HomeMy WebLinkAbout02.12.21 BOS Correspondence - FW_ Project Operations Compliance Report submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.
From:Schuman, Amy
To:Alpert, Bruce;Bennett, Robin;Clerk of the Board;Connelly, Bill;Cook, Holly;Cook, Robin;Kimmelshue, Tod;Lucero, Debra;Paulsen, Shaina;Pickett, Andy;Ring, Brian;Ritter,
Tami;Rodas, Amalia;Sweeney, Kathleen;Teeter, Doug
Subject:BOS Correspondence - FW: Project Operations Compliance Report submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.
Date:Friday, February 12, 2021 2:24:38 PM
Please see the email below from FERC.
Amy Schuman
Associate Clerk of the Board
Butte County Administration
25 County Center Drive, Suite 200, Oroville, CA 95965
O: 530.552.3300 |D: 530.552.3308 | F: 530.538.7120
Twitter | Facebook | YouTube | Pinterest
-----Original Message-----
From: 'FERC eSubscription' <eSubscription@ferc.gov>
Sent: Friday, February 12, 2021 2:15 PM
Subject: Project Operations Compliance Report submitted in FERC P-803-000 by Pacific Gas and Electric Company,et al.
.ATTENTION: This message originated from outside Butte County. Please exercise judgment before opening attachments, clicking on links, or replying..
On 2/12/2021, the following Filing was submitted to the Federal Energy Regulatory Commission (FERC), Washington D.C.:
Filer: Pacific Gas and Electric Company
No Organization Found (as Agent)
Docket(s): P-803-000
Lead Applicant: Pacific Gas and Electric Company
Filing Type: Project Operations Compliance Report
Description: Pacific Gas and Electric Company Incident Report Regarding Toadtown Canal Undermining for the DeSabla Centerville Hydroelectric Project P-803.
To view the document for this Filing, click here https://urldefense.com/v3/__https://elibrary.ferc.gov/eLibrary/filelist?accession_num=20210212-
5255__;!!KNMwiTCp4spf!QDQxIaLLcAT5AjoN3epJivQwlpP1kQVFfNPNHbRRpcfjtk1j2RpFyhWI-zq2wVJ2GXklUU4zJxY$
To modify your subscriptions, click here:
https://urldefense.com/v3/__https://ferconline.ferc.gov/eSubscription.aspx__;!!KNMwiTCp4spf!QDQxIaLLcAT5AjoN3epJivQwlpP1kQVFfNPNHbRRpcfjtk1j2RpFyhWI-
zq2wVJ2GXklWA2oQc0$
------------------------------------------------------------------------
Please do not respond to this email.
Online help is available here:
https://urldefense.com/v3/__http://www.ferc.gov/efiling-help.asp__;!!KNMwiTCp4spf!QDQxIaLLcAT5AjoN3epJivQwlpP1kQVFfNPNHbRRpcfjtk1j2RpFyhWI-
zq2wVJ2GXkl4dKlgIA$
or for phone support, call 866-208-3676.
tƚǞĻƩ DĻƓĻƩğƷźƚƓ 245 Market Street
San Francisco, CA 94105
Mailing Address:
Mail Code N11D
P.O. Box 770000
San Francisco, CA 94177
February 12, 2021
Via Electronic Submittal (E-Filing)
Mr. Frank Blackett, P.E., Regional Engineer
Federal Energy Regulatory Commission
Division of Dam Safety and Inspections
San Francisco Regional Office
100 First Street, Suite 2300
San Francisco, CA 94105
RE: DeSabla-Centerville Hydroelectric Project, FERC No. 803-CA
12.10a Incident Report Regarding Toadtown Canal Undermining
Dear Mr. Blackett:
Pursuant to Code of Federal Regulations (CFR) Title 18, Part 12.10a, this letter
an incident
resulting in damage to the hillside supporting the Toadtown Canal, which is part of
DeSabla-Centerville Hydroelectric Project, Federal Energy Regulatory
Commission (FERC) No. 803. PG&E operations staff discovered evidence of illegal
mining activities while performing a routine inspection of the canal in 2017. Since
discovery of the issue, stormwater runoff and erosion have contributed to
undermining of the canal liner. In 2018, PG&E implemented temporary support
measures (described below) to protect the canal in the areas where the hillside has
eroded and plans to complete long-term repairs during the spring of 2021.
Background Information and Summary of Incident
The Toadtown Canal is a concrete-lined canal that conveys water from the West
Branch of the Feather River to the DeSabla Powerhouse for generation of
hydroelectric power. During a routine inspection of the canal in October 2017, PG&E
staff discovered evidence of illegal mining activity in the hillside below the canal. The
unauthorized excavation is located about 5 to 10 feet downstream of a retired
spillway that was partially undermined by previous erosion (Figure 1). PG&E believes
that the erosion around the retired spillway may have exposed a quartz vein, which
prompted the illegal mining activity.
Mr. Frank Blackett, P.E., Regional Engineer
February 12, 2021
Page 2
Figure 1. Toadtown Canal Undermining
After the 2017 discovery, the mining activities ceased but the hillside continued to
erode as a result of stormwater runoff. In December 2018, PG&E established
periodic visual monitoring of the area as part of its routine canal walkdowns and
installed temporary wood cribbing to support the canal while a long-term repair plan
was developed. Design of the long-term repairs has been completed and PG&E
submitted the project package for FERC review on January 21, 2021. Pending FERC
authorization to proceed with the work, PG&E plans to complete the repairs during an
upcoming planned outage scheduled to begin on April 1, 2021.
During a review of the proposed repair area on December 9, 2020, members of the
project team observed evidence of what appeared to be new activity at the site and
assumed that the mining had resumed (Photo 1). PG&E notified FERC of the
observations via email on January 15, 2021, and, as a safety precaution, removed
the Toadtown Canal from service to allow engineers to assess the situation.
Mr. Frank Blackett, P.E., Regional Engineer
February 12, 2021
Page 3
Photo 1. Toadtown Canal Illegal Mining Site
On January 20, 2021, PG&E engineers reviewed the areas of undermining beneath
the shotcrete canal liner and retired spillway and did not observe evidence of
progressive deterioration or recent mining at the site, as was initially reported to
FERC. The liner appeared to be supported in fractured and blocky weathered
bedrock material. Although a relatively small area (approximately 2 feet by 3 feet) of
the underside of the sloped liner was exposed at the time of inspection, no cracks,
Mr. Frank Blackett, P.E., Regional Engineer
February 12, 2021
Page 4
stains, or other signs of potential distress or leakage through the liner were observed.
The contours of the undermining appeared very similar to those depicted in the
design drawings, dated March 20, 2020, for the proposed long-term repair project.
PG&E also reviewed the source of the December 2020 report that mining activity had
resumed at the site. After discussions with local operations and maintenance (O&M)
staff, PG&E determined that the erroneous report was based on the observation of a
tarp over the illegal mining area. The tarp was placed by O&M staff earlier in 2020 to
mitigate potential erosion but was misinterpreted by the observer as evidence that
activity at the mining site had resumed and subsequently led to an inaccurate
notification to FERC. PG&E has reviewed its canal observation records from the past
several years and found no observations or reports of berm seepage or damp areas,
or canal liner defects, including cracking, holes, or settlement that would indicate a
potentially unstable or deteriorating condition.
Corrective Actions
Based on the findings of the engineering inspection and assessment and subsequent
consultation with FERC, PG&Ereturned the Toadtown Canal to limited service on
January 22, 2021. Returning the canal to service during the winter season will reduce
the potential for snow and ice accumulation to create blockages and lead to
overtopping from side water that enters the canal during storm events. The return to
service is conditioned on the following risk mitigation measures:
Toadtown Canal has an automatic monitoring system that detects and sounds an
alarm within 30 minutes after a breach of the canal at the undermining location.
In the event of an alarm, upstream spill gates can be tripped remotely to cut flow
to the canal at the undermining location within approximately 1 hour.
PG&E will restrict flows under normal canal operation to no more than 50 cubic
feet per second (cfs), which is less than 50 percent
Maximum temporary flow, to accommodate potential side flow from winter storms,
will be limited to 65 cfs.
PG&E will patrol the site daily on weekdays (Monday through Friday) and during
winter storms (through weekends, if necessary). The increased frequency of
patrols will continue until the upcoming scheduled project outage.
Pending FERC authorization to proceed with the project, PG&E will begin the
Toadtown Canal undermining repair on April 1, 2021.
As noted above, PG&E filed a project design package for long-term repair of the
undermined area with FERC on January 21, 2021. The purpose of the project is to
protect the canal from potential damage by repairingthe undermined areas from
previous illegal mining activities and subsequent erosion. The repairs are scheduled
to begin in spring 2021 to align with a previously planned canal outage. The outage
Mr. Frank Blackett, P.E., Regional Engineer
February 12, 2021
Page 5
will begin April 1, 2021, and last until May 13, 2021. Work is proposed to be
completed by the end of the outage.
Because of shelter-in-place orders issued by the State of California in response to the
COVID-19 pandemic, all nonessential PG&E staff are working remotely and unable to
provide the notarized verification form for this report in accordance with FERC
guidelines (18 CFR 12.13). To accommodate the unprecedented conditions imposed by
the ongoing COVID-19 response, PG&E respectfully requests a variance from the
requirement to provide the verification form. If a completed verification form is required,
PG&E proposes to resubmit this letter with a notary statement after the shelter-in-place
restrictions have been lifted and PG&E staff have returned to their normal work
locations.
If you have technical questions concerning this
safety engineer, Ms. Kaitlyn Thatcher, at (707) 342-
engineer, Mr. Jonathan Edwards, at (530) 896-4400. For general questions, please
oni, at (530) 215-6676.
Sincerely,
David L. Ritzman, P.E., G.E.
Chief Dam Safety Engineer