Two underground tanks66,000 litres decommissioned
Preparing and foam filling two legacy tanks for a commercial M&E contractor, with corroded access points and residual diesel to remove.
A decommissioning choice for two legacy tanks
A commercial mechanical and electrical contractor asked Britteco to assess two underground tanks with capacities of 53,000 and 13,000 litres. Together they contained approximately 3,000 litres of residual diesel and sludge.
The contractor needed a practical decommissioning solution and a clear explanation of the available approaches. Britteco began with a site survey and prepared a site-specific Risk Assessment and Method Statement.
Assessing foam and concrete filling
The survey led to two options: concrete filling or foam filling. The team discussed the practical implications of each with the contractor, who selected foam based on cost, convenience and the possibility of removing the fill in future.
That choice was specific to this project. Foam filling and tank decommissioning should be assessed against the vessel, ground conditions and intended use of the site; a single filling method is not suitable for every tank.
Gaining access and removing residual contents
Corrosion around the access points complicated the preparation. Specialist equipment was needed to gain access, and corroded bolts had to be removed to open the hatch.
The team drained the tanks as far as practicable and used vacuum extraction to remove the remaining diesel and sludge before the foam-filling stage. The works required coordination with other contractors sharing the site.
Preparation and tank access formed a substantial part of the job. The project account records additional breathing equipment for the internal work, with the work controlled through the site-specific arrangements.
Decommissioned in situ
Following preparation, the tanks were filled with foam in situ. The existing project record describes a setting period of approximately 24 hours for the material used on this job; setting times depend on the specific system and conditions.
The completed work provided the contractor with a managed solution for both tanks, combining survey, access preparation, extraction and filling.
A different site, the same need for planning
For a harbour setting with a separate two-stage mobilisation, see the North Sunderland Harbour foam-filling case study. For the broader service scope, visit oil tank decommissioning.
Common questions
Frequently Asked Questions
Do underground tanks need to be emptied before foam filling?
Yes. Any remaining fuel, water and sludge must be removed first. On this project diesel and sludge were extracted from both tanks before any foam was pumped in.
Can very large underground tanks be foam filled?
Yes. This project covered two tanks of 53,000 and 13,000 litres. Foam can be pumped in through existing openings, so size is not a barrier.
Why foam instead of sand or concrete?
Foam is light, fills the whole void and can be pumped a long way from the vehicle, so there is little disruption on site. The right fill material depends on the tank, its location and any future use of the ground above.
How long do underground fuel tanks last?
Steel underground tanks corrode over time, and their condition cannot be seen from above ground. That is why tanks that are no longer needed should be emptied and made safe rather than left as they are.
Will I receive proof that the tanks were decommissioned?
Yes. We provide a certificate and records of the work, including the waste removed before filling.
Planning similar work?
Tell Britteco about the tank, its contents and the available access. Photographs and site details help the team understand the scope before discussing the next steps.
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