Environmental Efficiency has many years’ experience in Bund Design & Construction. The purpose of a bund is to provide containment for oil tanks or drums in the case of a leak or tank failure.  Bunds therefore need to be correctly designed to provide adequate containment.

 

Bund Capacity

The first consideration is to ensure the bund has adequate capacity.  The rules in Ireland and the UK used to be similar but following the Buncefield fire, the UK rules are significantly more rigorous than in Ireland.  The rules are summarised below

 

  Ireland   UK
  The bund capacity must be the greater of

  •   110% of the largest tank in the bund or
  •   25% of the total tank capacity.
 The bund capacity must be sufficient to contain the sum of the following:

  •   A loss of containment from tanks under the most likely failure scenario

    •  

  •   Allowance for rainfall prior, during and after the failure event

    •  

  •   A free board to contain a surge in liquid due to catastrophic tank failure

    •  

  •   A free board to contain firefighting foam

    •  

 

Whilst compact bund designs can be achieved by raising the bund walls, care needs to be taken that a confined space is not being created.

 

Fire resistance

A further consideration is whether the tanks within the bund contain flammable materials.  Where this is the case, steps should be taken to ensure that plastic water-bars in the bund walls are protected from fire.  This is a UK requirement though not so in Ireland.  This is usually achieved by overplating the joint with a metal plate on the inside wall.  In addition to the protection of joints in the event of a fire, care needs to be taken where pipes pass through bund walls.  During a fire, the pipe may expand and damage the wall leading to a loss of containment. Protection in this case is achieved by the use of puddle joints though best practice is to avoid pipe penetrations of bund walls.  For existing non-conforming pipe penetrations of bunds, a number of suitable upgrade options are available.

 

Testing

Once the bund has been built, it should be tested before tanks or other equipment are put in place.  In both the UK and Ireland this initial testing is by a hydrostatic test to BS8007:1987.  Once the bund in placed in service it will need to be regularly assessed for integrity.  For EPA licensed site in Ireland the default integrity assessment is by means of a hydrostatic test, in the UK this is by a visual inspection.

 

Environmental Efficiency is able to inspect bunds for compliance against both UK and Irish codes and provide advice on design and upgrade to meet the latest requirements.