10.4.1 Service History
Never assume the service history of a tank. This is especially true for older tanks. Verify the service history of any tank that will be closed and/or removed from a facility with management and/or Commerce. This is very important because substances present different health and safety hazards. If there is any doubt concerning the type of substance stored in tank, obtain an analysis of the substance prior to starting the closure or removal project.
10.4.2 Contained Substance
Accurately determining and verifying the substance contained in the storage tank is critical to the development of proper procedures for the safe handling of the substance. This is because substances can present numerous hazards that include:
Chemical (organic and inorganic)
Biological (bacteria or viruses)