The Lower River Roding Regeneration

The Lower River Roding Regeneration

Joanna Gray MICE, Jennifer Hawkes ALI & Peter Martin MLI

Halcrow, Waltham Cross, UK

Keywords

biodiversity; flood defence/management;

habitat; landscape; regeneration; river;

sustainability; urban development.

Correspondence

Jennifer Hawkes ALI, Halcrow, Waltham Cross,

UK. Email: [email protected]

doi:10.1111/j.1747-6593.2008.00109.x

Abstract

The Lower River Roding Regeneration (LRRR) project was funded by the Office

of the Deputy Prime Minister (ODPM) with a contribution from the Environ-

ment Agency and was charged with achieving environmental and social gains

along the highly urbanised lower 4.4 km of the River Roding. The funding

allowed d1.5 million for all elements of work within a 2-year-period. Of the

four sites constructed, two allowed significant river restoration to be achieved:

Creekmouth Open Space and Frogmore Frontage. In the former, an existing

flood defence was set back to create a tidal backwater. In the latter, a concrete

river wall was demolished and a graded riverbank was created. A total of 1 ha of

new saltmarsh was created on these two sites. The project demonstrates how

multiple objectives of river restoration, flood defence, habitat creation, im-

proved public amenity and urban regeneration can be achieved in an industrial

urban area.

Introduction

The River Roding rises in Molehill Green and flows

through Essex and east London, where it enters the tidal

Thames via Barking Creek. The Lower River Roding

Regeneration (LRRR) project was charged with the

task of assessing the final 4.4 km of the River Roding

and Barking Creek, of which the final 3 km are tidal,

for opportunities to achieve the multifaceted aims of

sustainability. For the purposes of the project, sustainable

projects were defined as those that delivered improve-

ments to ecology, green transportation infrastructure and

education related to sustainable living. This lower section

of the River Roding is surrounded by a highly urbanised

landscape with large zones of industrial and commercial

use and is largely contained by sheet piled or concrete

river walls with occasional expanses of reedbeds and

mudflats. Of the approximately 40 projects identified for

potential works, five were taken to the level of detailed

design and four were successfully implemented within

the timescales and budgets allowed.

Project background and information

The LRRR project was primarily funded by the Office of

the Deputy Prime Minister (ODPM) via the Sustainable

Communities Fund and part funded by the Environment

Agency for flood defence improvements. A number of

groups formed a steering committee, which guided the

project through its lifetime: the Environment Agency, the

London Borough of Barking and Dagenham, the London

Borough of Newham, the ODPM and the Thames Gate-

way London Partnership. Halcrow Group Ltd. were em-

ployed as lead consultants on the project and J. Breheny

acted as the main contractor.

Each of the four sites that were constructed as part of

the LRRR project (see Fig. 1) are unique and achieve

different objectives related to sustainability. At the con-

fluence with the River Thames, Creekmouth Open Space

is a site where works have transformed a flat expanse of

grassland with obstructed outward views and a low point

in the existing flood defence into a gently undulating

open space with expansive views over Barking Creek and

the River Thames, a rich intertidal habitat, a set-back

flood defence embankment, an improved public en-

trance, footpaths and seating areas.

Further upstream, the works at Cuckold’s Haven en-

hanced a small area of open space by providing an

alternative entrance, a dynamic seating area overlooking

mudflats and a tidal weir and information boards in-

tended to educate the public on the historic heritage and

ecological importance of the site.

On the opposite bank at Frogmore Frontage, there was

a low point in the existing concrete flood defence wall and

a footpath across the site that was convoluted and unsafe.

The opportunity was taken to remove the existing hard

Water and Environment Journal 22 (2008) 297–303 c� 2008 The Authors. Journal compilation c� 2008 CIWEM. 297

Water and Environment Journal. Print ISSN 1747-6585

defence and construct a new flood defence embankment,

which follows a gentle gradient from the riverbed to the

new footpath on the top with views across the river and

restored intertidal habitat as well as clear views across the

site.

Finally, at Mill Pool, works were carried out to improve

an existing urban seating area by raising levels to provide

clear views over the River Roding, comfortable seating

and historic information about the site.

Each site was unique in the challenges faced and

objectives achieved. The two most interesting sites with

regard to river restoration were Creekmouth Open Space

and Frogmore Frontage.

Creekmouth Open Space

The site

Creekmouth Open Space is a 2.6 ha area of grassland on

the site of the Barking Barrier that forms part of the tidal

Thames flood defences. The site was largely a level

expanse of grass with sheet-piled river walls along ap-

proximately 70% of the river frontage with a low bund

forming the remaining flood defence line (see Figs 2 and

3). The crest of this bund formed a low point in the flood

defences, placing the surrounding properties at risk. From

a social point of view, this site was the only open space

within a mile and suffered from poor pedestrian access

along a tarmac access road with little visual interest and

no opportunity for people to interact with the river or the

habitat of the area. Interesting views up the Thames were

obstructed because of low ground levels and high flood

defence walls. These problems provided the opportunity

for the project to address issues of river restoration,

improved flood defence, habitat creation and public inter-

action in a single project.

The works

At Creekmouth Open Space, today, visitors walk into the

site by a newly created entrance, up a footpath and across

the site towards one of two raised seating areas. The

riverside edge of the footpath forms the crest of a set-back

flood defence embankment for a portion of its length. This

embankment falls away into a tidal backwater populated

by reeds and sea club rush. Further along the path, visitors

walk along the base of a gently rising hill to a seating area

where one can enjoy views of the Thames’ mudflats and

resident wading birds (see Fig. 4 for an aerial photo of the

site).

Fig. 2. Looking across the site towards the Barking Barrier.

Fig. 3. Looking upstream from the Barrier.

Mill Pool

Cuckold’s Haven

Frogmore Frontage

Creekmouth

Open Space

River Thames

Fig. 1. The four constructed sites along the River Roding.

Water and Environment Journal 22 (2008) 297–303 c� 2008 The Authors. Journal compilation c� 2008 CIWEM.298

Lower River Roding Regeneration J. Gray et al.

Technical information

Engineering

This set-back flood defence line was constructed to current

height requirements with an additional 500 mm freeboard

to allow for the possibility of rising sea levels. A soil seepage

analysis was carried out and recommended that a 500-

mm-thick clay blanket cover the embankment structure

and intertidal area. A toe drain was constructed to capture

any small amounts of seepage that were anticipated to

filter through the blanket structure. Ground contamina-

tion was discovered during survey works, resulting in the

requirement that a minimum of 500 mm inert layer was

placed over all areas of cut and fill. Thus, the clay blanket

fulfilled dual purposes of sealing in contaminants and

solidifying the flood defence. All excavated material were

re-used onsite. The majority of soil from the backwater

construction was used to form a low hill allowing for views

over the surrounding landscape.

Once the new line of flood defence was intact, the

existing wall was breached. The mouth of the backwater

was designed with gentle slopes to reduce the risk of

scour. A brushwood revetment structure was constructed

across the mouth in the form of a brushwood blanket and

on the slopes in the form of parallel lines of brushwood

terracing. These brushwood features were fastened into

place with deep timber stakes and planted with several

thousand plug plants. This structure was designed to

capture silt and stabilise the mouth of the backwater (see

Fig. 5 for a photo and Fig. 6 for a plan of these works).

Ecology

Habitat creation and river restoration were key to the

success of this project. The design of the restored river

habitat was carried out in careful consultation with fish-

eries and ecology experts within the Environment

Agency and Halcrow. Every aspect of the public realm

Fig. 4. Aerial photo of Creekmouth Open Space

after construction.

Fig. 5. Brushwood blanket and terraces.


Lower River Roding RegenerationJ. Gray et al.

and engineering design was considered in detail to ensure

that the best environmental outcomes were realised.

The backwater was constructed to ensure that inverte-

brates, fish and birds particularly would benefit from the

works (see Fig. 7). As the habitat that occurs between

mean high water spring (MHWS) and mean high water

neap (MHWN) is rich in diversity (Nottage & Robertson

2005, p. 29–30) and rare along this river corridor, it was

decided that an aim of the project should be to maximise

its creation. This was achieved by designing the levels

such that the minimum level of the backwater was at

MHWN with slopes with a maximum gradient of 1 : 10

and a minimum gradient of 1 : 100. The backwater was

constructed to drain to the breech to eliminate the risk of

fish entrapment as tides recede. Gravel beds were placed

in areas along the line of MHWS to increase the habitat

potential for invertebrates. It was a win for sustainability

on site that these gravels were discovered during excava-

tion and were able to be stored and re-used for this

purpose.

The marginal plug planting that was carried out along

the brushwood revetment provides a good example of

using locally sourced native vegetation. Early on in the

Fig. 6. A plan detailing the construction of the brushwood revetment structure.

Fig. 7. The tidal backwater at high tide.



project when it became clear that the existing river bank

was going to be breached, a team arrived onsite and

collected over 6000 plants, primarily sea club rush (Scirpus

maritimus) and common reed (Phragmites australis), which

were grown during the winter months. Seed was also

collected and stored for later use. These plants were then

planted on the finished site and seeds were scattered, thus

giving the local seed bank a head start in the process of

establishment. It was also decided that, where planting

was not required for engineering purposes, large areas

were to be left unplanted to allow the habitat to establish

naturally over time.

Views could be opened up to the river and mudflats

without increasing the risk of disturbing local wildlife.

This was achieved by constructing a hillock set back from

the flood defence wall and with gentle slopes, offering a

high vantage point for viewing but at a safe distance from

sensitive habitats.

Lastly, a small area of native shrub planting was

established adjacent to the backwater to provide food

and refuge for birds who might feed within the backwater

area or adjacent grasslands and a wildflower meadow mix

was seeded over most of the site. Recently, a pair of

avocets was seen feeding in this area.

Regeneration

This open space sits on the cusp of the Thames Gateway

and is likely to see many changes in the future, including

the possible construction of the Thames Gateway Bridge,

new housing developments and the extension of the

Docklands Light Railway. Therefore, the works on site

were seen as an opportunity to mark the beginning of

regeneration in the area. Regeneration on this site oc-

curred in the form of improved public access and circula-

tion, opening up of the river for bird watching and other

hobbies and inviting greater interaction with local wildlife

and habitats. This would not have been possible without

support form the Environment Agency to transform an

operational open space into a demonstration of what can

be achieved by setting back flood defences.

Frogmore Frontage

The site

Frogmore Frontage is located immediately upstream from

the A13 road bridge. The existing site was characterised by

concrete flood defences in a poor repair state, level

expanses of grass and the convoluted route of a riverside

footpath winding around concrete walls and railings (see

Fig. 8). The presence of walls and other barriers made for a

feeling of danger for pedestrians and created areas for

antisocial behaviour to occur. Beneath the A13 bridge,

the concrete river wall returned at a right angle and

became a retaining wall for the site, leaving the area

beneath the bridge as a gentle riverbank, which was also

a low point in the flood defences. The site was owned by a

private company with an interest in improving the exist-

ing poor flood defences.

Technical information

Engineering

The construction of a new flood defence on this site

required many of the same methods as those used at

Creekmouth, with some new challenges. On this site, a

set-back flood embankment was also constructed, again at

the required level with a 500 mm freeboard. However, a

clay core was keyed into the embankments due to the

limited mass of land behind the structure. Seepage analy-

sis, based on a worst-case scenario flood event, assisted in

recommending the size of the core required, and recom-

mended that a toe drain be constructed to capture any low

levels of seepage. The land also carried high levels of

contamination, which required all cut surfaces to be

covered by a 500 mm layer of inert soil. Unfortunately,

due to space constraints onsite, cut material was removed

from the site for disposal.

Once the new defence was constructed, the existing

wall was cut with diamond drills and demolished. The cut

was made at the line of MHWN and gently angled,

following the finished levels to meet the upstream de-

fences (see Fig. 9).

To ensure the stability of the new banks and address

concerns about scour occurring between the hard and soft

defences, rock rolls were installed in the interface be-

tween the wall and the embankment. In addition, lines of

Fig. 8. Frogmore Frontage before works being carried out.



brushwood fagots were fixed to the new slopes using

timber stakes and planted with plugs to assist in stabilising

the new structure (see Fig. 10).

Ecology

As at Creekmouth, ecological gains through river restora-

tion were paramount to the success of this project, and

work was carried out in consultation with a number of

experts. To maximise habitat creation between MHWS

and MHWN, slopes were constructed at a 1 : 5 gradient,

becoming 1 : 3 above this zone to allow the appropriate

height bank to be constructed. Brushwood was used to

encourage siltation and the creation of saltmarsh. Native

species collected from Creekmouth were used for all

marginal planting.

Along the retained section of river wall, where this site

meets upstream flood defences, the opportunity existed to

construct a kingfisher nesting site. This was carried out by

diamond drilling a small hole into the concrete face and

backfilling behind the hole with compacted sand and a

small amount of concrete. This was then surrounded by

and covered with inert soil and seeded.

Regeneration

Frogmore Frontage is highly visible to those driving on

the A13 and is very close to the historic site of Barking

Abbey and the Mill Pool. Footpaths constructed provide

improved access to the riverbank but also tie into footpath

improvements further upstream. It has the potential to be

included in various river walks or circular walks around

the London Boroughs of Barking and Dagenham and

Newham, highlighting the river landscape and ecology.

Therefore, it is hoped that the works on this site to

improve ecology, flood defence and public use for walking

and cycling will be a stepping stone in the process of

regeneration in the area.

Other improvements to the site include improved ac-

cess to the river (see Fig. 11) and clear views to Cuckold’s

Haven Open Space on the opposite bank. The new flood

defence will present reduced maintenance costs to the

owners and a long-term solution to flooding in the area.

Discussion

In the summer of 2007, the Environment Agency’s

Thames Region carried out a study to assess fish utilisation

Fig. 9. Frogmore Frontage a few weeks after construction was com-

pleted.

Fig. 10. A construction section from the river’s edge (left) across the flood defence embankment.

Fig. 11. A photo of the finished site looking downstream.



of the restored riverbanks on these two sites. The main

findings confirmed that a number of fish were utilising

the restored habitat on both sites. It concluded that

Small size restored intertidal habitat within heavy

urbanised estuaries can function as relic marsh and

provide a successful nursery and feeding grounds for

juvenile fish. These fragmented habitats also help

establish an intertidal migratory corridor through

rivers, safeguarding fry from the high flows found in

the central channel (Gray 2007, p. 5).

In addition, through these two projects, approximately

1 ha of new saltmarsh was created. This is a habitat that is

subject to a Biodiversity Action Plan (Joint Nature Con-

servation Committee 2007). The successful creation of

saltmarsh on these sites has assisted the Environment

Agency in meeting current targets for BAP habitat crea-

tion in the Thames Estuary.

Conclusions

(1) The LRRR exemplifies how joined-up working be-

tween different bodies can enable sufficient funding and

impetus to achieve multiple objectives through careful

consultation, design and implementation on confined,

contaminated sites in an urban setting.

(2) It demonstrates how environmental enhancement

opportunities can be maximised on small sites with great

benefit to the environment and to the public.

References

Gray, J. (2007) Fish utilisation of restored intertidal habitats

in a tidal backwater of the Thames estuary. M.Sc. Thesis,

Kings College London, London, Unpublished and

provided digitally by the Environment Agency’s Thames

Region.

Joint Nature Conservation Committee. (2007) UK Biodiversity

Action Plan [online]. http://www.ukbap.org.uk/habitats.

aspx [accessed 20 September 2007].

Nottage, A.S. and Robertson, P.A. (2005) The Saltmarsh

Creation Handbook: A Project Manager’s Guide to the Creation

of Saltmarsh and Intertidal Mudflat. The RSPB/CIWEM,

Sandy/London.



The Lower River Roding Regeneration

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