Juvenile lamprey, a protected species, were living within the sediment at the river intake. During their larval stage this species live in burrows in the river bed. Any desilting work would likely kill the lamprey. To prevent this, a specialist team from APEM worked to capture and relocate any lamprey from in front of the intake screens. The Beasley Christopher team then carried out the desilting work. APEM provided an accredited Ecological Clerk of Works to oversee activities, ensuring there was no impact on water quality in the local river, the River Teise.
Acting as ECoW, APEM’s role was to monitor in-river conditions. This focused on dissolved oxygen and ammonia concentrations in and around the intake area during the silt removal operation. APEM is experienced at supervising desilting operations having undertaken them for water companies on many sites across the UK. We have found that fine sediment deposits may contain high quantities of decomposing leaves which can produce high concentrations of ammonia. Ammonia is highly toxic to aquatic life and is released into the water when silt is disturbed. This can also lower the concentration of oxygen dissolved in the water.
The river intake area at Smallbridge was enclosed by a PVC silt curtain with chain ballast during the operation to avoid any significant water discolouration or pollution in the river downstream.