Service life of fence posts treated by double-diffusion methods

Service-life tests indicate that Engelmann spruce, lodgepole pine, and Rock y Mountain Douglas-fir fence posts treated by double-diffusion methods perf ormed excellently after field exposure of 30 years with no failures. The te st site was located in the semiarid Central Plains near Nunn, Colorado. Alt hough Engelmann spruce posts generally defy treatment by other treating pro cesses, double-diffusion results in long service life. The annual service c ost of the untreated posts ranged from $1.39 to $1.60 per post depending up on the species. The annual cost of the treated posts was $1.10 per post bas ed on 1998 dollars.