Urban Transmission Upgrade Strengthens Grid Capacity

Metropolitan Seattle is growing, and reliable electrical infrastructure is essential to supporting residents, businesses, and the region's innovation economy. To meet increasing energy demand, Puget Sound Energy (PSE) launched Energize Eastside, a major transmission infrastructure program designed to improve system capacity, reliability and resiliency across the area. HDR partnered with PSE to provide permitting support, geographic information system (GIS) services, and construction compliance monitoring throughout the project's planning, design and implementation phases. 

Adding power capacity in a densely developed area that’s rich with environmental and community resources presented significant challenges. To minimize impacts, PSE upgraded the existing 115-kilovolt (kV) transmission corridor to a higher-capacity 230-kV system and added the Richards Creek Substation, enabling the expanded transmission network to serve more customers while maintaining the existing corridor. Our multidisciplinary team supported local, state and federal permitting efforts across multiple jurisdictions, helping streamline approvals and maintain project momentum.

Integrating Stream Restoration and Utility Infrastructure

As part of the broader Energize Eastside program, we partnered with PSE to develop a long-term solution addressing flooding and environmental challenges associated with Willows Creek and the Sammamish Substation. Decades of sediment accumulation caused by landslide activity in the upper watershed had filled portions of the Willows Creek channel, redirecting stormwater into nearby Ryan's Creek and contributing to recurring flooding concerns for adjacent properties. We evaluated multiple alternatives to restore the creek's natural function while balancing the needs of PSE, the City of Redmond and local stakeholders.

As engineering and environmental studies progressed, the effort evolved into a complex, multidisciplinary project that extended beyond traditional stream restoration. We worked closely with PSE to design a new alignment for Willows Creek through a highly constrained utility corridor with multiple transmission lines serving the Sammamish Substation. The team identified transmission structures requiring relocation or replacement to create a viable stream corridor and coordinated restoration activities with other major utility infrastructure improvements occurring in the area. Access to transmission and substation infrastructure was carefully designed to facilitate operations and maintenance throughout the project's life without impacting stream and riparian areas.  

The resulting plan delivers significant environmental and community benefits, including a mile-long salmon-bearing stream restoration, replacement of an undersized and sediment-clogged culvert, and wetland mitigation for the Energize Eastside project that supports broader regional infrastructure investments. By integrating ecological restoration with utility corridor planning and transmission system improvements, we helped develop a solution that advances flood resilience, enhances aquatic habitat and improves long-term environmental outcomes.

Permitting, GIS and Construction Support

Throughout the years-long permitting process, our environmental specialists prepared local permit applications for five jurisdictions, including Renton, Newcastle, King County, Bellevue and Redmond, as well as numerous state and federal agencies. Coordinated delivery across multiple technical disciplines enabled PSE to present comprehensive permit packages and efficiently address agency comments and requirements.

Our GIS professionals supported the program from initial planning through final permitting, producing high-quality mapping exhibits and implementing automated data-management workflows. Automating production, data management and cartographic standards helped PSE quickly address jurisdictional needs and design changes by efficiently incorporating changes, and producing quality maps that include design elements, survey details, utilities and sensitive areas.

To help maintain construction schedules and compliance, our construction monitoring team served as a critical link between project planning and field implementation. Regular coordination with contractors, proactive technical discussions and detailed reporting helped PSE meet key milestones, navigate permitting requirements and avoid potential construction challenges. 

Lasting Benefits for the Puget Sound Region

Now operational, the Energize Eastside Transmission Corridor provides increased electrical capacity and reliability for PSE customers while supporting long-term regional growth. Complementary environmental initiatives, including the Willows Creek restoration project, demonstrate how utility infrastructure improvements can be integrated with flood mitigation, habitat enhancement and community priorities to create resilient, sustainable solutions that benefit both people and the environment.