The duct keel/pipe tunnel I was asked to check (on an Ore/Oiler) using a wagon on rails was full of oil and gas, so I asked for the duct keel to be cleaned and ventilated for entry before my entry. I never heard from them after that. It seems they tried to clean the duct keel using water and detergent and entering a storm to slosh the water around in the duct and using a portable pump to get rid of the dirty water but failed. I never found out where the leak was - in a pipe or in the duct keel boundary structure to an oil tank.