The River Ritec flows towards Tenby, where it discharges via a 780 metre culvert/outfall system that passes beneath a railway embankment and sand dunes to discharge into the sea below typical low tide level. There is a history of flooding upstream of the culvert which imposes a restriction on the discharge of flows from the river catchment area during high river flow events. This is particularly true when high river flows coincide with high astronomic tide levels.
The valve installed below ground in a chamber at the beach end of the culvert is designed to close off the rising tide which can otherwise fill the length of the culvert and prevent “washing” of the Victorian brick culvert.
Due to its inaccessibility in the chamber, the actuator previously installed on the valve was locally operated by pushbuttons in a nearby top-side enclosure. However, local operation was imprecise, requiring call-outs at any time, day or night, and relying on human judgement for factors including the state of the tide, the rate of rainfall, the weather forecast and the risk of flooding.
In a contract awarded to Rotork Site Services by Natural Resources Wales (NRW – formally Environment Agency Wales), the old actuator has now been replaced with an IQ3 actuator and two ultrasonic level sensors installed in the valve chamber. The new installation is programmed to automatically close-off the rising tide to ensure that the length of the culvert is then available to act as a storm tank and receive as much river flood water as possible. By automatically opening the valve when the tide begins to recede, drainage capacity is also maximised, enabling any flooding that may have occurred to drain away as quickly as possible. As on other NRW sites, operation is now remotely monitored via a telemetry system and, if necessary, can be overridden from central control rooms and mobile devices.
Operation of the actuator is also supported by a Remote Hand Station installed in the top-side enclosure, which provides an exact duplicate of the actuator’s monitoring and control interface. From here the user can not only locally operate the actuator, but also interrogate, configure and download data from it using the Rotork hand-held setting tool with its secure wireless Bluetooth® link. Retaining all of the actuator’s functionality, the Remote Hand Station presents an identical window into the plant, showing diagnostic data including the valve torque and usage profiles and facilitating real time analysis directly at the cabinet to assist with preventative maintenance and asset management.