The first major development proposed for Block 57, a 20-story office and retail center in the ailing heart of downtown Salt Lake City, was unveiled Thursday before the Salt Lake Redevelopment Agency.

The Roger Boyer Co., a Salt Lake developer, wants to build a 350,000-square-foot, $40 million high-rise in the northwest corner of the block where the former J.C. Penney Co. Inc. building now stands.The City Council, which doubles as the Redevelopment Agency, was expected to meet Friday to consider providing a $4.3 million tax break, which Roger Boyer said his company must have to complete the project.

Boyer, who addressed the RDA for his company, is also requesting a 3 1/2-year option to buy another slice of Block 57, as well as 390 costly parking stalls to be built by the city, before he breaks ground on the project.

Block 57 has been the center of private and public efforts to resuscitate a downtown deemed "stagnant" by the Regional Urban Design Assistance Team, a group of planners who visited last month to study the city's business district.

The RDA was expected to meet in an emergency session to consider Boyer's proposal because he said his option to buy the land for the high-rise from Morris Pacific Co. ends Aug. 1.

RDA Executive Director Michael R. Chitwood called the plan for Block 57, bound by State and Main streets and Second and Third South, a significant proposal.

"It is an important development because not only is it the first development on the block, but it is also in the very best location on Block 57," he said, adding the northwest corner is closest to the most vital sector of downtown.

The high-rise would include retail and financial service storefronts at street level and office space above, Boyer said. That configuration is consistent with R/UDAT recommendations.

A 3,000-square-foot plaza would mark the outside entrance to the building, he said. Inside, Boyer plans a glass atrium.

The proposal could mark the beginning of the rebirth of the deteriorated block, plagued by run-down and abandoned buildings.

But Boyer, evoking language used by R/UDAT, said a single development would not be the savior of the block.

"No single project would bring the block back," but the high-rise would be a "stimulus" for the rest of the central business district, he said.

But the proposal comes with a high cost to the city. Boyer is requesting "three items to stimulate economic justification for the proj-ect." They include the $4.3 million tax increment, the parking stalls and the option to buy additional land.

Under the proposal, the Boyer Co. must get a $4.3 million tax return over the next 23 years, a plan known as a tax increment, which returns the difference in property taxes paid on a property's present and future value over an established length of time.

Boyer says he needs the tax break, in effect an 11 percent subsidy of the building's $40 million cost, because office space in downtown Salt Lake City is leasing for a paltry $10 per square foot.

In addition, the city must build 390 parking spaces which Boyer will lease for $50 monthly.

Under the city's master plan, parking spaces on Block 57 must be built underground, an expensive process, Chitwood told the RDA. Underground parking costs $6,000 to $8,000 a stall, while above-ground parking stalls cost $1,500 to $5,000 each, he said.

Finally, Boyer wants a 3 1/2-year option to buy RDA land on the northeast corner of the block, where a parking lot now stands, to begin the second phase of his plan. RDA policy won't permit exclusive options, Chitwood said, unless the agency is willing to amend the policy.

The proposal was first formally broached before council members Thursday although a city official said Boyer had approached some council members during the plan's developmental stages. The proposal met with mixed reactions.

Councilwoman Florence Bittner said Boyer's request for the 31/2-year option amounted to a "blank check," while Council Chairman Tom Godfrey said the exclusive option is contrary to the city's downtown master plan.

Councilwoman Sydney Fonnesbeck said the city had never granted such a hefty tax increment and wondered "how much we want to support the project."

Councilwoman Roselyn Kirk supported the plan. "Based on the fact he (Boyer) is willing to take a risk . . . we should be willing to give it a go," she said.