Denny Substation Project Overview
Investing in the transmission and distribution of electricity to maintain reliability and meet future needs
Power Planning Overview
For the past decade Seattle City Light has been analyzing how best to serve the emerging needs of the North Central Seattle area (South Lake Union, Uptown, Denny Triangle, and First Hill) plus our service territory north of the Ship Canal. Areas of analysis included:
- Customer reliability requirements
- Technical constraints of building an electrical distribution system
- Anticipated future growth
- System flexibility requirements
The North Central area is experiencing rapid growth as a result of the City of Seattle's efforts to create high-tech/professional jobs, add retail services, and grow the local economy. To ensure the long-term success of this redevelopment, the City of Seattle and its partners are making considerable investments to transportation, roads and storm water management. An upgrade of the electrical infrastructure is also needed to fulfill the City's vision for North Central neighborhoods.
The Denny Substation will be Seattle City Light's first new substation investment in nearly 30 years.
Based on City Light's analysis and work with current and potential new customers, an immediate need for a network distribution system supported by a new substation has been determined. This network and substation would provide the safest, most reliable, and cost effective way to meet emerging electrical load in the North Downtown areas and north of the Ship Canal. It would also provide the needed capacity and flexibility to manage load growth in other nearby urban centers by helping to alleviate electrical system congestion between the Broad, Canal, University and East Pine substations.
After a site selection analysis, in 2009 the Seattle City Council approved the purchase of three contiguous parcels of land at the corner of Denny Way and Stewart Street for development of the new Denny Substation. One of these parcels was the former Greyhound Bus maintenance shop (map of site
Denny Substation, Distribution, and Transmission Project ('Denny Substation Project') Scope
The Denny Substation Project involves the design and construction of a new substation, a transmission line to feed the substation; and, a network distribution system. If final approvals and permits are received, the project would be constructed in two phases between 2014 and 2020.
- Prior to the start of the facility design process, Seattle City Light began an environmental clean-up, including demolition of the former Greyhound Bus maintenance shop at the site. This work began in October 2012 and is on hiatus for the winter months. Work will resume in April 2013. More information about environmental clean-up is available here.
- Substation: The Denny Substation site is bordered by Denny Way, John Street, Minor Avenue, and Yale Avenue and consists of three parcels: the former Greyhound maintenance facility, the former City Investors Parcel, and a smaller parking lot east of the former Greyhound facility. Learn more about the Denny Substation.
- Transmission Line & Distribution System: The new transmission line will carry electricity to the new Denny Substation, and an underground distribution network will carry electricity from the substation to City Light customers. Underground distribution lines will be built in the South Lake Union and Denny Triangle neighborhoods. Learn more about the Transmission Line and Distribution System here.
Project Purpose and Benefits
- 2012 - 2014: Substation Site Clean-up, Design & Planning
- 2012 - 2014: SEPA Review
- 2014 - 2020: Construction of Substation, Distribution Network & Transmission Line
Electricity is an essential service. The availability of reliable electricity is key to our quality of life, paramount to economic vitality, and critical to public safety in our city and region. The Denny Substation will provide several benefits to the City of Seattle's electric system that include:
- Supporting current and future industries by increasing reliability with fewer power outages and service interruptions
- Meeting current and future energy needs north of the Ship Canal
- Improved electrical infrastructure will help draw new business, creating new jobs
The site acquisition and clean-up, SEPA review, design and construction of the Denny Substation Project is currently estimated to cost approximately $201.5 million. Funding comes from the utility's Capital Improvement Program.
City Light is committed to keeping the public and stakeholders informed about the project and encourages feedback. As the project proceeds, public engagement will take place frequently. We want to hear from you!
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Power Planning Continues
As part of our planning efforts, Seattle City Light has established a South Lake Union Network service area that will be served from the new Denny Substation. The Denny Substation Project will construct the initial portion of the network extending out from the new substation. The full build-out of that network will occur incrementally over time, as requested by individual customers.
Early planning for areas north of the Ship Canal indicates a need for an 115kV or 230kV transmission line to serve that area. The line would connect the Broad Substation to the Denny Substation, which will have the capacity to accommodate that connection if it is needed. However, City Light is further considering if and when such a line might be needed, and where the most logical route would be.