Saturday 1st March 2025 - More About Cliff Slumps

In my last blog (25th February), I mentioned about the boreholes positioned in the cliffs during the 1980’s.  Villager, Derek Paul, has checked and has been permitted to make public the response, to his question regarding the boreholes, from Coastal Management (CM) at North Norfolk District Council.  Derek was subsequently given permission and I am now, able to provide the contents of both Dereks and CM’s emails – as follows.

At a previous meeting held in Overstrand I asked the question of boreholes in the village The person concerned could not give me an answer, but would respond.  This has never been receivedThere has been another considerable fall recently, mainly due to drainage.    Can you advise me if these boreholes are in working order, and have been cleared regularlyLooking forward to an early reply.

Regards

Derek Paul

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Hello Derek,

Almost all of the cliff slips we see in North Norfolk are caused by below ground water and to answer your query, there are no working boreholes left in Overstrand.Overstrand has a very high ground water table as much of the below ground subsurface is a type of clay and or silty clay which is non porous and will not allow water to pass.I joined the council in 1980 and worked with Engineer Chris English who thought of the idea to try to reduce the amount of ground water in Overstrand by designing boreholes to intercept below ground water and take it into the chalk aquifer.He undertook a 'diving rod' survey to ty to locate 'underground' streams which were finding their way to the cliffs. Having completed the survey he then drilled a series of boreholes parallel to the cliffs in Overstrand to try to intercept the so called streams before they reached the cliffs over a number of years. I became part of the extended team to drill and manage the borehole works.In point of fact most boreholes did not access 'streams' at all but we did find the general level of ground water which we allowed to enter the boreholes via porous pipes at that level and allow the water to flow down into the chalk aquifer.We measured the boreholes 'water level' on a regular basis and they changed with the tide times - but very soon found that the boreholes ceased to flow over time as the chalk became blocked with 'fines' from the ground water. We tried endlessly to clear them - we jetted them - we hosed them, we flooded them - all to no avail - it did not work. So once the standing water level became constant it was clear they were no longer flowing and were then abandoned.We did try to drill a few more in the farm behind and in line with the old Overstrand Hotel slip and that borehole went all the way to the chalk and we found it was as dry as a bone.

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I hope all will appreciate this detailed explanation from CM regarding the boreholes and how they proved to be ineffective.

Moving on now to concerns about the Coast path, see my last blog.  I emailed CM regarding this and have included this below along with CM’s reply which I am able to make public.

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Hello, 

As you will be aware, the cliff slump below the Sea Marge, here in Overstrand, is now almost completely covering the promenade.  Coupled with the slippery surface, these are both a danger and hazard to walkers.  There is also the slump at the west end of the promenade to consider; this has blocked access in both directions at high tide.

The Coast Path, from Cromer to Mundesley, is routed along the beach and Overstrand promenade.  The route of the Coast Path is provided on a number of websites including Norfolk County Council’s, here is the link to the section of the map in question https://maps.norfolk.gov.uk/trails/?tc=PRO/406.

When and how are North Norfolk District Council planning to provide safe passage for walkers along Overstrand’s promenade, as well as the slump at the west end?

If you are not planning any immediate action, then perhaps you should advise the County Council so they can indicate on their maps the problem on this section and maybe suggest a suitable safe diversion.  Signage produced by the District Council, will also be appropriate as a warning to walkers.

Kind regards,

Janet Ellis

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Thank you for your email,

We are currently managing the situation and it is likely that we will have to close the centre section of the promenade where the cliff slip is being constantly fed by a very heavy flow of groundwater percolating through the cliff face and further slippage of the original cliff is also working its way down slope.

Again the slip at the west end is still active and being fed by a below ground water stream we believe comes through the grounds of the Pleasance and with the current weather is not likely to dry out for some considerable time.

Also we are actively managing the cliff slip on Clifton Way which is again being fed by an active spring of ground water and is encouraging the foundations of the old Overstrand Hotel to slip downslope. If we try to remove the debris - more debris flows down so it becomes a costly process to manage.

I will inform the County Council who Natural England have appointed to manage the Coastal Trail and leave it to them to decide how they will manage the trail for the immediate future.

Thank you for your comments.

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In response I sent the following to CM.

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Thank you, for your prompt reply with detailed explanations.

We walk along the promenade in the mornings, weather and tides permitting, and have been watching the gradual movement of the slumps, over the promenade.  We have also heard about villagers and visitors who have slipped on the area where the water is flowing from the cliffs, some sustaining injuries. 

To make the general public aware of the restricted promenade and danger of slipping I took a photo (attached) and posted this on my Overstrand Life Facebook page https://www.facebook.com/overstrandlife  The response was far greater than I expected with over 4,000 views and various comments and observations.  If you are in agreement, I would like to publish your response to my email in my next blog on Overstrand Life www.overstrandlife.online and link this to Facebook.  This will explain to the public, about the slips and the actions being taken by Coastal Management.

I would be interested to hear what actions Norfolk County Council plan, with regard to the Coast Path.

Kind regards

Janet

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I received the following below from CM which I have removed, at CM’s request, specific names.

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Hi Janet,

Many thanks for your email.

Regarding the England Coast Path, we have informed them of the cliff slump and I’ve been informed today that a National Trails officer is visiting the site to assess for a diversion. Given that the cliff slip has been continuous in its movement onto the promenade, we’ve advised that it is possible we will soon close a section of the promenade, at least temporarily whilst we assess the situation, and have advised National Trails that the Coast Path ought to be diverted in land. As I’m sure you can appreciate, the presence of Japanese Knotweed in this location complicates things hugely, as it cannot be disposed of as if it was just general cliff material.

In terms of putting the below on your blog, you can publish it. though if possible, could you remove xxxxxxx’s name from what you put out and call it ‘Coastal Management’s’ response? However, if you’re happy to wait a little longer, we are currently drafting a document to summarise the complexity of the cliff management in this location and what steps we are planning to take, which we will share with the Parish Council and yourself, which will be more comprehensive? We are hoping to get this out next week

Kind regards

xxxxxx

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I have decided not to wait until I receive the document mentioned in the above paragraph, simply because I feel everyone should be aware of how these coastal matters stand at present.  Peter said to me yesterday; he wonders if anything would have been progressed regarding the Coast Path if I hadn’t raised the question with CM at NNDC!

Let’s move on.  Today is the first day of meteorological spring and what a brilliant start it’s been.  It may still be cold, 6°C, but the sun and blue skies have been stunning.  On our walk first thing this morning we diverted from the footpaths, and our litter picking, to stroll along the field edges.  As you can see, from the photo below, it was a frosty start to the day but so peaceful with only birdsong to be heard.