Llan Ffestiniog WwTW with the MMBJV and Welsh Water Dwr Cymru:

Franklyn Yates Engineering mechanical installation at Llan Ffestiniog WwTW with the MMBJV and Welsh Water Dwr Cymru:

Franklyn Yates Engineering Limited were commissioned by the Mott McDonald and J N Bentley joint venture (MMB) in partnership with Welsh Water to install an upgraded water treatment plant, which controls the waste water from the neighbouring villages.

At present, Llan Ffestiniog WwTW has a temporary treatment works sited on a rented agricultural field whilst the old works are being upgraded. With the new plant up and running Welsh Water can have the benefit of no rental fees, whilst treating the waste water to deliver a high standard of treated water back to the watercourse.


  • Installation of steel walkways, access platforms, davit socket points and staircases.
  • Lamella and SAF unit platforms were designed, fabricated and installed.
  • Various pipework installations from the main inlet works, ranging from 50mm diameter to 200mm diameter following the different stages through the system and completing the water treatment cycle to the sampling chamber.
  • Installation of two submersible inlet feed pumps and two submersible storm pumps.
  • Primary and humus desludge pump installation complete with pipework, actuated valves and instrumentation.
  • Grit clarifier aeration modification.
  • With the more up to date system for aerating the clarifiers the existing blowers could be utilised as the old design used more energy and would have starved the SAF tanks of air.
  • Installation of the air blower pipework from the existing blowers to the two clarifiers and the two SAF tanks complete with three way actuated valves, instrumentation and pipe supports.


Due to the water treatment works being situated in a National Park all of the new plant and equipment installed has been set at a lower elevation than the plant and equipment that has been removed.  The more compact layout design has resulted in an enhancement of the character of the surrounding area.

The temporary works have also now been removed and the land in which it was situated is now being used for agricultural purposes.