Work to replace a bridge in Ottumwa will start this week.  The bridge on Ward Street over the Jefferson Drainage Ditch will be replaced.  Starting Wednesda (8/12), Ward Street and Harrod Avenue will be closed to traffic.  Alternate crossings of the Jefferson Drainage Ditch for north-south traffic are open on Ray Street and Ransom Street.  East-west traffic may use either Mary Street or Loomis Avenue. Construction is expected to take approximately two months.