Colorado_Transformer_21_Regasket_SOW_6-3-2026.pdf

CITY OF PALO ALTO UTILITIES

Colorado Transformer 21 Re-Gasket | Statement of Work | Page 1

Statement of Work Colorado Transformer 21 Re-Gasket City of Palo Alto Utilities Department

Project Re Gasketing of Leaking Secondary Bushing Colorado Substation – Transformer 21

Reference SO#40031492 / EL-89044

Location Colorado Substation Fiscal Year 2026–2027

1. Introduction The City of Palo Alto Utilities Department requires a qualified contractor to perform the removal and replacement of gaskets on the three (3) LV and one (1) XO secondary bushings of Transformer 21 at the Colorado Substation. The selected contractor shall furnish all labor, supervision, tools, equipment, materials, oil processing equipment, oil storage tanker with containment berm, testing instruments, safety equipment, transportation, hauling, disposal, and incidentals necessary to complete secondary bushing re-gasketing work on Transformer 21 at Colorado Substation.

The work generally consists of pre-testing, partial draining and storage of non-PCB mineral oil, gasket replacement at the bushing flanges and any disturbed manways, pressure testing, oil processing and refill, post-testing, demobilization, and delivery of test and service documentation. The Transformer is an RTE-ASEA 10MVA, 60KV-12470/7200V, Year of manufacture 1976.

2. Objective The objective of this contract is to stop oil leakage and restore the integrity and service readiness of Transformer 21 at Colorado Substation in coordination with the City’s designated project manager.

The contractor shall perform the work in a safe, professional, and workmanlike manner and complete the re-gasketing in accordance with the approved scope, project schedule, applicable safety requirements, manufacturer recommendations, and accepted industry standards for utility transformer maintenance and testing.

Core Scope Elements

• Perform pre-maintenance electrical and oil testing on Transformer 21.

• Partially drain and store oil, ensuring windings remain fully submerged. Backfill headspace with dry air and maintain continuous dry air supply. Perform air quality monitoring to ensure safe oxygen levels during work.

• Remove and re-gasket three LV bushings and one XO bushing,

• Clean flange surfaces and replace gaskets on disturbed manways or access covers.

• Pressure test the repaired interfaces and process/refill the transformer oil.

• Perform post-maintenance testing and provide test reports, oil results, and service documentation.

3. General Work Scope Prior to commencement of field work, the contractor shall coordinate with the City to verify equipment identification, access route, staging area, outage conditions, work area constraints, and the proposed construction sequence. The contractor shall review visible site conditions and identify any access limitations, obstructions, or conflicts that may affect the work.

Upon authorization to proceed, the contractor shall provide a complete Transformer 21 secondary bushing re-gasketing service, including pre-testing, oil handling, dry-air support, confined-space entry support, removal and reinstallation of the identified bushings, gasket replacement, pressure testing, oil processing, post-testing, cleanup, demobilization, and closeout documentation.

The contractor shall plan and sequence the work to minimize disruption to utility operations, maintain safe conditions at all times, protect existing facilities from damage, and coordinate with the City for all outage and return-to-service activities.

Work will be conducted within an energized substation. Transformers will be de-energized individually, one at a time, as required to perform the work. The contractor shall be responsible for ensuring that a qualified individual is in charge of the work and that all employees are provided with and wear appropriate fire-resistant (FR) clothing with a minimum required rating of 8 cal/cm2

4. Requirements and Deliverables

A. Pre-Construction Coordination

• Coordinate a pre-job site visit and planning /outage coordination meeting with the City project manager.

• Verify transformer information, access conditions, staging area, and oil handling setup requirements.

• Confirm the proposed work sequence, anticipated duration, outage needs, staging approach, and equipment delivery plan.

• Identify constructability issues, including access constraints, visible obstructions, site safety considerations, or field conditions that may affect performance.

• Submit product data or cut sheets for gasket materials, oil processing equipment, and test equipment if requested by the City.

• Provide a proposed work schedule prior to mobilization.

B. Work Performance

Pre-Testing

• Provide all labor, supervision, tools, equipment, materials, hauling, and incidentals necessary to complete the work, including the oil processing unit, oil storage tanker with containment berm, portable restroom, diesel fuel for generator, oil sampling supplies, gasket materials, test equipment, safety equipment, confined-space entry support, and required PPE.

• Transformer turns ratio (TTR) test.

• Core and winding insulation resistance test.

• Bushing and winding power factor and capacitance test.

• Winding resistance with the as-found HV DETC position and LV tap in neutral.

• Perform oil quality testing on the main tank and tap changer oil, as applicable, including moisture content, dielectric breakdown in accordance with ASTM D1816-2, and with power factor at 100°C.

Scope

• Partially drain non-PCB mineral oil from the main tank, estimated at approximately 750 to 1,000 gallons, to a level below the side-mounted LV bushing compartment while ensuring the windings remain fully submerged, and store the oil in a contractor-provided tanker and maintain required containment and spill protection throughout the execution of the project.

• Backfill the transformer headspace with dry air, maintain a continuous dry-air supply, and perform air quality monitoring to verify safe oxygen levels during the work.

• Complete confined-space entry procedures and documentation required for internal access to the transformer.

• Remove three LV bushings and one XO bushing, clean flange surfaces, install new gaskets, reinstall the bushings, and properly seal all interfaces.

• Replace gaskets on any disturbed manways or access covers used during the maintenance work.

• Perform pressure testing to verify the integrity of the repair and confirm the absence of leaks.

Oil Processing and Refill

• Filter the oil from the storage tanker (Provided by contractor) and process the oil using vacuum dehydration and filtration to achieve acceptable moisture content and dielectric strength and refill the transformer.

• Circulate oil as required to ensure uniform quality throughout the main tank and LTC compartments, and perform final oil sampling and testing to confirm compliance with applicable standards.

Post-Testing

• Perform post-maintenance testing, including TTR, winding resistance, insulation resistance, and power factor and capacitance as applicable, and compare results to pre-test values to confirm no adverse changes.

• Remove temporary equipment, work zone protections, and contractor-generated materials from the site, and demobilize from the substation upon completion of the work.

• Participate in a final inspection with the City and correct punch-list items related to the contractor’s work.

C. Closeout Deliverables

• Written notice that the work is complete and ready for final inspection.

• Participate in final inspection with the City, address contractor-related punch-list items, demobilize from the site, and submit required service documentation.

• Final site cleanup and removal of contractor-generated waste, temporary equipment, and surplus materials.

• Pre-maintenance and post-maintenance electrical test reports.

• Oil sampling and analysis results, including oil processing records.

• Air Quality and humidly reports.

• Pictures of work and inside of tank for documentation of condition.

• Service documentation identifying maintenance performed, gasketed locations, leak-check results, the as-left tap position, and a final invoice identifying the project and work performed.

5. Project Delivery Schedule This work is required as soon as practicable during Fiscal Year 2026–2027. This work shall be scheduled during a City-approved outage window, to be arranged with contractor in advance. Prior to mobilization, the contractor shall submit a proposed work schedule showing anticipated start date, duration, major activities, and substantial completion date.

The contractor shall promptly notify the City project manager of any condition that may delay performance or affect the agreed schedule.

6. Contractor’s Place of Performance The work shall be performed at Colorado Substation within the City of Palo Alto Utilities service area.

7. Contractor’s Quality Assurance and Monitoring of Work Deliverables and Interim Products The contractor shall perform all work in a neat, safe, and workmanlike manner consistent with applicable laws, CAL/OSHA requirements, confined-space entry requirements, manufacturer recommendations, and accepted industry standards for utility transformer maintenance, oil processing, and electrical testing.

The contractor shall maintain regular communication with the City’s designated project manager regarding project status, schedule, field conditions, issues, and completion of deliverables. Work that does not conform to the approved scope or quality requirements shall be corrected by the contractor at no additional cost to the City unless the City has approved a change in writing.

8. Project-Related, Utility-Furnished Information and Documents Sharing The City will designate a project manager for this work and will provide available project information necessary for performance of the scope, including site access coordination, outage coordination, work area limits, and operational constraints applicable to the substation.

The contractor shall obtain the City project manager’s approval before implementing any substantive deviation from the approved scope, schedule, work sequence, or materials used for the repair.

9. Project Management and Contract Administration The City will designate a project manager to administer the contract. All project communications affecting scope, schedule, access, safety, outage coordination, or field conditions shall be directed through the City project manager.

The contractor shall not perform extra work outside the approved scope without prior written authorization from the City. Contract modifications and change orders, if required, shall be issued by the City’s authorized representative.

10. Basis of Payment The contract shall be administered on a fixed-price basis for the work described in this Statement of Work unless otherwise specified in the executed agreement.

The contractor’s compensation shall include all labor, materials, supervision, testing, oil handling and processing, temporary facilities, containment, equipment, mobilization, demobilization, hauling, disposal, cleanup, overhead, and incidentals required to complete the work in accordance with this Statement of Work.

11. City Responsibilities

• Designate a project manager.

• Provide site access consistent with utility operational and safety requirements.

• Coordinate switching or outage activities necessary for the work and disconnect, de-energize, isolate, and ground required equipment to establish a safe work area.

• Confirm transformer identification, work limits, and site-specific operational or safety restrictions applicable to work at the substation.

• Provide available record information regarding the transformers and associated facilities in the work area, if available.

• Perform final inspection of the completed work and remove grounds when the equipment is ready for return to service.

• Re-energize equipment following completion of the work and City acceptance.

12. Assumptions and Exclusions Unless specifically authorized in writing by the City, beyond gasket replacement at the specified bushings and disturbed access points;, the base scope does not include major internal transformer components, PCB abatement or disposal;

repairs arising from concealed damage or previously unknown equipment defects; permit fees or engineering calculations not otherwise required by the City; or extended standby time caused by conditions outside the contractor’s control.

Any concealed condition, field conflict, or materially changed equipment condition that affects the contractor’s ability to perform the work as scoped shall be promptly reported to the City project manager for direction before the affected work proceeds.

13. Contractor Qualifications The contractor shall maintain all licenses, registrations, and insurance required under California law and for work at a City utility facility, including a valid State of California Contractor’s License and DIR registration requirements.

The contractor’s personnel shall be qualified and experienced in utility transformer maintenance, oil processing, high-voltage electrical testing, and confined-space entry, and shall comply with all City site access, security, and safety requirements.

14. Acceptance This Statement of Work may be attached to and made part of the applicable purchase order or agreement for Colorado Transformer 21 Re-Gasket.