The future Cascade Park, as portrayed by the city's Department of Planning and Development

Just hours before a scheduled public hearing on a planned upzone in South Lake Union, where Paul Allen's Vulcan development company owns about a third of the land, city planners laid out a Vulcan-backed proposal aimed at appeasing opponents of the upzone who say it doesn't include enough affordable housing and other incentives in exchange for the extra height Vulcan is getting. 

The upzone (which is controversial for the usual other reasons, including concerns about shadows and view blockage), would allow buildings as tall as 400 feet on the south end of the neighborhood, scaling back to upper limits of 240 feet along the water.

Those heights are much taller than the underlying zoning allows; to get them, Vulcan (or any developer) has to provide "incentives," in the form of payments for affordable housing, child care, forest land purchases, and other local infrastructure like transportation improvements. 

Vulcan is proposing to hand over to the city a 37,000-square-foot block of land, known as "Block 59," in exchange for the ability to build taller than the current city zoning code allows; the city would vacate another 17,000 square feet of space on Broad Street to create a full block for development.

The idea is that instead of putting money into an affordable housing fund to be used later, and possibly in a different neighborhood, the South Lake Union land could be turned into as many as 400 units of affordable and moderate-income housing immediately, with—according to the proposed agreement with the city—child care facilities, nonprofit office space, and a community garden.

" There's a significant additional public benefit attached to" the proposal, city planning director Marshall Foster said. "That opportunity was to work with the major land owner here, Vulcan, to identify a site where we could move forward ... to integrate and create affordable and workforce housing in the neighborhood. ... Having a site where the city could work creatively to bring that kind of partnership together was kind of a once in a lifetime opportunity."

In exchange, the city would give Vulcan up to $16 million in incentive zoning credits ($15.15 per gross square foot for an initial height increase already included in an earlier upzone proposal, plus an additiona. $12.90 per gross square foot for the additional height increase that's being proposed now), allowing the company to build taller buildings on land it owns throughout the neighborhood. 

City Planning Director Marshall Foster compared the $16 million to a "Starbucks card" that Vulcan could use at any Vulcan-owned site it wants, as long as it doesn't run out of development credits. "They would like to be able to use that prepaid bank on any site they own in the neighborhood," Foster said. 

Overall, the city's comprehensive plan calls for as many as 12,000 new housing units, including about 1,765 that are affordable to people making up to 50 percent of King County's median income, and about 1,500 affordable to people making up to 80 percent of the county median, in the area; however, city council member Nick Licata estimated that the proposal would only add about 300 affordable units.

The agreement does not include a specific number of affordable units. Foster says the city expects that about 37 percent of units in the neighborhood, overall, will be affordable to people making up to 80 percent of median, with some of those affordable to those making up to 50 percent. UPDATE: Per commenter request, a table of "affordable" rents by income level, household size, and apartment size in King County is here.

The council is holding a public hearing on the proposed upzone and land swap tonight at 5:30, in council chambers (600 4th Ave.); you can also watch online at the council's web site.