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Hodges200 Team-Baking Skills-WNN

‘Baking Skills’ Used for Repair at Lake Hodges Pumped Storage Facility

You might not think ‘baking skills’ would come in handy to fix a recent problem at the Lake Hodges Hydroelectric and Pump Station Facility. But those skills, along with initiative and ingenuity, were demonstrated by San Diego County Water Authority staff as part of the creative and complex repair.

The facility connects the City of San Diego’s Hodges Reservoir with the Water Authority’s Olivenhain Reservoir. The connection provides the ability to store up to 20,000 acre-feet of water at Hodges for emergency use.

The Lake Hodges Hydroelectric and Pump Station Facility moves water between Olivenhain and Hodges, and is able to generate up to 40 megawatts of energy on demand, helping to manage electrical demands throughout the County. It also generates revenue and helps offset energy costs.

Ground fault alarm alerts staff

A ground fault alarm on August 25, 2019 alerted staff to a potential problem with Unit 2, one of the facility’s two 20-MW pump-turbine units. A series of tests and inspections by staff with the Water Authority’s Rotating Equipment team discovered the insulation on the copper bus bars of the generator’s rotor were worn and damaged. The bus bars are part of a system that provides DC power to the 12 electromagnets which surround the outer surface of the pump turbine unit’s rotor.

The rotors are designed to spin at 600 revolutions per minute and it’s the rotor’s electromagnets acting upon the stators windings that generates power. The electromagnets are connected together by copper bus bars located on top of the rotor and the bus bars are secured to the rotor by clamping plates and rim studs. The bus bars are insulated to ensure the copper does not touch any other metal surface and cause an inadvertent ground fault.

“Although a single ground fault may not damage the pump-turbine unit, it may prevent it from starting, if two ground faults were to occur, significant damage to the pump-turbine unit would occur and would also be an extreme danger to anyone within the facility,” said Jim Fisher, Water Authority director of operations and maintenance.

Creative solutions and ingenuity save time, money

Among various factors, the primary cause of the insulation failure was determined to be improper wrapping and curing of the insulation during initial installation.

Water Authority staff developed solutions and also took on the repair tasks in September. By doing the work in-house, the Water Authority avoided a more extensive outage due to long lead times required by contractors and vendors to perform the same work, saving time and money.

“Staff did an excellent job maintaining the operation of Unit 1 while making the repairs to Unit 2,” said Fisher, “which allowed the Water Authority to avoid a total shutdown and loss of all revenue during this period.”

HodgesRepairWNN-Water Authority

Initiative and ingenuity by San Diego County Water Authority staff led to a creative repair solution at the Lake Hodges Hydroelectric and Pump Station Facility. Photo: San Diego County Water Authority

‘Baking skills’ come in handy to create new bus bars

New copper bus bars were fabricated, and each had to be precisely wrapped by 5 different types of insulating tape materials. This wrapping process alone took approximately 8 hours per bus bar. The bus bars were then baked for ten hours within newly designed and fabricated aluminum molds to ensure proper pressure was applied to the insulation layers during the baking and curing process.

Staff efficiently re-purposed and utilized an oven that had been retained from the San Vicente Dam Raise Project to perform the baking. The Rotating Equipment team’s efforts produced excellent quality results which would have been difficult even for a vendor to meet. The newly insulated bus bars were re-installed, and the unit has been operating safely and without issues.

The initiative, ingenuity, and highly technical skills and knowledge of our staff were once again on display throughout the repairs,” said Fisher. “Their dedication, talents and outstanding efforts continue to ensure the Facility’s efficient and safe operation.”

Unit #2 was tested and placed back into service on November 17, 2019.

Along with the bus bar insulation and curing process repair, staff also performed many other highly technical, innovative and precise processes to complete this repair work.

Water Authority staff inspect leak in Pipeline 4

Pipeline 4 Repairs Underway in North San Diego County

A recently discovered leak in a section of a pipeline in North County will be repaired in coming months while Pipeline 4 returns to service.

Crews have installed bulkheads in the pipeline to isolate a portion of Pipeline 4 for repairs. This will allow the pipeline to continue treated water deliveries throughout the county in a modified fashion starting the week of Sept. 16 and restores full service to retail water agencies. With the leaky section isolated, crews will make necessary repairs.

Four Water Authority member agencies – Fallbrook PUD, Rainbow MWD, Valley Center MWD, and Vallecitos Water District – have taken steps to manage water supplies while the pipeline was shut down to install the bulkheads.

Carbon fiber section will protect pipe

In August, Water Authority crews detected a leak in the 90-inch diameter Pipeline 4, one of five major pipelines the agency operates. The leaky section is near Camino Del Rey in Bonsall, in an area with no adjacent homes or business.

To find the cause of the leak, the Water Authority dewatered the pipe starting Sept. 9. Preliminary results of the investigation are that a weld seam, connecting a steel pipe section to a pre-stressed concrete cylinder pipe, separated in an area of very high water pressure.

The Water Authority is preparing to install a carbon fiber liner to give the pipeline several more years of service while a longer-term solution is developed and deployed.

After repairs are completed, a second 10-day shutdown of Pipeline 4 will be needed to remove the bulkheads and return the pipeline to full, normal operations.

Proactive approach keeps pipelines healthy

As part of its proactive approach to asset management, the Water Authority continually assesses and rehabilitates pipelines serving the San Diego region. The agency operates 310 miles of large-diameter pipelines, along with 1,600 aqueduct-related structures, and approximately 100 metering/flow-control facilities.

Approximately 82 miles of the pipelines are pre-stressed concrete cylinder pipes. These types of pipes were installed between the early 1960s and late 1980s, and have experienced premature failures and shown areas of degradation.

By relining the pipes or conducting timely repairs with the latest technology, the Water Authority has avoided major pipeline failures for more than decade.

 

Pipeline relining is an efficient technique that extends the lifespan of pipes while minimizing costs and impacts to nearby communities. Photo: Water Authority

Innovative Pipeline 5 Relining Completed

San Diego County Water Authority crews completed relining a segment of Pipeline 5 in Fallbrook and San Marcos in late July, reaching a milestone in a strategic, multi-decade pipeline relining program. The 2.3-mile segment of Pipeline 5 was relined with new steel liners that are planned to last for more than 75 years.

The proactive pipeline relining program is a crucial part of asset management efforts that improve the reliability of San Diego County’s water supplies.

30-year pipeline relining program

Since the relining program began in 1991, nearly 47 miles of pre-stressed concrete cylinder pipe have been rehabilitated. This constitutes more than half of the total PCCP in the Water Authority system. The remaining 35 miles are expected to be rehabilitated by 2027.

The Pipeline 5 project was conducted in eight segments to minimize impacts to the nearby communities of Fallbrook and San Marcos.

Proactive measures to protect infrastructure

Pipeline relining is an efficient technique used on long stretches of pipelines. It involves inserting new steel liners into the existing pipes. The new liners can extend the lifespan of the pipe by several decades.

“Relining our existing pipes is quicker and more cost-effective than excavating, removing and replacing an entire pipeline,” said Gary Olvera, senior construction manager at the Water Authority. “In partnership with our member agencies, the Water Authority has developed an efficient and proactive plan to ensure continued water supply reliability for the entire region.”

New steel liners can extend the lifespan of a pipe by several decades. Photo: Water Authority

New steel liners can extend the lifespan of a pipe by several decades. Photo: Water Authority

Innovative technique to minimize impacts

To access Pipeline 5, crews excavated dirt to create eight 25-foot by 60-foot access portals spaced roughly 525 to 2,500 feet apart. During construction, crews eliminated two of the originally planned portals, helping save more than $217,000. Most of the work was then performed underground, inside the pipe.

Once the new liner was installed, the joints were welded together. Then, each new steel liner was coated with a cement mortar lining. Finally, the portals were backfilled, the pipeline was disinfected, and the pipe was put back into service.

A welder works inside the pipe to connect the new joints. Photo: Water Authority

A welder works inside the pipe to connect the new joints. Photo: Water Authority

Maintaining regional water supply reliability

Large-diameter pipelines operated by the Water Authority and its 24 member agencies extend approximately 310 miles to convey water throughout San Diego County.

Approximately 82 miles of the pipelines are pre-stressed concrete cylinder pipes. These types of pipes were installed between the early 1960s and late 1980s and some are nearing the end of their service life.

By relining the pipes ahead of time or conducting timely repairs with the latest technology, the Water Authority and its member agencies avoid pipeline failures and improve the reliability of future water supplies.