Natural Resources Wales will start building work in St Asaph on Monday (7 April) so that temporary barriers can be installed at times of potential flooding.
A 10m section of wall will be raised and new concrete strip foundations will be constructed along 80m of the existing embankment.
This will enable a half-metre high temporary barrier to be installed quickly along a 40m stretch of the Elwy that will provide extra protection for local people.
The flood barriers will be installed by Natural Resources Wales emergency response workers when the River Elwy rises to a certain level.
This will provide a higher level of protection for homes in the Roe Parc and Spring Gardens areas which suffered severe flooding in 2012.
Work is also on-going by consultants for Natural Resources Wales to find the best long-term solution to reduce the risk of flooding for people in the area.
A report released last month outlined the six options which are being assessed before being discussed in full with the local community.
In response to the flooding, Natural Resources Wales undertook a programme of short term works to remove trees and debris from a four mile stretch of the River Elwy, and to alter the parapet fencing of Spring Gardens bridge so that it is less likely to cause blockage when the river is very high.
Keith Ivens, from Natural Resources Wales said:
“The flooding of 2012 brought misery to the lives of hundreds of people in St Asaph, and we are committed to finding a solution to reduce their risk of flooding in the future.
“This work we are carrying out will hopefully provide peace of mind for local people when river levels rise as we seek a more long term solution.
“We will have a procedure in place for our emergency response workers to install the barriers when they are needed as part of the key work they do during flooding incidents.”