Minneapolis-based Roers Investments, the developers who teamed up with apartment management czar Harry Bookey on the 211-unit Confluence on Third multifamily project in downtown Des Moines, is planning a five-story, mixed-use building at 1400 Walnut St. The Des Moines Plan and Zoning Commission will review site plans for the project when it meets Nov. 17. Walnut Apartments would include 90 residential units, 2,450 square feet of first-floor retail and office space, and 49 spaces of below-grade parking, according to a summary of the project on the Plan and Zoning agenda. The site currently is occupied by Gifford Brown Inc., which manufactures wire assemblies, multiconductor cable assemblies and printed circuit boards. Roers Investments is seeking vacation of surface, subsurface and air rights to accommodate features of the new building. Roers also is in the planning stages of a mixed-use project at 2301 Ingersoll Ave.