Bunded Tank Cleaning

Two separate areas

Primary tank and containment bund

Identify

Stored oil and the location of contamination

Scope of numeric rule

England business oil-storage guidance

Identify the primary tank and the containment area

The primary tank holds the stored product. The surrounding or integral containment provides a second barrier if product escapes. An open masonry or concrete bund and an integrally bunded tank can have very different access arrangements, even when both provide secondary containment.

Describe the installed design using available drawings or documentation. A double-skinned or twin-walled tank does not by itself count as secondary containment under the cited England business oil-storage guidance. The construction and its documented function need to be established rather than inferred from a product name.

Keep containment capacity separate from cleaning volume

Under England’s business oil-storage rules, a single fixed oil tank within the regulations’ scope requires secondary containment holding at least 110% of the tank’s capacity. The rules generally apply to relevant business oil containers with a capacity of 201 litres or more, subject to the specified exceptions. For example, a 2,500-litre container requires at least 2,750 litres of containment under that rule. This figure describes containment capacity, not the quantity of waste awaiting removal.

For multiple containers, the guidance uses the greater of 25% of their combined capacity or 110% of the largest container. Hydraulically linked containers are treated as one container for capacity purposes, with secondary containment generally required to hold at least 110% of their combined capacity. The detailed GOV.UK guidance also explains the arrangements for linked containers with separate or connected containment. Oil-storage requirements vary by jurisdiction and installation, so the applicable rules must be checked for the site concerned. Assess the applicable installation rather than treating the percentages as universal rules for every tank.

Describe liquid, sludge and debris separately

Rainwater, escaped product and settled debris can collect in a bund. Their appearance alone does not establish whether the liquid is uncontaminated. Product history and any relevant analysis help inform the assessment of the material and its receiving route.

Deposits inside the primary tank may differ from material outside it. Identify where each quantity is located and whether it is measured or estimated. Keep the collection brief clear about tank-interior residues and liquid or debris in the bund, preserving the distinction between these cleaning areas.

Plan access and the required condition

Openings, internal fittings and the space around the installation affect access. An integral containment space may not permit the same approach as an open bund. The assessment needs to establish which areas can be reached and how recovered material will leave the installation.

Define whether the aim is bulk liquid removal, deposit cleaning or preparation for a subsequent inspection. Cleaning can expose visible defects, but it does not repair a leaking tank or damaged containment. Keep maintenance findings and any separate repair scope connected to the actual observations.

Use the guide to prepare a focused enquiry

Include the tank location, stored product, design information and the area requiring attention. Photographs can help explain accessible surfaces and visible material. Identify any operational constraints and whether a separate inspection or maintenance activity follows the clean.

The tank interior and bund may be included in one project, but the scope should describe each separately. This helps align the removal method, waste assessment and completion record with the actual material and surfaces involved.

The storage tank contains the product, while the bund provides secondary containment if product escapes. Deposits inside the tank and liquid or debris in the bund are therefore separate cleaning issues. An integrally bunded tank can also have different access limitations from an open concrete or masonry bund.