Work on West Kirby marine lake to remove silt could cost more than £6 million.
A report prepared for councillors warns: “Unless action is taken to remove the accumulating silt and sand
build up on the lakebed, the future viability of the lake to safely operate water sports activities, particularly sailing and windsurfing, is in doubt.”
It adds: “There is a risk that continued degradation of the marine lake lining will compromise the upper parts of the lining at the interface with the walkway resulting in closure of the walkway. The marine lake circular walk is a very popular attraction resulting in thousands of visitors to West Kirby every year.”
An underwater survey of the lakebed in June this year found that to restore the depth to 1.6 metres, a total of 70,000m3 – or 24,720 tonnes – of material would need to be removed.
The report explains that the issue has been accelerated by an increase in wind-blown sand “as a direct consequence of increasing foreshore levels” which dry out as they become higher and are moved by strong winds.
The majority of the estimated cost of the work- thought to be between £3.9 million and £6.3 million – would be for dredging, transport and disposal of the material. A repair system using single sized pattern grouted stone would be used.
The report states: “The marine lake would need to be fully drained to undertake a repair along 1km of lake wall however once complete the empty lake would be resilient enough to withstand the drag forces during refilling.
“Draining the lake to repair the lake wall would allow for land-based excavation and disposal of the sand and silt deposits at the same time”.
It cautions that the sluice gates to drain the lake may not open due to their age, meaning pumps would have to be used to remove the water and could take up to a week.
Due to the lake being within a site of special scientific interest and needing permission, work would have to take place between April and September, with the earliest start date likely to be 2027, “although this could be later due to procurement timescales and processes”.
The report recommends that funding options are explored, including grants and the council’s capital programme.
It also suggests the council proceeds with developing a borough-wide beach management strategy rather than the current piecemeal approach of “multiple applications for assent…in relation to beach management at various coastal locations in Wirral”. It says this would “identify the timing and location of management activities that address the issues and use of all of Wirral coast” and “highlight incombination effects”.
The report will be considered by the environment, climate emergency and transport committee on Tuesday 2 December.