Site Layout and Construction Development for the Langford Mill Eel Screen

Plans are developing now for the installation phase of the Langford Mill Eel Screen project. Currently works are expected to start on site around August 2021.

The drawing below shows how the site will be laid out once the installation is complete. The main elements to be constructed are marked ‘new’ on the drawing.

During construction, the site will be fenced off (as indicated by the dotted red line) to maintain a safe working area separated from any passers-by. The maintenance platform, pathway and control systems inside the Mill building will be constructed first whilst the screen is manufactured off-site.

When the screen is delivered for installation there is likely to be a crane on site for a short time to lift it into the river but for most of the time the site presence will be a few construction engineers and smaller vehicles. Our vehicles will access the site via the existing double gates off the B1019 Maldon Road (between the Mill and the village Hall). There are no road closures or long-term traffic lights anticipated to support the access arrangements but there may be occasional short duration traffic controls to enable larger vehicles to safely navigate the entrance. More details will become available on traffic management once the construction plans are in place.

Chosen Solution for the Langford Mill Eel Screen

To meet the legal requirements of 'The Eels (England and Wales) Regulations 2009' Essex & Suffolk Water have an obligation to install fine screening at our main raw water intakes to prevent eel entrapment within pumping systems. At the Langford Mill, the chosen option is a static 'Eco-Screen' which will sit in the river in front of the intake and water will filter through the fine mesh panels to the original pumps inside the Mill building. If the screen starts to block with the debris in the river, sensors will detect the difference in levels and will initiate an automated cleaning operation. This activates a wiper arm with bristles (like a large toothbrush) that will draw the debris up the screen to a trough and a wash water system in the trough will flush the debris into a catchment trolley which will be regularly cleared by our Operatives.

For the Eels Regulations, the key parameter is the speed at which the water engages with the screen, called the 'approach velocity'. This needs to be low enough to enable eels and fish to swim away rather than being drawn towards the screen and unable to escape. To achieve the right approach velocity the screen needs a large surface area. This meant that some screening types were not suitable for the Mill as the number of units and overall footprint would have been excessively large in this location, we therefore selected the most compact solution available to minimise the visual impact. The photomontage below depicts how the screen will fit with the existing structures. It will be a dark colour to blend in with the surroundings as much as possible.

Hi everyone, this is just a short update to let you know that the designs for the new eel-friendly screen at the Langford Mill are progressing well and I will soon be able to share some drawings here on the portal so you can see what we’re planning to install.

I also wanted to make you aware if you’re in the local area that we will have a couple of groups on site next week carrying out some non-intrusive surveys so please don’t be alarmed if you see a few more vehicles and people around than usual.