MILL RESIDUE VOLUME FACTOR CHANGES IN IDAHO AND MONTANA

This paper reports mill residue factors indicating volumes of residue generated per thousand board feet (MBF) of lumber produced and per tho usand square feet (MSF) of plywood produced by mills in Idaho and Mont ana. Historic trends and projected changes are detailed. Since 1969 th ere has been an approximate 30 percent reduction in the volume of resi due produced per MBF of lumber and a 20 percent reduction per MSF of p lywood produced by Idaho mills. Montana's sawmills and plywood plants saw a 16 and 11 percent decline, respectively. The largest changes amo ng the various components of mill residue were decreases in sawdust, p laner shavings, and bark. Much smaller changes were observed in the vo lume of chips or coarse residue generated, and the volume of coarse re sidue generated per unit of lumber and plywood produced increased slig htly over the past 25 years in Montana. The analysis indicates that in the next decade, the volume of mill residue per unit of lumber produc ed will decline 9 to 25 percent; for plywood the decline is expected t o be 10 to 14 percent, Improved mill technology, such as better log po sitioning, thinner sawkerfs, smaller target green lumber sizes, greate r drying and planing efficiency, and plywood lathes capable of peeling to a smaller core diameter, has been primarily responsible for reduct ions in the volume of residue produced.