Kaiser Aluminum Corporation has completed a USD 25 million expansion at its Trentwood rolling mill in Spokane Valley, marking another step in the company’s two-decade-long investment programme at the site. The project follows a pause during the pandemic and brings the total investment in the plant to about USD 415 million since 2005.
The latest phase expands one of the mill’s heat-treating furnaces, increasing output by around 5 per cent, according to Kevin Barron, vice president of manufacturing. He described the project as an efficiency upgrade that keeps staffing steady at about 1,000 full-time employees.
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The work was carried out within the existing 65-acre facility, which sits on 565 acres of land bordered by the Spokane River, Sullivan Road, and Trent Avenue. It is the seventh stage of the company’s modernisation plan, aimed at maintaining competitiveness in aerospace and industrial markets.
Construction began in early August and was wrapped up late last month. Spokane-based Garco Construction served as the main contractor, while Power City Electric handled electrical and mechanical work. Equipment suppliers included Otto Junker USA of Ohio, SMS Equipment of Alberta, and Barnhart Crane & Rigging of Post Falls.
Barron said some of the equipment used in the expansion had been purchased before the COVID-19 outbreak, but had been stored until work could resume. Kaiser had paused capital projects during the pandemic after several years of steady investment at Trentwood.
Earlier, in 2015, the company announced a five-year, USD 150 million plan to boost capacity at the site, following USD 240 million in infrastructure upgrades between 2005 and 2015. Over the past 20 years, Kaiser’s investments have mainly focused on expanding heat-treating and material-stretching capabilities, along with improvements in rolling throughput, homogenising and casting operations.
Kaiser reported net sales of USD 844 million for the third quarter of 2025, up from USD 748 million a year earlier. Shares of Kaiser Aluminum (Nasdaq: KALU) closed at USD 93.31 on 3 November, compared with a 52-week high of USD 97.60 and a low of USD 46.80.
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Headquartered in Franklin, Tennessee, Kaiser Aluminum operates 13 production facilities across the United States and Canada. The Trentwood mill is one of three in the country producing heat-treated aerospace-grade aluminium and is the only such facility located west of the Mississippi River.
The Trentwood plant was originally built by the U.S. government after the 1941 attack on Pearl Harbor to streamline aluminium supply for wartime aircraft manufacturing, including the Boeing Company. Before being acquired by Henry J. Kaiser in 1949, it was operated by Alcoa.
Kaiser later renewed ties with Boeing, a relationship that continues today. In October, Boeing began a statewide aerospace supply chain tour at the Trentwood site to highlight the partnership and its role in Washington’s economy.
Barron said the event highlights aerospace’s importance to the state. Boeing estimates its annual economic impact in Washington at USD 19.5 billion, working with about 1,100 suppliers and supporting roughly 285,000 direct and indirect jobs. Nationally, Boeing says it contributes USD 97 billion to the U.S. economy and partners with nearly 10,000 businesses across all 50 states.
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