A large turnout is expected at Thursday night's public hearing on proposed construction of an interchange on U.S. 89 at Hill Field Road - a project estimated to cost $10 million that will require demolition of nine homes and a dairy outlet.

The hearing, to be conducted by the Utah Department of Transportation, is set for 7:30 p.m. Thursday, Feb. 28, in the Layton High School auditorium.UDOT is proposing to build a diamond-shape interchange and additional access roads around the intersection. It is not directly connected to a long-range improvement plan for U.S. 89 but is considered a first step in that direction.

The intersection handles heavy commuter traffic of Hill Air Force Base workers in the morning and afternoon. It is one of the busiest intersections in Davis County, according to UDOT traffic surveys.

Two interchanges were designed by UDOT engineers, one a three-tiered direct connection structure and the diamond-shape interchange, which UDOT is backing.

The first would require demolition of two additional homes and is considered less safe by UDOT engineers, in addition to costing about $3 million more.

The UDOT-endorsed interchange includes four access ramps, an overpass over U.S. 89, one traffic signal and two service roads. It is the construction of the service roads that requires demolition of the homes and the dairy store, according to UDOT plans.

According to UDOT, an environmental impact study shows only minor adverse effects on air and water quality, noise pollution and nearby wetlands. The impacts, engineers say, can by mitigated.

If approved, UDOT will ask for bids on the project late this summer with construction beginning in 1992.