Union Mills — A grain silo explosion Monday, June 24, killed a worker at Union Mills Co-op. Initial reports fingered fertilizer as the cause, but sources later clarified that it was in the grain silo and that fertilizers were stored at a separate location. The victim was identified as James Swan, 67, of Union Mills. Union Mills Co-op, in northwestern Indiana about 50 miles southeast of Chicago, is owned by Co-Alliance, an Avon, Ind.-based farmer-owned supply and marketing cooperative serving rural communities in Indiana, Ohio, and southern Michigan.