This week, the developers behind an already-approved office tower at 110 N. Wacker filed a zoning amendment to increase the size of the building by 100,000 square feet. If approved by the City of Chicago, the measure would grow the total floor space of the 52-story Bank of America-anchored skyscraper to a maximum of 1.6 million square feet.

The latest application also confirms a redesign by Chicago architect Goettsch Partners. The move will see the glassy riverfront skyscraper ditch its previous three-setback layout for a beefier—and arguably less elegant—two-tier design.

The change will help accommodate the requested increase in square footage while retaining the tower’s previously approved height of 800 feet. The building’s serrated western facade—designed to maximize views up and down the Chicago River—and its waterfront riverwalk will remain as previously shown.

Developed as a joint venture between Texas-based Howard Hughes Company and Chicago’s Riverside Investment and Development, 110 N. Wacker has been proposed to replace the low-rise General Growth Building. The team was hoping to begin work on the new tower as early as next month.

A potential wrench was thrown into the mix this winter when the federal government launched what is called a Section 106 Historic Property Review to consider any “adverse effects” the new development would have on the existing General Growth property. The review was triggered after it was determined that the midcentury building met some of the criteria for historic preservation.

The extra layer of federal oversight will inform the U.S. Army Corps of Engineers’ decision to approve a permit required for the 110 N. Wacker’s stormwater outfall structure to flow into the jurisdictional waters of the Chicago River. According to a report by the Chicago Tribune, the developers and the Army Corps of Engineers will meet today to discuss the matter.