River Lagan dredging project

The Department for Communities is the navigation authority for the 4.8km stretch of the River Lagan between Stranmillis Weir and the Harbour Commissioner’s limit on the downstream side of the Lagan Weir. There is a requirement on the Department to maintain a navigable channel through the river – typically this is achieved by maintaining the river bed at a designated level of -1.2m AOD (Above Ordnance Datum).

In the past, the water quality of the river was poor and at low tide unsightly smelly mud flats were exposed. The bad smell was due to decomposition in the mud releasing gases into the air and this increased during the summer months as the higher temperatures increased decomposition. The banks of the river were overgrown and deserted, wildlife was practically non-existent and there were few fish. Due to these environmental issues, the 'city turned its back on the river' and this was reflected in the decline along its banks with derelict lands and little investment in the area.

Since 1994 however, a programme of dredging works has delivered significant environmental and regeneration benefits for the city. The legacy and continued realisation of these benefits is dependent on further investment in dredging the impounded River Lagan.

The last maintenance dredge of the River Lagan was completed in 2011. The Department has carried out a series of investigations to consider siltation rates in order to determine the volume of material that has built up over this period and to assess dredging options to reinstate the -1.2m AOD level.

A contract has been awarded to local firm ABCO Marine Limited, which will see approximately 55,000m3 of materials removed from the River over the coming months. The project will start in mid-September and is due to finish spring 2020.

The work involves thousands of tonnes of silt being removed by diggers and disposed of at an NIEA approved location out at sea. The River will be initially closed to navigation for safety reasons during the period of the contract. However, as sections of the dredging works are completed these will be handed back to the river users. Please see plan below.

Anticipated dredge quantities of each dredge section (A-E)

Sectional Dredge Area Total Area (m2) Dredge Volume (m3) Duration
A 28,819 16,000 Approx. 5 weeks
B 13,671 5,000 Approx. 2 weeks
C 15,159 5,000 Approx. 2 weeks
D 38,478 10,000 Approx. 3 weeks
E 52,219 14,000 Approx. 6 weeks

Strategic Context

The following strategic objectives contained within regional and local policies are dependent on the River Lagan being maintained:

  • to enhance the quality of life for the people living in the surrounding areas of the river
  • to improve the water quality for the benefit of aquatic life, those that use the river for recreational purposes and the general environment of the city
  • to reduce the risk of flooding in the area; and
  • to encourage business growth and promote the development of economic infrastructure.

Dredging the Impounded River Lagan to remove sediment build up will improve the quality and aesthetics of the river and assist in flood management, critical to ensuring that these strategic objectives are delivered.

It is expected that the dredging works will have a minimal impact on the residents living near the River, however, should you have any issues regarding the works, the ABCO Marine site team can be contacted via the following methods;

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