Fort Worth Launches Unique, Aggressive Sewer Inspection/Cleaning Program

By Jeff Griffin, Senior Editor | July 2011, Vol. 66 No. 7

FWWD’s inspection contract uses the Fly-Eye HD Profiler System developed by Cleanflow Systems in New Zealand and distributed in the United States as the Fly-Eye Pipeline Inspection System by CUES. The inspection system collects and processes data on internal pipeline conditions including debris level, ovality, H2S erosion, lateral location and damage without requiring flow diversion, flow interruption or manhole ring removal.

“Currently only four units exist,” said Gadberry, “and two are deployed in Fort Worth. This technology assimilates a huge dataset for condition assessment. However, the primary goal is to identify lines for cleaning, hence the cost effective ‘inspect-before-cleaning approach’.”

Cleaning
Ace Pipe Cleaning Inc./Carylon Corporation has the contract for cleaning pipe identified during the inspection process. Various technologies are used, depending on cleaning requirements, including high-velocity and power-driven buckets and scrapers.

“Over the course of implementing our sewer assessment program,” said Gadberry, “we discovered that the clean-and-inspect methodology used for smaller-diameter pipes did not fare well for our larger pipes. The cost to clean big pipes is expensive, ranging from $3 to $40 per linear foot. Add in the cost for debris disposal, by-pass pumping, CCTV inspection and other essentials, and wise choices are necessary when dealing with big pipes.”

Making inspections before cleaning showed debris in large pipes has a tendency to build up at junction structures and in the connecting pipes, then quickly dropped off a short distance outside the structure. The inspections have allowed cleaning to target areas where it is needed.

Gadberry said that by inspecting before cleaning, it was estimated that cleaning costs of large-diameter pipes can be reduced as much as 30 percent.

“To date,” he continued, “approximately 187,000 feet of pipe has been inspected of which 75,000 feet required cleaning. At a total cost of $1.23 million, this represents an approximate cost savings of 36 percent over the conventional clean and inspect approach -- $1.23 million versus $1.91 million. This is a very cost-effective approach, especially when savings are projected over the one million feet of large-diameter interceptors within the FWWD’s collection system.”

Post-cleaning sonar inspections have substituted for post-cleaning CCTV inspections to confirm the cleanliness of the pipe.

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