ROY — Hill Air Force Base has — for now — settled on one developer with which to negotiate how the estimated $500 million first phase of a 550-acre commercial and retail development on the base will unfold along the east side of I-15.

Bruce Evans, Hill's enhanced use lease program manager, said he hopes that within the next four to six months Hill will sign a master lease agreement with developer Sunset Ridge Development Partners LLC, with construction to begin sometime after that.

"This does not mean we have chosen the permanent developer — we hope it does," Evans said Friday during a press conference inside the Air Force Museum near the base.

Sunset's partners include Utah-based Woodbury Corp., Hunt ELP Ltd. of Texas and California-based Flintridge Partners LLC. Sunset was chosen from a group of 10 companies that last March answered Hill's request for qualifications.

Sunset now enters what Hill officials call "exclusive negotiations" with the base on how the private company will finance, plan, design, construct and operate the development.

"Over time we will work out all those details," Evans said.

The developer will own the structures it builds, but will lease the land underneath from Hill.

"Our goal here is to fulfill the needs of the Air Force," said Jeffrey Woodbury, vice president of development and acquisitions for Woodbury Corp. in Salt Lake City.

Hill officials say they need about 1.3 million square feet of inefficient, dilapidated, World War II-era office space replaced, which the developer agrees to do as part of an in-kind payment to Hill. It's unknown how much Hill expects to make from lease revenue over the span of the agreed-upon maximum 50-year lease on what it calls "underutilized military land."

The goal for the Air Force and its developer is to create one giant technology office park that would serve government and commercial interests. Hotels, restaurants and retail space also may become part of the development, which in its first phase includes between 100 and 150 acres of land.

Evans made it clear that this latest development is separate from the estimated $105 million housing project being headed by the private Boyer Hill Military Housing. Boyer's plan is to tear down 469 old units to make way for new housing, parks and open space. More than 200 existing homes have been renovated so far.