The tale of the Arena District land that almost became home to Columbus’ casino adds another chapter tonight when the Board of Education is to vote on whether to accept a half-million-dollar property-tax settlement. The issue: What was the parcel worth for that brief period in 2009 and 2010 when, according to a voter-approved amendment to the Ohio Constitution, it was one of only four sites in the state where casino gambling would be legal? In November 2009, Ohio voters cleared the 18.3 acres just west of the Huntington Park baseball stadium as a site where gambling could be conducted, making it much more valuable than the contaminated former tool factory owned by Jaeger Machine Co.