The enormous new proposed development on property partly owned by The San Francisco Chronicle, dubbed 5M (short for 5th and Mission) has the potential to be transformational for the section of SoMa around 5th and 6th Streets. The mixed-development, on lots surrounding the Chronicle building all the way to Howard Street, would bring with it something in the neighborhood of 700 new residences, as well as hundreds of thousands of square feet of office space and new retail. But if that sounds like a good thing to some, it has affordable housing advocates, and Supervisor Jane Kim's office, nervous about the future implications for the (albeit downtrodden) affordable housing stock along 6th Street. The residential hotels that account for the current character of the street are considered an important source of affordable housing, and the 5M project, it's feared, will "accelerate speculation" in the neighborhood, as the Business Times is reporting.

The developer, Forest City — the same developer working on the huge Pier 70 project — will be held to the one-third affordable housing threshold that was mandated by Prop K in November, but they are saying that building one third of the units as below-market-rate will mean that they need to construct more office space in order to balance the numbers — something that some neighbors do not want. But there are multiple options on the table to get to the 33 percent mark, including possibly refurbishing one of those 6th Street SROs, and partnering with the Tenderloin Neighborhood Development Corp. to build affordable housing off-site.

More clear details about the project won't be coming until later in the spring as most of this gets hashed out between the parties involved — including the exact numbers of units and office space square footage. Currently there are two "schemes" on the table, one of which is dominated by residential development with more open space, and one of which is more office-heavy, with less open space.

The project will likely go up for Planning approvals in May or June.

Previously: New 5M Development At 5th And Mission Hires American Architect Kohn Peterson Fox, Designs Look Rad