Jackson has completed works at Marsh Lane Weir on behalf of the Environment Agency to enable the installation of stop logs for annual maintenance on the flood gates.
This £415K project involved the design and build of steel stop logs as well as the construction of two concrete slabs to facilitate permanent steel framed storage racks adjacent to the weir structure within the EA’s own compound.
Stop logs are barriers used to control water levels in rivers, canals and reservoirs. They are designed to fit between concrete walls or across channels, and can be covered with a tarpaulin to create a decent seal.
Marsh Lane Weir consists of two large tilting weir gates within a flood channel which do not operate frequently. At their current state, the ability to operate the gates in order to use them for operational and maintenance procedures is challenging; therefore the EA are unable to assess the condition of the gates in a dry environment.
Jackson collaborated with the EA to create a stop log solution that allows these units to be easily and readily available and installed either for routine maintenance or during an emergency scenario. It would also allow the EA’s operatives to access the gates without affecting the river and, in a semi-dry environment. When not in use, the stop logs are stored in the racks within the compound.
The stop logs for Marsh Lane Weir have been designed to be installed using a self-engaging lifting beam which eliminates the need for divers to unhook chains. They have been designed to interlock with each other to ensure that the seals line up correctly each time they are installed. To install the stop logs, a 130t crane is positioned within the compound and is used to lift and lower the units into pre-existing guide channels in each of the pier walls.
Once installed on the upstream channel of the river, the process is repeated to the downstream channel, which creates a cofferdam. Water is pumped out using two 6’’pumps. The cofferdam can be either pumped down all the way to allow inspection of the apron slab, or just enough to allow the gate to be visually inspected and raised/lowered to check for any issues.
Once the gates have been used and inspected the stop logs are removed and stored back onto the storage rack in their designated slots for the next time.
Jackson’s Site Agent, Brad Dovey said: “We were very pleased to have the opportunity to deliver this project on behalf of the EA. I found the design process, especially on stop logs of this size, along with the challenge of putting together the process of how these were to be installed quite enjoyable. The cherry on the cake was the ease of how it all came together. Another satisfied team!’