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Transmission Infrastructure Program

The interconnection process

There are eight steps in the interconnection process. Western may modify this process based on specific circumstances of the requested interconnection.

Step 1: Contact Western and submit application

Step 2: System impact study

Step 3: Facilities study and design

Step 4: Environmental review

Step 5: Land acquisition

Step 6: Design and construction

Step 7: Review and testing, interconnection agreement, and energize

Step 8: Project close-out

Step 1: Contact Western and submit application

Before submitting an application, discuss the proposed project with a representative at the Western office that controls the area in which the interconnection will occur. It helps us determine what studies are necessary.

Generally, the requesting entity should register with the appropriate reliability council before requesting interconnection with Western. After initial contact, Western will provide interconnection related information, including the Application for Interconnection, the Tariff if applicable, Western's applicable General Power Contract Provisions and other supporting safety, environmental and operations information.

Requesters should submit formal requests for interconnection at least 18 months before equipment or construction specifications are to be issued for bid. This lead time allows Western to develop a proposed plan, designs and specifications for Western-owned, -operated and -maintained facilities, and to review line taps owned by others.

Western may take up to 30 days to process the interconnections request.

If Western denies the request for interconnection, we will provide a summary of reasons and make every reasonable effort to help the requesting entity revise the request.

Submit Application

Provide as much of the following information as possible to help expedite the design or review process. This information is also listed in summary form on the Application for Interconnection.

  • Single-line diagram(s) showing the proposed interconnection, including any relaying and metering facilities.
  • Drawing(s) indicating the physical arrangements of existing and proposed facilities.
  • Geographic location of the proposed interconnection, including land ownership pattern, if available. If a tap, indicate adjacent structure numbers.
  • Description of the proposed routing, approximate lengths and conductor size of transmission line additions or modifications, and dimensions and configurations of new structures.
  • Description and ratings of any proposed breakers, switches, metering, associated communications, relaying and other related equipment.
  • Description of transformer voltage and rating, winding connections, impedance if available, and proposed method of protection.
  • Proposed construction schedule.
  • Description of the generating resources or loads to be served by the interconnection and the proposed transmission path(s) and service arrangements between resources and associated loads, where applicable. The description should include:
    • Power output or load requirements, including 10-year projections, by delivery points, of winter and summer peaks for loads served or generation supplied through the point of interconnection;
    • Size, type and ratings of large equipment;
    • Reliability and special operation requirements; and
    • Impedance, frequency, voltage, reactive power and protective relaying characteristics of the interconnecting resource or load.
  • Appropriate revenue and telemetering equipment specifications. The data should include load control boundary metering, current and potential transformer ratios and register and contact initiator ratios with multipliers.
  • Copies of relevant planning or operational studies.
  • Copies of relevant environmental impact assessments, reports, or projections; or description of anticipated scope of environmental review

Step 2: System impact study

Western will conduct a system impact study that assesses the capability of the transmission system to support the requested interconnection. The study will use the criteria and process detailed in Sections 4 and 5 of Western's Federal Energy Regulatory Commission Form 715 (available upon request) when the request occurs in the WECC area, and use the MAPP system impact study methodology (available upon request) when the request occurs in the MAPP area.

Within 30 days of receiving the application for interconnection, Western will provide a System Impact Study Agreement in which the requesting entity agrees to advance funds for Western to perform the study. The requesting entity must sign and return the agreement to Western within 15 days or the request is deemed withdrawn.

Western will make every effort to complete the system impact study within 60 days. The study will identify system constraints and redispatch options and any necessary additional direct assignment facilities and network upgrades.

Once the system impact study is complete, Western will provide the requesting entity with a report.

Within 30 days after receiving the results of the system impact study, an entity requesting both interconnection and transmission service may request to enter into an Expedited Service Agreement. This agreement specifies advance compensation requirements. The Expedited Service Agreement provides one contractual agreement for the full interconnection process, from facilities study to operation and maintenance, including transmission service.

Western will provide the requesting entity its best estimate of new facility costs and other charges, but the estimate is not binding. For further information, refer to Section 19.8 of the Tariff, or contact the appropriate Western office.

Step 3: Facilities study and design

The facilities study determines upgrades or modifications needed at the point of interconnection. Within 30 days after Western completes the system impact study, we will provide a Facilities Study Agreement in which the requesting entity agrees to advance funds for Western to perform the study. The requesting entity must sign and return the agreement to Western within 15 days or the request is deemed withdrawn.

Western will make every effort to complete the facilities study within 60 days. The study includes estimates of the cost of facilities design and construction as well as the time required to complete design and construction. We will provide a facilities study to the requesting entity for review.

Step 4: Environmental review

As a Federal agency, Western conducts an environmental review of any action affecting Western's transmission facilities. The environmental review process can range from a categorical exclusion to a comprehensive environmental impact statement complete with the required public process and is conducted simultaneously with other studies.

Requesting entities must advance funds to Western for the environmental review process. The environmental review process uses input from the studies and construction planning processes and may be concluded before or after completion of these technical studies, when applicable. Continuation of the interconnection process at any and every step is contingent upon favorable environmental review.

If the environmental review shows that the interconnection does not satisfy Federal environmental criteria, Western will either deny the request or work with the requesting entity to revise aspects of the interconnection request to meet environmental criteria. Such revisions may occur at various steps during the process.

Step 5: Land acquisition

After the environmental process, negotiations for any necessary land rights begin. Negotiations should be complete and the land rights obtained before construction begins. Requesting entities must advance funds for Western to conduct the necessary land acquisition activities. Western will, unless otherwise agreed to by Western and the requesting entity, perform all land acquisition activities.

Step 6: Design and construction

Once the facilities study is complete, Western will tender a Construction Agreement to the requesting entity, which has 30 days to sign and return the agreements to Western and provide advance payment. Western cannot continue without funding in place. Western will design the interconnection, unless otherwise agreed to by Western and the requesting entity. Western will also, unless otherwise agreed to by Western and the requesting entity, perform all construction.

Step 7: Review and testing, interconnection agreement, and energize

Once construction has been completed - and before energizing the new interconnection - Western will review and test the new facilities. Before energizing, Western must also receive the appropriate as-built drawings, operating instructions and other relevant materials.

When the facilities are found to be in conformance with Western's criteria, we will issue an Interconnection Agreement to the interconnecting entity. The Interconnection Agreement - also termed mutual services, operations and maintenance, control area, or consolidated agreement in some regions - provides for the long-term operation and maintenance of the interconnected facilities. It generally includes sections on licensing, maintenance, operations, special instructions and funding. When to the benefit of Western and the interconnecting entity, the Interconnection Agreement may be tendered at the same time as the earlier Construction Agreement.

The interconnected facilities may be energized following execution of the Interconnection Agreement. If Western does not maintain direct control of the facilities, then we will maintain backup control of all facilities deemed to be vital to system stability.

Step 8: Project close-out

Western will develop a final report with a list of lessons. We invite the interconnecting entity to join in developing a joint final report that benefits Western and the entity.