GRASS VALLEY, Calif. May 8, 2024 – NID updated their webpage listing their Directors’ questions to PG&E at their last board meeting with answers provided by the utility corporation. A new development appears to be the permanent repair only on the South Yuba pipe, damaged by a rockslide in early February. “PG&E is no longer pursuing the temporary repair on the South Yuba pipe after receiving guidance from NID staff.”
Some of the answers provided are falling under the confidentiality clause in the joint operating agreement between the two entities and are not being made available to the public. NID’s Board of Directors meeting today starts at 9:00 am and can be viewed on their YouTube channel.
Questions by NID Directors during the April 24 workshop with PG&E rep
Director Trevor Caulder: Can you provide information about the South Yuba Canal Pipe? Please let us know what additional information we can provide about the pipe.
Board Vice President Ricki Heck: What is the update on the timing of the temporary repair? And when that happens, what are the expected flows in the South Yuba Canal? Because the 350 cfs (cubic feet per second) we’re talking about is the horn; it’s not the pipe, correct? NID has provided guidance not to pursue the temporary solution on the South Yuba pipe, and PG&E is instead focusing on the permanent repair. The schedule to return this facility to service is around August 1. Once the single discharge horn is repaired and returned to service at Spaulding 1 we anticipate being able to move approximately 400 cfs into the Drum Canal, and a portion of this water will be diverted into the South Yuba canal for delivery to NID.
Board Vice President Heck: Does PG&E have a plan or a schedule regarding construction and timing for that temporary repair? PG&E is no longer pursuing the temporary repair on the South Yuba pipe after receiving guidance from NID staff.
Director Chris Bierwagen: Could you give us an idea of the scope or the magnitude of the damage to the Pipe? A landslide in February destroyed approximately 240 feet of the pipe.
Board Vice President Heck: How much of the 50-inch pipe was damaged? Is it 20 feet? Is it 100 feet? A landslide in February destroyed approximately 240 feet of the pipe.
Board Vice President Heck: Once that temporary pipe repair is complete, what are the expected flows? Response subject to and provided pursuant to Confidentiality of the COA.
Board Vice President Heck: Do you know what the timing of the procurement of the piping is? I understand part of the problem is getting the materials necessary to do this. PG&E has procured the pipe earlier than expected, which is one of the reasons the decision was made not to pursue the temporary repairs.
Board Vice President Heck: What is the timing of doing that final rock stabilization? The rock scaling and slope stabilization work associated with the South Yuba Pipe repairs is estimated to be complete by mid-May, however site conditions will dictate the actual completion date. PG&E’s project schedule reflects a completion date of the pipe repair of August 1st.
Board Vice President Heck: What kind of materials are you using for that? We are not clear what this question refers to, please provide some additional information so that we can provide an accurate response.
Board Vice President Heck: what is the schedule for the permanent fix? When do you anticipate the permanent fix for that section being completed? Currently PG&E’s schedule anticipates a return to service around August 1.
Board President Rich Johansen: that permanent fix will probably not correspond to our irrigation season, but it might be in the offseason. How does that impact our refill of Scotts Flat next year, for 2025? We will have to defer to NID water management staff for questions related to refill forecasts of NID owned reservoirs. Our teams communicate frequently so that they have the latest information.
Board Vice President Heck: when you say you have a team working you 24/7, is that 25 people? Is it 100 people? Can give us a sense of how many resources PG&E has dedicated to the repairs]? Response subject to and provided pursuant to Confidentiality of the COA.
Board Vice President Heck: do you have a team working on the pipe and a team working on the horn? Yes, we have separate teams working on the South Yuba pipe repairs, and the Spaulding 1 PRV discharge horn and structural repairs.
Board Vice President Heck: I’m trying to get a sense of the timing — when would that need to occur in order to help Scotts Flat? If they can’t get this repair done until next June, we’re not going to refill Scotts Flat. But if they could get it done in October or November … Not sure what this is in reference to, need a bit more background on the question.
Director Caulder: what’s the maximum capability of that conveyance? If this is in reference to the South Yuba Canal, during high demand deliveries are approximately 100 cfs.
Board Vice President Heck: could you please update us on the timing to repair Horn 1? I understand we have now a new date of June 18th. Can you tell us with certainty when you expect to have that Horn 1 at least partially operational for the 350 CFS? The schedule provided, reflects a date of June 18th. Please note this amount of water will be conveyed into PG&E’s Drum canal and a portion of this water will be diverted downstream for delivery to NID through the South Yuba Canal.
Director Karen Hull: What variables have you locked down that make you feel confident that June 18th is the date? Do we have a high degree of confidence in this? The schedule we’ve provided to NID staff has the timeline for each construction milestone. Right now, there is a high level of confidence that we will be able to return the Spaulding 1 powerhouse to service in mid-June. PG&E will make NID aware of any changes to the schedule.
Board Vice President Heck: can you let us know whether you can provide a detailed construction schedule to NID staff with sequential steps? PG&E has provided a detailed schedule to NID staff with timelines for each milestone.
Board Vice President Heck: you’re going to do the partial repair to the Horn 1 so that we can get some flows. Can those repairs be done given that you have a collapsed foundation? The repairs to the single discharge horn and the structural columns are being done concurrently.
Board Vice President Heck: can the water go through the horns while you are completing the repairs that the foundation? June 18th is the schedule to have a single PRV discharge horn and the structural columns complete.
Director Karen Hull: can you confirm the historical flow that is able to be managed in that repaired horn? Has it always been able to carry 350 to 400 CFS? Because we’re looking at 400 CFS coming through. Past testing information and equipment specs indicate that we can pass approximately 400 cfs into the Drum canal. The equipment will be tested prior to being returned to service.
Director Chris Bierwagen: these two horns are all in the No. 1 Powerhouse? Yes
Board Vice President Heck: could you give us a detailed explanation on the collapse of those columns? The upstream column (closest to the discharge horns) was completely destroyed, and the downstream column was badly damaged.
Board Vice President Heck: did it happen simultaneously with the shutdown of the horns? I’m just trying to get a sense of the timing, like which came first? The leak on the PRVs was discovered and then when we dewatered the Spaulding Tunnel and discharge pit the damage to the columns was discovered. They are typically submerged.
Director Karen Hull: there was some inspection work done in fall of last year around September-October. I’m wondering if that identified the need to make some degree of repairs in the area, so what is the progress from that discovery to when we have a major problem? I’d just like to understand about what the company was doing then and then how it led up to the new discovery. The FERC inspection from last fall identifiedsurficial erosion (rust), this was unrelated to the damage discovered to the discharge horns and structural columns.
Director Trevor Cauldwell: did the horn failure and the foundation failure happen at the same time, or did one lead to the other? Response subject to and provided pursuant to Confidentiality of the COA.
Board Vice President Heck: how are the columns going to be repaired, and do they actually really need replacement versus just to patch or repair? One is completely destroyed and the other is severely damaged. Replacement is required.
Board Vice President Heck: can that horn operate with the collapsed foundation? Work is being performed concurrently.
Board Vice President Heck: that underwater portion where the problem occurred, has that been routinely inspected? And if so, at what frequency? PG&E performs its inspections in accordance with FERC and DSOD requirements. The inspections comply with regulatory requirements and are informed by various operational conditions.
PG&E’s technical staff would be happy to meet with the NID staff to share its methodology for these inspections.
Board Vice President Heck: it would be really great if we could see, if the public could see, the frequency of the inspections and what were the results. Similarly, PG&E performs its inspections in accordance with FERC and DSOD requirements. As stated above, the inspections comply with regulatory requirements and are informed by various operational conditions. PG&E’s technical staff would be happy to meet with the NID staff to share its methodology for these inspections.
Board Vice President Heck: what is your schedule to repair the second horn? We anticipate taking and additional outage this winter to begin this work. The timing is subject to change based on additional input on water delivery needs from NID and PCWA.
Board Vice President Heck: while the repair is underway for the Horn 2, will there need to be outages? Yes, we are coordinating with NID staff on the timing of the outage and are evaluating options to keep water moving through Spaulding 2 into the South Yuba Canal.
Director Karen Hull: is there a timeline for repair of that system? Per the latest schedule shared with NID, the dates are June 18th for PRV discharge horn and structural columns at Spaulding 1. August 1st for the South Yuba Pipe. PG&E is planning to take an outage on Spaulding 1 this winter to return and perform the repairs on the second PRV discharge horn. The return date to complete the second discharge horn is pending and we are communicating closely with NID staff about timing.
Board Vice President Heck: For future repairs and/or replacement of components, “it’s weather-dependent” would not be a reason to not continue forward? Weather can be a factor to access the facilities, weather delays will be accounted for in our schedule for any work that may be performed this winter.
Board Vice President Heck: What is your estimated time for all of these outages? Please provide a detailed schedule to NID of what you’re perceiving these outages to be. We have provided schedules for the current work being performed, and will share a schedule for the 2nd discharge horn once that work is initiated.
NID GM Hanson: it would be very helpful if PG&E would take consideration of releasing the schedule. The schedule has been provided.