Automatic Bund Dewatering

Bund rainwater removal

If you have effective bunding around your oil tanks it will not only capture oil but also rainwater. Any water contained within the bund will reduce the bund’s storage capacity and could reduce the capacity below legislative requirements.

We can supply, install and maintain automatic bund dewatering devices.

The device sits inside a specially constructed sump and works continuously and automatically 24/7. The system discriminates between oil and water to within 5mg/l (5 parts per million) and pumps out only the water leaving the oil behind.

bundguard dewatering device

You may require authorisation or a permit from the regulator (Environmental or sewerage undertaker) depending on where the discharge from the bund is directed. We have experience in liaising with the regulators and completing permit applications to ensure any installs will be legally compliant.

Removing water from a bund manually can pose operational problems for site personnel as any "waste contaminated with oil is classed as hazardous waste unless you can show there is under 0.1% oil." (GPP2). Ensuring waste removed is not classed as hazardous can be a very difficult and time consuming process.

bund dewatering installation

We can install the system as part of a new bund we are constructing, or can retrofit the system into an existing bund. Retrofitting the system will include installing a sump into the bund and running cabling for the pump.

The robust, all stainless steel, pump and sensor unit is located in the sump and monitors the different liquid levels. The control unit activates the pump as required to remove only clean water to the foul sewer or interceptor (depending on site circumstances).

The use of the automatic bund dewatering system removes the need for regular emptying of the bund by waste contractors thus reducing your costs, environmental impact and carbon footprint. It is ideal for unmanned or remote sites e.g. electricity substations where installing a bund dewatering device would negate the need for regular maintenance visits.

Bund Dewatering Interceptor 

above ground oil separator

For sites using automatic bund dewatering devices , but where the discharge is not sent to a drain line with an interceptor already installed an above ground oil interceptor is a robust and cost effective solution.

Above ground oil interceptors work in the same way as a regular interceptor, using phase partition and coalescing devices to separate oils and debris preventing them from being released into the environment. The systems we provide have been tested in line with the British Standard BSEN 858 which requires systems discharging to storm drainage/soakaways to ensure oil separation to at least 5ppm.

Benefits of installing an above ground oil interceptor include:

  • Cost effective compared to a traditional interceptor install.
  • Quick and easy install, lightweight composition of the interceptor means it can be manually handled into position.
  • Accessible silt trap chamber and coalescer makes servicing quick and easy.
  • Oil sensor links to bund dewatering pump, preventing further pumping from the bund if oil is detected
  • High Flow rate of up to 3 litres per second.
  • Automatic bypass overflow returns water to the bunded area.
  • Oil capacity of up to 70 litres.
  • Sludge volume of 100 litres.


“By commissioning GPT Environmental to retrofit automatic bund dewatering units we have been able to significantly reduce maintenance costs and ensure our bunds have the storage capacity to contain a catastrophic failure.”

Health Board - Environment & Estates Manager

Extracts from Legislation and Guidance

"It is recommended that the water be collected in a sump formed in the base of the bund and removed using a manually operated pump or by baling. A fail-safe automatic pumping system can be used, which monitors the oil and water interface, and automatically activates to pump out only water.”

Guidance note for the Control of Pollution (Oil Storage) Regulations

"If rain water has collected in your bund, it will reduce the amount of oil it can contain. If it’s necessary to remove accumulated rainwater, we recommend you do this with a manually operated pump or by bailing from the sump. In remote locations, you could use automatic systems that can distinguish between the oil and water in the bund. If you install one of these systems, you need to contact us for advice on where you can dispose of the discharge and if you need a permit or authorisation."

Above ground oil storage tanks: Guidance for Pollution Prevention 2 (GPP 2)

"Dispose of sump water safely and legally. Water taken out of the bund might be contaminated. Any accumulated water, oil or debris should be removed and disposed of in line with waste management legislation.......

In Northern Ireland, Wales and England, waste contaminated with oil is classed as hazardous waste unless you can show there is under 0.1% oil."

Above ground oil storage tanks: Guidance for Pollution Prevention 2 (GPP 2)

Need advice for services and products? Call us now 01656 741 799

Geo Pollution Technologies (UK) LTD - company number - 04689357


GPT head office is based in South Wales and covers all areas of South Wales, West Wales and Mid Wales including Cardiff, Swansea, Bridgend, Newport, Port Talbot, Powys, Llanelli, Neath, Pembrokeshire and Aberystwyth.

We also cover the South West of England from our premesis in Exeter including Cornwall, Devon, Taunton, Redruth, Truro, St Austell, Falmouth, New quay, Torquay, Paignton, Bristol, Plymouth, Bath, Gloucester and Somerset, .

We also operate across the midlands, London, Birmingham, Leicester, Northampton, Derby, Stoke, Nottingham, Coventry, Liverpool, Worcester, Southampton, Swindon, Manchester, Sheffield, Slough, Heathrow, Leatherhead and Surrey.