• Our responsibilities

     Coatbridge gas holder Coatbridge gas holder

     

    Why we’re dismantling our gas holders

    Gas holders were used to store natural gas for over 150 years, but they became redundant when the gas industry found a way to store gas within underground pipe networks.

    It’s no longer sustainable for us to keep the redundant structures in a safe and visually acceptable condition long-term. Our regulator, Ofgem, is funding the removal of gas holders across the UK. We own 110 gas holders and we’re committed to dismantling 50% by 2021. We’re also committed to redeveloping the land they sit on for use that’s more beneficial to the local community, such as housing and business premises.

     

    Our environmental responsibilities

    The majority of gas holders owned by SGN are generally above ground metal tanks, full of water that acted as a seal when the holders were operational. 

    Over their lifetime, a film of oil covered the surface, and at the bottom you’d typically find a build-up of paint flakes, oils and other detritus, commonly known as sludge. Sludge is often classified as hazardous waste so, together with our contractors, we decided to find the best environmentally friendly process to dispose of this. 

    For most of our sites, we’re now able to reduce the sludge volume sent to landfill by 50-60% through separating the water from the solids using a mobile plant and equipment, including a plate filter press system.

     

    Animated diagram showing the dismantling of a gas holder

     

    1. Oil that sits on top of the water within the tank is recovered and removed, and taken to a recycling facility to be re-used.
    2. The rainwater is pumped through a water treatment system, out into the foul drainage system.
    3. Any residual ‘grey’ water is also passed through a water treatment system and out in the foul drainage system.
    4. The remaining ‘filter cake’ is then processed and sent to landfill.
    5. Thousands of tonnes of dismantled steel are transported off site for re-use in the metal industry.