DCL-25-044, 2024 Annual Nonradiological Environmental Generating Report
| ML25118A336 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/28/2025 |
| From: | Rebel T Pacific Gas & Electric Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| DCL-25-044 | |
| Download: ML25118A336 (1) | |
Text
Pacific Gas and Electric Company"'
PG&E Letter DCL-25-044 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Power Plant, Units 1 and 2 Trevor D. Rabal Manager, Environmental Protection 2024 Annual Nonradiological Environmental Operating Report
Dear Commissioners and Staff,
Diablo Canyon Power Plant Mail code 104/5/521 P.O. Box 56 Avila Beach, CA 93424 805.441,5435 Trevor.Rebel@pge.com Enclosed is the 2024 Annual Non radiological Environmental Operating Report for Diablo Canyon Power Plant, Units 1 and 2. This report is being submitted in accordance with Subsection 5.4.1 of the Environmental Protection Plan, Appendix B of Facility Operating License Nos. DPR-80 and DPR-82.
Pacific Gas and Electric Company makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter.
If you have questions concerning this report, please contact me at (805) 441-5435.
Sincerely, ptwi--
Trevor D. Rebel armb/5094171 O Enclosure cc:
Diablo Distribution cc/enc: Mahdi 0. Hayes, Senior Resident Inspector Matthew T. Keeling, Executive Officer, Central Coast Regional Water Quality Control Board Samson S. Lee, NRR Project Manager John D. Monninger, NRC Region IV Administrator A member of the STARS Allia nee Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek
Enclosure PG&E Letter DCL-25-044 2024 ANNUAL NONRADIOLOGICAL ENVIRONMENTAL OPERATING REPORT DIABLO CANYON POWER PLANT, UNITS 1 AND 2 Pacific Gas and Electric Company April 2025
Enclosure PG&E Letter DCL-25-044 page 1 of 5
- 1. Introduction Pacific Gas and Electric Company (PG&E) has prepared the 2024 Annual Nonradiological Environmental Operating Report in accordance with the Environmental Protection Plan (EPP), which is Appendix B of Facility Operating License Nos. DPR-80 and DPR-82 for Diablo Canyon Power Plant (DCPP), Units 1 and 2, respectively. The report describes implementation of the EPP per the routine reporting requirements of EPP Subsection 5.4.1. PG&E remains committed to minimizing the environmental impact of operating DCPP.
- 2. Environmental Monitoring 2.1. Aquatic Issues Aquatic issues are addressed by the effluent limitations and receiving water monitoring/reporting requirements contained in the DCPP National Pollutant Discharge Elimination System (NPDES) permit. The NPDES permit includes applicable requirements of the California State Water Resources Control Board's Ocean Plan and Thermal Plan.
2.1.1. Routine Influent and Effluent Monitoring During 2024, DCPP submitted quarterly NPDES reports containing routine influent and effluent monitoring data and permit compliance summaries to the Central Coast Regional Water Quality Control Board (CCRWQCB). The reports were submitted electronically during the month following the end of each calendar quarter via the California Integrated Water Quality System (CIWQS), an internet database application. DCPP also submitted an annual NPDES report for 2024 to the CCRWQCB in February 2024 via the CIWQS application. The annual report contained monitoring data summaries in tabular and graphical form, and a summary of permit compliance and corrective actions, as applicable, for 2024.
2.1.2. Receiving Water Monitoring Program (RWMP)
The NPDES RWMP, required by the CCRWQCB, included the ecological monitoring, temperature measurements, and State Mussel Watch activities.
Environmental monitoring programs have recorded biological changes in the discharge area since plant start-up. These programs monitor intertidal and subtidal communities of invertebrates, algae, and fish in the discharge cove and at stations north and south of DCPP. During 2024, environmental monitoring continued under the revised RWMP.
The revised RWMP continued historical monitoring tasks, including
Enclosure PG&E Letter DCL-25-044 page 2 of 5 temperature monitoring, State Mussel Watch activities, and intertidal and subtidal surveys (with additional stations and increased sampling frequencies).
DCPP submitted the NPDES Receiving Water Monitoring Program:
2023 Annual Report (PG&E Letter No. DCL-2024-513) to the CCRWQCB and the NRC on April 18, 2024. The 2024 Receiving Water Monitoring Program Annual Report will be submitted at the end of April 2025.
During 2021, final resolution of the plant thermal discharge impacts settlement agreement was realized. The settlement addressed impacts on receiving waters from past and ongoing power plant cooling water discharges. Regardless of the thermal discharge impacts settlement resolution, the plant NPDES permit remains under administrative extension, under which current receiving water monitoring requirements remain in effect.
PG&E has submitted an application for NPDES permit renewal.
Accordingly, modification of the current permit receiving water monitoring program will not occur in the interim period.
2.1.3. Thermal Effects Study DCPP submitted the final thermal effects comprehensive assessment report (PG&E Letter No. DCL-98-585) to the CCRWQCB and the NRC in 1998.
2.1.4. 316(b) Studies DCPP submitted the final 316(b) report, entitled 316(b) Demonstration Report (PG&E Letter No. DCL-2000-514), to the CCRWQCB and the NRC on March 1, 2000.
2.2. Terrestrial Issues 2.2.1. Grazing, Mastication, Herbicide Application, and Erosion Control Herbicides are used as one component of an overall land vegetation management program that includes transmission line corridors and rights-of-way. The company continues to use only herbicides registered by the Environmental Protection Agency and approved by state
Enclosure PG&E Letter DCL-25-044 page 3 of 5 authorities and applies them in accordance with all applicable regulations.
Components of the vegetation management program used on the entirety of the DCPP lands include rotational livestock grazing, mastication, and herbacide application. These practices are utilized to reduce fuel loads, create fire breaks, maintain line clearance, and increase line of sight in rights-of-ways. Mastication is a vegetation management tool that reduces ground disturbance and is effective at controlling vegetation when used in conjunction with herbicides.
PG&E continues to implement erosion control activities at the plant site and in the high voltage transmission line corridors as part of an overall land management program. These erosion control activities consist of routine maintenance and prevention efforts performed periodically on an as-needed basis, including seasonal storm activity and wildfire damage repair as applicable.
2.2.2. Preservation of Archaeological Resources A. CA-SLO-2 Site Management Archaeological site CA-SLO-2 is managed in compliance with the Archaeological Resource Management Plan (ARMP) and Operating Procedure EV1.ID2. All projects undertaken within site CA-SLO-2, or immediately adjacent, are to be screened following the procedure described in EV1.ID2. The review determines if the project constitutes Current Approved Activities described in EV2.ID1. If project activities have the potential to affect the archaeological site, a more thorough impact assessment is completed. PG&E would invoke the notification procedure identified in the ARMP if a significant impact to the site was anticipated or occurred inadvertently.
The annual photo-monitoring of CA-SLO-2 was conducted by PG&E Senior Consulting Scientist for Cultural Resources, Mike Taggart, on December 10, 2024. The following is a summary of the results presented in the 2024 CA-SLO-2 Monitoring Memorandum (Taggart 2025).
The portions of site CA-SLO-2 located away from the coastal bluff and road cuts are stable, with no observed erosion or other significant changes since the last monitoring event.
Area 1A recovered from minor slumping the prior year. The soldier pile wall along the northern road cut continues to stabilize the slope and catch any slumping material. Giant rye planted in 2011 is well established and appears effective in anchoring the soil. Within Area 1B,
Enclosure PG&E Letter DCL-25-044 page 4 of 5 a small amount of brush was cleared by hand with loppers within 25 feet of the 230kV tower in December of 2024. The clearing on the gravel cap was made to operate ground-penetrating radar (GPR) as part of a broader cultural study underway on the Diablo Lands. The vegetation clearing and GPR operation was monitored by a member of the yak titu titu yak tiłhini (YTT).
Natural erosion within subunits of Area 3 has continued gradually and is punctuated during significant storms. Increased erosion around the Fields Cove stairs in the northern margin of 3A two winters ago prompted safety concerns, leading to the establishment of an alternative means of accessing the cove for water sampling. There is no sign of impacts from the alternative pedestrian access to the cove.
Measures were implemented in 2024 to block overland vehicular travel noted during the prior years monitoring. Corrective action was documented in the DCPP Corrective Action Program which resulted in the installation of K-rails to block vehicular access and communication to work groups at DCPP that require access within CA-SLO-2.
Monitoring in 2024 confirmed that the measures have been effective in keep vehicles on the established road.
No other notable events, projects, or ARMP compliance tasks related to the management of CA-SLO-2 occurred in 2024.
B. Native American Correspondence There were no requests from tribal representatives to access the CA-SLO-2 site in 2024. However, PG&E conducted focused tribal outreach in 2024 related to DCPP Land Stewardship projects, DCPP Decommissioning planning, License Renewal Project, and the Diablo Canyon Intake Cove Dredging Project.
The DCPP Land Stewardship Team (LST) partnered with YTT, Cal Poly, and Far Western for a comprehensive cultural resource inventory of the coastal plains of the Diablo Canyon lands. The study is using archaeological survey, remote sensing, drone photography, and ethnographic research to update documentation of the lands. Work begun in 2024 is continuing in 2025.
YTT participated in a four-day archaeological investigation hosted by PG&E on the North Ranch in partnership with the Yoshida family and Cal Poly in the spring of 2024. The LST also met with YTT to plan a cultural burn for the South Ranch lands, scheduled for the fall of 2025.
Enclosure PG&E Letter DCL-25-044 page 5 of 5 PG&E provided an update to regional tribes on DCPP Decommissioning by way of letter in December 2024. The letter summarized the status of the County of San Luis Obispos environmental review, including the 2023 Draft EIR, anticipated 2025 Final EIR, and upcoming opportunities for comment and consultation.
At the request of the Nuclear Regulatory Commission (NRC) in furtherance of consultation for License Renewal, PG&E provided YTT with copies of all previously conducted archaeological surveys within the Diablo Canyon lands, historic photos of the lands, and hard copy maps of resources located within the 750-acre License Renewal APE.
Similarly, PG&E provided specific reports to the Santa Ynez Band of Chumash Indians (SY) in June of 2024 at the direction of the NRC.
A Cultural Resources Treatment and Monitoring Plan (CRTMP) was developed and implemented for a dredging project to fulfill Special Condition #8 (as amended) of the CCCs Staff Report regarding coastal development permit application number 9-23-0599. Prior to dredging activities, YTT was consulted on the CRTMP. Tribal monitors from YTT and SY observed remote operated vehicle (ROV) video survey of the intake before and after dredging. No cultural material was observed by tribal or archaeological monitors.
PG&Es Senior Consulting Scientist for Cultural Resources continues to serve as a primary point of contact for engagement with tribes concerning management of CA-SLO-2.
- 3. Unusual or Important Environmental Events There were no unusual or important environmental events during 2024.
- 4. Plant Reporting Requirements 4.1. EPP Noncompliance There were no EPP noncompliances during 2024.
4.2. Changes In Station Design There were no changes in plant design or operation, tests, or experiments that involved an unreviewed environmental question or a change to the EPP.
4.3. Nonroutine Reports There were no nonroutine events during 2024 per the EPP; therefore, no nonroutine reports were submitted to the NRC.