Aberthaw Tidal Power Station

2021 Outline Design by Edward Grist

(14) Debris and Sediment Removal

  1. Debris and Sediment Accumulation
  2. Sediment collection
  3. Sediment Removal Barge
  1. Debris Accumulation Point

  2. Large debris is prevented from entering the barrage by coarse screens. Accumulations are removed by estuary vessels designed for the purpose. Sediments follow the changing tidal flow direction. Four collection and removal points are provided to reduce the amount of sediment that passes through the barrage water turbines and valves. Walkways are provided between the buffer ponds and below the Machine Hall. These walkways are 2.5m below the barrage roadway level. This is 0.5m above the highest tide level.

    Debris and sediment collection geometry
    Access to the walkways is from the transit channels at each end of each Machine Hall. They stop 10m short of meeting in the middle to avoid the security risk created by a route that bypasses the Machine Hall.
    A one metre step between buffer ponds provides a temporary 'store' for the occasions where substantial amounts of sediment are deposited. Typically this is when sandbanks move position during a severe storm.
    A specially adapted barge is used from which the recovered sediment can be deposited in the sea at a suitable location. This does not constitute 'dumping' because the sediment always was seaward bound as part of the estuary eco-system. The objective of the system is solely to minimise the amount of sediment that passes through the water turbines.
  3. Sediment collection

  4. 3554
  5. Sediment Removal Barge

  6. Sediment is ingested by solids handling pumps suspended from the walkways. The sediment is pumped into an open trough at walkway level from where it is flushed down to a Sediment Removal Barge in the marine life transit channel. The discharge point of the recovered sediment / water mixture onto the barge is located