WET News

OCTOBER 2014 WET NEWS 15 Maintaining Nottingham's flood defence • Built in 1955, the Colwick Sluice plays a vital role in protecting Nottingham against flooding. Carrying out maintenance on the sluice brought its own challenges. TEchkNoW • PLC-controlled hoists feature an encoder to determine the position of each stoplog and when it is in place • The new system uses the existing set of tracks, along which the new lowering mechanism travels • The stoplogs require a mobile crane on site to move the sections from the storage area to the lowering carriage NEEd To kNoW • The stoplogs each weigh 3.8 tonnes • The area around the sluice gate has to be inspected, which means the water must be held back just upstream of the gate • The last major work to be carried out at Colwick was in 1995, when the sluice gates were replaced and fresh concrete was laid in the base T he Colwick Sluice in Not- tingham is a key compo- nent of the flood defence apparatus designed to protect the city; one that the Environ- ment Agency (EA) has been up- grading in order to improve the efficiency of essential mainte- nance work. As part of this project ECS Engineering Services has installed a new semi-automated stoplog deployment system that provides the EA with 'dry' access to the sluice gate mecha- nism, speeding up operations considerably. Originally built in 1955, the Colwick sluice consists of five sluice gates and forms a key control point for the water levels of the River Trent and is used by the EA to protect Nottingham against flooding. The last major work to be carried out at Colwick was in 1995, when the sluice gates were replaced and fresh concrete was laid in the base to alleviate river bed erosion on the downstream section of the river. Labour intensive Periodically the EA is required to carry out maintenance on the sluice gates. In some cases, this requires the area around the gate to be inspected, which means that the water must be held back just upstream of the gate. This is done using a stoplog system, which consists of a number of steel sections that are lowered into slots located in the concrete structure of the sluice. ProjEcT SPEcS • Upgrade the Colwick Sluice in Nottingham • Design and install a bespoke system that will automate the deployment of the stoplogs • Undertake a site survey to determine the most efficient system to lower mechanisms ThE VErdIcT "From a technical perspective this is quite a complex installation, but the overall contribution to both speed and improved safety is considerable. This represents a 65% reduction in manpower and a 75% reduction in time, but more importantly the whole team can work within the hand railing on the sluice, greatly improving the health and safety aspect of the operation." Phil Anderson, project manager for ECS Once in position, the gate is opened and the trapped water is released, allowing the inspec- tions to be carried out. The procedure to install the stoplogs, each weighing 3.8 tonnes, was very labour intensive. Extra safety A mobile crane was required to move each steel section from its storage position to the sluice, where it was positioned and lowered by two separate hoists. The procedure for keeping the stoplog level during the lower- ing procedure was essentially done by eye, requiring addi- tional personnel to those involved in controlling the stoplog. Working close to the water also requires extra safety pre- cautions to be taken to ensure that personnel remain as safe as reasonably possible during the work. To ensure the safety of the maintenance team, each man working on the sluice structure had to wear a harness, which was connected to the structure via a lanyard. In addition, there was a boat team in place on the river in case a rescue was required. In all, a team of seven was required to operate the lowering system, with additional support from the mobile crane. The EA planned to improve this procedure, both in terms of efficiency and safety and turned to one of its framework suppli- ers, ECS Engineering Services. ONSITE FLOOD RISK MANAGEMENT The Colwick Sluice in Nottingham is a key component of the flood defence apparatus designed to protect the city

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