The plant's first life began with urgency. In 1942, with the United States fully committed to World War II, the War Department contracted Alcoa to build an aluminum reduction plant on farmland near Riverbank in Stanislaus County. Aluminum was the essential material of aerial warfare, light enough for airframes and strong enough to hold together at combat speeds. The Riverbank facility produced 48,000 tons of aluminum per year, translating to 96 million pounds annually, feeding the factories that built the bombers, fighters, and transport aircraft that carried the war across two oceans. By August 1944, with Allied victory in sight and aluminum stockpiles sufficient, the plant closed. It had operated for just two years, but in that span it had contributed a significant share of the metal that kept American air power in the sky.

Seven years of silence ended in 1951 when the Korean War brought the plant back to life, this time under a different mandate. The Army converted the aluminum smelter into a munitions factory, and Riverbank became the largest producer of steel cartridge cases in the United States. The conversion reflected a shift in what modern warfare demanded: not raw materials for aircraft, but finished ammunition in quantities that staggered the imagination. Production continued through the Korean War and into the tense early years of the Cold War, the plant running until 1958. When it shut down again, the facility sat idle for nearly a decade, its massive buildings and rail infrastructure waiting for the next conflict to justify reopening the doors.

That conflict arrived in 1966. The escalation of American involvement in Vietnam created enormous demand for mortar shells and artillery projectiles, and Riverbank was reactivated to meet it. For fifteen years the plant manufactured the ordnance that defined the ground war in Southeast Asia, its production lines turning out shells that would be loaded onto cargo ships, transported across the Pacific, and fired from firebases and forward operating positions in jungles half a world away. The plant remained in production until 1981, well after the fall of Saigon, continuing to build stockpiles for a military that was recalibrating after withdrawal. When the lines finally stopped, the Riverbank Army Ammunition Plant had been activated and deactivated three times across three wars, each cycle leaving behind more industrial infrastructure and more environmental damage.

Decades of heavy manufacturing left more than empty buildings. Groundwater and soil across the site were contaminated with heavy metals, a legacy that earned the Riverbank plant a place on the EPA's National Priorities List as a Superfund site. More than $72 million in federal funding has been directed toward cleanup, remediation, and monitoring since decommissioning. In 2005, the Base Realignment and Closure Commission recommended the facility's official closure, with its remaining functions transferred to Rock Island Arsenal in Illinois. The Riverbank Local Redevelopment Authority took over in 2010, and the site's future began to take an unexpected shape. Aemetis, a renewable fuels company, signed on to develop the 125-acre complex into a sustainable aviation fuel and renewable diesel production facility. The plan calls for roughly $500 million in investment, a 90-million-gallon annual production capacity, and more than 650 permanent jobs. The plant's existing infrastructure, including 710,000 square feet of buildings, a four-mile railroad loop, and an onsite hydroelectric substation powered by low-carbon hydroelectric energy, made the conversion feasible. A factory built to fuel one kind of flight may yet fuel another.