Polk County supervisors gave final approval today to a property exchange that will provide a partial solution for the space-challenged courthouse and set in motion a new phase of downtown redevelopment.

The deal was approved by unanimous vote and will result in the transfer of the abandoned Polk County Convention Complex to Wellmark Inc., which has agreed to sell the property to the YMCA of Greater Des Moines. The YMCA plans a $22.5 million renovation and construction project for the center.

Polk County’s tab for the transfer of the convention center is $500,000. It will receive the former J.C. Penney’s building at 222 Fifth Ave. from Wellmark. In addition, the supervisors approved spending $1 million toward the demolition of the downtown Riverfront YMCA, where city leaders have high hopes for future development.

Supervisors credited Greater Des Moines businessmen Bill Knapp and Jim Cownie with setting the deal in motion. They also were behind the creation of Des Moines Redevelopment Co., a nonprofit organization of businesses and business leaders who have agreed to guarantee development loans. The group so far has the ability to borrow up to $9 million.

Des Moines Redevelopment has purchased land near the Iowa Events Center where it hopes a conventional hotel will be constructed.  On Monday, the group launched its search for a developer for a 450-room, four-star hotel and convention center.

Meanwhile, real estate documents on the Polk County land deal with Wellmark could be filed in the next few days and some court functions and the Polk County attorney’s office could move into the former J.C. Penney’s building by the end of the year.

Renovation on converting the former convention complex into a YMCA, including construction of an Olympic-size pool, could be completed by January 2015. A local contractor has been selected to lead the project.