Tag Archives: Dredging

Canvey Island Sea Wall Erosion, should be the Real Focus of CPBC’s Attention. Residents again being kept in the Dark?

The condition of the Canvey Sea Wall, or Sea Defence system, is causing serious concern, despite the lack of news or information.

The cause, which should not be too surprising, is currently under investigation.

Further inland on Canvey a large Green Belt site, identified as being deliverable and developable by Castle Point borough council, was the subject of a pre-development Ground Investigation Report, probably the first, and most thorough investigations of its type on Canvey Island, to be made public via the cpbc planning portal.

The Ground Investigation Report indicated what should be serious concerns to the cpbc development committee and planning officers, should they refer to it and give it the respect it warrants.

We suspect, however, committee members are unaware of its existence!

Despite this site being a full Kilometre from the Estuary, the effects of tidal water which surrounds Canvey Island have been found!

The Ground Investigation Report was carried out to consider what Risk the subsoil and water table might have on development structures, such as Housing.

It found;

Geotechnical Risks*
Poor bearing capacities of the low strength / loose soils;
Aggressive ground and groundwater conditions
Shallow groundwater (possibly under tidal influence)

The High Water table found on Canvey Island is well known to residents, however what was surprising is that this water consisted of a level of saline, or sea water, content!

In effect our Sea Defence is incapable of stopping Tidal Water from penetrating UNDER the sea wall.

If these influences can be found 1 kilometre from the sea wall, how much more damaging are they to the Sea Defence itself?

The constant changes via the ground water saturation and drying processes, and the less than stable subsoil beneath the Sea Defence foundations will over time, challenge the longevity of the structure. Whilst the effects of the Tide itself is more obvious!

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The effects of the more frequent passing of larger and larger transport vessels along the Thames, requires monitoring, as does the constant dredging.

As recently as September 2017 we were reassured that these Sea Defences are “well maintained”, and whilst these images probably indicate superficial damage we have learnt that the Environment Agency have identified some areas of the Sea Defence causing them serious concerns!

The Environment Agency are known to have carried out surveying inspection works and are considering what steps are required to maintain the integrity of the Canvey Island Sea Defence.

*Geotechnical engineering is the branch of civil engineering concerned with the engineering behaviour of earth materials

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Southend Fleet, Launch Invasion on an Unprepared Canvey Island!

This week the Port of London Authority held a poorly advertised public meeting on Canvey Island.

Consequently very few Canvey residents were in attendance, however there was a strong contingent from the Southend fishing community and environmentalists who expressed serious concern with regard to the effects of the ongoing dredging of the Thames.

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Apart from the loss of fisheries there has been a marked deterioration of the foreshore and an increase build up of catchment areas such as sand banks due to sediment movement and removal of surface covering.

The Port of London Authority’s stand point was that they issue licences for dredging having under done a “cause and effect survey” and that there should be reports that reflect any outcomes.

It was asked why these reports were not readily available.

When asked did the PLA actually check up on the outcome by way of post dredging  surveys the answer was NO!

The evenings programme was primarily to show how much activity is coming online on the Thames by way of recreational use and more consequentially the increased container and fuel tanker activities at the PLA’s various Terminals.

I tried to emphasis that their comment about the fact that when they championed that water freight reduced the amount of road activity when supplying London helped to improve air quality that this was not accurate.

Locally it actually increased heavy goods vehicle movements alarmingly, on an already over used road network.

The primary response from the PLA remained that Global Trade was of the utmost importance to the country’s economy, beyond any detrimental issues…..!

Cllr Howard mentioned that the Government was spending £308million on the Thames improvement and that Canvey had benefitted from this.

Cllr Howard further asked the PLA “whether the Holehaven Creek was being allowed to silt up”?

The reply was that that was not the case and in fact the area will be eventually the subject of more activity from the Coryton storage site.

This being opposite Canvey’s earth and clay protected section of our sea defence, the potential erosion of which through dredging and water borne freight movement may be of some serious significance to the island’s Flood Risk.

Concerns over foreshore erosion through dredging and shipping movement are an ongoing issue, see HERE.