Aqueduct inspection leads to repair of damaged pipe section

The San Diego County Water Authority’s shutdown of its Pipeline 4 for inspection led to the urgent repair of a segment of prestressed concrete cylinder pipe.

A section of pipe west of Interstate 15 and approximately 1,000 feet south of Camino Del Rey was found to be sufficiently distressed during the inspection to warrant urgent replacement. The pipe was identified as needing urgent repairs on March 4, and Fiberwrap completed the installation of a carbon fiber lining between March 5 and March 7.

“Just an outstanding effort on the part of Fiberwrap,” said Gary Eaton, the County Water Authority’s director of operations and maintenance.

The CWA’s Aqueduct Protection Program includes periodic aqueduct condition assessment inspections, and scheduled shutdowns allow for such inspections as well as for maintenance. Pipeline 4, which carries treated water, was shut down in February 2005 to perform internal pipeline inspections and to replace valves.

A prestressed concrete cylinder pipe section was identified as being in need of urgent repair. The section is 24 feet in length and the pipe, which was originally installed in November 1970, is 90 inches in diameter. “Its deterioration rate was getting to the point where we felt we needed to make the urgent repair,” Eaton said.

The section of pipe had sustained some damage during its 1970 installation. “Over the years we’ve seen it started to deteriorate,” Eaton said.

The shutdown was scheduled to end March 8, and the need for repair was determined on March 4. Due to the location of the damage and the proximity to pipeline access points, carbon fiber was selected for use in the repair of the pipe section. The CWA called its list of contractors who could provide urgent repairs. “All of this has to happen very rapidly,” Eaton noted.

Three contractors sent representatives to visit the site, but two of those either didn’t have the material available or were not able to obtain work crews that soon. Fiberwrap, Inc., was able to perform the work, and a $137,000 contract to Fiberwrap was awarded.

Fiberwrap crews worked around the clock and completed the repair, allowing the shutdown to end on schedule.

The four shutdowns during fiscal year 2004-05, which included 55 miles of internal inspections, also led to the replacement of one 24-inch butterfly valve at the Rainbow 6 take-off structure.