By Joe Naiman
Village News Correspondent 

CWA ratifies contracts for Moosa Canyon pipeline repair

 

Last updated 10/11/2019 at 4:53am



The San Diego County Water Authority ratified two contracts for the repair of Pipeline 4 in Moosa Canyon.

A unanimous CWA board vote Sept. 26 ratified a $950,000 contract with J.F. Shea Construction Inc. for the repair of Pipeline 4 and a contract for $871,342 with Fibrwrap Construction Services, Inc., for the carbon fiber relining of Pipeline 4.

The action also authorized the continuation of the emergency declaration which exempts the CWA from the normal contract procurement process and from California Environmental Quality Act review.

The CWA’s Second Aqueduct includes Pipelines 3, 4 and 5. Pipelines 3 and 5 provide untreated supply to CWA member agencies while Pipeline 4 distributes treated water to member agency turnouts.

Pipeline 3 is a steel pipe 72 inches in diameter, Pipeline 4 is a pre-stressed concrete cylinder pipe 90 inches in diameter and Pipeline 5 is a PCCP 96 inches in diameter. The pipelines are 40 feet apart from each other at their centers, which translates to 32 to 33 feet apart from each other at their perimeters.


CWA staff observed water discharging from the side slope of Moosa Creek, Aug. 2. When the water was sampled it was identified as treated water, which ruled out groundwater and narrowed the source to Pipeline 4 or the Rainbow Municipal Water District pipeline.

CWA and Rainbow developed a plan to conduct additional investigations to determine which pipeline was the source of the leak, and CWA and Rainbow staff determined Aug. 6 that the leak was from Pipeline 4.

CWA acting general manager Sandra Kerl declared an emergency the following day. The declaration required ratification by the CWA board at the next board meeting, and that occurred on a unanimous vote Aug. 22.

Although the emergency declaration allows the CWA to move forward without the environmental review process, the CWA will coordinate with the environmental agencies.

The operating pressure within Pipeline 4 at Moosa Canyon exceeds 300 pounds per square inch and a catastrophic failure could create considerable environmental damage as well as damage to Pipelines 3 and 5 and to a Rainbow pipeline in the area.

Kerl worked with two contractors who have previously provided work on the Second Aqueduct. J.F. Shea Construction Inc. was authorized Sept. 5, to proceed on the installation and removal of two internal steel bulkheads and the temporary aqueduct pressure relief system near the Red Mountain Reservoir.



Pipeline 4 was shut down Sept. 9, for the installation of the bulkheads to isolate the pipeline, which will allow for inspection to determine the specific repairs.

“It’s about a mile of Pipeline 4 that’s being taken out of service,” CWA engineering manager Neena Kuzmich said.

The bulkheads were installed Sept. 10-11, and the pipeline was returned to service Sept. 18 although a second shutdown will be necessary to remove the bulkheads.

The Sept. 11 discovery of sedimentation from Moosa Creek flowing into the pipe provided direction for the next action.

“We actually have to install a pressure relief system,” Kuzmich said.

A temporary aqueduct pressure relief system was installed near the Red Mountain Reservoir to provide pressure relief upon resumption of water deliveries.

The pipeline inspection also allowed for the determination of the repair method. Relining an internal section with carbon fiber composite is less invasive than pipeline excavation and replacement, which also would require more time and have more of an environmental impact.

CWA staff provided Fibrwrap with a notice of award on Sept. 13. The CWA ratification of the contract allowed that work to proceed.

“This is going to be a temporary fix,” Marty Miller said, who chairs the CWA’s Engineering and Operations Committee and who represents the Vista Irrigation District on the CWA board.

Miller has been on the Vista Irrigation District board since December 2008 and said that the district has used the relining process in the past.

“It’s a real good process,” he said.

The CWA worked with the Metropolitan Water District of Southern California and the affected agencies regarding the shutdown and other aspects of the repair process.

“It really has been a pretty extraordinary effort,” Kerl said. “I think that this is an excellent example of cooperation from all parties.”

 

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