Rehabilitation Runner Up

Mockingbird Lane, a busy boulevard running through midtown Dallas, serves flourishing business districts, affluent neighborhoods, posh country clubs and heavy traffic generated by the nearby Dallas Love Field airport. Alongside the thoroughfare is a critical underground water transmission main that stretches for more than three miles. This important transmission main is responsible for serving the Highland Park and University Park city municipalities that are part of the Dallas County Park Cities Municipal Utility District (DCPCMUD).

After being built in 1948, the 36-in. diameter pre-stressed concrete cylinder pipeline (PCCP) has never suffered any failures during its entire service life. As 2009 rolled around, the DCPCMUD’s water treatment facilities were overdue for a major overhaul and upgrade. Although the utility originally allocated an additional $15 million for replacing the aging pipeline, the DCPCMUD decided that a condition assessment should be performed since it didn’t know if the pipeline even needed to be replaced.

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Since the pipeline is the only source of water for 30,000 customers, it couldn’t be taken out of service for an inspection. With that in mind, the DCPCMUD needed an inspection method that allowed the transmission main to remain in service. From there, the DCPCMUD contacted The Pressure Pipe Inspection Co. (PPIC) about its PipeDiver product. PipeDiver, a high-tech pipe-condition diagnostic device, is designed for “free-swimming” through a full high-pressure pipeline while detecting and assessing damaged sections of pipe.

On Feb.10, 2010, PPIC conducted a non-destructive evaluation of the PCCP portion of the 36-in. water supply main. After a pre-launch equipment test was conducted, the PipeDiver product was launched into the pipeline. By using in-place and man-operated monitoring devices, the PipeDiver’s location was tracked from aboveground checkpoints — constantly updating and recording its movement. Three hours and three miles later, the PipeDiver tool successfully finished its inspection through the pipeline. After the PipeDiver was retrieved from the pipeline, the PPIC field technician downloaded the pipeline assessment data for analysis.

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According to PipeDiver’s preliminary data, only three pipes out of 1,100 pipe segments showed any distress of concern, and only one had five to 10 wire breaks per joint.  Thanks to the assessment data, the DCPCMUD decided against replacing the one moderately distressed pipe. It also saved about $10 million to $15 million in funding that would have been spent replacing the entire pipeline. On top of the money saved from the pipeline itself, the DCPCMUD also avoided the expenses associated with traffic control, permits and other issues, as well as complaints from nearby neighborhoods already tired of traffic construction and repair disruptions.

Although the pipeline will eventually need to be replaced, the existing pipeline will last much longer due to an ongoing re-inspection program with PipeDiver. That way, the utility can only replace what needs to be replaced and keep current infrastructure in working order for many more years to come.

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Project Owner: Dallas County Park Cities Municipal Utility District

Engineer: CDM

Contractor: The Pressure Pipe Inspection Co.

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