Terminal staff should also identify which transfer can continue while the vessel is unavailable. The cleaning vehicle, temporary storage and live product movement must not compete for the same bund crossing or manifold area.
Label the receiving container for each layer before recovery begins. A clear identity for usable product, water, heavy bottoms and washings lets terminal staff reconcile the quantities without relying on the order in which vehicles leave the bund.
Oil, water and bottoms leave in order
The lowest suction and drain points show where water or bottoms may remain. Compartments, heating coils and the available bund crossing then shape the recovery route.
Drains, bunds and transfer routes during recovery
Oil tank cleaning can move free product, water, sludge and washings through the same equipment area. Plan where each stream will go and how hoses or vehicles cross the site. The bund and nearby drains should remain protected while liquids are transferred. A low drain used for water draws may not share the normal fuel suction, which is why both routes need to appear on the recovery sketch before a vehicle is positioned.
GOV.UK guidance on business oil storage explains responsibilities for tanks and secondary containment. The site retains those responsibilities during cleaning and decides how remaining usable fuel is handled.
Where water and settled bottoms are the main issue, oil tank cleaning can separate recovery from any later surface or inspection work. An inspector may need seams, plates and outlets exposed beyond what is required for continued storage.
Contents history for the contractor
Separate recovery routes for product, water and sludge
Before the tank is opened, the operator sets the order for free fuel, water, bottoms and washings. Bund drainage and product-transfer routes stay under operator control.
Required surfaces for storage, inspection or repair
Return to storage may require different areas from a tank moving to inspection or repair. The contractor lists the relevant surfaces and any remaining limits.
Product transfer before the tank bottoms are disturbed
Early planning lets the operator align product recovery with oil tank cleaning and avoid losing useful information about the tank bottoms. If inspection follows, the contractor can also define the finish through tank inspection preparation.
State whether the tank has a low drain, floating suction, compartments or internal supports. These features influence where water and sludge collect and how the final material can be recovered.
Include recent water-draw and filter findings where available; they can help locate the part of the tank where contamination is collecting.
Water and sludge often collect below a floating suction or behind floor supports. A recent water draw and the outlet height help locate that material. The tank’s operating team can then compare the recovered layers with later inspection or fuel-quality findings.
Terminal or depot operations may need some tanks and transfer lines to remain active. The work plan marks the live boundary, tanker position and route across the bund before hoses are laid. That coordination is separate from the physical order used to recover the tank contents. It also identifies the person who can pause a neighbouring transfer if conditions change.