Precast filter bed system for Welsh waste water scheme

Precast filter bed system for Welsh waste water scheme

Precast filter bed wall panels and tiles from FP McCann were specified for Llanfaethlu waste water treatment works in Anglesey.

Constructed over 40 years ago and owned and operated by Dwr Cymru Welsh Water (DCWW), the waste treatment works consists of a single filter bed with precast concrete walls and tile bed.

The brief was to replace the existing filter bed with two new 10 metre diameter beds, at the same time keeping the Llanfaethlu works operational throughout the whole construction process. The scheme was split into two phases, phase 1 is to extend the capacity of the existing waste water treatment facility whilst maintaining operations and once complete phase 2 is to undertake on-line modifications and upgrades to the existing works.

Prior to commencing the demolition of the existing filter bed, the first of the new beds was built. Each waste treatment bed consists of 37 wall units 2.50m high and 208 filter bed tiles. Individual wall units have been cored to accommodate feed pipes and washout pipes.

Each of the filter bed wall panel units are married to the other using a unique stainless steel bolting system. Props were used to support every third concrete unit while steel fixings were secured.

Phase 1 is now complete with the first new bed brought into immediate operation and the demolition of the old waste treatment plant itself replaced with a brand new filter bed.

With a combined weight of approximatley 50 tonnes, around 500 separate pieces of precast concrete filter bed wall and tiles were supplied from FP McCann’s Littleport factory, and have been used to construct both filter beds. Day to day treatment operations continued uninterrupted and phase 2 of the scheme is scheduled for final completion later this autumn.

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