Valves provide flood defense for school

Summary

March 11, 2014 - There are many good reasons for introducing a level of automation to manually operated river sluice gates. Sluice gates are vitally important for defending against flooding during periods of persistent rainfall, when swift and reliable operation can prevent serious disruption and damage to property. Alternatively, during periods of drought, sluice gates play an important role in maintaining the river level. The automation of a sluice gate is a relatively simple operation in itself. However there are many factors including the location of the gates and the availability of power which can turn the exercise into a multi-disciplined task demanding a range of mechanical, electrical, civil engineering and project management skills. This was the situation facing Canford School, a co-educational boarding school set in 250 acres of ground on the banks of the River Stour in Dorset, when an upgrade was needed to the operation of three river sluice gates. Installed many years ago, the gates enable the upstream area of the river to be accessed, mainly for school sports use in year-round rowing activities. The two-metre square gates were equipped with open mesh gearboxes and handwheels, together with counterbalancing weights attached to each gate by a lifting chain and open pulley. Manual operation of the gates took a long time and required a great deal of effort, as well as presenting a potential trapping risk to the operator. In recent times, changing weather patterns had also increased the risk of flooding to school property. Automation was therefore essential not only because of the flooding threat but also from a health and safety viewpoint.

Following a consultation with the Environment Agency, Canford School selected Rotork’s dedicated Site Services Division to perform the project on the sluice gates. Rotork’s proposal encompassed all aspects of the task in an extended scope contract, enabling them to organise the total supply of the work together with project management services. A major benefit of this approach for the customer is the simplified contractual route that the extended scope contract enables, by minimising the number of separate sub-contractors that need to be employed. Central to the upgrade was the installation of three Rotork IQ electric valve actuators and a local control centre. However, being in a wooded environment some 60 metres distant from the nearest power supply, considerable extra work was also required, as summarised below.

• A full survey of the existing sluice gates and hinterland. Measuring existing equipment for design and fabrication of adaptation for the actuators and protective shielding for the open pulleys and chains.
• The supply and installation of an isolation and distribution board to an existing power supply in a building 60 metres from the river.
• A cable detection survey and excavation of the cable route. Supply and installation of power cabling with a total length of 110 metres in ducting above and below ground between the power supply, the local control kiosk and the actuators. Installation of a concrete pad and a GRP kiosk for the local electrical control panel.
• The design, fabrication and installation of the actuator control panel, providing local isolation and push button open and close operation for each gate.
• The supply of lifting equipment to remove the existing open mesh gearboxes and pedestals, one at a time to facilitate manual operation of two gates at all times.
• The design, fabrication and installation of three new actuator mounting pedestals and six pulley guards.
• Installation of Rotork Gears IB9 sealed gearboxes with machined drive nuts to suit existing spindles and cover tubes to protect the spindles and prevent potential entanglement. Installation of three Rotork IQ35 electric actuators. Setting the actuator open and close limits and commissioning of the completed installation.

Following the completion of the work the time and effort required to operate the sluice gates has been dramatically reduced, enabling the school to manage the river level and flow with increased efficiency and in complete safety. In the future there may be scope to further upgrade the operation by installing river level sensors, the signals from which would operate the actuators fully automatically.