LOCATION:
The £12.9m Tipner Lake scheme covers 1.85km of coastline from the Mountbatten Centre to the Portsbridge roundabout. The area has environmental designations that include SPA, RAMSAR, Important Bird Area, SSSI, Designated Shellfish Waters and Bass Nursery Area.
Year 1
Year 2
The flood defence was constructed over three years to respect the designated environmental protections the area benefits from. It provides a continuous defence and protection against a 1 in 500-year coastal flood event.
Construction of a 4m high, reinforced concrete seawall comprising large areas of encasement and sheet pile installations along the entire frontage of Tipner Lake.
Reconstruction of a shared footpath and cycleway directly behind the seawall.
Landscaping, planting and creation of ‘social spots’ to provide places for people to stop, relax and enjoy the views.
A network of paths improved access to the coastal path.
Removal of the 250m Lower Wade Way slipway and causeway and construction of a replacement, shorter slipway.
Challenge
Unexpected ground conditions and the seawall not having the load-bearing capacity anticipated by the new design put the project nine weeks behind schedule, threatening the sequencing of the works which were programmed to take place between April and October over three years to accomnmodate over-wintering birds.
Solution
With the winter working restrictions, we were at risk of construction works with being pushed into a fourth year.
To bring the project back on programme we proposed undertaking non-piling and site preparation works over the first winter period. We sought and obtained agreement from Natural England for our approach and the necessary variation requests for both the planning permission and licence consents were duly granted.
An ornithological watching brief was in place to ensure there was no significant disturbance to waders and Brent Geese feeding on the intertidal area adjacent to the seawall. The ornithologist provided a weekly report for distribution to all relevant parties including Natural England.
All works were suspended during extreme weather events (frozen ground conditions for more than one week) to prevent any significant effect on SPA birds.
Outcome
The completed project came into public use in the autumn of 2019.
As part of our community engagement activity on this project we worked with the adjacent Hilsea Lido to bring a bespoke mural by local artist ‘My Dog Sighs’ to life.
