Ecosulis Completes Abberton Reservoir Dredging Contract for Carillion

Posted by Glyn Onione on 28/06/2011

Ecosulis have completed a significant excavation and dredging project on Abberton Reservoir for Carillion and Essex & Suffolk Water.

The scheme will eventually raise the main dam and top water level of the reservoir by 3.2m. Enlarging the capacity of Abberton Reservoir will secure additional water resources (60% capacity increase) and improve the Reservoir’s value for biodiversity with large new wetlands being created.

This huge 1200 ha site, with a reservoir of 485 ha, is one of Europe's top wetland sites (SSSI; RAMSAR; SPA) with up to 40,000 ducks, swans and geese visiting each year. Essex Wildlife Trust manages the reserve which is situated on a well-protected bay of the reservoir, created in 1975 with the advice of Sir Peter Scott. This varied site also attracts large numbers of passage waders such as ruff and spotted redshank from the coast in winter along with thousands of golden plover. The reservoir boasts an impressive list of visiting rarities in winter or whilst passing through on migration.

Mature hedges and thickets in the surrounding grassland provide nesting habitat for a wide range of small birds, particularly warblers, nightingales and finches.

The team has successfully excavated over 10,000m3 of clay and silt from the reservoir bed thus creating a flow channel to a temporary drinking water pumping station which will be commissioned whilst the existing facility undergoes a major refit to cope with higher abstraction levels.

A 350m long and 9m deep silt curtain enveloped the works throughout the contract and at no time did turbidity levels rise at the off take pumping station, although only metres away from the excavation. An additional 200m long emergency curtain remained on standby throughout the contract period but was never required or mobilised.

Despite unseasonably strong winds the project has been completed on time and to specification.