In order to diagnose the problems, cut the timbers into short sections and longitudinally split each section in order to see how far the preservative has penetrated. Reuse of any treated timber pile supplied by an outside source is not recommended. Not knowing the applied treatment, past use, or if diesel fuels have been applied to the surface used to give the appearance of a recent retreatment could decrease the life of the pile. Some unscrupulous suppliers of used timber piles should be avoided, because some contractors have applied diesel fuel to the outside of the piles to bring the embedded creosote to the surface. Deep foundation