New Groynes For Clacton and Holland – Will They Work – Jan 2014

Plans for new groynes at Clacton and Holland have been exhibited and are available at TDC website. Will they work?  Here are some reasons to think not.

You can see the planning application by going to
idox.tendringdc.gov.uk/online-applications/

and entering

13/01195/FUL

into the search box. Here you can download the exhibition poster

Here’s what is proposed

newGroynesDescription

And here’s the plan

proposedClactonGroynes

 

Now the first thing that comes to mind is there is somewhere in Tendring with rock groynes about 90 metre long and 90 metres apart, Seawick.

And just to be helpful there is a single case at Seawick where the groynes are about 180 metres apart and, as I’ve shown before(here and here), the beach where groynes are 180 metres apart is significantly more eroded.  What’s more there is a little reef in the middle of the two groynes.

However the groynes at Seawick do not have the fishtails proposed for Clacton and Holland.  Here’s the plan of proposed fish tails.

proposedClactonFishTails

So they’re a sort of Y at the end of the groyne with one branch about 50 metres long and the other about 20.5 metres long.

There are already fishtails at Jaywick so, with the help of Google, let’s have a look at those.

jaywickGroynes

It seems to me the groynes are about 600 metres apart and the longer of the fishtails is about 200 metres.

So here the groynes are between 2.4 and 3 times further apart than what is proposed at Clacton and Holland yet the longer of the fishtails is 4 times longer.

Hmmmm

Now I am not an engineer, all I can do is look at what has been built and what is proposed and notice differences.

What do you think?

If use Google again to move slightly west we can see the groynes at Seawick (which are about 90 metres long) compared to one of the groynes at Jaywick.  It is obvious the beaches are very different.

You can also see the beach between the two western most groynes is substantial worse than the the rest of the Seawick groynes, despite the little reef.

seawickAndJaywickGroynes

Remember 90 metre groynes are what is proposed for Clacton and Holland and some of the spacing will be more than 180 metres.

Perhaps the fishtails are the difference which will make THE difference, even though they are proportionately 60-75% smaller than at Jaywick.

There is another, different, reason for doubt.  The building is supposed to take between 3 and 6 years.  As Trevor Bright, a former project manager at BP, this is a huge difference.

It should be obvious having a builder round for twice as long is going to cost more.  So how can project costs be controlled?

 

 

 

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2 Responses to New Groynes For Clacton and Holland – Will They Work – Jan 2014

  1. Trevor Bright says:

    Jeremy has made some very valid points. We also do not know what the groynes will look like from a side elevation.
    1. The dimensional plan of a typical groyne does not show the rocks that are currently placed along the sea wall for a lot of the distance involved.
    – Are these coing to be covered by recharge as beach level is proposed to be 1m below sea wall height or will they be removed?
    – What will happen below Cliff Road and along by Eastcliff where the rocks are currently level with the top of the sea wall?
    – Near the pier will the sand just be pushed up on to the wave-walkers or is it proposed to carry out other works in this area?

    2. The dimensional plan of a typical rock groyne also shows the Mean High Water Spring (MHWS) at being 30 metres from the sea wall and Mean Low Water Spring (MLWS) at 60 to 70 metres from the sea wall.
    – How steep will this make the beach?
    Again it would be nice to be able to view a side elevation.

    • Jeremy says:

      Thanks for the comment Trevor

      As usual you immediately spot details others pass by.

      Regarding the slope of beach a little trigonometry shows if the tidal range is 4m and distance between MHWS and MLWS is 30m then the slope is about 8 degrees (arctan(4/30))
      If the tidal range is 3.5m and distance between MHWS and MLWS is 40m the slope is about 5 degrees

      To be honest I was surprised the slopes were so low as my impression of Seawick and Felixstowe is the slope is much more. Perhaps I did the sums wrong!!

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