HomeMy WebLinkAbout12.23.22 Board Correspondence - FW_ Part 12 Consultant Safety Inspection Reports submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.
December 23, 2022
Power Generation
77 Beale Street
San Francisco, CA 94105
Mailing Address:
Mail Code N11D P.O. Box 770000
San Francisco, CA 94177
Via Electronic Submittal (E-File)
Frank L. Blackett, P.E., Regional Engineer
Federal Energy Regulatory Commission
Division of Dam Safety and Inspections
100 First Street, Suite 2300
San Francisco, CA 94105-3084
RE: DeSabla-Centerville Hydroelectric Project, FERC No. 803-CA
Philbrook Dam, NATDAM No. CA00345
10th Part 12D Inspection – Status Update for Recommendations 15 and 17
11th Part 12D Inspection – Status Update for Recommendations 1 and 9
Dear Frank L. Blackett:
This letter presents an update on the status of Pacific Gas and Electric Company’s (PG&E)
efforts to address Recommendations 15 and 17 from the 10th 5-year Part 12D safety
inspection report (dated June 2015) and Recommendations 1 and 9 from the 11th 5-year
Part 12D safety inspection report (dated October 2020) for Philbrook Dam, which is part of
PG&E’s DeSabla-Centerville Hydroelectric Project, Federal Energy Regulatory
Commission (FERC) No. 803.
PG&E submitted our original plans and schedules for addressing the 2015 R-15 and R-17
and 2020 R-1 and R-9 in a letter to your office, dated December 15, 2015 and December
31, 2020, respectively. PG&E provided our most-recent update regarding these
recommendations on July 15, 2022, with a commitment to provide FERC with a plan and
schedule for completing the stability analysis by December 31, 2022. PG&E’s status
update is provided in Enclosure 1 of this letter.
Should you have technical questions concerning this matter, please contact Kaitlyn
Daniels, dam safety engineer for PG&E, at (707) 342-7885. For general questions, please
contact Jackie Pope, license coordinator for PG&E, at (530) 254-4007.
Sincerely,
Robert O. Ellis, P.E., G.E.
Deputy Chief Dam Safety Engineer
Enclosure:
1. Status Updates to Address R-15 and R-17 from the 10th Part 12D Safety Inspection Report
and R-1 and R-9 from the 11th Part 12D Safety Inspection Report
ENCLOSURE 1
Enclosure 1
1
DeSabla-Centerville Hydroelectric Project, FERC No. 803-CA
Philbrook Dam, NATDAM No. CA00345
Status Updates to Address
Recommendations 15 and 17 from the 10th Part 12D Safety Inspection Report
Dated June 2015
Recommendations 1 and 9 from the 11th Part 12D Safety Inspection Report
Dated October 2020
Recommendations 15 and 17 (R-15 and R-17) were provided in the 10th Part 12D
safety inspection report (dated June 2015) and Recommendations 1 and 9 (R-1 and R-
9) were provided in the 11th Part 12D safety inspection report (dated October 2020) for
Philbrook Dam, which is part of Pacific Gas and Electric Company’s (PG&E) DeSabla-
Centerville Hydroelectric Project, Federal Energy Regulatory Commission (FERC) No.
803. For reference, the recommendations are copied below, followed by an update on
the status of PG&E’s efforts to address the recommendations and updated plans and
schedules (in italics).
10th Part 12D Safety Inspection Report Recommendations
R-15: PG&E should complete the currently proposed geotechnical evaluations and
possibly other investigations that may be determined necessary to complete a
seismic stability evaluation of the Main and Auxiliary Dams.
PG&E received approval of our drilling program plan (DPP) and FERC
authorization to proceed with the planned geotechnical investigation in a letter to
PG&E dated August 5, 2022. PG&E subsequently received Division of Safety of
Dams (DSOD) approval to proceed in a letter to PG&E dated August 30, 2022.
PG&E mobilized and began drilling work on October 3, 2022. Unfortunately,
winter weather conditions forced an early demobilization of the driller from the
project on October 27, 2022. Remobilization to the project during the remainder
of 2022 is not considered feasible.
To date, PG&E has completed the test pit explorations and approximately half of
the drilling borings included within the DPP. Soil samples from the completed
borings have been submitted for laboratory testing. Restoration of all disturbed
area of the dam was complete before demobilizing from the site. PG&E plans to
remobilize in August/September of 2023 to complete the remaining field
investigation program. Contingent upon successful completion of the remainder
of the drilling work, PG&E plans to provide the updated stability analyses for
FERC review by July 31, 2024.
R-17: Section 8 of the STID should be updated to include the results of the updated
stability analyses after the additional field and laboratory investigations are
preformed and the stability analyses are finalized and accepted by FERC.
As noted in the status update for R-15 (2015) above, PG&E was unable to
complete the field investigation program in 2022. PG&E plans to complete the
Enclosure 1
2
remainder of the drilling work in 2023, with submittal of the updated stability
analyses to FERC by July 31, 2024. PG&E will provide a plan and schedule for
updating Section 8 of the supporting technical information document within 90
days of receiving FERC approval of the updated stability analysis. If FERC has
not accepted the studies before the next Part 12D safety inspection, PG&E will
review the status of the studies with the next Part 12D independent consultant by
November 1, 2025.
11th Part 12D Safety Inspection Report Recommendations
R-1: It is recommended that the field investigation and seismic stability analyses be
performed as soon as practical. This is a carryover of recommendation R-15 from
the 2015 Part 12D report. The results of the field investigation and analyses are
needed to properly classify PFMs 5 through 9 and 16 through 19. The IC should
be given an opportunity to review the proposed drilling program before it is sent
to FERC and DSOD for approval. The analyses should use updated ground
motions and current methodologies for evaluating liquefaction and seismic
deformation potential.
As noted in the status update for R-15 (2015) above, PG&E was unable to
complete the field investigation program in 2022. PG&E plans to complete the
remainder of the drilling work in 2023, with submittal of the updated stability
analyses to FERC by July 31, 2024.
R-9: It is recommended that the slope stability analyses for both dams be updated
using revised subsurface characterization and strength data from the upcoming
seismic stability assessment (Recommendation 1). In addition to the seismic load
cases and permanent deformation analysis discussed in Recommendation 1, the
analyses should include long-term (static) loading with the reservoir at NMWSE,
flood loading (with the reservoir up to the dam crest), and rapid-drawdown
conditions with the reservoir drawn down from NMWSE to dead pool. PG&E may
consider including seepage analysis under flood loading conditions to
characterize the phreatic surface within the embankments for the flood loading
cases.
As noted in the status update for R-15 (2015) above, PG&E was unable to
complete the field investigation program in 2022. PG&E plans to complete the
remainder of the drilling work in 2023, with submittal of the updated stability
analyses to FERC by July 31, 2024.
From:Clerk of the BoardTo:BOS
Subject:Board Correspondence - FW: Part 12 Consultant Safety Inspection Reports submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.Date:Tuesday, December 27, 2022 8:47:08 AM
Please see Board Correspondence below.
Shaina PaulsenAssociate Clerk of The BoardButte County Administration25 County Center Drive, Suite 200, Oroville, CA 95965T: 530.552.3304 | F: 530.538.7120
-----Original Message-----From: 'FERC eSubscription' <eSubscription@ferc.gov>Sent: Friday, December 23, 2022 1:25 PMSubject: Part 12 Consultant Safety Inspection Reports submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.
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On 12/23/2022, the following Filing was submitted to the Federal Energy Regulatory Commission (FERC), Washington D.C.:
Filer: Pacific Gas and Electric Company Pacific Gas & Electric Company (as Agent)
Docket(s): P-803-000Lead Applicant: Pacific Gas and Electric CompanyFiling Type: Part 12 Consultant Safety Inspection ReportsDescription: Pacific Gas and Electric Company submits update on the status of efforts to address Recommendations 15 and 17 from the 10th 5-year Part 12D Safety Inspection Report, etc. for Philbrook Dam, part of DeSabla-Centerville Hydroelectric Project under P-803.
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