Covers Farm: infill lorries could destabilise the M25

Squerryes’ infill lorries might destabilise the motorway embankment near the BP garage. (Morants Promotions’ application KCC/SE/0495/2018 to restore and ‘stabilise’ Covers Farm). KCC are still waiting for answers.

Why is the haul road a big engineering issue?

Highways England, the agency in charge of the M25 and a body that Kent County Council has to consult,  said that the proposed infill lorries might destabilise the motorway embankment in thcutting beneath the road bridge leading to Biggin Hill. They worry about the proximity of the temporary road with its proposed 200 40-tonne tipper truck movements a day. Please see Highways England’s letter below:
highways_england_spatial_plannning_mgr_request

Kent County Council planners put these concerns to Morants Promotions (Squerryes) and got some response.

It’s our understanding that Kent County Council have received a report on the   application from the engineering consultancy Amey. KCC requires information from Morants on the effect of the proposed haul road on the M25 embankment near the BP Garage roundabout.

Potential environmental impact

In addition, KCC has requested from Morants Promotions further information concerning the potential impact on biodiversity at the proposed sites.

Once Kent County Council Planning has received the requested information, there will be a further 6-week public consultation on the proposed restoration and ‘stabilisation’ of Covers Farm before KCC Planning reaches a decision on the application.

Pinchpoint_3
Google aerial map showing proximity of the proposed haul road route to the M25 embankment near the road bridge from Biggin Hill that joins the BP garage/Beggars Lane roundabout. The lack of width of the land owned by Squerryes at the point joining the roundabout forces this routing to go so close to the M25. Artist’s impression. Map ©2018 Google LLC, used with permission.

Squerryes’ claim of a risk to the M25

Squerryes’ engineer and a press release in December 2018 had suggested that the slope instability at the north of Covers Farm quarry could present a risk to the embankment of the M25. In fact Highways England have no concerns about the stability of embankment just to the north of Covers Farm. Evidence of this includes: the response to an FOI request to Highways England (HE); correspondence between our Town Council and HE, and the correspondence that you can click on below between Kent County Council and a Highways England Planning Manager.
highways_england_spatial_plannning_mgr_request

FOI Request Any identified risk to M25 westbound carriageway and hard shoulder at Westerham, Kent. (3)

Claim that Kent County Council consider the original Covers Farm plan “no longer fit for purpose”. It just ain’t true!

Another instance where Squerryes have been “economical with the actualité”:
In the recent Stabilisation and Restoration of Covers Farm Sandpit Main Report Paragraph 5.5 it was claimed,
“… in discussions with KCC it was agreed that the original restoration scheme was no longer appropriate, since it would resolve neither the geotechnical nor drainage concerns, and would create a site that was not fit for purpose in terms of minimizing the risk to adjoining land.”

However, please see the note of the telephone conversation between an elected Westerham Town Council officer and KCC Planning Officers in which they have no knowledge of KCC ever declaring that the original plan was no longer fit for purpose.
note of telephone conversation with adam tomszewski and andrea hopkins (2)

What is “Covers Farm”?

One kilometre to the west of Westerham is a huge depleted sand quarry known as Covers Farm. The sand used to be extracted for tile-making.

In 1983 a planning condition (Kent CC Minerals and Waste) imposed on working the pit stated that, once depleted, it should be restored to low quality agricultural land. This was to have been achieved simply by moving material around on site, with no importation of further material.

The pit is owned by the big local landowner, Squerryes Estate. Last year Squerryes took back the liability for the restoration of the site from the last company to have worked the pit, Redland Monier.

Morants Promotions Ltd, a holding company for Squerryes Estate, have submitted a planning application to Kent County Council Planning Group for the ‘Restoration’ of Covers Farm sandpit. Their plan involves importing 84,200 tipper trucks of inert waste. CONSULTATION ON THIS APPLICATION HAS NOW CLOSED, BUT YOU CAN STILL READ IT https://www.kentplanningapplications.co.uk/Planning/Display/KCC/SE/0495/2018?cuuid=55125

Here’s a summary of the application and some background

On site there is some sand, bits of tiles and lots of Gault Clay, a lot of this forming a kind of saddle across the middle. Rainwater has accumulated in two lakes, one to the north, the other south. As we have said, in 1983 Kent County Council made an order for the Covers Farm to be restored to low quality agricultural land, simply by draining the excess water and by moving the deposits about on site.

In 2017 Squerryes Estate took back the liability for the last firm to have worked the pit, Redland Monier.

Squerryes’ engineer is now claiming that the walls of the northern lake are unstable. The Gault Clay that once capped the north face has evidently slid down the northern side. The engineer assumes that this clay is now lining the lake, preventing it from draining into the sand beneath. The engineer says that there is a risk of the lake overflowing from its the north-eastern rim, causing flooding in that area.

Squerryes’ engineer proposes to build huge dykes, called ‘bunds’, partly in the water, as you see in the upper part of the plan below, and then to slowly drain the displaced water to a second pond to the south and eventually into a sandy area also to the south of the site. However the Technical Annex 6 on Flooding and Drainage leaves many aspects of this process unclear.
img001
The idea is that the land would be built up and contoured so that the surface water would drain into a central stream and several ponds in order to flow into the point described to the south.

But the engineer claims that to build these bunds/dykes he has insufficient material on site. He says that he needs to import what called ‘engineering material’, inert landfill (builders’ waste or spoil from construction sites and major excavations in Greater London). In order to achieve the final land contours desired, it’s estimated that 800,000 cubic metres of inert landfill is needed.

It’s remarkable that when the proposed site was twice the size, at the pre-application stage last year, the engineer was already claiming that he needed 800,000 cubic metres. This figure seems arbitrary. What is the actual quantity of material required to carry out the proposed engineering and landscaping? Once this project is granted, might Squerryes not end up asking for more importation?

84,200 tipper trucks would be required to bring in 800,000 cubic metres. It’s envisioned that 66% of it would be brought via Sundridge and Brasted, and 33% down Westerham Hill, with possibly a smaller proportion (up to 15%) coming via Tatsfield and the Croydon Road.

img004
Map showing potential sources of the 800,000 m3 of inert landfill and the suggested routes for bringing them to the site. 66% from the Eltham area via the M25 Junction 5 through Sundridge and Brasted; 33% from North Bromley via Biggin Hill and Westerham Hill. Source: “Technical Annex 10 Transport”.

The proposed timescale for this operation is 5 years.

The ‘temporary’ road or ‘haul’ road

To spare Westerham High Street from all these lorries, Squerryes propose to build a single lane ‘temporary’ road (4m wide with passing places) between the BP garage roundabout and the Croydon Road just metres where the Croydon Road passes under the M25. Please see the maps below.

img003
Relief road to the west of the London Road. NB: it runs very close to the M25 cutting below the London Road at this point..

The ‘temporary’ road would then continue westward to the north-east corner of the pit. This crossing would be controlled with traffic lights. Here the lorry movements would equate to 3 tipper trucks either toing or froing every 10 minutes, for 5 years.

img002
Relief road to the east of the Croydon Rd. The crossing would be controlled by traffic lights. Further to the west would be the access point to the quarry. NB: overhead floodlights at this point.

The entry point to the pit for all these tipper trucks is Point B on the map below.

Route of relief road
Possible route of new road (Covers Farm Restoration Proposal, Jul 2017 ) Possible location of 600 houses (Which Way Westerham, May 2017)

Why? Is any of this necessary? What is the evidence?

Why 184,200 tipper trucks if the Kent Order said, ‘Use the material on site’?
Given that this would amount to danger and disruption to road users and residents along the A25 and the A233, is all this haulage necessary?

In the Technical Annex 7 (the geotechnical report) the engineer has drawn on a theoretical material and data from other sites. There is no quantifiable scientific geological data taken from the Covers Farm site. Instead, the engineer has relied on visual inspection. Could what he observed be the result of weathering? Is the observed slippage something that’s happened in the past? Are the slopes now i fact stable?

Draining the water. Is there really a danger of the northern lake overflowing to the north-east?
The claim is that the lake is filling at the rate of 30,000 cubic metres per year. This would mean that the water level is rising at the rate of 10% per year. Is this feasible? Photographs of the water level in successive years and even decades suggest rather that the water level rises and falls.


What are other feasible options?

Could you drive a row of submerged piles to buttress the northern slope? Where failure of the slope next to Junction 6 of the M25 was observed, this was the chosen solution. The work was quickly completed. This solution, scaled to the length of the northern face of Covers Farm would require about 400 lorries and it would take approximately 9 months.

So why is the 800,000 cubic metre solution, lasting 5 or 6 years, the only one given any detailed consideration? It so happens that the revenue from having all this inert waste could net you millions.

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