NEVADA COUNTY, Calif. April 23, 2024 – PG&E appears to be working on a temporary repair of the damaged pipe section of the South Yuba Pipe and implement a permanent fix once “pipe is procured for those long‐term repairs,” according to a document filed by the State Historic Preservation Officer (SHPO) with the Federal Energy Regulatory Commission (FERC.)
The South Yuba Pipe and the Spaulding Powerhouse #1 are both out of commission, effectively cutting off water supply to the Bear River (Drum Spaulding) and Deer Creek systems.
February rockslide
PG&E retained ownership of an approximately one mile-long stretch of the South Yuba Canal directly below Spaulding Reservoir when Nevada Irrigation District (NID) purchased this 17-mile stretch of flume and tunnel from PG&E for $1 in 2023 after ten years of negotiations and regulatory permitting.
During a storm event in early February a rockslide damaged a section of the pipe, taking this conveyance to the Bear and Deer Creek water systems out of commission.
In March, PG&E’s Spaulding 1 Powerhouse suffered an unscheduled outage/failure rendering the Drum Canal inoperable. This is the primary source of water for Rollins Lake, and it is also a secondary source of water for Deer Creek/Scotts Flat. Further inspection also revealed two columns of the powerhouse’s foundation had collapsed. This has effectively cut off water supply to NID and neighboring Placer County Water Agency (PCWA) from the high-elevation water reservoirs.
Repair work has started on the “Flume of Doom”
“The tentative schedule for the South Yuba Pipe repairs is currently estimated to be late summer/fall based on the procurement of long lead time pipe and couplers, which have been ordered,” a previous update from PG&E read. It would appear the utility is moving forward with temporary repairs.
The SHPO letter posted to the FERC library reads, in part:
This undertaking is located in Nevada County, California on the South Fork of the Yuba River. A rockslide demolished a section of the South Yuba Canal (SYC) in the vicinity of Lake Spaulding. The SYC is a feature of PG&E’s FERC‐licensed hydroelectric project known as the Drum Spaulding Hydroelectric Project. PG&E proposes to complete both temporary and permanent repairs to this segment of the canal. The SYC pipe traverses the steep, northwest‐facing slope of the South Yuba River canyon and is typically supported by timber “cradles” founded on a narrow bedrock ledge. Where the ledge is too low or not wide enough, the pipe foundations are built up using hand‐stacked dry masonry walls, concrete piers, and steel bent structures. A grip‐strut walkway and handrail are attached to the top of the pipe to provide access along the alignment. The work is occurring on PG&E property, and although FERC approval is required, no other federal funding, permitting or approvals are needed.
There are two phases to this project: the first phase is a temporary repair which includes installation of temporary piping and supports. The second, more permanent phase will be implemented once pipe is procured for those long‐term repairs. As part of the permanent solution, long‐term rock stabilization measures will be installed to prevent this damage from occurring again.
SHPO letter dated April 22, 2024
Last week, a reader sent us footage of a helicopter removing tree debris from the slide.
Plans to restore some waterflow in June
The estimated time to restore 50% capacity to the #1 powerhouse is June 12th. PG&E plans to complete repairs to the first discharge horn and structural columns then restore water flows through the powerhouse. “We believe that this alternative might allow us to meet a completion date closer to the previously communicated June 8th estimated return to service date, but with reduced water capacity of about 400 cfs versus full capacity of 760 cfs. We could return in the fall or winter to repair the second discharge horn when demand for water deliveries is lower,” said a PG&E spokesperson in early April.
The deadline to complete partial repairs has changed three times so far.
