Articles & Case Studies

Decked out for safety on the River Parrett

Posted: Thursday 24th December 2009

Management of an outfall chamber valve on the River Parrett has been made safer, easier and more secure for Environment Agency personnel with the installation of a special access platform from Technocover.

The water security specialist, part of Technogroup, has designed and manufactured a raised steel platform giving safe access for inspection, operation and maintenance of the valve.

Project designers, Black & Veatch, specified the access platform to meet a range of operational requirements stipulated by the client, the Environment Agency ncpms (National Capital Programme Management Service). These included the need for easy lifting and replacement of cover elements allowing personnel access in line with the EA’s strict manual handling criteria to safeguard operatives.

The valve acts as a tidal flap, preventing salt water from the Parrett entering a converging moorland watercourse which provides fresh water for irrigating lower lying agricultural land.

Providing a secure, raised deck area of approximately 3.1m by 2.5m overall, the platform includes a hinged and lift-assisted twin-leaf access hatch with integral safety grids for fall protection. The hatch opens up to give a 1340mm by 620mm clear opening for installation of a ladder to gain access to the valve for maintenance or replacement.

A separate hinged cover gives a 500mm by 350mm clear opening for operation of a spindle to open and close the tidal flap from the safety of the platform. A section of open mesh units gives an instant view of the chamber valve without the need to open covers or descend to river level.

All system components were hot dip galvanised after manufacture with a high specification Duragalv zinc coating to give extra protection against the salt water present in this tidal section of the Parrett.

The chamber outfall emerges from a vertical wall adjacent to steep sections of riverbank, located right next to a public road and houses. The platform not only provides safer operational access to a hard-to-reach feature, but also creates a physical barrier to deter unauthorised persons from interfering with the outfall.

David Widgery, project manager for Black & Veatch, said: “Working space was narrow and we did not want to impose any load on the existing head wall. Instead, we installed bearing piles with a reinforced concrete capping beam in the road verge, and formed reinforced concrete foundation pads on the buttress steps, with Technocover providing a neat solution to span between the beam and the foundation pads.”

Technocover engineered brackets into the platform for installation of aesthetic timber safety posts and handrails, and adapted part of the frame to provide a flange for bolting to the beam. Locking bolts on the covers and drop-in decking elements reduce the risk of unauthorised users tampering with or removing the units.

Jim Wright, project manager for the Environment Agency ncpms (National Capital Programme Management Service), said: “We are delighted with the solution. The covers are very easy to use and spring assisted, therefore requiring little effort to raise and close them. The tamper-proof locking also makes then secure. The design provides safe access for our operations people and also addresses public safety issues by reducing the risk of injury to the general public who may trespass on the structure.”

All enquiries to Terry Batten at Technocover Ltd Tel: 01938 555511 Fax: 01938 555527 Email:

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