Mineral extraction

Aggregate dredging

© BMAPA

Dredging for marine aggregates is by far the largest activity within this sector, which also includes the extraction of salt.

Eleven companies are generally involved in the production of marine aggregates in the UK. In 2008, these companies landed 19.3 million tonnes of primary aggregate for construction in the UK and abroad representing an estimated landed value (turnover) (before processing and on land sorting ) of £116 million and a GVA of £54 million. A further 2 million tonnes were extracted for beach replenishment. Those secondary market values for the marine aggregate dredging industry that could be identified included £80 million GVA from processing and £303 million GVA from sales of concrete products in 2005. Ancillary market values from exploration and transport were more difficult to define in total but indicators include a dredging fleet replacement value of £1 billion.

Marine aggregates mainly come from the eastern and southern coasts of England (Regions 2 and 3) with smaller amounts off Wales and north-west England (Regions 4 and 5). There is currently no dredging within Northern Ireland and Scottish waters due to an adequate land supply of aggregates and lack of suitable and easily accessible resources on the seabed. The maximum depth that dredgers can practically operate in is around 50 m and is limited by available technology and vessel size.

The marine aggregate dredging industry employs about 640 staff, 500 of which are ship crew and the rest provide shore support and administration. A further 600 staff are employed on the wharves that receive UK marine aggregates and about 500 related to the primary delivery of sand/gravel (i.e. from wharves to the point of initial use).

Activity within the sector is driven by the demand for construction material and the availability of land-based aggregates in comparison with marine aggregates. In 2005, marine sand and gravel accounted for 19% of total sand and gravel sales in England and 46% in Wales. Estimates of proven reserves suggest that there is still a large amount of marine resource available, sufficient for at least 50 years production at current rates of extraction.

A well supported research fund (the Aggregate Levy Sustainability Fund), well developed onboard monitoring systems and regional environmental assessments, mean that there is good understanding of the environmental impacts from marine aggregate extraction and the characterisation of regional aggregate resources and palaeo-landscapes. Pressures from marine aggregate dredging include removal of sand and gravel, damage or disturbance of benthic habitats, and smothering from extraction operations and sorting of sediments. However, the proportion of seabed directly impacted by removal is just 0.007% of the UK continental shelf (UKCS) and impacts are managed through licence-specific environmental impact assessments.

In 2008, the sea salt extraction industry had a combined turnover of about £4 million from the three companies in operation in Cornwall, Anglesey and Essex. Extraction of sea salt is limited by the availability of high quality marine resources and is driven by markets at home and abroad.