Specialists from Natural Resources Wales (NRW) are taking a, new innovative approach to flood maintenance work on the River Rhymney which is benefiting both people and wildlife.
Approximately 900 tonnes of shoal had built up in the river near the flood banks at Ystrad Mynach, causing the river to flow into a deep, narrow channel. This was damaging the flood banks, making them unstable.
The shoal needed to be removed to make sure the flood defenses could continue to protect people from flooding, but traditional excavation methods could have threatened wildlife in the river.
To combat this, a different approach was taken and water was diverted around the shoal so the excavator could work in a dry environment – reducing the movement of silt which can harm fish and insects.
Special silt wattles and silt mats were used to slow down the flow of the river and to capture sediment dislodged by the work. Working with company Frog Environmental, an innovative ‘bubble curtain’ was also trialled for the first time in a river in the UK.
This curtain of air bubbles stretches across the river and helps to manage silt, as well as providing an acoustic barrier to absorb sound and increasing oxygen levels in the river – protecting fish and other river life during the disturbance.