Northern Gateway Flood Defence
VolkerStevin was appointed by the Welsh Government to complete flood prevention works, which were finished in April 2015. The scheme which was part of the multi-million pound Northern Gateway project was broken down into three packages and involved strengthening and reinforcing the existing flood defences along the banks of the river Dee in Clwyd.
VolkerGround Engineering was engaged to install 1.5km of sheet pile wall along a length of the existing embankment, to ensure the bank’s structural integrity over the next 100 years.
The wall comprised 8m long AU 14 section sheet piles predominantly driven by Hydraulic Pressing techniques utilising a Kowan ZU-100 Press. This was specifically requested by the client in order to minimise vibration transmission to the adjacent river so as not to interfere with migrating fish patterns. Over limited sections where this was not possible a high frequency excavator mounted Movax side grip hammer was substituted.
The ground conditions underlying the site along the length of the embankment comprised granular made ground and fine sand, typical of river alluvial material.
Once the piles had been installed the river bank was reinstated to the intended standard of protection and raised wherever the crest of the defence was low.
