During 2000 Thames Water established the aquifer supplying the plant sand filters treating water had become blocked and were running slow.
It was established that this was being caused by algal blooms, which were ultimately causing production to be impacted.
The Granular Activated Carbon (GAC) process was selected as the best treatment process and to complement this a 50Ml/d pre-treatment works was also constructed which would allow for the eventual removal of the slow sand filters.
The treatment works comprised of a dissolved air flotation and rapid gravity filter process. Treatment processes include:
– Raw Water Abstraction
– Coagulant and pH Correction (Acid) Dosing
– Coagulation/Flocculation/DAF
– pH Correction (Caustic Dosing)
– Rapid Gravity Filtration
– GAC
– Disinfection
– High Lift Pumping
The plant is able to deal with any algal blooms more effectively and also reduce ongoing operation and maintenance costs.
The four REIDsteel buildings which provide cover to these processes had to be of high Architectural value given that the site is located across the valley from Alexandra Palace. Planning Permission was therefore a very long, drawn out, affair which meant that the plant became operational in 2008.
There are five different cladding systems with Rigidal’s aluminium standing seam on the roof and the walls clad in a mixture of Kingspan’s horizontally laid microrib profile cladding, Terracotta tiles, sinusoidal sheets and blockwork. The steelwork was galvanised for long life, with galvanised box section purlins and rails. The internal cladding faces had to be uprated from their normal specification to reflect the aggressive internal environment.
In addition to the technical challenges of cladding these four buildings with so many different materials the works had to be delivered in a constrained site footprint with Hornsey Reservoir and the New River bordering the site on two sides.
REIDsteel were chosen for this work for our highly regarded reputation for completing complex and challenging projects on time and to budget with excellent cooperation and coordination with the Principal Contractor and other trades.
