The site plan for Costco, a members-only big box retail store proposed on nearly 21 acres north of Northeast 36th Street and east of Interstate Highway 35 in Ankeny, was approved Wednesday by Ankeny’s Plan and Zoning Commission. While the site plan does not require any other city approvals, construction of the 198,250-square-foot facility likely won’t begin until sometime in 2022. Infrastructure, including sewers and streets, must be installed at the site and, pending approval of the City Council, that work likely won’t begin until spring 2022, according to a city spokesperson. Costco’s plans include construction of a warehouse retail store, tire center and a distribution center, the company’s first in the Midwest, according to a city document. A free-standing fuel facility is also planned. The project is planned in a development called Spectrum 36, a 125-acre area east of Interstate 35 and north of N.E. 36th Street that is expected to include commercial and multifamily developments.