Rehabilitation and Repair

PG&E reports on emergency repair work at Spaulding 1 powerhouse

PG&E reports on emergency repair work at Spaulding 1 powerhouse
(photo courtesy PG&E)

The dam at Spaulding Reservoir is expected to begin spilling water, which will significantly increase flows on the South Yuba River, PG&E said.

Due to PG&E’s “ongoing emergency repair work at Spaulding 1 powerhouse,” spill from Spaulding Reservoir into the South Yuba River is anticipated to start earlier this year and flows could potentially be greater and more dynamic than previous years, the company said.

Spaulding 1 is part of the Drum-Spaulding Hydroelectric Project.

“During a routine inspection at PG&E’s Spaulding 1 powerhouse on March 6, a leak was discovered adjacent to a pressure relief valve,” PG&E is reported to have said. The Union reported that “PG&E’s Spaulding 1 powerhouse sustained an infrastructure failure that curtailed water flow into the Drum Canal.”

Per The Union:

“PG&E informed Nevada Irrigation District (NID) and the Placer County Water Agency (PCWA) that the completion of repairs on the Spaulding 1 powerhouse will take longer than first expected, according to Paul Moreno, principal, marketing and communications for PG&E. It was expected that a pressure valve in the Spaulding 1 powerhouse could be replaced by June 8 and allow water flow to resume for the NID and the PCWA, however, the damage turned out to be more extensive than expected.

“‘We discovered that both of the discharge valve horns were damaged. It is an elbow shaped valve that needs to be designed and engineered,’ Moreno said. ‘To repair both discharge horns and structural columns, we anticipate the estimated schedule and return to service date for Spaulding 1 powerhouse is now early August as there is not enough space to work on both discharge horns and make structural repairs at the same time,” Moreno said.

An alternative option is to complete repairs to one of the discharge horns and structural columns, then restore a partial water flow 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,’ Moreno said. ‘But with reduced water capacity of about 400 cfs versus full capacity of 760 cfs.’

“The tentative plan would be for PG&E to return in the fall or winter to repair the second discharge horn when demand for water deliveries is lower.”

Flows on the South Yuba River below Lake Spaulding at Langs Crossing are about 20 cubic feet per second (cfs). With Spaulding Dam expected to spill as early as April 5, flow will increase to about 300 to 600 cfs. Typical flows in this part of the river for this time of year range from about 10 to 325 cfs.

Peak flows may be as high as 4,000 to 6,000 cfs and potentially higher if there is a significant rain-on-snow event or multi-day heatwave accelerating snowmelt.  The South Yuba River flows go as high as 10,000 feet during winter storms.

With the Spaulding 1 powerhouse not operating, water that normally would be diverted through the Spaulding 1 and 2 powerhouses remains in Spaulding Reservoir, raising the water elevation faster.