AQW 830/16-21 Written question to the Minister for Infrastructure
To ask the Minister for Infrastructure, of the 26km of sea defences designated by the Drainage Council since its establishment in 1947, (i) how many individual sea defences were created; (ii) what type of defences were installed; (iii) what date work was completed; (iv) what was the cost of each defence created as a result of the designation determined.
Asked by Kellie Armstrong MLA on 8 June 2016
- Answered
- Written
- After due date
- Tabled
- 8 June 2016
- Answer due by
- 23 June 2016
- Answered
- 4 July 201626 days after tabling
- Department
- Department for Infrastructure
- Priority question
- No
Answer
(i) How many individual sea defences were created;
Rivers Agency is responsible for 26km of sea defences comprising of 41 individual structures (including two tidal barriers.) The defences are located at the Foyle estuary, Belfast, Strangford and Carlingford Loughs.
(ii) What type of defences were installed;
The majority of the sea defences maintained by the Rivers Agency are earth embankments with an armouring layer applied to the sea facing sloping surface. The function of the armouring layer is to reduce the erosive power of the waves. Some embankments can be cored with steel sheet piles and may be topped by a vertical or re-curved concrete wall to reduce wave overtopping.
The two tidal barriers are substantial concrete structures with control gates that curtail the passage of sea water into the Quoile estuary at time of high tides.
(iii) What date work was completed;
The construction of the early sea defences commenced in the early 18th century, primarily to reclaim land. Throughout the nineteenth and twenty century major construction works have continued to improve both the degree of protection and their structural resilience. Recent major works included the 2005 upgrading of the Newtownard's Sea defences at a cost of £3.7m and the refurbishment of the Quoile tidal barrier in 2005 at £725k. Currently the Department is exploring options to upgrade the Newry coastal defences at Greenbank.
(iv)What was the cost of each defence created as a result of the designation determined.
Given the time period that has elapsed since these defences were originally constructed it is not possible to estimate the actual cost of each defence created. However, the Modern (Gross) Replacement value for the sea defences that Rivers Agency maintains is some £46.4m.