Boston Barrier

Introduction

The Boston Barrier partnership is between the Environment Agency, Lincolnshire County Council, Boston Borough Council and Black Sluice Internal Drainage Board, who are all working together to reduce the risk of tidal flooding to over 17,000 properties in Boston.

Common vision for water management in Boston and the surrounding areas

The partner organisations consisting of the Environment Agency, Lincolnshire County Council, Boston Borough Council and the Black Sluice Internal Drainage Board are committed to delivering a complex and ambitious range of projects in Boston, principally but not exclusively to deliver; flood risk protection, effective land drainage, and water level management to promote economic and environmental benefits and enhance navigation. These projects are:

• The Boston Tidal Barrier
• Water Level Management in Boston and the Fens Waterways Link
• The Black Sluice Pumping Station and South Forty Foot Catchment

Whilst the projects all have commonality in terms of a number of shared objectives, such as flood risk protection for example, there is also the potential for conflicting demands. Partner organisations will work together to ensure a coordinated approach to delivering the projects to ensure, where possible, that decisions are not taken individually which could prejudice the future delivery of the other projects or shared objectives, either in the short or longer term.

The Boston Tidal Barrier

The Boston tidal barrier is a £100.7 million scheme programmed to be delivered by 2019, which will provide improved flood protection to over 20,000 homes and businesses, protecting against tidal surges such as the 2013 event which flooded over 820 homes and businesses. The barrier has the ability to be utilised in the future to control water levels in the Haven generating economic and environmental benefits for Boston and aiding navigation between The Witham and The Black Sluice Navigation, once appropriate subsequent approvals have been sought and granted.

Water Level Management (WLM) and the Fens Waterways Link

The ultimate aspiration is for Boston to hold stable water levels upstream of the barrier to reflect those in the river Witham throughout the boating season. This would create an attractive and vibrant riverside environment and encourage the town to "turn towards the river" and celebrate its waterways heritage, attracting private sector investment to meet new demands from tourists, visitors, maritime visitors and residents. The design of the barrier is, therefore, being carried out on a no regrets approach whereby future measures to deliver water level management upstream of the barrier will not be precluded.

The Fens Waterways link will be a major waterway development eventually connecting over 240km of existing and new waterways, linking the Cathedral cities of Lincoln, Peterborough, Ely and Cambridge.  Projects contributing to the Link are being developed and delivered at Bedford, Denver, Northampton, Boston, Hubberts Bridge and Crowland. The Link will increase boating visitors to the Fens with towns like Boston providing heritage, character and a place to rest and relax. A stable water level in Boston will encourage boats to moor and visit the town and will also ease their on-ward travel into the Black Sluice and beyond.

The Black Sluice Pumping Station and South Forty Foot Catchment

Following the consultation on the future of the Black Sluice Pumping Station and the South Forty Foot catchment, the South Forty Foot Steering Group has been established to assist in shaping the future of both. Provisionally, a two year transitional arrangement is proposed, where the EA continue to operate the BSPS, but with increasing involvement of the BSIDB.

This will involve, looking for solutions and funding opportunities for future management viewing the entire catchment holistically, whilst taking account of; flood risk, land drainage, water resources, water level management and navigation, the water framework directive and the ecosystem.

Boston Barrier Community Hub

Residents can visit the  Community Hub, located on Marsh Lane in the Riverside Industrial Estate, to find out the latest information about the tidal barrier and meet with the project team to ask any questions.

To begin with, the Environment Agency plans to open the community hub on Wednesdays from 10am to 4pm - although it may open more at key periods as the tidal flood scheme progresses. It will also be a place to find out more about the other Environment Agency projects happening in the area.

The tidal flood defence remains on track to be completed by December 2019.

Background

The Boston Combined Strategy was published in March, 2008, after extensive consultation. The strategy aims to "manage the risk from tidal flooding in Boston whilst enabling opportunities for regenerating the town's waterways".

When the barrier is built and the banks immediately downstream are raised, Boston will be protected from a tidal surge with a 0.3% annual probability (or 1 in 300 chance of happening in any one year). Unfortunately, we cannot protect against the most extreme tidal surges, but the barrier will protect Boston in most cases and give the town one of the best standards of protection against tidal flooding in the country.

Where will the barrier be located?

We want to try and explain why the barrier is being built in the right place and why the mouth of The Haven was discounted.

The purpose of the Boston Combined Strategy was to "determine a 100 year strategy approach to flood risk management and navigation improvements in Boston." This strategy identified a multi-functional barrier, as the best solution for addressing flood risk management and waterway objectives in Boston.

A structure downstream of the port has many disadvantages, including:

• Navigation has to be maintained at all times. During construction we would be required to create a large bypass channel to accommodate shipping vessels
• Environmental damage to The Wash - an internationally designated site.
• Problems with access for construction plant and machinery.
• Problems with utilities (e.g. mains electricity supply).
• Increased cost of a larger and more complex barrier to prevent/limit collision damage and allow port vessels to navigate through.

For the reasons above, the Boston Combined Strategy discounted a barrier downstream of the port. Even if the barrier was just a tidal flood defence, the preferred location would still be where it is now - for the same reasons.

Will the barrier increase flood risk along the Haven?

The barrier will not increase flood risk along The Haven. This is because a tidal surge happens differently to river flooding. A tidal surge happens much like a spring tide only the tide comes in higher.  As the North Sea level rises, it moves through the Wash and into The Haven until it meets a hard defence or high land.  It is the level of the North Sea that dictates what height The Haven rises to. Even if the channel of The Haven was dredged to increase depth and width, because there is always more water in the North Sea than there is capacity in The Haven, the level in The Haven will always match the North Sea. Putting a barrier in the Haven does not make the height of a tidal surge any higher or lower than it would have been anyway.

Will Boston town be better protected than communities along the Haven?

Once the barrier is built, communities along the Haven and the town itself will have exactly the same protection from tidal flooding. The maximum height that the barrier can hold water in the Haven is governed by the height of the Haven banks. Once the low spots have been raised, this will be a minimum of 6.3 metres Above Ordnance Datum.

How have Boston residents been involved?

Before the business case was developed, the Environment Agency engaged with key partners and the local community on the concept of a multi-functional tidal barrier in Boston and how this would reduce flood risk and help to regenerate the town. There were a series of drop-in sessions in 2011 to provide an opportunity for local residents and businesses to comment on the location of barrier. There was good attendance from local residents living near the proposed barrier location. A key element of the project will be extensive consultation with the local community, river users and businesses on how they want the landscape around the tidal barrier to be constructed.

Got any questions or want to receive updates about the Boston Barrier?

If you have any questions about the Boston Barrier or if you'd like to receive updates about the project then please email the Environment Agency