Difference between revisions of "Case study:Greenwich Peninsula"

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{{Project overview
 
{{Project overview
 
|Status=Complete
 
|Status=Complete
 +
|Project web site url=www.estuaryedges.co.uk/
 
|Themes=Flood risk management, Habitat and biodiversity, Hydromorphology, Social benefits, Spatial planning, Urban
 
|Themes=Flood risk management, Habitat and biodiversity, Hydromorphology, Social benefits, Spatial planning, Urban
 
|Country=England
 
|Country=England

Latest revision as of 13:59, 10 October 2019

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Location: 51° 30' 12", 0° 0' 11"
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Project overview

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Status Complete
Project web site http://www.estuaryedges.co.uk/
Themes Flood risk management, Habitat and biodiversity, Hydromorphology, Social benefits, Spatial planning, Urban
Country England
Main contact forename Toni
Main contact surname Scarr
Main contact user ID
Contact organisation Environment Agency
Contact organisation web site http://www.environment-agency.gov.uk
Partner organisations Greenwich Peninsula Regeneration Ltd
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Tidal terraces

Project summary

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Prior to 2000 1.7km of flood defences were replaced and refurbished on the eastern side of the Greenwich Peninsula. A further 700m is proposed on the western frontage.

  • Greenwich Peninsula is a 190 acre development site and is therefore London’s largest regeneration scheme.
  • The mixed use development consists of 10,000 new homes, 3.5 million square feet of office space – a brand new business district for London, with over 150 shops and restaurants.
  • The site is being developed in phases/plots in line with the overall masterplan produced by Terry Farrell and Partners.
  • Many of the features incorporated at this site are being used as good practice with other developers across London.

Monitoring surveys and results

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  • The intertidal terraces provide valuable habitat for fish and other animals and birds, as well as creating a new landscape feature for people to enjoy.
  • Flood defences designed to protect from tidal flooding with an allowance made for the future effects of climate change.
  • Surface water flood risk reduction on each plot will be provided in line with the London Plan policies.

Lessons learnt

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cost neutral


Image gallery


during construction
planned development
ShowHideAdditionalImage.png


Catchment and subcatchment

Catchment

River basin district Thames
River basin London

Subcatchment

River name Thames Middle
Area category Less than 10 km²
Area (km2)
Maximum altitude category
Maximum altitude (m)
Dominant geology
Ecoregion Great Britain
Dominant land cover Urban
Waterbody ID GB530603911402



Other case studies in this subcatchment: Barking Creek near A13, Barking Creekmouth, Chambers Wharf, Cuckolds Haven Nature Area, Lower River Roding Regeneration Project, Mill Pool, Saving Chiswick Eyot, Wandsworth Riverside Quarter


Site

Name Greenwich Peninsula
WFD water body codes GB530603911402
WFD (national) typology intertidal
WFD water body name THAMES MIDDLE
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present Yes
Species of interest
Dominant hydrology Estuary
Dominant substrate Estuarine mud
River corridor land use Urban
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 2400
2,400 m
2.4 km
240,000 cm
Project started 1997/01/01
Works started 1997/01/01
Works completed
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Flood risk management, Navigation
Hydromorphology Structure & condition of intertidal zone
Biology Fish, Macrophytes
Physico-chemical
Other reasons for the project millenium project, housing development


Measures

Structural measures
Bank/bed modifications Bank improvement, creation of intertidal terraces
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish No Yes No No No Improvement

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://www.ecrr.org/LinkClick.aspx?fileticket=toZTNTJ5zXA%3d&tabid=2624 Estuary Edges design guidance link

Supplementary Information

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The site

• Tidal range 7m.

• Over 1300m of sheet piling was in poor condition and needed to be replaced.

• Peninsula being redeveloped for high-density, high-value housing and facilities.


What the developers did

• In all locations, the existing sheet pile wall was cut down to near beach level and capped.

• Approximately 7–15m inland, either sheet pile or an L-shaped concrete wall were installed.

• Site 1: infill material was installed over wide area at stable angle of repose and allowed to colonise naturally.

• Sites 2 and 3: terraces were created between the new wall and the foreshore using gabions and wooden piles, maximising the area between Mean High Water Neap and Mean High Water Spring tide levels wherever possible at slopes of 1:7 or less. Growing medium initially protected under coir matting.

• Sites 2 and 3 were planted with a variety of saltmarsh plants through coir matting. Substrate particle size distribution was a close match to foreshore for both stability in local area and habitat value. Eastern wall, Greenwich Peninsula, London: Site 2 during construction


The result

• Wave action led to lifting of the matting and extraction of many young plants, necessitating some replanting, though there was also considerable natural colonisation.

• Re-planting of Sites 2 and 3 directly into substrate without erosion matting was most successful with Common Reed, Grey Club-rush Sea Club-rush and Sea Aster, several species surviving well below or above the main ‘saltmarsh zone’.

• Failure to install rhizome breaks has led to excessive dominance by Common Reed, which may need to be corrected.

• Freshwater outfall locations became areas bare of much vegetation, and reinforced geotextile mat used at these locations eventually looked unsightly.

• Extensive monitoring has shown intense use of the terraces by Sea Bass and other species.

• Flounder and adult Common Goby did not appear to ascend submerged terrace steps. One solution to this is shown in the design for the terracing at Site 3, where a series of terraces sloping in three dimensions was created in the form of an ‘ecological sculpture’. (In future schemes, cutting down of the old sheet pile to beach level should be considered to avoid the creation of barriers to certain fish species).

• Limited scope for human access, which might be addressed in future schemes by a variety of slipways or floating pontoons (where ecological and safety constraints permit).

• Overall considered to be a highly successful, benchmark design, though a few gabions appear to be breaking down after ten years (probably due to use of welded gabions) and repairs/renewals may be necessary to retain certain terraces (woven and plastic-coated gabions are always the preferred option if gabions are to be used).