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Introduction
Market Sectors
Services - Buildings
Services - Environment
■	Air Quality Management
■	Archaeology
■	Asset Management
■	Aviation
■	Coastal Management
■	Contaminated Land
■	Dams & Reservoirs
■	Development Infrastructure
■	Ecology
■	Environmental Engineering
■	Environmental Impact Assessment
■	Environmental Management
■	Environmental Monitoring
■	Flood Risk Management
	■	Braid Burn Flood Prevention Scheme
	■	Pendle Water Flood Alleviation Scheme
	■	River Witham Phase 2 and 3
	■	Strategic Flood Risk Management Framework
	■	Wallasea Wetland Creation Project
■	Geotechnical
■	Pipelines and Water Distribution
■	Renewable Energy
■	Sewerage
■	Small Hydro Power
■	Strategic Environmental Assessment
■	Waste Management
■	Water & Wastewater Treatment
■	Water Management
Services - Transportation
Sustainability
Capabilities A - Z

Environment Brochure

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Wallasea Wetland Creation Project

Wallasea Island, Essex

Project outline

The existing River Crouch frontage bank of Wallasea Island was in a poor condition and unstable in parts as the tide cuts away and undermines it so in 2001/2002 Bullen Consultants (now part of Faber Maunsell) designed, tendered and supervised the construction of a 2.1km long 4.5m high secondary sea wall on Wallasea Island (near Southend) within a relatively short time frame of 12months. Design of the earth embankment utilised wet low strength materials excavated on site from a new soke dyke and extensive areas of scrapes which created new wetland habitats.

Following the success of the works Faber Maunsell were subsequently appointed to design and supervise the construction of further flood defences leading to the creation of 110hectares of new wetland habitat. The project created new valuable habitat for rare plants, insects, fish and wild birds. Additionally, the flood defences that protect this part of Wallasea Island were significantly improved to a 1 in 200 year standard.

The new wetlands compensate for two areas of habitat lost to port developments in the 1990s. The European Court has subsequently ruled that compensatory habitat should have been provided as a condition of planning. The form of replacement would have to be by “Managed Realignment”.

In addition to the previously constructed 2.1km long sea wall the project involved the building of a new 1.7km long sea wall further inland using locally won clay. Due to poor ground conditions the new wall was constructed in two stages. 700,000t of pollutant free mud, imported by sea and which would otherwise have been dumped at sea, was beneficially used to raise the existing ground level to create conditions for saltmarsh to develop and to create a more robust flood defence and natural landscape.

The new wetland stretches for 4 km from West to East and is divided into three separate sections, each with a land link to the old sea wall. The existing sea wall was breached in six locations in 2006 to allow the tide back onto the 300 acres between the new and existing sea walls. Behind the new sea wall and running parallel to it is a new freshwater habitat to provide nesting habitat for birds such as avocet and redshank. A mini cliff for water voles and deeper areas for amphibians and water insects were also provided.

After breaching the new mudflats and saltmarsh will provide a natural defence to dissipate wave energy, thus avoiding the need for the new seawall to be provided with expensive hard concrete revetment.

Key features

Largest manage realignment project in Europe to date
Creation of 110ha of new wetland
Project balances the needs of wildlife, flood management, landscape and people
Detailed design of new sea wall utilising wet low strength materials excavated from on site
Multiple breaches undertaken within a tidal cycle
Use of ECC, Options A

Skills utilised

Geotechnical investigations
Detailed design
Contract document preparation
Planning supervisor role
Site supervision