WEST VALLEY CITY — The largest metropolitan landholding by a single owner in the United States lies mostly undeveloped along the Salt Lake Valley's west bench, and its owners now have a final plan for what they want to do with it.

The last of four summits was held Wednesday at the E Center to develop a master plan for the 75,000 acres of Salt Lake County land owned by the Kennecott Land Co. along the Oquirrh foothills.

Planner Peter Calthorpe of Calthorpe Associates, the company designing Kennecott Land's plan, unveiled the company's updated vision, which would include all sizes of commercial and retail centers, housing from dense urban centers to spread-out foothill neighborhoods, a university campus, parks, community centers and possibly a ski resort.

It would all be tied together by a "transit spine," ultimately connecting current light-rail lines to a new north-south line running the length of the west bench development, from the Davis County line to the Utah County line. And, one day, the area is expected to be home to a half-million new Wasatch Front residents.

"We trusted that you'd help us make the plan better — and you did," Kennecott Land vice president for long-range planning Jim Schulte told summit participants Wednesday.

The summits have been part of Kennecott Land's unique planning process. Typically, developers and landowners develop an idea of what they want their land to become, plotting out subdivisions and strip malls and industrial sites. Then, they approach city and county governments seeking zoning changes and permits.

But Kennecott Land, through the Salt Lake County Council of Governments, has been working with stakeholders — from city and county leaders and planners to public utilities to environmentalists to regional planning groups — to create a collaborative master plan first. The first summit, held in September, introduced the participants to Kennecott's ideas for the land — walkable communities built on environmentally sound principles focusing on diverse housing and well-planned commercial development — and gathered preliminary input. A draft of the plan was presented in October, and a few weeks later, participants gathered again to give their detailed feedback.

That feedback led to the final plan presented Wednesday. Calthorpe incorporated more east-west transportation, plotted out locations for parks, schools and trails and made other changes based on the suggestions.

The plan calls for an urban center off I-80 north of Magna. From that center, transit and roads would flow toward Kennecott Land's Daybreak community, already under construction in South Jordan. Along that spine would lie smaller clusters of development — "town centers," "village centers" and "neighborhood centers." Most of the development would be centered there, a corridor meandering roughly along an 8400 West alignment.