A state agency has decided to give the public an early look at tentative proposals from two developers competing to build a 650-foot residential tower in Kakaako that would soar above Honolulu’s tallest existing buildings.

The Hawaii Community Development Authority asked developers Lend Lease and Forest City Enterprises Inc. to post limited elements of their proposals online at hcda-public-consultation.org.

The competing plans call for between roughly 800 and 1,000 residential units in one or two towers on 2 acres of state-owned land bordered by Keawe Street, Pohukaina Street and Mother Waldron Park.

HCDA sought tower proposals for the project dubbed 690 Pohu­kaina in January under an initiative Gov. Neil Abercrombie announced a year ago to produce urban housing for moderate-income workers.

Producing a building about 250 feet higher than presently allowed should make it easier for a developer to deliver more affordable housing because of the economy of scale, according to HCDA.

The agency received bids in August from Australia-based Lend Lease and Ohio-based Forest City, and has tasked its board of directors to choose a plan with which to proceed.

A board vote is scheduled for Dec. 13, after each developer presents their plan at a Nov. 20 HCDA meeting.

However, details of each developer’s plan could be changed before best-and-final offers are due Nov. 16.

The tentative Lend Lease plan calls for 1,002 residential units in two towers — one rising 650 feet and one rising 400 feet.

About half the units would be reserved for people or families earning between 100 percent and 140 percent of Honolulu’s median income.

The upper end of the income limit equates to $79,970 for a single person or $114,240 for a family of four.

Based on that, maximum unit sale prices would be just under $400,000 for one person or a bit over $550,000 for a family of four. Maximum monthly rental rates would be about $2,000 for a studio to about $3,000 for a three-bedroom unit.

Part of the evaluation by HCDA will be how competitive the developers are on unit affordability.

The information posted for Lend Lease did not specify whether the units would be for sale or rent. Lend Lease would not provide any details beyond what was posted in accordance with an HCDA request.

Lend Lease also plans to provide state office space, community space and retail space in the project. The developer also plans to rehabilitate historic elements of Mother Waldron Park and relocate its basketball and volleyball courts. A development cost was not disclosed.

Lend Lease anticipates it would finish the smaller tower with 397 units by March 2016, and the larger tower with 605 units by October 2018 if market conditions are favorable.

Lend Lease said its two towers would produce a visual landmark in Honolulu along the lines of what Aloha Tower represented when the clock tower at Honolulu Harbor was the city’s tallest building.

The towers also could serve as a reference point indicating where one of the city’s planned rail stations will be if the transit project is realized.

"Creating a residential sub-community of 2,000 residents near the proposed Halekauwila transit station will create a vibrancy that has been missing for decades since the time the area was an authentic residential neighborhood," Lend Lease said in its conceptual plan.

The conceptual plan from Forest City includes one 650-foot tower with 804 units, about half of which would meet HCDA workforce housing income limits. However, the developer submitted three tower design options. The other options feature the same number of units in a pair of towers that rise up to 560 feet or 400 feet.

All of Forest City’s planned units would be rentals. "We’re really focused on the workforce housing," Jon Wallenstrom, a Forest City development official in Hawaii, said in an interview. "It’s important to bring significant workforce housing into the core of Honolulu."

Other elements of Forest City’s plan — including development cost, unit rents, delivery timetable and the amount of commercial, community and state office space — were not disclosed.

Last month, HCDA said it would not publicly disclose any proposal details until developers presented their plans at a public meeting before the board.

HCDA is accepting public comments on the plans on its website.

After HCDA’s board makes its selection, it would be up to agency staff to negotiate a detailed development agreement with the winning developer.

Negotiations could take eight months, HCDA estimates. After an agreement is approved, it could take a little more than two years to complete design and permitting work, which includes an environmental impact statement and amending the building height limit in Kakaako. If all is approved, HCDA estimates construction might begin as early as mid-2016, with completion three years after that.