Awe-inspiring in its authenticity, the elaborate swimming pool that sits within Bayswater’s historic Porchester Centre has been lovingly restored to its former glory.
During the difficult times of the pandemic restrictions, the Essex- based Hydrospec team was engaged by SLM (Everyone Active) and Westminster City Council to undertake a comprehensive refurbishment of its 1925 constructed ‘First Class’ swimming pool. This followed the award-winning refurbishment of the Teaching Pool carried out by Hydrospec in 2018.
The revitalisation of the heritage pool, nestled within the Grade II* Listed civic complex, was a highly complicated and delicate process, with sensitivity of design at the heart of its success. The works included six weeks of enabling works to strengthen the pool structural walls due to deflection and repairs to long time cracks in the structure.
New structural floors and internal reinforced wall structures and new in-situ entry steps were constructed and finished with waterproof tanking renders and bespoke tiling within the pool in accordance with the planning conditions for this Grade II* listed building. Hydrospec’s John Cheek explains: ”This meant that the tiles had to be especially manufactured to exact colour and size of the original glazed bricks that were removed to the approval of English Hertigage.” “This enabled the pool to be fitted out with new compliant fittings to a new circulation design, improving this from the old end to end method previously adopted with a single main drain,” he says.
Additionally, the freeboard height was lessened and the surface water removal design improved by installing a number of outlets into the long side scum channels, which were not previously in circulation. Listed building consent did not allow the removal of the scum channel or the coping stones so new and extra outlets were diamond drilled and installed. The pool’s filtration system was extensively improved including the replacement replacement of approximately 15 tonnes of the original cast iron and mild steel sections of pipework due to corrosion/rust precipitation not only causing staining in the pool tank (certainly not welcome in the new pool) but restrictions in the pipe’s internal bore, thus increasing water velocities beyond good design practices. The original strainer and gate valves were also removed with the pipework, again responsible for causing restriction to the pool’s circulation design. New larger bore uPVC pipework was installed to achieve modern day standards in relation to velocities and turnover rates with the reduction in the pools capacity. New main isolation valves have been installed near to the pool structure. John again: “In order to reduce pressure losses within the pipework, the use of slow bends not elbows have been implemented on the main suction line back to the plant room, the new pipework services have been installed on galvanised support framework and supported to enable free expansion.”
The existing 11kW circulation pumps were replaced with new Herborner 7.5kW pumps with energy efficient motors and corrosion resistant wet end, matching those fitted to the teaching pool in 2018. A new bespoke pump strainer basket has been installed, complete with clear lid and inspection glass. Existing electrical control panel had elements renewed where needed and new automated backwash control system installed, simplifying a complicated process and minimising the risk of operation errors.
John explains: “The face pipework and valves on the existing systems were modified and renewed to allow the installation of pneumatically operated valves. Operators only have to activate a backwash procedure by pressing a start button and remain present for the operation stages of which are displayed on the colour 10” monitor mounted to the new control panel.” Safety interlock, incorporated within the electrical controls to inhibit heating, UV and chemical dosing in the event of no flow situations. The filters’ internal pipework was refurbished where necessary including the replacement of the internal underdrain’s and then re-filled with recycled crushed glass media. The existing troublesome plate heat exchangers were replaced with new Bowman shell and tube models. New heating valve actuators and thermostatic sensors fitted. BMS systems (by others) were also interfaced with the pool plant to control heating actuators when pool circulation pumps are off, avoiding the risk of heat damage to the uPVC pipework which had been experienced in the past.
New chemical dosing systems were installed in October 2018 comprising of Granudos 45 dosing systems and Kuntze chemical controllers complete with remote monitoring facilities. “The change of donor to calcium hypochlorite helped extend the life-cycle of the steel and cast pipework to 2020 standards provides excellent water quality to both pools,” says John. The Hanovia main pool UV system was reinstated after repair. An automatic mains water top-up system was installed on the main pool to monitor and maintain the operational water level of the pool. In addition, there is the facility to raise the water level, by button activation, to raise the pool water level to a pre-backwash level to account for the water loss and minimises the impact on pool operations as undertaken overnight. This system design/installation also overcome a non-compliance issue with the Water Authority. Owing to the building’s rich cultural import, the recreation of Herbert Shepherd’s original design, dating back almost a century, was painstakingly carried out by Hydrospec, in adherence with conservation conditions set out by Westminster City Council’s planning department.