FA1192 – Slow Sand Filters, Bed Rebuild and Bed Refurbishment.
Thames Water Utilities Limited | Published September 2, 2014
Cappagh Public Works Limited, Watercare Utilities Limited, Western Carbons Limited
45252126, 45200000, 45500000, 71322100
Thames Water is responsible for the public water supply of millions of customers in London and the Thames Valley. A large percentage of that drinking water supply is provided through filtration processes, namely Slow Sand Filtration (SSF).
SSF beds are used as a secondary filtration process to remove turbidity and pathogens, filtering water through a bed composed of layers of sand, shingle (gravel) and GAC (Granular Activated Carbon).
There are 114 Slow Sand Filter beds spread out across five operational Thames Water sites.
Thames Water has an ongoing operational maintenance plan for SSF bed rebuilds which will entail typically rebuilding 25 SSF beds a year. These will be delivered partly in-house.
As part of the maintenance of these Slow Sand Filter beds, two main activities need to be carried out on a regular basis. These activities are:
— Bed Rebuild which consists of two sub-activities:
a) The removal of all layers of shingle, sand and GAC from the Slow Sand Filter bed,
b) The reinstallation of all layers of shingle, sand and GAC back into the Slow Sand Filter bed to a predetermined level (once internal processes are carried out on the shingle, sand and GAC).
Bed rebuild will be covered by lot 1 in this notice.
— Bed Refurbishment which consists of the repair of the bed structure once all layers of shingle, sand and GAC are removed from the Slow Sand Filter bed. This refurbishment mainly includes the repair and potential replacement of the porous blocks that make up the bed floor structure. Additional works might be required for the bed refurbishment such as filter shell repairs or repair/replacement of coping stones and crash barriers.
Bed refurbishment occurs in between the two sub activities of Bed Rebuilds.
Bed refurbishment will be covered by lot 2 in this notice.
Bidders may apply for any one, or more, lot.