ECS upgrades Broxbourne flood gate lifting equipment for EA

As part of an upgrade programme on the local water control structures, the Environment Agency (EA) contracted ECS Engineering Services to replace the overhead lifting gantries used to insert maintenance stoplogs that form part of a set of radial flood gates near Harlow, Essex.

Located at Broxbourne, the Kiora radial gates form part of the extensive flood prevention equipment on and around the River Lee. Originally built as part of a flood alleviation scheme, the two Kiora radial gates are part of a network of sluices and weirs designed to maintain the water level in the flood relief channel and associated lakes, but also allow flood water to be discharged towards the Thames when necessary.

A radial gate is used to automatically control water levels within a channel. When they are closed the gates allow no flow to pass. As the upstream water level rises, the gates automatically open allowing water to pass through.

The site is owned and operated by the Environment Agency (EA) which is required, from time to time, to carry out maintenance work on the radial gates. To enable this to be completed safely, the site is equipped with two overhead gantries that are used to lower steel stoplogs into the water channel either side of the radial gate. This can effectively create a ‘dry-dock’ by preventing the water from reaching the radial gate under maintenance.

As designated lifting equipment, the gantries are governed by Lifting Operations and Lifting Equipment Regulations (LOLER), which require the EA to ensure that the equipment is fit for purpose and subject to regular, thorough examinations.

The existing lifting structures span the river to allow the electric hoist to position the stoplogs in either of the radial gate channels. One of the issues was the existing height of the gantry as it could pose a hazard to personnel walking under it. Part of the contract design was to increase the overall height of the gantry as well as ensuring that it is was designed to lift the steel stoplogs, with a suitable safety margin, in this case a Safe Working Load (SWL) of 2,200kg was requested. To carry out such work ECS is accredited under BS EN 9010-2 to level EXC3 which includes buildings and bridges. This means that the quality processes and manufacturing expertise is appropriate for EXC3 projects and all ECS work has the CE mark for its steel fabrications.

Improving the design height of the lifting beams also had a knock-on effect on the electrical system, as well as the control building itself. Given the weight of the stoplogs and the hoists, the designers had to ensure that there was no vibration or deflection in the vertical plane when the system is in use.

Jamie Wesley, Commercial Manager, Water Control Division, explains: “This contract forms part of our on-going commitment to delivering projects for the EA across the UK. Although it appears relatively simple, in fact a great deal of design work had to be completed to ensure that the entire structure supported the stoplog operations even before we started work on site.

“We have a group of very experienced design engineers that can draw up and specify these designs, to enable our in-house fabrication department to complete the manufacture of the beams. Our team of on-site engineers were responsible for the installation, testing and commissioning of the project.”

“In order to deliver the requirements of the project, we had to make some substantial changes to the control building before installing the new electrical system to run the hoists; as well as designing and installing the completely new overhead gantry. The entire installation was tested and certified to the relevant standards before we handed the site back to the EA and completed the operator training.”