Two huge regional hospitals in northern Colorado — Longmont United Hospital and Poudre Valley Health System in Fort Collins — said Monday that they will jointly build a medical campus for underserved southwest Weld County. The 70-acre complex is planned for the northeast corner of Interstate 25 and Colorado 52 in Frederick. "The campus will fill a need for convenient medical services that have been absent in our area," said Mayor Eric Doering. "Our area will also benefit from new job opportunities and economic growth." A site master plan for the campus will be under development until late fall. The campus size and cost have not been determined, said Longmont United spokeswoman Karen Logan. The first building to go up is expected to be an urgent care center, followed by other medical buildings. Mitchell Carson, Longmont United's president and chief executive, said rapid growth in southwest Weld demanded that a high-quality medical facility be developed there.