Replenishing beaches on the Essex coast

The vessel, which is operated by Van Oord, had been berthed at Harwich Navy Yard for some months since finishing its work at the Felixstowe beach replenishment project over the summer. It was towed the short length of Essex coastal waters by Felixstowe harbour tug

Svitzer Melton

, with the multicat

Grey Mammoth

assisting at both ends.

Although classified as suction dredger, Sliedrecht 27 is not self-propelled and is being used as a pumping station to transfer offshore dredged gravel to the shore in the area between Cocketwick and Lion Point Breakwaters on the foreshore fronting Jaywick. The 1973 built, 1,605gt vessel is 108m long by 13.5m wide with a draft of 3.33m. It has a suction pipe of 1,050mm diameter and a discharge pipe of 900mm diameter.

The dredged materials will be supplied by the suction dredgers Sand Falcon and Sand Harrier which usually deliver sea dredged aggregates to the building trade in London.

The project to raise and widen the existing beach involves construction of a 185m long offshore breakwater (including 40,000 tonnes of rock), 250,000 m3 of beach nourishment and an outfall extension (150m). Work started in September and is scheduled for completion by the end of the year.

The existing seawall was constructed in the 1940s and has a residual life of 20 years. The EA reports that the seawall is most vulnerable at the centre of the beach with facing concrete broken and washed away and the sea penetrating the sea wall. The new beach will have a shallow 1:60 gradient with approximately 250,000 m3 of material, all delivered by sea.

The plans show a new breakwater and an extension to the Brooklands outfall. Neither of these two elements required planning permission as they are below low water level and therefore outside the local council’s jurisdiction. These elements are within the control of DEFRA.

Flood protection is the reason why the Environment Agency is supporting the scheme. The existing bay is being scoured by the sea, exposing the sea wall that has in the past been protected by sand. The EA had considered other options including doing nothing, doing minimum beach recharge, offshore breakwater alone and beach recharge alone. The chosen option offers the most effective solution.

Ovenden Earthmoving Company Ltd, which specialises in earth moving, crushing, recycling and coastal defence work has been awarded the contract for the onshore work by Van Oord.

This is the second contract awarded to Van Oord UK Ltd on the English east coast. The first is the Happisburgh to Winterton Sea Defence Project which is worth approximately €9m. This is a continuation of previous works that have been undertaken by Van Oord over the last 10 years.

These works are expected to last for the same amount of time as the Jaywick project. The work includes 280,000 m3 of beach recharge and the building and refurbishment of rock groynes and revetments. The trailing suction hopper dredger Geopotes 15 will be deployed for this project.

By Graeme Ewens