Long Rock coastal works
A section of sea wall at Long Rock, Penzance is having rock armour added to secure its longer term future.
In January 2016, severe storms caused substantial damage to the wall, which supports a well-used coast path and, only a few yards further back, the mainline railway connecting Penzance to London Paddington. Emergency works were quickly carried out by Network Rail, but the sea wall showed signs of further deterioration, resulting in Cornwall Council closing the coast path in the interests of public safety. Further works by Cormac in July 2016 stabilised the wall, and the coast path was reopened.
Despite the remedial fixes working well, they were only a temporary measure. Damage around an exit for a stream that passes through the wall is only the most visible part of wider issues that will continue to worsen unless action is taken.
As the preferred Shoreline Management Plan solution agreed with the Environment Agency, Cornwall Council has instructed us to add rock armour to this section of the wall. The remedy is cost effective, will extend the life of the sea wall by around 20 years and has the advantage that, should it ever be required, it can be removed.
- Adding rock armour will see us installing large boulders in front of the wall, which help absorb and redistribute the energy of incoming waves. In turn, this reduces erosion and the potential for further damage, and so substantially prolongs the life of the structures behind the armour.
- We are minimising the area of beach required to install the armour by burying the lower layers beneath the foreshore.
- The work will take away around three to four metres of the beach in front of the sea wall, which is much less of an impact than similar works elsewhere. We’re using smaller rocks – up to two tonnes rather than the standard size, which can be in excess of five tonnes – and sinking the lower layer as far as we can without impacting on its effectiveness.
- An exclusion zone around the works will be required, restricting access around the beach area and occasionally interrupting access to the coast path.
The capacity of the nearby Long Rock car park, at the rear of railway depot, will be reduced by 50 percent, as we will be using part of our base of operations. This will minimise disruption by reducing the need for additional traffic movements for transporting materials, equipment and so on.
The work itself will need to take place between tides, which will mean we will be operating outside standard working hours on occasion. However, any noise should be minimal given the distance and elevation to even the closest properties. Our standard noise minimisation procedures, such as use of low-noise equipment and acoustic barriers, will still be applied where needed.
Works of this nature are always going to have an impact at some level, but we are confident that we can keep any disruption to a minimum. We'd like to thank everyone in advance for their patience, co-operation and understanding.