Second shutdown of Pipeline 5 at Moosa Creek set for May 4-11

The actual repair work for a San Diego County Water Authority pipeline in Moosa Canyon is now complete, although a shutdown to remove the isolation bulkheads will be needed and the SDCWA pipeline will be shut down May 4-11.

“The carbon fiber repair has been completed, and we're preparing for a shutdown of Pipeline 5, May 4, to remove the internal steel bulkheads,” Neena Kuzmich, CWA engineering manager, said. “After we remove the bulkheads Pipeline 5 will resume normal operations.”

The CWA’s Second Aqueduct includes Pipelines 3, 4 and 5. Pipelines 3 and 5 distribute untreated supply to CWA member agencies, while Pipeline 4 conveys treated water to member agency turnouts. Pipeline 5 is a prestressed concrete cylinder pipe 96 inches in diameter and was built in 1982.

In August 2019, CWA staff observed water discharging from the side slope of Moosa Creek, and four days later a leak in Pipeline 4 was identified as the cause. The CWA contracted for repair work, which including a shutdown to remove isolation bulkheads was completed Nov. 10.

The Pipeline 4 leak led CWA staff to conduct an inspection of Pipeline 3 and Pipeline 5 in late January, when the two pipelines could be drained for access during a planned maintenance-related shutdown. Pipeline 3 was found to be in good condition with no signs of distress, but Pipeline 5 was found to have signs of distress in the same area of the Pipeline 4 failure and a follow-up engineering analysis indicated that Pipeline 5 was overstressed and at risk for failure.

The operating pressure within Pipeline 5 at Moosa Canyon exceeds 400 pounds per square inch, so a catastrophic failure could create considerable environmental damage as well as damage to Pipelines 3 and 4 and to a Rainbow Municipal Water District pipeline in the area.

A CWA board vote Feb. 27 authorized CWA general manager Sandra Kerl to take the necessary contracting and other actions for the repairs on Pipeline 5 in Moosa Creek. The authorization of Kerl to issue contracts allowed their issuance before the March 26 board meeting.

The contracts were issued through a competitive acquisition waiver process rather than through the normal competitive procurement process. J.F. Shea Inc. was issued a contract for the Pipeline 5 bulkhead installation and removal and FibrWrap Construction Services Inc. was given the Pipeline 5 carbon repair contract. Those two companies were also given the Pipeline 4 contracts through a competitive acquisition waiver.

The March 26 CWA board meeting included a briefing on the progress of the Pipeline 5 repairs but no action items for the pipeline.

A shutdown to install the isolation bulkheads began March 30 and lasted until April 4. FibrWrap mobilized and began preparation April 6 and started installing the actual carbon fiber material April 12. The carbon fiber repair work was finished April 17.

“We did our proper walkthrough,” Kuzmich said. “The work was completed and accepted on the 21st and 22nd.”

The April 23 CWA board meeting also included a nonvoting item on the progress of the work.

“All work has been completed as of April 22,” Kuzmich said. “We still have to do a shutdown and remove the bulkheads.”

The May 4 shutdown date will allow time for the carbon fiber to cure before contact with water occurs.

The design life expectancy of the carbon fiber lining is approximately 10 years, and the repair will be followed by a canyon wide analysis to determine a long-term solution. The request for proposals for a permanent solution study for all three pipelines is expected to be issued in early summer.

Joe Naiman can be reached by email at [email protected].