Activities in preparation for the forthcoming improvement works at Val de la Mare reservoir have started. Later this summer Jersey Water will be installing a water tight ‘membrane’ on the reservoir side of the dam, which will both prolong the life of the dam itself and prepare for any future extension works which may be needed.
Stages of the Project
The first stage of the project, which is happening over the next few weeks, is to improve the approach routes to the top of the dam, which will enable access for vehicles and equipment. The second stage, which will take place during June, July and August, will be to install the frameworks and support equipment from which the membrane will be positioned on the reservoir side of the dam. This final stage of the project will happen in September and October and will be undertaken by specialist international contractors. The project is due for completion in November this year.
During the period of the works, both top and lower car parks will remain open throughout, and there will be unrestricted access along the East of the reservoir as normal. To the West of the reservoir (the Mont Rossignol side), walkers and joggers will still be able to follow the walking route from the top car park along the reservoir down towards the dam and back up to the top car park. They will simply not be able to cross the path at the dam itself to the lower part of the reservoir, as this part of the path will be closed off while the work is taking place. The temporary changes to the routes will be clearly marked and information will also be available on Jersey Water’s website at www.jerseywater.je
Between now and August, water from Val de La Mare will be drawn down and used within the system in the normal way. Queen’s Valley and the Island’s other reservoirs will be kept as full as possible during this time, and will be used whilst Val de la Mare is out of service. As well as its usual initiatives to remind people to use water efficiently in the summer, the Company will also have the desalination plant on standby should it be required.
Jersey Water is also working closely with the Environment Department, a UK specialist and the Jersey Freshwater Angling Association to safely transfer the fish stocks in the reservoir to other locations.
Commenting on the works, Managing Director and Engineer Howard Snowden said:
“This is an important and necessary project, both for the existing dam and also as a vital part of the preliminary plans prior to any possible future extension of the reservoir.
The reason for the work having to be done in the summer is driven by several factors. It is a specialist engineering and technical operation that requires temperate conditions for safe installation. Also, and equally importantly, if we leave it until the autumn to start the work, we will miss the essential opportunity of refilling the reservoir from the winter rainfall which comes between November and April.
We are putting every contingency in place for the possibility of a dry summer, and will introduce restrictions only as a last resort. However, our options are limited, as this work has to be done; so we cannot emphasise enough to our customers and to the Island in general that using water sensibly is imperative.”
As to the public access which Jersey Water allows to the reservoir, we are keeping users of the walkways informed of how the access to the paths will change during the period that the work will be taking place, and we thank everybody for their patience in advance.
We hope, due to our Universal Metering Programme and changes in peoples’ behaviour to water usage, to be able to put off the final extension of the reservoir for a number of years. Nevertheless, this work is still necessary now as part of safeguarding the dam’s future. The project is included within the Company’s capital expenditure programme so we do not expect this single project cost to have any affect on water charges”.
Notes to Editors
Since the Val de la Mare dam was first built 50 years ago, work has regularly been done
to maintain its safe condition. Advances in dam maintenance and protection technologies have meant that these types of plastic membrane are now commonplace in dams all over the world.
The dam, like many structures of its time, has been subject to the effects of AAR (‘Alkali Aggregate Reaction’), a very slow chemical reaction which occurs with some types of concrete.
The membrane will reduce the effect of the AAR, so prolonging its life indefinitely.
The project will also form a key part of ensuring the long-term performance of the dam before any extension works may be necessary in the future, as the demands for water resources in the Island increase and rainfall patterns become more uncertain.
For further information, please contact:
Managing Director & Engineer