WEST VALLEY CITY — As the owners of 75,000 acres of Salt Lake County land along the Oquirrh foothills work toward a plan that could one day bring a half-million new residents to the Salt Lake Valley, county and city planners, government leaders and others are throwing in their two cents' worth.

At the third of four west-bench planning summits at the E Center on Wednesday, participants representing the many players who will ultimately be involved in the plan gave input, asked questions and raised concerns about Kennecott Land's master plan for the west bench, which was announced in its tentative form at a summit earlier this month.

Kennecott Land President Peter McMahon called Wednesday's summit "the most important of these four sessions. It's when we get to hear from you because we need to hear from you."

At the last summit, shortly after the plan was revealed to them, summit participants filled out a survey ranking and rating the issues they consider most important in the planning process. At the top of their list were public transit, environment and parks and open space. Lower on the list were such questions as who would have jurisdiction and provide services to the new developments and what role community and cultural resources such as libraries and health-care facilities would play.

Ranked as their top spending priority was economic development, followed closely by roadways and public transit.

"Obviously there may be a message here: There's a connection between transportation and jobs," county planner David White said.

The plan would focus on two urban centers — areas of about 1 million square feet of retail space mixed with some residential and office space — connected by a "transit spine" running parallel to the Oquirrh Mountains, along U-111 in some areas.

The two urban centers would be at Kennecott Land's new Daybreak community in South Jordan and another at the far northern end of the company's land holdings, west of Magna along I-80.

Kennecott Land owns 93,000 acres of undeveloped land, a holdout from Kennecott Utah Copper's mining operations, in and near the Oquirrhs, with 75,000 of those acres lying within Salt Lake County. That land is seen by many planners as the nexus of future growth in the valley.

The summits, organized by the county's Council of Governments, bring together mayors and planners from cities throughout the county, Kennecott officials, representatives of the Wasatch Front Regional Council, Utah Transit Authority and Utah Department of Transportation planners, lawmakers, environmental groups and others.