west end of the main, and inspected over 2 miles between access points with the assistance of Dallas Fire Rescue.
In total, 980 pipes were inspected. Only 6 were identified as having broken prestressing wires (ranging from 10 to 60 wire breaks each).
The ability to perform a condition assessment in mains located under river crossings, or facing other geographical challenges, is critical for water utilities to maintain the integrity of their pipelines and extend the operating life of their buried infrastructure assets. DWU can rest assured, knowing that the section underneath the Trinity River was found to be in good condition.