DRAFT_B2_03.04_CUIR_Subproject_1_Power_Outages_and_Linac_Downtime_Plan.pdf

CUIR Subproject 1 Power Outages and Linac Downtime Plan

Critical Utilities Infrastructure Revitalization (CUIR)

Project # 20-SC-79 at

SLAC National Accelerator Laboratory

CUIR-WPC-0114

DRAFT

CUIR Plans and Procedures Document Title: CUIR Subproject 1 Power

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The only official copy of this file is located in the CUIR Controlled Document Site.

Before using a printed/electronic copy, verify that it is the most current version.

Document Approval:

Originator: Lori Shewchuk – CUIR Power Outage and Downtime Planning Advisor

• Content/Format • SME Input • Actionable

Reviewer: Kelsy Westendorf – CUIR Subproject 1 Manager

• Scope Alignment • Facts • Details • Schedule •Subcontractor Coordination

Reviewer: Victor Longa – F&O Electrical Operations Subject Matter Expert

• Facts • Details • Concepts • Standards • Best Practices

Reviewer: Boris Ilinets – F&O Electrical Engineering Subject Matter Expert

• Facts • Details • Concepts • Standards • Best Practices

Reviewer: Amy Ancheta – CUIR Design Manager

• Mission Alignment • Facts • Details • Concepts • Standards • Best Practices

Reviewer: Tim Carnes, on behalf of JER Honeycutt – CUIR Construction Manager

Subcontractor Coordination Standards • Best Practices

Reviewer: Oliver Lopez – Deputy Chief Operating Officer

• Alignment with LDT Power Outage Schedule • Verify F&O Managed System and Building Impacts

Reviewer: Sharon Vetter – Project Downtime/Outage Scheduler

• Alignment with Accelerator Downtime Schedules • Verify Impacts to Accelerator Operations

Reviewer: Tracy Ng – CUIR Project Manager

• Clarity • Reference • Scope Alignment • Schedule Alignment

Approver: Janet Kan – CUIR Project Director

• Final Authorization

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Document Informed Date: August 4, 2025 (Revision 2) Mike Dunne – ALD LCLS Directorate

John Schmerge – ALD Accelerator Directorate

Ian Evans – Director, Environment, Safety, & Health (ES&H)

Paul McIntyre – ALD SSRL

Al Owens – Research Technical Manager, AD LFD Acc Area Management

Alayna Albert – CUIR QA Manager

Mark Hogan – Director, FACET-II

Brendan Curran – Director, Facilities & Operations

John Hogan – LCLS-II-HE Project Director

Martina Martinello – CRMF Project Director

Anuneet Krishna – Chief Electrical Engineer, F&O

Revision History

Revision Date Released Description of Change

R2 September 5,

• Rearranged sections to align with current SP1 construction packaging structure.

See Table of Contents section 4.1 – 4.5.

o Package A: Linac Power Distribution System Improvements o Package B: Master Substation Building Expansion o Package C: 230kV Transformer Replacement o Package D: K5B Substation and Sector 4 Switchgear Installation o Package E: IR12 SCADA Hardware

• Updated power outage dates to align with the four-week power outage duration.

R1 August 1, 2024

• Added Section 4.8 New SCADA hardware at IR12 S726.

• Updates to Sections 4.1.3, 4.2.3, 4.7.3 to reflect temporary power preparations to begin two weeks in advance of outage start dates.

• Updates to Section 5 to include diesel exhaust fluid and fueling twice daily, maintenance and fueling check lists, and to begin preparation of temporary generator power two weeks in advance of outage start dates.

• Updated outage dates for Sections 4.3.3. 4.4.3, 4.5.3, 4.6.3.

• Updated Figure 1 to reflect updated outage dates listed above.

• Updated Section 9 to reference ES&H Manual for Control of Hazardous Energy requirements.

R0 October 31, Original Release.

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TABLE OF CONTENTS

1 Background 2 Purpose 3 Roles and Responsibilities 4 Power Outages and Downtime Alignment

4.1 Linac Power Distribution System Improvements (Package A)

4.2 MSS Building Expansion (Package B)

4.3 230kV Transformer Replacement (Package C)

4.4 K-5B Substation Installation & Sector 4 Switchgear Installation (Package D)

4.5 IR12 SCADA Hardware (Substation 726) (Package E)

5 Temporary Power 6 Planned Power Outage Windows

6.1 Schedule

6.2 Communication Plan

6.3 Risks and Consequences

7 Emergency Response 8 References

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Acronym Definition CAM Control Account Manager CM Construction Manager COHE Control of Hazardous Energy DB Design-Build DBB Design-Bid-Build DEF Diesel Exhaust Fluid F&O Facilities & Operations GFP Government Furnished Property KSub KSubstation kV Kilovolt kW Kilowatt LCLS Linac Coherent Light Source LCLS-II Linac Coherent Light Source II LCLS-II-HE Linac Coherent Light Source II High Energy LOTO Lock Out Tag Out MCC Motor Control Center MH Manhole MSS Master Substation PM Project Manager POC Point Of Contact RFP Request For Proposal SCADA Supervisory Control and Data Acquisition SOW Statement of Work SP Subproject SSA Solid-State Amplifiers SWGR Switchgear VVS Variable Voltage Substation WPC Work Planning and Control UPS Uninterrupted Power Supply

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1 Background The Critical Utilities Infrastructure Revitalization (CUIR) Subproject 1 – Critical Electrical System Improvements includes major electrical system upgrades and a modernization scope. Safe, reliable, and resilient electrical infrastructure is essential to SLAC’s scientific mission. The utility improvements planned in Subproject 1 (SP1), along with the planned project delivery methods, are presented below:

Subproject 1 – Critical Electrical System Improvements Delivery Method

Linac Power Distribution System Improvements (Package A)

• Provide a Linac Power Distribution System Improvements along the Linear Accelerator to provide redundancy and physical independence from the existing south duct bank.

Design-Build

Master Substation Building (B016) Expansion (Package B)

• Installation of new 12.47kV switchgear to provide connection points for future Reactive Power Compensation equipment and for the new 12kV Feeder Cables Pathway to be installed by CUIR.

• Expand the existing Master Substation Building (B016) to accommodate new switchgear and new B016S substation (formerly K-15B substation).

Design-Build

230kV Transformer Replacement (Package C)

• Modernize the SLAC Master Substation by replacing and upsizing up to two 230kV 65MVA transformers.

Design-Build

K-5B Substation and Sector 4 Switchgear Installation (Package D)

• Provide a new substation K-5B near Sector 9.

• Provide a new switchgear at Sector 4 to allow connection and switching of VV1, VV2, and VV4 to the Cryoplant substation main breakers.

Design-Bid-Build

IR12 SCADA Hardware (Package E)

• Replaces power monitoring hardware at IR12 (Substation 726) by including SCADA input at substation relay doors and adding an integration hub.

Design-Bid-Build

The planned electrical improvements involve multiple equipment installations, reconfigurations, and tie-ins to the existing electrical system at SLAC. Subproject 1 Packages A was awarded in June 2025.

Package B Design-Build construction contract is planned to be awarded in 4Q FY26. Package C Design- Build construction contract is planned in 1Q FY27. Subproject 1 Design-Bid-Build construction contracts, Packages D and E, are planned to be awarded in 3Q FY26.

Construction activities of Packages A and E are predominantly planned between the months of October 2025 and completed by September 2026. Construction Packages B, C, and D will be completed in FY2027 and FY2028 based on the current delivery timeline of electrical equipment (GFPs).

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2 Purpose The purpose of this document is to:

1) Establish a preliminary electrical power outage schedule in alignment with accelerator program downtimes.

2) Identify the roles and responsibilities of each party.

3) Establish schedule constraints that Subproject 1 Subcontractors should adhere to.

3 Roles and Responsibilities

Role Responsibility

CUIR Outage & Downtime Plan Advisor

• Establishes power outage schedule for planned construction activities prior to award of construction subcontract.

• Coordinates with science programs and division stakeholders to communicate accelerator operation and downtimes.

CUIR Subproject 1 Manager • Responsible for delivering scope, cost, and schedule in accordance with Subproject 1 baseline.

• Has the authority to approve or decline the DB/DBB Subcontractor’s proposed change on power outage and Linac downtimes, project scope, cost, and overall delivery schedule.

CUIR Construction Manager

(CM)

• Responsible for review and release of the DB/DBB Subcontractor’s Work Planning and Controls.

• Responsible for the release of the DB/DBB Subcontractor to Work

• Responsible for field coordination with SLAC organizations (e.g., Facilities & Operations, Accelerator Division, Environment, Safety & Health, etc.).

• The CM is the DB/DBB Subcontractor’s field point of contact (POC).

• The CM is also the POC for the F&O operations technicians (electricians, mechanics, instrumentation/controls) involved in the power outages.

Facilities & Operations (F&O) Electrical Engineering SME

• Responsible for notifying Subproject 1 Manager and the Outage & Downtime Plan Advisor of technical changes impacting the existing electrical system.

• Reviews Switching Orders and Electrical Work Plans.

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• The F&O Electrical Lead is the top of the line management responsible for the training and safety compliance within the electrical department.

• The F&O Electrical Lead coordinates with the CAM and CUIR Outage and Downtime Plan Advisor.

F&O Electrical Operations Subject Matter Expert

• Reviews and advises on the SLAC power outage plan schedule, durations, impacts, and changes.

• Responsible for writing the electrical work plan package for switching operations for the power outages. The packages are submitted to the F&O Operations Manager or F&O Director for review and approval.

• Coordinates with the CUIR Outage and Downtime Plan Advisor, CM, and F&O High Voltage Supervisor to ensure the SLAC power outage plan is executable.

F&O Electrical High Voltage Supervisor

• Responsible for the safe execution of LOTO, COHE, and switching operations performed by the SLAC electrical technicians.

• Assign the F&O electrical high voltage team to work closely with the DB/DBB Subcontractor for the LOTO, COHE, and switching activities.

• Coordinates with the F&O Electrical Operations Engineer, CM, and DB/DBB Subcontractor’s electrical foreman for pre-power outage preparations, generator temporary power activities, switching/LOTO/ZVV activities, and re-energization activities.

Area Manager Program Facilities Manager Laboratory Stakeholders

• Review this plan to ensure the proposed CUIR power outage activities are aligned with the needs and schedule of the affected facility and programs.

• Provide technical and operational information and feedback to the CUIR Outage and Downtime Plan Advisor on future revisions to this plan.

• Responsible for preserving the beam downtime identified in this plan and informing the CUIR Outage and Downtime Plan Advisor immediately of any changes to the beam downtime.

• Additionally, Area Managers have the responsibility and authority to:

o Release SLAC workers within their areas o Release Subcontractor work within their areas to the

CM; the CM then releases the Subcontractor to work

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Deputy Chief Operating Officer • Establish Long Down Time (LDT) power outage requests and data intake schedule

• Collaborate with Project Downtime & Outage Scheduler to identify power outage impacts to programs or projects

• Coordinate with F&O Electrical Engineering SME and F&O Electrical Operations SME to verify power outages duration, switching orders, and temporary power needs.

Project Downtime & Outage Scheduler (Lab wide)

• Responsible for facilitating and aiding in the coordination of planned power outages within accelerator downtime periods, verified by Deputy Chief Operating Officer, and potentially impacted systems and buildings.

• Holds weekly meetings to communicate planned downtime activities, including utility outages and accelerator status.

Subcontractor for Packages A, B, C, D, and E

The Subcontractors are responsible for the development of the design and construction schedules, which demonstrate alignment with the CUIR power outage windows and downtime schedules.

Their schedules and planning activities for each scope shall include:

• Identification of constraints and/or constructability issues

• Coordination activities with CUIR CAM and CM assigned to construction activities happening at the same time.

• Participation in LOTO and COHE processes

• Preparation of WPC and execution of work

• Temporary power diesel generators

• Assumptions

4 Power Outages and Downtime Alignment The SLAC Science Program Downtimes and Infrastructure Power Outages are planned well in advance.

SLAC is committed to the Department of Energy to provide a specific number of operating hours of beamtime each fiscal year. The Downtimes are carefully planned for non-operation. Subcontractors’ work scope must align with pre-set downtime windows and power outages durations to avoid impacts to beam operating schedules. See Section 6.3, Risks and Consequences.

Beyond April of 2027, the beam downtimes are assumed to follow a typical and recurring pattern. Review and coordination between SLAC and Subcontractors will take place to continue planning in these out years.

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Figure 1. Summary Schedule of SP1 power outages and alignment across Linac downtimes

The next sections provide details of the scopes of work in SP1 and their power outage plans. The work scopes are not necessarily in the order of execution.

4.1 Linac Power Distribution System Improvements (Package A)

Figure 2. Roof-mounted 12kV Medium Voltage Cables and rooftop supports and cable trays extending from Sectors 1 to 30

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Figure 3. Rooftop Cable Tray Supports – Seismic and Gravity

4.1.1 Assumptions

The 12kV feeder supports, cable trays, and cables will be installed on the roof of the Klystron Gallery.

This work is assumed to occur while the accelerator is running and beam operation is on in Sectors 10-

30. Seismic and gravity supports of the cable tray will be prefabricated off-site and brought to SLAC for installation following inspection. The Subcontractor will then install the seismic and gravity supports in the field.

For Package A scope, the construction work is assumed to be performed 8 hr/day, 5 days/week, with a minimum of 2 crews working concurrently. The actual construction work duration will be dependent on the Subcontractor’s means and methods; however, we assumed that the schedule duration presented in this plan is adequate for the Subcontractor to complete the planned scope.

Cryoplants' warmup time will be from January 2026 to January 2027. Installation of the two (2) new CUIR cables at the 905S substation serving the Cryoplants must be connected within this warmup time to provide alternative power during the Cryoplant warmup time.

Two (2) additional CUIR cables, CUIR 3 & 4, will be tied into existing KSubstations KCT1, K4, K3, K2, and S519 after installation of the roof cable trays. In the event that the KSubstations are not ready for tie-in during the July to August power outage, additional 12.47kV planned outages are required to complete the cable to substation tie-ins.

4.1.2 Anticipated Workflow and its Duration

The following work activities have been identified as able to occur prior to the outage window:

Prepare generators, containment, cables and protectors, delineators and barriers for temporary power

• Construction work to begin in November 2025, after approval of design.

• Installation of supports cable tray and cables on roof

• Installation of tap boxes and tees in tap boxes The following work activities have been identified as occurring during a power outage:

• Connect temporary power

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• Make up of connectors in vault and terminations to existing SWGR in B016 and to 905S

• Inspections, testing, readiness review, and energization of new cables

• Remove temporary power The following work activities have been identified as able to be completed before the CuRF Linac downtime window in 2026:

Excavation for vault and trench ways at Sectors 29-30 to B016 and the future expansion (see 4.2) The duration of work activities to complete the 12kV feeders and pathways is estimated to be 6 months.

4.1.3 Power Outage Window Dates for Linac Power Distribution System Improvements (Package A)

Activity Start End Duration

(workdays M-F)

Installation and termination of new CUIR1 and CUIR2 cables at the 905S substation

July 2026 July 2026 15

Installation and termination of CUIR1, CUIR2, CUIR3 and CUIR4 cables at existing Switchgear in the original B016

July 2026 July 2026 15

Temporary Power Generators:

- Set up two weeks in advance of outage

- Remove within one week of completion of work

Scope: 12.47kV Feeders & Pathways

Generator # Location Substation/ Equipment

Generator KVA Actual

Size Request

KW

A 1 B002 Sec 4 North 905S 400 320

A 2 B905 Sec 4 B905-

4MTS-1001

300 240

A 3 B016 Existing Switchgear

300 240

A 4 B016A New Switchgear

300 240

Temporary power estimated generator locations, load, and sizing

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4.1.4 Impacted Science Programs

The power outage listed in Section 4.1.3 is expected to impact the following science programs:

• Cryoplants 1 or 2. It should be noted that one Cryoplant can remain in operation during the cable tie-ins at 905S, and also during the permanent switchover to the new MSS switchgear

• Next Linear Collider Test Accelerator (NLCTA)

4.1.5 Impacted Operations

The power outage listed in Section 4.1.3 is expected to impact operations in the following manner:

• Existing switchgear operations in Master Substation Building 016 when new equipment is tied into each bus.

• To complete terminations of CUIR3 and CUIR4 at S519, K2, K3, K4, and KCT1, existing cables C1, C2, and C3 will need to be de-energized to disconnect and connect existing and new cables, respectively.

4.2 MSS Building Expansion (Package B)

The Package B MSS Building Expansion scope includes different activities that trigger separate outages.

The different activities are described in Sections 4.2.1, 4.2.2, and 4.2.3, which will be executed under one subcontract.

4.2.1 480V, 175kW Diesel Generator Relocation (Package B)

Figure 4. Master Substation Existing Generator Relocation

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4.2.1.1 Assumptions

The existing 175kW backup generator will require relocation prior to the start of Building 016 expansion.

The Subcontractor will coordinate with F&O to propose a suitable location to store the generator within the MSS yard.

4.2.1.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring prior to the power outage:

• Prepare generator, containment, cables and protectors, delineators and barriers for temporary power

The following work activities have been identified as occurring during the power outage:

• Connect temporary power

• Relocate and install the existing generator at the new location

• Remove temporary power The duration of work activities to complete the 175kW backup generator relocation is estimated to be 2 to 3 weeks.

4.2.1.3 Power Outage Window Dates for MSS 480V, 175kW Diesel Generator Relocation

Activity Start End Duration (workdays)

Cutover to install a temporary generator and disconnect 175kw backup generator

August 2026 August 2026 1

Cutover to remove temporary generator and reconnect 175kw backup generator

August 2026 August 2026 1

Scope:

MSS

Generator

Generator

Location Substation/ Equipment

Generator KVA Actual

Size Request KW

B 1 B016 SE side of building

Existing

ATS

220 175

Temporary power estimated generator locations, load, and sizing

4.2.1.4 Impacted Science programs

The power outage listed in Section 4.2.1.3 is expected to impact the following science programs:

• None anticipated

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4.2.1.5 Impacted Operations

The power outage listed in Section 4.2.1.3 is expected to impact operations in the following manner:

• In the event of a power outage to the MSS B016 while the generator is disconnected and prior to temporary power being in place, there would be loss of breaker controls in the MSS. Power may not be readily restored.

• Short outages (<1 day) to transfer load from existing generator to temporary generator and back.

4.2.2 K15B Demolition and Replacement (Package B)

Figure 5. Master Substation K15B removal and replacement

4.2.2.1 Assumptions

Substation K15B feeds a Motor Control Center (MCC) that powers several loads. It is anticipated that a SLAC portable substation (Government Furnished Property) will be used to provide temporary power for the MCC and its loads.

4.2.2.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring prior to the power outage:

• Obtain temporary power portable substation for existing Motor Control Center load

• Prepare portable substation, cables and protectors, delineators, and barriers for temporary power

The following work activities have been identified as occurring during the power outage:

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• Connect temporary power

• De-energization and disconnection of existing K15B substation

• Remove K15B

• Construct MSS B016 expansion

• Install new MSS Switchgear Install new B016S Substation to replace the removed Substation K-15B

• Terminate B016S Substation feeders to new MSS Switchgear upon its commissioning

• Transfer of Motor Control Center to new B016S Substation

• Remove temporary power

• Energize B016S Substation and Motor Control Center The duration of work activities to complete the K15B substation replacement is estimated to span 13 months while awaiting the building expansion, switchgear, and B016S installations.

4.2.2.3 Power Outage window Dates for K15B Demolition and Replacement

Activity Start End Duration (workdays)

Cutover to install Temporary power for MCC and place MCC on P-Sub (portable substation) or to alternate 480V source (TBD by SLAC)

July 2026 July 2026 1

Cutover to connect MCC to new switchgear in expansion and remove P-Sub or alternate 480V source (TBD by

SLAC)

August 2027 August 2027 1 existing K15B

Portable Substation* (P-Sub)

Location Substation/Equipment P-Sub

KVA

Actual

Duration

B 1 B016 North parking

Existing MCC 300 13 months

*Portable Substation is SLAC Government Furnished Property (GFP) DB Subcontractor shall connect as temporary power equipment

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4.2.2.4 Impacted Science programs

• None anticipated.

4.2.2.5 Impacted Operations

The power outage listed in Section 4.2.2.3 is expected to impact operations in the following Building 016 Expansion (Package B)

Figure 6. Master Substation Medium Voltage Switchgear in B016 Expansion

4.2.3.1 Assumptions

The new MSS Switchgear will be installed after the MSS Building 016 expansion is substantially completed to set the gear inside.

Buildings B308 and B311 are assumed to be removed by SLAC prior to the start of the DB Subcontractor’s construction activities in the MSS. This removal activity is off-project and not within CUIR’s scope.

4.2.3.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring during a power outage:

• Installation of new switchgear terminations to the existing system The following work activities have been identified as occurring during the Linac downtime:

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• Grading and excavation activities for the MSS B016 expansion The following work activities have been identified as occurring outside of the actual power outages once the MCC is on temporary power:

• Construction of the expansion building

• Installation of the MSS Switchgear and the B016S substation will occur after substantial completion of the expansion building

• Complete terminations of B016S feeder to the new MSS Switchgear

• Complete terminations of the new CUIR cables to the new MSS Switchgear (See 12kV feeder and pathway for outage schedule to transfer new CUIR cables to the new switchgear)

The duration of work activities to complete the Building Expansion is estimated to be 9 months.

The duration of work activities to complete the MSS Switchgear installation and commissioning is estimated to be an additional 3 months.

4.2.3.3 Power Outage window Dates for MSS Medium Voltage Switchgear installation in Building 016 Expansion

Activity Start End Duration (workdays)

Power outage for tie-ins of new Switchgear to buses 1&2, when operating on one HV transformer

July

July

Reconfiguration of the CUIR1, CUIR2, CUIR3, and CUIR4 cables in the vault to transfer the cables to their new source at the new Switchgear in the B016 expansion

October 2027 October 2027 10

Switchgear

Generator

Location Substation/ Equipment

Generator KVA Actual

Size Request KW

B 1 MSS Yard New Switchgear

400 320

Temporary power estimated generator locations, load, and sizing

4.2.3.4 Impacted Science Programs

The power outage listed in Section 4.2.3.3 is expected to impact the following science programs:

• None anticipated

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4.2.3.5 Impacted Operations

The power outage listed in Section 4.2.3.3 is expected to impact operations in the following manner:

• A bus outage will be needed for each Bus 1 and Bus 2. The outage will impact the bus, not the transformers. The transformers will remain energized.

4.3 230kV Transformer Replacement (Package C)

Figure 7. Master Substation HV Transformers

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Figure 8. Incoming 230kV lines to transformers T1 and T2

4.3.1 Assumptions

The main transformers, T1 and T2 in the MSS, step down the incoming 230kV to 12.47kV. These transformers will be replaced one at a time. The Laboratory will be powered by a single transformer during each replacement execution. The single transformer operation scenario is expected to be approximately 12-months long during the replacement of each transformer.

A portion of work can be performed for the replacement while the 230kV is energized. Depending on how the Subcontractor executes the work, the 230kV may be required to be shut down with a need to transfer to the 60kV source. Coordination and planning in advance with PG&E is required.

While on the 60kV system, the lab will coordinate with science programs on priority of site wide power.

The power will be limited to 17.5MV. Should the Cryoplants be required to be in operation, only one Cryoplant, but not two Cryoplants, can be in use.

The transformer replacement work is not dependent on the 12-month downtime as shown in Figure 1.

4.3.2 Anticipated Workflow and its Duration

T2 is deemed to be in better condition than T1. Therefore, SLAC prefers, and plans, to have T1 replaced first. 230kV outages to the site are expected for each transformer’s demolition phase.

The following work activities have been identified as occurring during a power outage:

• De-energize T1 and its controls sources (battery, pneumatic, hydraulic, etc.), determine/disconnect/safe-off

• Transformer T1 disassembly and removal

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• Preparation of pad/site for new transformer

• Transporting new transformer and setting it in place

If it is required to additionally safe-off T2 incoming lines, the additional steps are:

• Transfer loads to the 60kV source

• De-energize and remove T2 incoming lines from breaker to T2

• Reconnection of 230kV lines to T2, following removal of existing T1 and setting of new T1

• Inspections and re-energization authorization of 230kV lines to T2

• Re-energization of 230kV lines to T2

• Transfer of loads to T2

• PG&E coordination as required

For the Transformer T2 replacement, the DB Subcontractor will evaluate their means and methods and work plans. If the 230kV breaker and auxiliary equipment (PTs/CTs, etc.) in front of T2 are required to be temporarily removed and put back in service, this task will be incorporated into their plan as part of the work.

The duration of work activities to replace one transformer (prefer replacement of T1 first) is estimated to be 12 months. Similarly, the same estimate of 12 months is anticipated for the second transformer (planned to be T2). The replacements will be executed in series.

4.3.3 Power Outage Window Dates for 230kV Transformer Replacements

Activity Start End Duration (workdays)

Shutdown of 230kV power to disconnect and remove cables for adequate clearance to remove the first transformer being replaced and set new transformer

October 2027 November

(1 continuous month)

Shutdown of 230kV power to disconnect and remove cables for adequate clearance to remove the second transformer being replaced and set new transformer

November

December

(1 continuous month)

If both T1 and T2 230kV are de-energized, a transfer of site load to the 60kV line is required, limited to 17.5MW

October 2027 November

November December

2-3 days to transfer each way

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4.3.4 Impacted Science programs

The power outage listed in Section 4.3.3 is expected to impact the following science programs:

During each transformer replacement, the lab will be put on 60kV power line. When on the 60kV system, senior lab management will determine the critical loads and curtailment of SLAC loads.

• Outages are planned for the 230kV power to be de-energized. Transfer to the 60kV system will impact all science programs. Science programs' priority would need to be coordinated within the lab leadership.

4.3.5 Impacted Operations

The power outage listed in Section 4.3.3 is expected to impact operations in the following manner:

• Depending on how the DB Subcontractor performs the removal and setting activities, the site may be required to transfer to the back-up 60kV system for one-month periods.

• The 60kV system limits the SLAC site to 17.5MW of power distribution capacity.

4.4 K-5B Substation Installation & Sector 4 Switchgear Installation (Package D) The Package D K-5B Substation Installation & Sector 4 Switchgear Installation package includes different activities that will occur within the same pre-coordinated outage window. Package D scope presented in Sections 4.4.1 and 4.4.2 will be executed under one subcontract.

4.4.1 K-5B Substation Installation

Figure 9. New Substation K-5B at Sector 9

Package D, New K-5B Substation, is to be completed in four construction phases:

• The first construction phase (K-5B phase 1) includes all trenching work required to provide vaults and conduits to MHE-05 re-configuration. It is assumed that this work to be completed without a power outage or science downtime.

• The second construction phase (K-5B phase 2) will be aligned with the 3 Linacs downtime from July 2026 to August 2026 and during the Cryoplant warm up period. During this time, certain existing equipment fed from the cables in MHE-05 may be switched to an alternate feeder to provide general power to Sectors 19 to 30 continuously.

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• The third construction phase (K-5B Phase 3) will be road widening, underground utilities diversion, and installation of a concrete pad. This phase is assumed to be completed without a power outage or science downtime.

• The fourth and final construction phase (K-5B phase 4) to install the K-5B transformer and low voltage switchgear GFP (Government Furnished Property) is assumed to be completed without a power outage or science downtime to complete.

4.4.1.1 Assumptions

• The civil work planned for all phases of the project is assumed to be completed without a power outage or science downtime.

• All trenching work required to provide vault and conduits to MHE-5 re-configuration is assumed this work to be completed without a power outage or science downtime.

• Road widening, underground utilities diversion, and installation of a concrete pad are assumed to be completed without a power outage or science downtime.

• To stay within a 4 week outage schedule, the following Extended Work Hours Alternatives are planned *

A. 10 hr/day, M to Sa => 20 work days with 10% reduced productivity => 22 work days [7/6/2026 to 7/30/2026, 4 weeks]

B. 12 hrs/day, M to Sa => 17 work days with 20% reduced productivity => 21 work days [7/6/2026 to 7/29/2026, 4 weeks] *Assume needed SLAC resources are available to support planned schedule *The original schedule was based on 8hr/day, M to F, => 25 work days

4.4.1.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring prior to the power outage:

• Prepare generators, containment, cables, protectors, delineation, and barriers for temporary power

• Excavate for and install vault and conduit/chase to K05SF6SW The following work activities have been identified as occurring during a power outage:

• De-energize MHE5

• Connect temporary power

• Install new cable and tap boxes

• Remove unused spare cables from K05SF6SW to MHE5

• Perform inspections, testing, and readiness review presentation for re-energization authorization

• Re-energization Removal of temporary power will occur when re-energization is complete.

The duration of work activities to complete the K-5B phase 1 is estimated to be 4 weeks.

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The K-5B phases 3 and 4 installation work can be performed outside of the power outage. The K-5B concrete pad and its containment, the transformer and low voltage switchgear equipment installation, and installation of 90% of its feeder can occur outside the power outage.

The duration of work activities to complete K-5B phase 2 is estimated to be 5 months.

4.4.1.3 Power Outage Window Dates for K-5B Substation (Package D)

Activity Start End Duration

(workdays M-F)

Installation of cable; cable removal in manhole

July 2026

August 2026

Temporary Power Generators:

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K-5B &

S4

SWGR

Generator # Location Substation/ Equipment

Generator KVA Actual

Size Request

KW

D 1 B002 Sec 1 North K1E 125 100

D 2 B002 Sec 1 South K1-A&B 220 175

D 3 B002 Sec 3,4; Door 3-5 K2 125 100

D 4 B905 Sec 4 905S 400 320

D 5 B905 Sec 4 B905-4MTS-

300 240

D 6 B002 Sec 5,6; Door 5-5 K3 300 240

D 7 B002 Sec 7,8; Door 7-5 K4 220 175

D 8 B002 Sec 8 Door 8-5 KCT1 CT1201 220 175

D 9 B002 Sec 9,10; Door 9-5 K5 220 175

D 10 B002 Sec 9,10; Door 9-5 K5A 240 200

D 11 B002 Sec 11,12; Door 11-5 K6 220 175

D 12 B002 Sec 13,14; Door 13-5 K7 220 175

D 13 B002 Sec 15,16; Door 15-5 K8 220 175

D 14 B002 Sec 17,18; Door 17-5 K9 300 240

Temporary power estimated generator locations, load, and sizing

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4.4.1.4 Impacted Science programs

The power outage listed in Section 4.4.1.3 is expected to occur between Sectors 0 to 18 and impacts the following science programs:

• LCLS-II

• FACET-II

Cryoplants 1 & 2

• S10 Laser Facilities

• Master Oscillator Timing system (LCLS I would be down if Timing system is down or on temporary power).

• RF Hut

• LCLS-II-HE installation

• Next Linear Collider Test Accelerator (NLCTA)

4.4.1.5 Impacted Operations

The power outage listed in Section 4.4.1.3 is expected to impact operations in the following manner:

• No power for power outlets and lighting for the Klystron Gallery, Accelerator Housing and Injector, and the S10 Laser Facility

• Power off for 12kV cables C1, C2, C3, VV1, VV2 and VV4 which result in impacts to equipment at Substations K6, K7, K8, K9, K5, K5A, K2, K3, K4, S519 (K1A/B, K1C, K1D, K1E), KCT1, and Variable Voltage Supply Substations VVS5 and VVS10

• KSubs and VVSs from Sectors 21-30 will be powered from either their normal or alternate C cable/VV Cable.

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4.4.2 Sector 4 Switchgear Installation (Package D)

Figure 10. Sector 4 Pad-mounted Switchgear location

The Sector 4 switchgear installation period will be performed during the WarmLinac downtimes from July 2026 to August 2026 and the Cryoplant warm up period. The work is to be completed in two construction phases:

• The first construction phase (S4SG phase 1) includes all trenching work required to provide vaults and conduits to MHE-02 re-configuration, in addition to installation of the new S4 Switchgear GFP (Government Furnished Property). It is assumed that this work to be completed without a power outage or science downtime.

• The second construction phase (S4SG phase 2) will be aligned with the 3 Linacs downtime from July 2026 to August 2026 and during the Cryoplant warm up period. During this time, certain existing equipment fed from the cables in MHE-02 may be switched to an alternate feeder to provide general power to Sectors 19 to 30 continuously.

4.4.2.1 Assumptions

• The civil work planned for all phases of the project is assumed to be completed without a power outage or science downtime.

• To stay within a 4 week outage schedule, the following Extended Work Hours Alternatives are planned *

A. 10 hr/day, M to Sa => 20 work days with 10% reduced productivity => 22 work days [7/6/2026 to 7/30/2026, 4 weeks]

B. 12 hrs/day, M to Sa => 17 days with 20% reduced productivity => 21 work days [7/6/2026 to 7/29/2026, 4 weeks]

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*Assume needed SLAC resources are available to support planned schedule *The original schedule was based on 8hr/day, M to F, => 25 work days

4.4.2.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring outside of the actual power outage:

• Prepare portable substation, cables and protectors, delineators and barriers for temporary power for Sectors 0-18 (Same temporary power outage as the K-5B scope in Section 4.1)

• Prepare site pad and switchgear installation work, including excavation for ductbank and vault The following work activities have been identified as occurring during a power outage:

• De-energize manhole circuits

• Connect temporary power

• Reconfigure cables in manhole

• Inspections, testing, readiness review, and re-energization

• Remove temporary power The duration of work activities to complete the Sector 4 pad-mount switchgear is estimated to be 4 months.

4.4.2.3 Power Outage Window Dates for Sector 4 Medium Voltage Switchgear

Activity Start End Duration (workdays)

Installation of pad-mount SWGR, conduit, cable; cable reconfiguration in manhole

July 2026

August 2026

Temporary Power Generators:

- Set up two weeks in advance of outage

- Remove within one week of completion of work

- See section 4.4.1.3 for generator list

4.4.2.4 Impacted Science programs

The power outage listed in Section 4.4.2.3 is expected to occur between Sectors 0 to 18 and impact the following science programs:

• LCLS-II

• FACET-II

• Cryoplants 1 & 2

• S10 Laser Facilities

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• Master Oscillator Timing system (LCLS I would be down if Timing system is down or on temporary power)

• RF Hut

• LCLS-II-HE installation

• Next Linear Collider Test Accelerator (NLCTA)

4.4.2.5 Impacted Operations

The power outage listed in Section 4.4.2.3 is expected to impact operations in the following manner:

• No power for power outlets and lighting for the Klystron Gallery, Accelerator Housing and Injector, and the S10 Laser Facility

• Power off for 12kV cables C1, C2, C3, VV1, VV2, VV4, which result in impacts to equipment at Substations K6, K7, K8, K9, K5, K5A, K2, K3, K4, S519 (K1A/B, K1C, K1D, K1E), KCT1, and Variable Voltage Supply Substations VVS5 and VVS10

• KSubs and VVSs from Sectors 21-30 will be powered from either their normal or alternate C cable/VV Cable.

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4.5 IR12 SCADA Hardware (Substation 726) (Package E)

Figure 11. New SCADA hardware installation at IR12 (Substation 726)

4.5.1 Assumptions

The Subcontract will be awarded prior to the October to November 2026 planned power outage.

The current configuration of 12.47kV service feeders to Substation 726 will not change prior to and during execution of Package E.

4.5.2 Anticipated Workflow and its Duration

The following work activities have been identified as occurring prior to the power outage:

• Receive new switchgear door panels with SCADA electrical protection and control hardware pre-installed

• Prepare portable substation, cables and protectors, delineators and barriers for temporary power

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Figure 12. Simple single line schematic of Substation 726

The following work activities have been identified as occurring during the power outage:

• De-energize Substation

• Connect temporary power

• Remove existing doors and equipment

• Install new doors, hardware, and connect devices

• Inspections, testing, readiness review, and re-energization

• Remove temporary power Bus 1 de-energization will remove power from IR4 and 6 for approximately 1.5 weeks.

Bus 2 de-energization will remove power from IR4 and IR6, and all other loads on Bus 2 for approximately

1.5 weeks. This work scope includes the tie-breaker device.

The duration of work activities to complete the SCADA Hardware installation is estimated to be 3 months (Includes pre-construction, construction, commissioning, and Transition to Operations).

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4.5.3 Power Outage window Dates for IR12 SCADA Hardware (Substation 726)

Activity Start End Duration (workdays)

Power outage for installation of devices in doors of existing switchgear

October 2026 November 2026 15

Temporary Power Generators:

SCADA

Generator

Location Substation/Equipment Generator KVA Actual

Size Request

KW

E 1 IR12 B725 high bay and lift stations 220 175

E 7 IR12 B726M mech pad 125 100

E 2 IR12 for the North Arc

B726 125 100

E 3 B901 901S 220 175

E 4 North Campus Sewer Main Sand Hill Road 31 25

E 5 IR4 Substation B646 220 175

E 6 IR6 Substation B666 220 175

E 8 IR10 Panelboard 31 25

4.5.4 Impacted Science programs

The power outage listed in Section 4.5.3 is expected to impact the following science programs:

• LCLS personel at B901

• LCLS-II-HE cryomodule storage IR12, IR4, and IR6

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4.5.5 Impacted Operations

The power outage listed in Section 4.5.3 is expected to impact operations in the following manner:

• PEP areas - IR12 and IR10

• Alpine Gate

• Sewer meter for main sewage leaving site - Sand Hill Road

• B901 (HVAC curtailment), B901 Security Gate

• IR4 B640

• IR4 and IR6 Substations

• N. Arc area

• B720 Storm water & Sewer lift stations

5 Temporary Power Unless backup power systems are installed by SLAC before execution of the CUIR Subproject 1 construction packages, the CUIR Subcontractor will provide temporary power for the identified outages:

Package A - Refer to Section 4.1.3 Package B – Refer to Sections 4.2.1.3, 4.2.2.3, and 4.2.3.3 Package C - Refer to section 4.3.3 Package D - Refer to Sections 4.4.1.3 and 4.4.2.3 Package E - Refer to Section 4.5.3

Portable diesel generators and their required incidentals for reliable performance shall be provided.

These generators will support critical loads at designated areas approved by SLAC. Temporary generator needs generally include the following:

• Both the Klystron Gallery (above grade structure) and Accelerator Housing (tunnel below) require general purpose receptacle power and lighting for the outage duration; critical load requirements to be determined through area managers and stakeholders for generator sizing

• Sector 0-30, 3 Injector Guns (LCLS II, FACET II & LCLS I), Cryoplants 1&2 (905S), and Cryomodules (S0-7 K1-K4) will provide critical systems power requirements to determine load requirements for generator sizing

• Generator power will be provided for each K-Sub K1-A/B, K1E, K2, 905S, B905-4MTS-1001, K3, K4, KCT1, K5, K5A, K6, K7, K8, K9, at the Master Substation and for the PEP areas affected by the SCADA work

• Generators shall operate on a 24/7 schedule

• Generators will be located on the north side of the Gallery with proper containment, delineation, and barriers

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• Generators shall be provided with maintenance service history logs to ensure that they have been maintained and serviced at regular intervals and in good working condition. Generators that are shown to have problems or poor performance will not be accepted by the Subcontractor to be brought to SLAC.

• SLAC stakeholders should expect planned generator outages for scheduled maintenance of generators. The DB/DBB Subcontractor will provide this maintenance schedule when the generators have been identified and dispatched to SLAC, and in advance of any maintenance activities.

• A failed generator is expected to be replaced with an onsite spare within 1-2 hours

• Replace spares put into service with another delivered to site within 24 hours

• Provide a schedule and documentation of fuel and operational checks to be performed 3 times a day in a checklist or a form acceptable to the project

• A schedule of fueling the generators and adding high-quality Diesel Exhaust Fluid (DEF) is required to be submitted. The schedule shall show this activity twice a day at 12 hour intervals

• Provide 600V rated cabling from generator to KSub secondary main, including protective coverings and supports across Gallery openings

• For estimated generator locations, loads, and sizing, see tables in sections 4.1.3, 4.2.1.3, 4.2.2.3, 4.2.3.3, 4.3.3, 4.4.1.3, 4.4.2.3, and 4.5.3

• The generators shall arrive two weeks in advance of the start of the power outages, to prepare for their mobilization, containment, cables and cable protection, delineators, inspections, and readiness for connection and operation

6 Planned Power Outage Windows

6.1 Schedule

The Subcontractor is responsible for providing look-ahead schedules and progress reports. The power outage work plan should include mitigations to ensure the outage schedule and window durations will be maintained, without reducing safety or quality.

6.2 Communication Plan

As a best practice, the Subcontractor will hold daily meetings between their Superintendents and CUIR’s CAM, CM, and Outage & Downtime Plan Advisor for a status discussion – what was completed that day per the plan, what was not, and what is planned for the next day. Close and frequent communication and field observations will enable the Subcontractor and CUIR teams to understand if the work is on time and as scheduled. Good communication will also tell if the activity is ahead of schedule or slipping. The team is expected to work collaboratively to evaluate situations and events and identify if and what actions are required.

If a schedule slip occurs or appears to be on the verge of occurring, a watch mode or action mode would go into effect. The watch mode, being the schedule, has a simple recovery by the Subcontractor, where an action mode would be something more significant and higher risk of not completing work by the

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Document Number: CUIR-WPC-0114 Page 35 of 35 window date. The Subcontractor is responsible for informing the CAM and CM of schedule impacts. The CAM is responsible for informing the Project Manager and Project Director. The Project Manager will inform stakeholders, and the Project Director will inform Senior Lab Management. The Subcontractor is responsible for providing corrective actions and a recovery plan.

6.3 Risks and Consequences

The Subcontractors will identify and provide risk mitigation plans to stay within the available power outage windows.

Missing or exceeding planned power outage windows is unacceptable for the lab and greatly impacts science missions. Subsequent outage windows may not be available due to accelerator operations, and beamtime with users is planned two to three years in advance. Subcontractor will bear the risk of construction schedule delays when planned outage windows cannot be utilized.

7 Emergency Response In the event of an emergency during outage work, the Subcontractor will follow their documented safety procedures and policies. The Subcontractor will immediately communicate to the Construction Manager the emergency. SLAC protocols for emergency response are then initiated.

8 References

• SLAC ES&H Manual

• SLAC ES&H Manual Chapter 42 Subcontractor Safety

• SLAC ES&H Manual Chapter 51 Control of Hazardous Energy

• SLAC Enhanced Rigor Work Planning and Controls RN-2021-001-R0