Beneficial use of dredged sediment
Blackwater Estuary (Essex)
The work at Maldon has been done for several years/decades at two key locations. The most regular work occurs on the saltmarsh spit on the north bank of the Chelmer River (immediately downstream of the Hythe Quay at Maldon, Here, in 1993, four gaps in the marsh were plugged with wooden planks bolted to timber piles at roughly 2.4m centres and infilled on both sides with dredged material using a mechanical grabbing arm attached to a barge. In 2001 dredged material was used to further nourish the saltmarsh. This work has been done for 10 years and is ongoing as material are excavated to maintain the accreting harbours and channel of upper Blackwater Estuary (Chelmer River Section). Around 2,500 tonnes of channel maintenance (approx. 2,000m3) dredge arisings are placed annually. On an intermittent basis small amounts are also placed on the south bank of the river west of Northey Island. This has been done for 30 years. All this work is done by excavating with a back hoe to a hopper (often on exposed drying intertidal) and then depositing by same backhoe approach. This keeps the materials relatively well consolidated during the whole process and enhances the stability of the deposits.