WHAT: 12-branch Vancouver-based credit union with 71,700 members.ASSETS: $816 million.FOUNDED: 1952.LOOKING AHEAD: Has submitted plans to construct a 20,000-square-foot addition to its operation center at 200 S.E. Park Plaza Drive, Vancouver.ONLINE: Columbia Credit UnionVancouver-based Columbia Credit Union has submitted a request to construct a second office building at its main operation center off Southeast Mill Plain Boulevard.The proposal is for a 20,000-square-foot, two-story structure located just north of the site’s existing 33,000-square-foot building at 200 Park Plaza Drive. The center is located on 2.7 acres about one block north of Mill Plain at Southeast 131st Avenue, next to Columbia Credit Union’s Cascade Park branch.Reasons behind the proposal were unclear on Monday, as credit union officials were not available by phone or email.Columbia Credit Union operates 12 branches in Clark County, including nine Vancouver branches and one each in Ridgefield, Washougal and Battle Ground.In 2003, Columbia Credit Union moved some of its services out of the operation site in east Vancouver, transferring personnel and services to a fifth-floor office space in downtown Vancouver. At the time, the credit union leased 20,000 square feet in the Murdock Building at 703 Broadway. That move transferred about 30 employees, including business banking staff and mortgage and trust services.The move relocated Columbia’s downtown branch to the first floor of the Murdock Building. The relocation was prompted by the credit union’s sale of its former downtown branch property — at 503 W. Sixth St. — to Columbian Publisher Scott Campbell, who bought the site to build a new office building for the newspaper. The building constructed by The Columbian is now Vancouver City Hall.Credit union leaders said in 2003 that it was important the organization maintain a downtown presence. They had also considered adding 20,000 square feet of space to the east Vancouver site.